Roman Engineering

JUANELO TURRIANO LECTURES ON THE HISTORY OF ENGINEERING Roman Engineering Alicia Cámara Muñoz and Bernardo Revuelta Pol (eds.) JUANELO TURRIANO LECTURES ON THE HISTORY OF ENGINEERING ROMAN ENGINEERING «That the greatness of the empire might be attended with distinguished authority in its public buildings» Vitruvius Lectures given at the course: Roman Engineering. «That the greatness of the empire might be attended with distinguished authority in its public buildings» held in Segovia from 9th to 11th November 2012 and organised jointly by the UNED and the Fundación Juanelo Turriano. Course coordinated by Alicia Cámara Muñoz and Bernardo Revuelta Pol. English edition 2016 www.juaneloturriano.com Original title: Ingeniería romana. «Que la majestad de tu Imperio cuente con el adecuado prestigio de edificios públicos» (Vitruvio) © Fundación Juanelo Turriano, 2013 Translation: Interlinco Servicios Lingüísticos y de Comunicación, S.L. Photographs: José María Álvarez Martínez, Fernando Aranda (Confederación Hidrográfica del Guadiana), Gonzalo Arias, Carlos Caballero, Fundación Juanelo Turriano, Giacomo Gillani, Irene Glendinning, Max Guy, Eduardo Saavedra, Giorgio Viazzo, Alonso Zamora Design, modelling and production: Lucam Ediciones del Umbral © of the edition, Fundación Juanelo Turriano © of the texts, their authors © of the photographs and drawings, their authors The Fundación Juanelo Turriano has made every effort possible to find out who the owners of the copyrights are for all the images that appear here and to find out what reproduction permits are required. If there have been any unintentional omissions, the owners of the rights or their representatives may write to Fundación Juanelo Turriano. FUNDACIÓN JUANELO TURRIANO TRUSTEES PRESIDENT Victoriano Muñoz Cava VICE PRESIDENT Pedro Navascués Palacio SECRETARY José María Goicolea Ruigómez MEMBERS José Calavera Ruiz David Fernández-Ordóñez Hernández José Antonio González Carrión Fernando Sáenz Ridruejo José Manuel Sánchez Ron HONORARY PRESIDENT Francisco Vigueras González FOREWORD This book is the outcome of the course held at the Centro Asociado de la UNED in Segovia, as a result of the collaboration between the University and the Fundación Juanelo Turriano, which financed it. Its title, Roman Engineering: that the greatness of the empire might be attended with distinguished authority in its public buildings, included the words of Vitruvius, which expressed the close relationship between public works constructed by engineers and the grandeur of an empire that, thanks to those infrastructures, controlled the extensive areas under its domain. We wanted to answer questions such as: What kind of communication systems existed in a huge empire? What role did religion play in hydraulic engineering? To what extent did public works make citizens’ lives easier? How was water supplied to a city? What do we know about the Segovia Aqueduct? How can we identify a bridge as being Roman? How did the Spanish Renaissance interpret Roman Engineering? The fact that the course took place at the same time as the Artifex Exhibition, in the Casa de la Moneda de Segovia (Segovia Mint), enabled the attendees to gain great insight into all the aspects of engineering and how they were applied to the Empire’s cities and territories. This book is the first in a series of publications by the Fundación Juanelo Turriano containing the lectures given by well-known specialists in the university courses, with a view to helping to inform society about the history of engineering. TA B L E O F C O N T E N T S 1 Aquae Augustanae ......................................................... 9 JOSÉ MARÍA ÁLVAREZ MARTÍNEZ 2 A few traces from the Construction of Segovia’s Aqueduct ................................................................... 31 ALONSO ZAMORA CANELLADA 3 Hydraulic Engineering and Religion in the Roman Empire: Trajan and the Canal Construction ............... 49 SANTIAGO MONTERO HERRERO 4 Roman Roads: the Backbone of the Empire ............... 69 CARLOS CABALLERO CASADO 5 Design and Construction of Roman Bridges in Hispania ................................................................. 87 MANUEL DURÁN FUENTES 6 Artifex. Roman Engineering in Spain ....................... 103 BERNARDO REVUELTA POL 7 Ingenious comparisons: the look of the Renaissance ............................................................. 121 ALICIA CÁMARA MUÑOZ BOOKS PUBLISHED BY FUNDACIÓN JUANELO TURRIANO ............. 144 1 Aquae Augustanae JOSÉ MARÍA ÁLVAREZ MARTÍNEZ Director of the Museo Nacional de Arte Romano de Mérida Everybody who reached the Augusta Emerita settlement along the Roman road from Asturica or the one from Corduba must have found it not only an unequivocal sign that they were arriving at a large metropolis reflecting the grandeur of the Empire, but also a cause for great admiration not different from the impression one gets these days when one sees the symbols that summarize anyone of our most representative cities, when they came across the majesty of the arches of San Lázaro [FIG. 1], or those of Los Milagros, which had to be constructed to span the valley of the Albarregas River and to enable the water to flow in at an acceptable elevation from which to distribute it at will throughout the old colony. These arches, which form part of two of the three aqueducts planned in Augusta Emerita, greatly attracted the attention of the learned, historians and archaeologists, who spoke highly of them when describing their splendid remains. All of this spawned a large amount of literature, most of which was repetitive in nature and concerned the aforementioned arches, or the heads of two of the aqueducts: the Proserpina and Cornalvo reservoirs. Interesting graphic documents such as those for which we are indebted to Villena1, Fernando Rodríguez2 o Laborde3, to menFIG. 1 The San Lázaro aqueduct, according to A. de Laborde. tion the most outstanding examples, must also be 9 added to the aforementioned, to a greater or lesser extent, complete and thorough descriptions. This panorama, object of definition in the past by Jiménez Martín, the author of a synthesis work on the aqueducts, and of one of their main critical studies4, has recently made significant progress and it has been possible to provide substantial descriptions, especially with regard to all that concerns the Rabo de Buey-San Lázaro duct, and considerable graphic documentation with respect to the routes taken5. However, we are missing analyses concerning the layouts and in-depth studies of the preserved stonework that will help us to gain a better insight into their structure, the construction phases, repairs done and details that will enable us to establish the correct chronological order, not so easy to determine6. Among the major studies to which reference must be made are the aforementioned one by Jiménez Martín7, the very complete study by Fernández Casado8 - full of worthy contributions, the descriptions provided by Mélida9, the considerations by Hauschild10 and the recent work resulting from the activities carried out by the Confederación Hidrográfica del Guadiana [Guadiana River Basin Hydrographical Authority] on the ducts11. As far as partial aspects and specific ducts are concerned, reference must be made to the works of Plano y García12, Celestino Gómez13, Álvarez Sáenz de Buruaga14, Canto de Gregorio15 and Feijoo16. We would not like to forget either the collaboration provided to us by the Escuela de Topografía de Mérida [Merida School of Surveyors], namely with García Morant and his team, who offered as a result, after applying surveying and geophysics, the discovery of a considerable section of the Proserpina-Milagros aqueduct17. THE WATER COLLECTION The degree of knowledge shown by those responsible for designing the new Augusta Emerita settlement is extremely surprising. When implementing the infrastructure, the architecti et libratores certainly knew how to make the most of the conditions offered by the existing bell shaped landscape of Mérida, to establish a basic and essential architectural feature of its territory as they did with the hydraulic ducting. It is true what Roso de Luna and Hernández-Pacheco18 once said, that there are very few natural springs and water sources in Mérida area, which is why those that did exist were put to the very best possible use and very small streams such Las Arquitas, Las Tomas and other nearby brooks were well channelled, together with all the discharges flowing from the Valhondo Estate, which would appear to have been collected in a now barely visible reservoir, after which it flowed through galleries (cuniculi) to the main current of Rabo de Buey duct, and the one that starts in Casa Herrera zone, which is strangely enough often confused with an inflow from the Cornalvo aqueduct19. Completely different matter was the Cornalvo and Proserpina reservoirs, outstanding examples of Merida architecture. When the first of these20 was at its maximum storage capacity, it could hold up to ten million cubic metres of water and occupied an extensive slate valley, 300 m above sea level, some 100 m less than the altitude of the city that it supplied. So, just by the construction of a dam a large reservoir could be created at very little expense. 10 ROMAN ENGINEERING Channelling the Las Adelfas stream into the Proserpina duct. FIG. 2 The second one, referred to as the Proserpina dam because in the 18th Century an inscription appeared in the vicinity dedicated to the Goddess dea Ataecina Turobrigensis Proserpina21, with a capacity of 6 hm³, before it began to silt up, was erected in a large dip in the granite terrain in the Merida countryside, 245 m above sea level, 25 m higher than any other elevation in the city. The catchment area that supplied the dip with its waters was composed of several small streams. Most of the water flowed into the perfectly channelled aqueduct22, from the stream known as Las Adelfas [FIG. 2], whose source is close to the current Highway 630, together with the supply provided by the Las Pardillas stream. The two reservoirs are situated outside the valley comprising the major streams, so they both can be regarded as genuine natural basins composed of gently sloping dips on the ancient peneplain, which bring together excellent conditions for water storage23. They are exceptional examples of Roman hydraulic architecture although, as several authors have stated, the two models are rather different in nature. The Cornalvo reservoir [FIG. 3] has a dam that is 222 m long at the crown and is about 18 m high. At the end of the 19th Century, on a period of time when there were several drought spells that made more than one person, not only in Merida but also in other FIG. 3 View of the Cornalvo reservoir. AQUAE AUGUSTANAE 11 places, think about reinstating the old Roman aqueducts and using them once again to supply the city with water, consideration was given to restoring the facilities, which were in a poor state of repair with many of its surfaces missing. The idea was the brainchild of Francisco Rus, and although the plans were drawn up in 1913, they were not put into action until 1926, when the project was carried out, albeit with certain modifications to the original, by Juan García y García. This caused the original facies being covered over, although various documents and illustrations from the period make it possible to obtain a general idea of what it was like. It consisted of three longitudinal walls running parallel to the waters and other smaller walls set at right-angles to the water that delimited spaces in the form of latticeFIG. 4 Cornalvo. Water outtake tower. work, the bottom part of which was filled with earth and the top part with concrete. It was thus possible to refer to the dam as having three distinct parts, corresponding to the above-mentioned transverse walls. Dressed-stone facing was applied to the staggered surface. The usual earth parapet was laid on the downstream side, this being an average of 10 m thick24. Although the structure cannot be fully appreciated today, at least to the extent that one might like, the construction characteristics of its interesting outtake tower can be clearly seen, this construction lying at a certain distance from the dam itself for safety and practical purposes, yet joined to it by an arch, whose starting point is marked by the springer set into the tower, most of whose arch-stones have fortunately been retrieved [FIG. 4]. The tower is approximately 20 m high and it is almost rectangular in section. It was equipped with outtakes on two levels, one at the bottom of the basin and the other a few metres deeper. Such is the knowledge that has been obtained about the nature and the structure of the dam that the recent studies conducted have modified the conception that we had of its construction idea25. We owe this information to Dr. Arenillas and his team26. Chronology dates the dam at a later time probably than the first stage of Aqua Augusta duct. Celestino Gómez gave his description providing very interesting information about its outflow systems27, which we will not go into details about here, in view of the limited time that we have to devote to such considerations28. The «modernity» of this dam is truly surprising29, the Madrid example at El Gasco, dating back to the 18th Century bearing witness to its permanence; but if we analyse certain other examples perhaps it is not so modern. 12 ROMAN ENGINEERING Nevertheless, as we have already pointed out, the analysis of the stonework of its sluice-gate tower is more revealing and akin to examples from Emerita and its sphere of influence. In spite of what has been said about its bossage, it is not consistent with the bossage on the bridges of Merida of clear Augustea chronology, as we have already stated30. It would appear to be stonework of a different kind that to begin with we could associate with the type to be seen on the western face of the Amphitheatre and that may be consistent with one of its stages that just might be a result of Flavio’s modifications31 and, perhaps, with the faces of other singular and well-known works, such as the Alconétar Bridge itself, which was one of the most important works out of the many that were carried out in FIG. 5 Caput aquae. Aqua Augusta. Vía de la Plata32 by Emperor Trajan, at the start of his rule. All in all, what we are expressing here are no more than impressions gleaned from a visual analysis, which would have to be backed up by a thorough study that has yet to be conducted. The truth of the matter is that the observations in question lead us to think of a later period than Augustus’, however much of this ducting work, whose name we fortunately know, Aqua Augusta33 [FIG. 5] would date from that period. That Augustea chronology, cleared up by the above-mentioned inscription and by certain construction details on the route, such as the arches without arch stones, a feature that is certainly very old, to which Jiménez Martín attracted attention because of the Caño Quebrado section34, leads us to consider a possibility whose enunciation is not really ours to give, because it is an observation made by Celestino Gómez, who put forward the theory that the major inflow from El Borbollón, which runs from the hills of Campomanes as far as the Albarregas Valley through well-constructed piping, through which a slight current of water still flows – in spite of the damage done to this spot by a eucalyptus plantation that ended up by almost completely drying up the Caput Aquae [headwaters] –, namely that this could have been the very first major Augustian hydraulic duct35, logically augmented by other inflows and by the fact that these reaches run through the Albarregas Valley itself. It is a very plausible theory, because it also indicates a considerable knowledge of the environment, a clearly practical approach, as it was possible at little cost, to bring water of an excellent quality, to Emerita36. Probably at a second stage…. at which period of the Flavios, Trajano?, if we take into account the characters from the stonework of the outtake tower, the duct was strengthened by the dam, and maybe its path was widened by the so-called «Vía Ensanche», which AQUAE AUGUSTANAE 13 Aerial view of the Proserpina dam. FIG. 6 is a conclusion that Jiménez Martín37 also came to, although we are not so sure about this ourselves. As far as the Proserpina Dam [FIG. 6] is concerned, a few years ago the Confederación Hidrográfica del Guadiana and Professor Miguel Arenillas’ team were able to study it. After carrying out emptying and cleaning works, they were able to bring to light data of great interest that has come to change our traditional way of understanding the reservoir38. Much was known about its structure, 425.80 m long at the crown and 21 m high, with three alignments in plant view, but it has now been possible to obtain a much more complete information after the aforementioned works. The upstream section had a concrete core faced with dressed and rough stonework [FIG. 7], stepped in the same way as at Cornalvo, albeit with a rather different arrangement and provided with nine rectangular abutments, also made of granite and staggered. Downstream, there was the usual parapet, in this case rather strong, that supported stonework situated next to the dam itself, with sixteen small abutments arranged between the two outtake towers, which in this case are joined to the dam itself39. These towers were subjected to major alterations in the 17th and 18th Centuries in order to put the complex into operation and to enable some nearby mills and wool-washing facilities to operate. The vertical structure of the dam, now known in its entirety for the first time, shows signs of several stages corresponding to several restoration activities, records existing for some of these, mainly the work that was performed in the 17th Century, on the orders of the Governor Felipe de Albornoz, assisted by commissioners and aldermen Diego del Carpio and Juan de Tovar. We know that this was a major restoration work thanks to certain documents, unfortunately rather scanty, but mainly owing to the news, also brief, written down by the city chronicler Bernabé Moreno de Vargas40. Subsequently, according to certain documents in Merida’s Municipal Archives brought to light by Álvarez Sáenz de Buruaga41, further works were done in 1700 and 1730 – which possibly managed to overcome the problems observed since 1654, although the difficulties at that time, the 14 ROMAN ENGINEERING FIG. 7 Proserpina dam structure. war against Portugal, prevented them from being carried out – and at the beginning of the 19th Century. The dam elevation was studied to the most possible extent by the authors of the rehabilitation, consolidation and enhancement project for the complex. The data that were extracted proved to be extremely useful and made it possible to gain insight into its nature and to clearly establish the different stages that could be identified in its structure. There would appear to have been two distinct stages for the dam construction: a minor phase, which was completed with the rounded abutments that it has been possible to observe for the first time, and a second phase that involved the heightening of the works where the aforementioned staggered abutments appear [FIG. 8]. We must reiterate, that it is a pity we do not have the specifications for the major dam remodelling project implemented by Governor Albornoz at the beginning of the 17th Century, as we do have in the case of the study for the large bridge spanning the Guadiana river, and we believe the restoration work took place almost at the same time. In the case of the bridge, a good account of the project is given in the Merida Council Corporate Agreements Books42. However, we must mention one significant piece of information, i.e. we have observed on a considerable part of the dam, oblong shape stones similar to those that appear on the five new arches that were laid during the FIG. 8 Lower part of the Proserpina dam and outlet tubes. aforementioned restoration. AQUAE AUGUSTANAE 15 One of the new contributions yielded by the recent study that certainly did not go unnoticed to us was the discovery of a wooden stopper, almost one metre long, which may have been used to unblock one of the outlet ducts [FIG. 9]. The Carbon 14 test conducted on it revealed evidence that clearly dates it back to the 1st Century AD, probably about halfway through. If the result of this test are valid, this could be furFIG. 9 Wooden stopper for an outlet tube. ther evidence to be taken into account when correctly dating the duct works, which now, after Feijoo’s interesting considerations, have been brought forward to the period of Arab domination, which does not seem likely to us43. However, with regard to the dating of the duct, which as can be seen is a matter of some controversy, and is the subject of all sorts of opinions, we would like to draw attention to certain architectural aspects considered by FernándezCasado44 and Alfonso Jiménez45, which at the time we could not see or were reluctant to accept. It is clear that the layout of the pillars for the raised arches of Los Milagros, and particularly the padstone or cornice that finishes the first part of the pillar, have to be compared to certain examples taken from Lusitanian bridge architecture, Alconétar, for example, where arches appear lowered in much the same way as the arches of Los Milagros, suggesting therefore to a proximity to the Trajanian Period46. THE ROUTES Although information exists concerning a considerable part of the route followed by the Augustian aqueducts from their source until they reach the city, and subsequently branch off, the information is incomplete and still has to be studied. We are going to examine this state of affairs duct by duct. Cornalvo The aqueduct, now perfectly laid out, led off from the reservoir described above and included the inflow coming from El Borbollón, the waters being abundant and of excellent quality. flowing down actually from the true caput aquae at the Sierra de Mirandilla heights, between the Zorrilla and La Vieja Estates. The channel with its cover remains almost intact, apart from breakages causing leaks at many points. Small shafts or vents can be observed every so often to aerate the duct and make cleaning easier. At present, and because of the above-mentioned eucalyptus plantation, the once considerable flow of water has been reduced almost to a trickle. A detailed study has not been performed, yet the ducting, the route and its peculiarities have been surveyed and drawn on plans with more or less correction. However, a 16 ROMAN ENGINEERING description is indeed available for some specific sections as a result of the interest aroused by the stonework uncovered. The channel, according to appraisals made by Fernández Casado, ran through a small underground gallery whose height varied depending on the lay of the land as it ran down and making use of the subsurface waters throughout the first section, first with waterlogging FIG. 10 Specus along the Cornalvo duct. and then with the bed full of sediments. Certain manholes are observed, whose current purpose is to serve as shafts to draw off water from the gallery47. Once the first section of the channel has ended, it passes through the village of Trujillanos and goes along the hillside, running closer to the surface and appearing in the open in some gullies where major stonework can be seen. Some of the best examples of these remains emerge at the spot known as Caño Quebrado, close to the road leading to Valverde and in the grounds of Merida Psychiatric Hospital. These structures feature substructio and arcuationis [substructures and arching]. The upstream wall and part of the downstream block are perfectly preserved. Judging by the lay of the land in the gully, it has been estimated that there may have been twenty arches. The slight traces of one of them still remain, which was supported by a pillar, but there are no signs of distinct archstones48 in it. Others traces of stonework can be observed in the Cerro Gordo gully, albeit with a simpler structure, given that in this case the channel is raised above a wall by about 30 m, in the middle of which there is a 86 cm drain with an overflow49. From this point until it reaches the city the channel only occasionally comes to the surface, although it does emerge near the former Nacional V Highway, where two spiramina [vents] can be seen. It was possible to uncover the aqueduct during excavations in the area of the necropolis, and its characteristics are similar to those described, with a height of approximately 50 cm. It is clear that it made its way to the city across the football pitch, towards the old water cistern. We suspect that just as it entered the settlement, on the enclosure wall, there would have been an inscription bearing its name (Aqua Augusta). A great deal of information has been gleaned from the remains found in the grounds of the Giner de los Ríos Public School, through which the duct ran on its way to the Theatre and Amphitheatre, which it supplied [FIG. 10]. Recent excavations dug at the site of the former Guardia Civil barracks, with a view to constructing the new Visigoth Museum, have yielded data that, together with the information already compiled beforehand, enable us to know not only where the duct off- AQUAE AUGUSTANAE 17 shoot was leading to the Vía Ensanche, but also to establish, in spite of what Richmond50 thought, that the aqueduct did not run along the line of the city walls, but that the wall left the duct within the city walls and ran parallel to them, only a short distance from them, the two structures creating a sort of passage between them. We do not know the exact location of this aqueduct’s piscina limaria [settling basin]. However certain more or less plausible hypotheses have placed it in the vicinity of the former Nacional V Highway. The major section that can be seen in the Vía Ensanche is of great interest though. It consists of a preserved substructio 85.70 m long and 3.08 m thick, whose maximum height is 2.20 m. The base is composed of a concrete core with an opus incertum [irregular work]) face, with the typical presence of mortar in the joints, this being highly characteristic of works in Mérida. The specus [roofed channel] is 57 cm wide and it is also 57 cm high. This section was equipped with an arcuationis scheme, which is accounted not only for its structure but also for the presence of certain square or rectangular stumps for pillars. It is assumed that the duct ended up in the bull-ring, next to the Casa del Mitreo. Rabo de Buey-San Lázaro The route followed by this aqueduct is, apart from certain as yet unanswered questions, the best known of all. One of the main reasons for this is that, as its waters were used until recently, Merida Council decided on several occasions to order works to be done to improve the way in which its inflows were being used. The most important of these works were carried out towards the end of the last century, on the initiative of Miguel Nogales and ordered to be undertaken by the Mayor Pedro María Plano, who gave a good account of the results of the activities in his book51. One of the problems that still have to be overcome when establishing the correct layout of the aqueduct is to suitably determine the inflows that the main duct receives, although progress has been made in recent years52. It did have one major inflow, the discharge coming from the Valhondo Estate, the essential details of which have been made known by Álvarez Sáenz de Buruaga53. The water, in abundance, and with a greater flow rate than it has today, three litres per second, was taken from the Valhondo stream itself and from small runoff sources nearby. The construction of a dam, now partially buried, was a good choice, and this is the real caput aquae of the duct. A series of galleries lead off from this point, and these, now in ruins, were so badly destroyed that at the end of the last century, when an attempt was made to recover these inflows for the city, it was impossible to channel them towards the main duct at Las Tomas-Rabo de Buey, and it proved to be more feasible to construct new galleries, higher and wider than the Roman ones, with side walls made of stone without mortar to enhance the filtration of slight water currents that increased the flows in the duct. It then runs through iron piping into the Rabo de Buey Cistern. The layout of the main duct is well known today, not only because of the above-mentioned works that took place at the end of the last century, but also because of the surveying work carried out by the students at the Escuela de Topografía de Mérida under the supervision of Dr. Hernández Ramírez54. 18 ROMAN ENGINEERING Las Tomas-Rabo de Buey duct gallery. FIG. 12 Stairway leading down to the Las Tomas duct gallery. FIG. 11 It starts in what was known in the 16th and 17th centuries as the Mari-Pérez valley, which in the last century came to be known as Las Tomas. The offshoot coming from Las Hospitaleras would have been located there, at its caput aquae. From that point, the water flowed for about 4 km, mainly through underground galleries, until it reached the town. We are not going to go into great detail about the whole ducting, but we will address its essential features. A total of 99 dormers, shafts or spiramina are positioned throughout the entire gallery, which not only served in some instances, to enable workers to go down to the duct, for the purpose of which a series of stairways had been strategically located, but also served as windows or skylights to enable the light to filter through into the long covered section. These works are perfect, with layers of dressed stone, currently covered with square granite slabs. The distances between them vary, as is the case with most Roman aqueducts that we know of. Throughout the length of the duct there are four shafts leading down to its interior [FIG. 11]. Outside, the entrances are similar to the ones in most other examples. They are equipped with dressed stone stairways. The walls are made of diorite masonry, and the roof well defined with brickwork, a result of what would appear to be restoration work (they were originally made of stone). The cuniculi or galleries [FIG. 12] are of different heights, higher along the first section and lower as the galleries approach the hill known as Rabo de Buey, showing evidence of the diorite masonry in well-defined layers, the presence of brick bearing witness to repairs made down through the years. The roof is composed of layers of stone, and sometimes the bare rock serves to cover. At times, the specus, varying in width but never exceeding 80 cm, takes the form of a hydraulic lining with chamfered angles, and sometimes the pavement is simply exposed concrete. AQUAE AUGUSTANAE 19 Bottom arches made of stone on the San Lázaro Arching. FIG. 13 The connection points with other ducts are well worth to be observed, especially where they join the old Valhondo duct in the vicinity of La Godina. The gallery system, which causes such a great impact on those that can visit it today, is typical of the Roman world, and although the ones in Merida are spectacular in themselves, reference must also be made to other major examples, namely those in Algeria55, Ascoli56, in Gallia (France) in several well-known places: Antibes, Vienne, Arles, FontGiraud de Saintes, Rodez, Poitiers, Cimiez, Nîmes, etc., and in Hispania, Segobriga57. The piscina limaria, just like the one for Proserpina’s duct, was probably located on the Rabo de Buey Hill, at the foot of which the Albarregas Valley dip begins. Based on the fact that not only the width but also the depth in this zone was greater than in Los Milagros, it was decided to construct longer and higher arches than those constructed for its contemporaries. But unfortunately for a variety of circumstances worse luck befell these arches, one of such circumstances being the construction, of an aqueduct in the 16th century, useless and showing to what extent awareness in hydraulic matters relevant to aqueducts had, making use of materials, and sometimes the structure of the earlier aqueduct, which may well have already been in ruins at that time. Only two side pillars with an irregular layout and a central one that is rectangular remain of the impressive arched bridge [FIG. 13]. They are joined by semi-circular arches. As far as can be made out, in accordance with the soil conditions in the area, these constitute the intermediate part, and a change of direction can be detected in the downstream face towards the artillery barracks and the Amphitheatre House, where most of the arcuationis would have ended up. At the first level there is an ashlar masonry foundation over which a second level is laid. The pillars are provided with pronounced bossage. In the arches, the archstones are not as bossed, but the keystone stands out. The second level shows evidence of a combination of stonework and brickwork, the same brick that is used for the roofs and, perhaps, also on its spandrels and on the horizontal strips that cross the entire pillar and appear on all the faces, four layers of stonework alternating with four layers of brick. 20 ROMAN ENGINEERING Unfortunately, part of the aqueduct, the section close to the Amphitheatre House, was destroyed several decades ago, when Miguel Galán was Mayor, and its remains, just like the remnants of the Rabo de Buey section, appear scattered on the ground. The duct entered into a castellum [distribution cistern], to which reference will be made later, via a substructio that can be seen in the enclosure of that house. Proserpina-Los Milagros Now that the details of the water collection process in the reservoir have been explained and its characteristics have been dealt with, we can consider the aqueduct’s route to the city. The water flowed out through a narrow gallery into which it is possible to enter as far as to the nozzle tube. The outlet is in the orchard belonging to the Pacheco family, adjacent to the reservoir, where a small modern aqueduct is still preserved, records of which can be found in the Mérida Council Corporate Agreements Books. This small raised aqueduct, which in fact would be more aptly referred to as a channel, was constructed to channel the water that was lost after the Roman works were abandoned, so that these resources could be used to drive several mills, whose ruins can still be seen today. The designing process was difficult, because several obstacles had to be overcome: gullies, small dips and granite blocks. All of this accounts for the considerable work that had to be done and the detours that the aqueduct had to take invariably seeking the best elevations and the level contours rather than crossing them, which explains why the route was eventually almost 10 km long. Much has been said about the nature of this duct, especially by Fernández Casado, who refers to the open-air stretch58. This is by no means exact, because in our prospecting activities along the entire ducting we have found more than enough traces of roof covering. The channel was devised in much the same way as other Merida ducts. It is a stonework composed of opus caementicium [Roman concrete] with an outer face of dressed stone or opus incertum. The use of brick as caementa [rough quarry stones] can be observed here and in the roof that covers the channel. It must also be pointed out that the caementa get of smaller size as the aqueduct moves away from the caput aquae the material used being then local stone, with presence of river pebbles in those sections lying closest to the Guadiana river. The channel emerges for the first time 500 m away from the reservoir. As far as the Montijo crossroads, in the Cuarto de la Charca Estate, interesting construction structures being found and, something hitherto unseen in Merida, a tunnel excavated FIG. 14 Proserpina duct tunnel in the Carija Estate. in the local granite block [FIG. 14]. AQUAE AUGUSTANAE 21 Stone works in the gullies along the Proserpina duct route. FIG. 15 The tunnel is approximately 1 km from the reservoir and dug with a view to passing through the above-mentioned rock mass. It was detected thanks to geophysical prospecting conducted by the Universidad Complutense de Madrid under the supervision of the Escuela de Topografía de Mérida and ourselves. The required excavations were then carried out, which led to the spectacular discovery of the specus open in the rock. Spiramina had been sunk at intervals. This measure is known to have been adopted in several examples from the Roman world, including the Nîmes Aqueduct. These were major works that not only took place in the above-mentioned estate but also in the Carija Estate, where gullies had to be spanned. In the latter case, the works for spanning the three gullies that we know of, involved substructionis of constant thickness. The starting points still remain but the arcuationis sections in the central part no longer exist. Perhaps the second gully reveals the most interesting details. The construction on the surface is 24.40 m long and 2.85 m high. The substructio is 1.40 m wide, whereas the specus is 56 cm wide [FIG. 15]. Beyond the third gully, the channel runs through rather flat granite terrain, constituting one continuous stretch. When it approaches the Montijo crossroads it is raised on a 1.20 m high wall. The channelling crosses part of the Araya Estate, before making its way towards the Carija Pass, then running into the La Calera Estate, from which it starts to descend to- Close-up of the piscina limaria in the Proserpina duct. FIG. 16 FIG. 17 The Los Milagros Archings. wards the city passing close to a modern fountain, El Sapo, where the layout takes the form of a 130 m long hairpin. Reference must be made to the piscina limaria of the duct, discovered on the municipal cemetery hill [FIG. 16]. It is a catchpit 3.60 x 3 m on the inside, equipped with a bottom outlet, floodgate chamber and spillway outlet. From this height, the specus runs along an increasingly high wall and then carries on supported by pillars and arches in the Albarregas Valley. The arched section from the aforementioned settling pit to the existing terminal on the El Calvario hill is 827 m long, the maximum height being 25 m. The structure reveals how skilful the Roman engineers were when it came to overcoming these types of problems. The solution basically consisted of a series of pillars with a strong concrete core and a lining of stonework and brick, five and five layers respectively. The pillars are 3 m wide and are sometimes provided with a sloping abutment, 2 m wide and 2.50 m long [FIG. 17]. The pillars are connected with brick arches, although the arches that flank the Albarregas River are made of stone. The pillars erected over the river are equipped with wedge-shaped cutwaters. The specus, for the most part missing, ran over the arches. The change of direction to reach the castellum where the duct ended can be seen perfectly. AQUAE AUGUSTANAE 23 The castella [distribution cisterns] A lot of discoveries were made about aqueducts as a result of the excavations that took place in what were known as the Amphitheatre House and the El Calvario Hermitage, because each of them led to the finding of castella, one for the Las Tomas duct and the other for the Proserpina duct. We have already dealt with the possible existence of the Cornalvo castellum in the vicinity of Casa del Mitreo, next to the bull-ring. In fact, the San Albín hill is the ideal place for it to be located judging by topographic data of the land. The Las Tomas duct castellum was discovered during the course of the above-mentioned excavations. It is a long rectangular building constructed with stone, masonry and bricks, the sides being rather thick to enable the brick roof, which covers the entire space, to rest on them [FIG. 18]. According to Jiménez Martín59, its function was to enable the impurities in the water to settle, so it would be more of a piscina limaria, an opinion that we do not entirely agree with. The whole floor of the building, which lies at a lower level than the channels themselves, is lined with hydraulic mortar. However, the rest of the building has a fine coating of lime and sand, onto which a series of triangles were painted, in the form of pediments, composed of adjacent red and green lines. Underneath these lay some depictions already unrecognisable when they were found. It is thought that these paintings could have been associated with the blessing of the waters. Castellum divissorium in the Las Tomas duct. Illustration by PÉREZ VIGO. FIG. 18 24 ROMAN ENGINEERING FIG. 19 Nympheum in the Proserpina duct castellum aquae. We believe that it is a divissorium [fork], in which even before the main duct arrives, it branches off to supply a suburban zone perfectly located in the vicinity of the aqueduct with a view to supplying at least two areas: the theatre and amphitheatre on the one hand, and the central part of the city, on the other hand, as can be clearly seen in the duct found when excavating the Museum. It is impossible to ascertain now, but there might have been a large castellum aquae next to the walls, as is the case with the Proserpina Aqueduct. The structure of the large cistern at the end of the Proserpina Aqueduct is also very interesting. It was found under the El Calvario Hermitage, where ever since olden times a structure associated with the ducting60 was thought to have existed. It is almost a square-shaped construction, like a nympheum associated for its source of supply and character with the neighbouring castellum61. It is 15.40 m long on the best preserved side. The stonework is no more than 2.70 m high [FIG. 19]. The cistern is seated on natural rock surface, for which purpose a concrete platform was laid to provide a flat base. A layer of roughly cube-shaped granite blocks runs along the entire length of the construction, constituting the real foundation base. The top part of the construction has a very uneven diorite masonry surface and the entire core was made of concrete. A lacing course comprising two lines of brick, a highly distinctive characteristic of this particular hydraulic complex, was laid between the masonry, in order to suitably smoothen the rows of stone and to speed up the construction process without waiting for the previous line to cure. AQUAE AUGUSTANAE 25 Two steps led up to the central part of the fountain. The interior was 5.85 m long, 2 m high and the walls and floor were lined with a layer of grey veined marble as can be deduced from the small remnants that have been preserved. Clear traces of past restoration attempts can also be observed. The preserved part of the top of the construction is covered with a 33 cm thick layer of hydraulic mortar and a small channel is set in its centre, which is all that is left of the several ducts leading into the cistern. The fact that this fountain is positioned where it is, next to the castellum and at the start of the cardo maximus, the main street in the city, is proof of its importance, and it had a highly-effective ornamental function at the entrance to the city from the north. The location of this castellum, next to the city walls, is almost general, but sometimes it was built closer to the centre of settlements. 26 ROMAN ENGINEERING NOTES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. A. M. CANTO: «La Arqueología Española bajo Carlos IV y Godoy: Preludio a los dibujos emeritenses de Villena y Moziño (17911794)», Anas, no. 7-8, 1994-1995, pages 31-56; Id.: La arqueología española en la época de Carlos IV y Godoy. Los dibujos de Don Manuel de Villena Moziño. 1791-1794. Madrid, Ediciones El Viso, 2001, no. 9, 10, 17, 19, pages 140-143, 156-162. S. ARBAIZA BLANCO-SOLER and C. HERAS CASAS: «Fernando Rodríguez y su estudio arqueológico de las ruinas romanas de Mérida y sus alrededores (1794-1797)», Academia. Boletín de la Real Academia de Bellas Artes de San Fernando, no. 87, 1998, pages 309-364. A. DE LABORDE: Voyage pittoresque et historique de l’Espagne. París, 1806, v. II. A. JIMÉNEZ MARTÍN: «Los acueductos de Emerita», Augusta Emerita. Madrid, 1976, pages 111-125. The work of ÁLVAREZ SÁENZ DE BURUAGA and his activities at the School of Surveyors at the Universidad Politécnica de Mérida, encouraged by his lecturers and particularly by Dr. Hernández Ramírez, who provided us with data of great interest where establishing the exact layout of the ducts is concerned. All of this amounts to a major breakthrough in awareness about the hydraulic complexes and serves as a starting point for systematic work that has not been possible until now. A joint effort concerning the ducts of Merida is what should be carried out, with the participation of multidisciplinary teams. A. JIMÉNEZ MARTÍN: Op. cit.; Id.: «Problemas de los acueductos emeritenses», Habis, no. 7, 1976, pages 271-292. C. FERNÁNDEZ CASADO: «Acueductos de Mérida», Informes de la Construcción, no. 205, 1968, pages 51-74; Id.: Acueductos romanos en España. Madrid, Instituto Eduardo Torroja, 1972. J. R. MÉLIDA: Catálogo Monumental de España. Provincia de Badajoz. Madrid, 1925, vol. I, pages 106 et sec. TH. HAUSCHILD: «Problemas de las construcciones romanas en Mérida», Augusta Emerita. Madrid, 1976, pages 107-109. The numerous works conducted recently by a considerable number of qualified professionals have been extremely useful, including contributions made by Fernando Aranda, José Luis Sánchez Carcaboso, Juan Martín Morales y Miguel Arenillas, with their respective teams. For reference of their works see A. VELÁZQUEZ JIMÉNEZ: Repertorio de bibliografía arqueológica emeritense III. Emerita 2010. Mérida, 2011. P. M. PLANO Y GARCÍA: Ampliaciones a la Historia de Mérida. Mérida, 1894, pages 22 et sec. R. CELESTINO GÓMEZ: «Los sistemas romanos de abastecimiento de agua a Mérida. Estudio comparativo para una posible cronología», Revista de Obras Públicas, December 1980, pages 959-967. J. ÁLVAREZ SÁENZ DE BURUAGA: «La conducción de Rabo de Buey-San Lázaro, de Mérida», Estudios dedicados a Carlos Callejo Serrano. Cáceres, 1979, pages 71 et sec. A. M. CANTO DE GREGORIO: «Sobre la cronología augústea del acueducto de Los Milagros de Mérida», Homenaje a Sáenz de Buruaga. Madrid, 1982, pages 157 et sec. S. FEIJOO MARTÍNEZ: «Las presas y los acueductos de agua potable, una asociación incompatible en la antigüedad: el abastecimiento en Augusta Emerita», in T. NOGALES (ed.): Augusta Emerita. Territorios, espacios, imágenes y gentes en Lusitania romana. Monografías Emeritenses, 8. Mérida, 2005, pages 171 et sec. J. M. ÁLVAREZ, J. GARCÍA MORANT et. al.: «Localización de la conducción romana desde el reservoir de Proserpina» hasta Mérida mediante la aplicación compartida de la topografía y la geofísica», Jornadas sobre Teledetección y Geofísica aplicada a la Arqueología. Madrid, 1992, pages 189-196. We have referred to the literature on Merida’s waterworks on several occasions, updating the information from time to time. Some of the most significant papers on the subject include: «Las conducciones hidráulicas emeritenses. Estado de la cuestión», in J. MANGAS and S. CEBALLOS (edit.); El agua en las ciudades romanas. Madrid, 2007, pages 183-212; «Los primeros años de la colonia Augusta Emerita», in E. LA ROCCA, P. LEÓN and C. PARISI PRESICCE: Le due patrie acquisite. Studi di Archeologia dedicati a Walter Trillmich. Bullettino della Comisione Archeologica Comunale di Roma. Supplementi, 18, pages 27-40. I. ROSO DE LUNA and F. HERNÁNDEZ-PACHECO: Mapa geológico de España. Explicación de la Hoja n.º 777. Mérida (Badajoz). Madrid, 1950, p. 69. J. ÁLVAREZ SÁENZ DE BURUAGA: Op. cit., pages 71 et sec. The name Cornalbo or Cornalvo dates back a long way and the idea was to use it in relation to the Latin name Cornus Albus for of the shape of its basin and the whiteness of some parts of its shores. J. ÁLVAREZ SÁENZ DE BURUAGA: «El nuevo hallazgo de la perdida lápida emeritense de Proserpina», A EspA, vol. 30, 1957, pages 245-251. This discovery is unusual that is undoubtedly associated with the presence of some place of worship to the infernal goddess that was considered to be an entrance to the kingdom of darkness. FRONTIN: De aquae ductu urbis Romae (Ed. P. Grimal, Guillaume Budé, Paris, 1961), XV, 1; X, 5,6. I. ROSO DE LUNA and F. HERNÁNDEZ-PACHECO: Op. cit., p. 31. R. CELESTINO GÓMEZ: «Los sistemas romanos de abastecimiento de agua a Mérida. Estudio comparativo para una posible cronología», Revista de Obras Públicas, December 1980, pages 964 et sec.; J. A. FERNÁNDEZ ORDÓÑEZ et. al.: Catálogo de noventa presas y azudes españolas anteriores a 1900. Madrid, 1984, p. 32. A good source for this is provided by a drawing by Fernando Rodríguez, towards the end of the 18th Century. S. ARBAIZA BLANCOSOLER and C. HERAS CASAS: Op.cit., no. 42 and 43, A-5959, pages 339-340. M. ARENILLAS et. al.: «Apuntes documentales para la historia de la presa de Cornalvo», V Congreso de Historia de la Construcción. Madrid, 2007, pages 57-73. R. CELESTINO GÓMEZ: «Los sistemas...», p. 966. With regard to the technical details concerning the Cornalvo Reservoir, we would recommend the excellent studies carried out by the Confederación Hidrográfica del Guadiana. F. ARANDA GUTIÉRREZ and J. L. SÁNCHEZ CARCABOSO: «Las grandes desconocidas de las presas romanas principales: La Alcantarilla y Cornalbo», I Congreso Nacional de Historia de las presas. Mérida, 811 November 2000. Actas, I (F. BUENO, ed.). Badajoz, 2002, pages 273-278; J. MARTÍN MORALES et. al.: «La presa de Cornalbo en Mérida». I Congreso Nacional de Historia de las presas, I, pages 279- 287. AQUAE AUGUSTANAE 27 29. Such «modernity» has led more than one to suspect that much of the structure was modified in the 18th Century. We do not 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 28 think that it is very right given that the dam structure itself remains the same, yet certain aspects of the dam as a whole were modified, in view of the fact that the well-known politician from the second half of the «Age of Enlightenment» Conde de Campomanes installed, by Royal Decree, a variety of devices of an industrial nature on the estate bearing his name. J. M. ÁLVAREZ MARTÍNEZ: El Puente romano de Mérida. Monografías Emeritenses, 1. Badajoz, 1983. Sobre los paramentos del Puente, pages 60-61. T. NOGALES BASARRATE: Espectáculos en Augusta Emerita. Espacios, imágenes y protagonistas del ocio y espectáculo en la sociedad romana emeritense. Monografías Emeritenses, 5. Badajoz, 2000. Concerning the phases of the Amphitheatre, pages 34 et sec. Concerning this subject: J. M. ÁLVAREZ MARTÍNEZ: «Calzadas romanas de Hispania e ideología imperial», Vía Claudia Augusta. Un’arteria alle origini dell’Europa: ipotesi, problemi, prospettive. Attii del Convengo Internazionale. Feltre, 24-25 September 1999 (V. GALLIAZZO, ed.). Treviso, 2002, pages 375 et sec. J. HIERNARD and J. M. ÁLVAREZ MARTÍNEZ: «Aqua Augusta. Una inscripción con letras de bronce de Mérida», Sautuola III, 1982, pages 221 et sec. A. JIMÉNEZ MARTÍN: «Los acueductos...», p. 114. R. CELESTINO GÓMEZ: «Los sistemas…», pages 960-961. Concerning this subject: J. M. ÁLVAREZ MARTÍNEZ: «Los primeros años de la colonia Augusta Emerita. Las obras de infraestructura», in E. LA ROCCA, P. LEÓN and C. PARISI PRESICCE: Le due patrie acquisite. Studi di Archeologia dedicati a Walter Trillmich. Bullettino della Commissione Archeologica Comunale di Roma. Supplementi, 18. Rome, 2008, pages 36-38. A. JIMÉNEZ MARTÍN: «Los acueductos...», pages 115-116. Regarding the work carried out in the 1990s on the Proserpina Dam we would suggest those conducted by the Confederación Hidrográfica del Guadiana and by the team led by Professor Miguel Arenillas, which are of greater interest because of their technical contribution and given that they provide new data that make it possible to gain further insight into the reservoir structure: M. ARENILLAS et. al.: «La presa romana de Proserpina (Mérida)». Confederación Hidrográfica del Guadiana. May 1992; J. MARTÍN MORALES: «Hormigonar Proserpina», I Congreso Nacional de Historia de las Presas, II, pages 75 et sec.; J. SERENO MARTÍNEZ: «Aproximación a los usos históricos de los reservoirs. La Charca de la Albuhera de Carixa (Proserpina) en los siglos XVII, XVIII Y XIX», I Congreso Nacional de Historia de las presas, II, pages 235 et sec. Cfr. M. ARENILLAS et. al.: op. cit., p. 14. B. MORENO DE VARGAS: Historia de la ciudad de Mérida. Madrid, 1633 (second re-edition. Mérida, 1974), pages 87-88. J. ÁLVAREZ SÁENZ DE BURUAGA: Materiales para la Historia de Mérida (de 1637 a 1936). Los Santos de Maimona, 1994, passim. J. M. ÁLVAREZ MARTÍNEZ: El Puente, pages 53-55. S. FEIJOO MARTÍNEZ: Op. cit., pages 195 et sec. C. FERNÁNDEZ CASADO: Los acueductos romanos. Madrid, 1972, un-numbered pages. A. JIMÉNEZ MARTÍN: Op. cit., pages 120 et sec. J. M. ÁLVAREZ MARTÍNEZ: «Trajano y las obras públicas en Hispania», J. GONZÁLEZ (ed.): Trajano, Óptimo Príncipe. De Itálica a la corte de los Césares. Sevilla, 2004, pages 49 et sec. C. FERNÁNDEZ CASADO: Acueductos romanos de España. A. JIMÉNEZ: «Los acueductos…», p. 114. C. FERNÁNDEZ CASADO: Ibidem. I. A. RICHMOND: «The first years of Augusta Emerita», Archaeological Journal, LXXXVII, 1930, pages 99 et sec. P. M. PLANO Y GARCÍA: Ampliaciones, pages 22 et sec. Especially the studies conducted by the Confederación Hidrográfica del Guadiana engineers. J. ÁLVAREZ SÁENZ DE BURUAGA: Op. cit., p. 658, further note. J. HERNÁNDEZ RAMÍREZ: «El conducto de Rabo de Buey-San Lázaro (Mérida)». Mérida. Ciudad y Patrimonio, 2, 1998, pages 3965. J. BIREBENT: Aquae romanae. Algiers, 1964. M. PASQUINUCCI: «Studio sull’ urbanistica di Ascoli Piceno romana», Asculum, I. Pisa, 1975, p. 59, fig. 84. M. ALMAGRO: «El acueducto romano de Segobriga (Saelices, Cuenca)», R.A.B.M., LXXIX, 4, 1976, pages 875 et sec. C. FERNÁNDEZ CASADO: Acueductos romanos de España. A. JIMÉNEZ: «Los acueductos de Emerita», p. 119. J. M. ÁLVAREZ MARTÍNEZ: «En torno al acueducto de Los Milagros», op. cit., pages 49-60. Excavations, later than the ones carried out in the early 1960s, provided more data for establishing the structure of the complex: T. BARRIENTOS VERA: «Intervención arqueológica en el solar de la calle Adriano, 62. El Cerro del Calvario», Mérida. Archaeological Excavations. Report, 2, 1996, Mérida, 1998, pages 27-54. ROMAN ENGINEERING BIBLIOGRAPHY M. ALMAGRO: «El acueducto romano de Segobriga (Saelices, Cuenca)», R.A.B.M., LXXIX, 4, 1976. et. al.: «Localización de la conducción romana desde el reservoir de Proserpina hasta Mérida mediante la aplicación compartida de la topografía y la geofísica», Jornadas sobre Teledetección y Geofísica aplicada a la Arqueología. Madrid, 1992, pages 189-196. J. M. ÁLVAREZ MARTÍNEZ: El Puente romano de Mérida. Monografías Emeritenses, 1. Badajoz, 1983. Sobre los paramentos del puente, pages 60-61. — «Calzadas romanas de Hispania e ideología imperial», Vía Claudia Augusta. Un’arteria alle origini dell’Europa: ipotesi, problemi, prospettive. Attii del Convengo Internazionale. Feltre, 24-25 Settembre 1999 (V. GALLIAZZO, ed.). Treviso, 2002. — «Trajano y las obras públicas en Hispania», J. GONZÁLEZ (ed.): Trajano, Óptimo Príncipe. De Itálica a la corte de los Césares. Sevilla, 2004. — «Los primeros años de la colonia Augusta Emerita. Las obras de infraestructura», in E. LA ROCCA, P. LEÓN and C. PARISI PRESICCE: Le due patrie acquisite. Studi di Archeologia dedicati a Walter Trillmich. Bullettino della Commissione Archeologica Comunale di Roma. Supplementi, 18. Rome, 2008, pages 36-38. J. ÁLVAREZ SÁENZ DE BURUAGA: «El nuevo hallazgo de la perdida lápida emeritense de Proserpina», AEspA, Vol. 30, 1957, pages 245-251. — «La conducción de Rabo de Buey-San Lázaro, de Mérida», Estudios dedicados a Carlos Callejo Serrano. Cáceres, 1979. — Materiales para la Historia de Mérida (de 1637 a 1936). Los Santos de Maimona, 1994. F. ARANDA GUTIÉRREZ and J. L. SÁNCHEZ CARCABOSO: «Las grandes desconocidas de las presas romanas principales: La Alcantarilla y Cornalbo», I Congreso Nacional de Historia de las presas. Mérida, 8-11 November 2000. Actas, I (F. BUENO, ed.). Badajoz, 2002, pages 273-278. S. ARBAIZA BLANCO-SOLER and C. HERAS CASAS: «Fernando Rodríguez y su estudio arqueológico de las ruinas romanas de Mérida y sus alrededores (1794-1797)», Academia. Boletín de la Real Academia de Bellas Artes de San Fernando, nº 87, 1998, pages 309-364. M. ARENILLAS et. al.: «La presa romana de Proserpina (Mérida)». Confederación Hidrográfica del Guadiana. May 1992. M. ARENILLAS et. al.: «Apuntes documentales para la historia de la presa de Cornalvo», V Congreso de Historia de la Construcción. Madrid, 2007, pages 57-73. T. BARRIENTOS VERA: «Intervención arqueológica en el solar de la calle Adriano, 62. El Cerro del Calvario», Mérida. Excavaciones Arqueológicas. Memoria, 2, 1996, Mérida, 1998, pages 27-54. J. BIREBENT: Aquae romanae. Argel, 1964. M. CANTO: «La Arqueología Española bajo Carlos IV y Godoy: Preludio a los dibujos emeritenses de Villena y Moziño (1791-1794)», Anas, no. 7-8, 1994-1995. — La arqueología española en la época de Carlos IV y Godoy. Los dibujos de Don Manuel de Villena Moziño. 17911794. Madrid, Ediciones El Viso, 2001. A. M. CANTO DE GREGORIO: «Sobre la cronología augústea del acueducto de Los Milagros de Mérida», Homenaje a Sáenz de Buruaga. Madrid, 1982. R. CELESTINO GÓMEZ: «Los sistemas romanos de abastecimiento de agua a Mérida. Estudio comparativo para una posible cronología», Revista de Obras Públicas, December 1980, pages 959-967. S. FEIJOO MARTÍNEZ: «Las presas y los acueductos de agua potable, una asociación incompatible en la antigüedad: el abastecimiento en Augusta Emerita», in T. NOGALES (ed.): Augusta Emerita. Territorios, espacios, imágenes y gentes en Lusitania romana. Monografías Emeritenses, 8. Mérida. C. FERNÁNDEZ CASADO: «Acueductos de Mérida», Informes de la Construcción, no. 205, 1968, pages 51-74. — Acueductos romanos en España. Madrid, Instituto Eduardo Torroja, 1972. — Los acueductos romanos. Madrid, 1972, Un-numbered pages. J. A. FERNÁNDEZ ORDÓÑEZ et. al.: Catálogo de noventa presas y azudas españolas anteriores a 1900. Madrid, 1984. FRONTIN: De aquae ductu urbis Romae (Ed. P. Grimal, Guillaume Budé, Paris, 1961), XV, 1; X. TH. HAUSCHILD: «Problemas de las construcciones romanas en Mérida», Augusta Emerita. Madrid, 1976, pages 107-109. J. HERNÁNDEZ RAMÍREZ: «El conducto de Rabo de Buey-San Lázaro (Mérida)». Mérida. Ciudad y Patrimonio, 2, 1998, pages 39-65. J. HIERNARD and J. M. ÁLVAREZ MARTÍNEZ: «Aqua Augusta. Una inscripción con letras de bronce de Mérida», Sautuola III, 1982. A. JIMÉNEZ MARTÍN: «Los acueductos de Emerita», Augusta Emerita. Madrid, 1976, pages 111-125. — «Problemas de los acueductos emeritenses», Habis, no. 7, 1976, pages 271-292. J. M. ÁLVAREZ, J. GARCÍA MORANT AQUAE AUGUSTANAE 29 and C. PARISI PRESICCE: «Los primeros años de la colonia Augusta Emerita», en Le due patrie acquisite. Studi di Archeologia dedicati a Walter Trillmich. Bullettino della Comisione Archeologica Comunale di Roma. Supplementi, 18, pages 27-40. A. DE LABORDE: Voyage pittoresque et historique de l’Espagne. Paris, 1806, v. II. J. MANGAS and S. CEBALLOS (eds.): El agua en las ciudades romanas. Madrid, 2007. J. MARTÍN MORALES: «Hormigonar Proserpina», I Congreso Nacional de Historia de las Presas, II. J. MARTÍN MORALES et. al.: «La presa de Cornalbo en Mérida». I Congreso Nacional de Historia de las presas, I, pages 279- 287. J. R. MÉLIDA: Catálogo Monumental de España. Provincia de Badajoz. Madrid, 1925, vol. I. B. MORENO DE VARGAS: Historia de la ciudad de Mérida. Madrid, 1633 (second re-edition. Mérida, 1974). T. NOGALES BASARRATE: Espectáculos en Augusta Emerita. Espacios, imágenes y protagonistas del ocio y espectáculo en la sociedad romana emeritense. Monografías Emeritenses, 5. Badajoz, 2000. M. PASQUINUCCI: «Studio sull’ urbanistica di Ascoli Piceno romana», Asculum, I. Pisa, 1975. P. M. PLANO Y GARCÍA: Ampliaciones a la Historia de Mérida. Mérida, 1894. I. A. RICHMOND: «The first years of Augusta Emerita», Archaeological Journal, LXXXVII, 1930. I. ROSO DE LUNA and F. HERNÁNDEZ-PACHECO: Mapa geológico de España. Explicación de la Hoja nº 777. Mérida (Badajoz). Madrid, 1950, p. 69. J. SERENO MARTÍNEZ: «Aproximación a los usos históricos de los reservoirs. La Charca de la Albuhera de Carixa (Proserpina) en los siglos XVII, XVIII Y XIX», I Congreso Nacional de Historia de las presas, II. A. VELÁZQUEZ JIMÉNEZ: Repertorio de bibliografía arqueológica emeritense III. Emerita 2010. Mérida, 2011. E. LA ROCCA, P. LEÓN Back to Contents 30 ROMAN ENGINEERING 2 A few traces from the Construction of Segovia’s Aqueduct ALONSO ZAMORA CANELLADA Former Director of the Museo Provincial de Segovia First of all it must be pointed out that it will be necessary for you to appreciate the aqueduct as one single entity, regardless of the era or the character of its constituent components. If at the outset it just consisted of a set of works, subject to repairs and modifications later, it has nowadays become a multi-faceted monument which is not always possible to completely comprehend in its successive occurrences, not even to put date to these occurrences. In turn, each piece of it has to be valued as an intrinsic part of a whole, as being essential for it to operate and, thus, essential for its preservation throughout History. Traces from construction, repair or use can be found in all zones. When there was no masonry, for example, the building was raised with irregular rubble-stone, using a technique often repeated down through History, of which manufacturing process little remains, apart from being rather unrepresentative. In this case we will refer in particular to the marks left from hewing and raising the granite of the building ashlars and arcuationis (arches), because granite is a material that gets these signs easier to identify. We can group these markings into a number of types: extraction and finishing, raising and laying. THE CHANNELS The first thing that had to be done when it came to planning the construction layout, once the decision had been taken to erect it, was the use of chorobates, water levels that enabled the user to visually establish the horizontals and the slopes that the future channel had to adhere to, in such a way that gravity allowed the water to flow from the col- 31 lection point to the places where it was to be utilised. This required suitable gradients to be established, as well as small pits every so often for cleansing and energy-loss purposes, at short distance in this case. These sort of continual shaft were known as spiramens or lumens, and they were essential to the aqueduct maintenance, because they made it possible to prevent unwanted pressures, enabled cleaning and repair tasks to be performed and caused a better oxygenation and purification of the water. The channel could be constructed underground, on the surface or raised above surface. It usually consisted on an assembly in which the three types were combined, depending on the levelling requirements and the time or money available. They were also built in tunnels or siphons, or cut into granite blocks, for example. The corrugus were normally open-air channels conveying water for industrial use. The specus, for human consumption instead, were roofed channels covered with slabs. This was what the Segovian monument was like in the La Granja road area, before the cobijas (covers) used to protect them were removed. It seems reasonable to assume that that this was the system utilised from the draw-off point to that area. Roman concrete is generally very cohesive. The type of concrete that was perhaps most extensively, but not exclusively, used in hydraulic works was known as opus signinum, a mixture of limestone, stone – crushed to a greater or lesser extent – and brick, also crushed, all of which was well mixed and introduced into and pressed in coffer work, which served to mould it. This same mixture was also used to make the channels, when they were not made of wood or lead (sometimes with the hallmarks of the workshops concerned), or ceramic piping. In other cases, such as when siphons were arranged, they were formed with stone drums that had holes drilled in their centre, the joints being tongued and grooved and waterproofed with oil and mastic, a paste that cures and ends up strongly adhering the contact points. As was the case with other hydraulic works, the edges between the ground and the sides were reinforced, also with signinum, in order to improve the hardening of that zone and prevent the corners from being directly eroded by the impurities entrained in the water, basically by the very remarkable scouring effect of the sand, while at the same time facilitating the cleaning process. THE DESANDERS Concern over the purity of the water led the classic world to construct desanders, decanters or «water towers». A turrisaquae or piscina limaria is a hut that houses a central pool, the channel water flowing in and out this pool. The alignments of the two stages do not coincide, in such a way that the water has to swirl in the pool, losing velocity and entrainment force. As a result, the impurities settle on the bottom, from where they are drained away through a trap. Along the same lines, the foam, i.e. the floating matter, can be removed via a different pipe, also used when it is necessary to cut off passage through the main outlet, in order to carry out cleaning activities or to do repairs. The Segovian duct has two desanders, both of which have been repaired or reconstructed on several occasions; they can be seen close to La Granja road. 32 ROMAN ENGINEERING EXTRACTION TRACES With the granite still in the quarry, the sections of the blocks to be extracted were marked with small lines by means of hewing. Several wedges were stuck into these marks, in such a way that the desired block was gradually split off. The result is the presence of marks, equivalent to half the widest surfaces of the wedges, because the other half was left on the un-extracted part of the granite. They are usually arranged similar distances apart, their depths also being similar and they often disappear when subsequent work has been carried out on the edges. Iron wedges replaced the older wooden ones that swelled up when wet or covered with ice. It is a system that nowadays has been replaced almost entirely by mechanical machinery. Some of these marks can be detected on the upper banks of the channels, in the first overhead zone, before the large desander. The masonry bases in this zone contain a channel made of granite blocks, whose shoulders were covered with small slabs on either side. These traces can be seen most clearly on the edges of the referred slabs, especially on the inner ones. They were placed there in the 1974 restoration, and I have not seen this type of remains anywhere else, as they would have normally been removed by the finishing treatment given to stone ashlars and/or by erosion down through centuries. Whatever the case may be, the above surface construction began with the search for suitable foundations. Trenches were performed to locate the hardest and least weathered rock, on top of which the first ashlars for each pillar were placed. Once these had been correctly positioned and the top level of these «foundation pits» had been reached, these were filled with nearby rubble; any remnants of other materials used as filler, such as bits of ceramic, will help to date the time of the filling process and, therefore, the date on which work in this zone of the monument was completed [FIG. 1]. First overhead section of the aqueduct. Traces of the metal wedges inserted to force the extraction or controlled fragmentation of the granite. They are arranged with an even gap and their sections and depths on the cleavage plane are also similar. Photograph: A. ZAMORA. FIG. 1 A FEW TRACES FROM THE CONSTRUCTION OF SEGOVIA’S AQUEDUCT 33 FIG. 2 Slings, tongs and holivela wedges, systems used to lift the ashlars. Tongs, i.e. the intermediate option, were the ones most used for the Segovia Aqueduct. Source: J.P. ADAM: La Construction …. p. 52. There are some doubts about where the granite came from, because the exact locations of the quarries from which it was extracted have not been fully identified. It is also possible that the typical boulders were used, several of which still lie in the surrounding area. More than one point were probably used, laying not very far from the monument, perhaps covered over by subsequent works. This hypothesis is supported by the fact that several types of stone were used, as can easily be seen when observing the monument. The hewing was done with the usual tools, virtually the same ones that are still used today: the scalprum (flat chisel), the scoplum (cutting chisel), the malleus (mallet) and several types of aschiae (axes), mainly the dolabra (pickaxe), the bipennis (double-headed axe) and the upupa (the present hachette, with two cutting edges arranged in opposite directions). If we are talking about construction with ashlars in general, the result of the way of doing it is referred to as opus quadratum. In the Segovian case it is fairly used, the size of the stones being quite similar. All of the stonework was laid in such a way that the ashlars on top cover the joins of the ashlars below (hiden joint), to protect them and to improve stability, without the use of mortar (dry, or face to face joint). HOISTING TRACES It is assumed that the tympanon was used, this comprising two parallel wheels joined by cross beams forming a cylinder, inside which one or more people move, using their weight to make it turn and cause the rope on the axle to wind up, operating like a winch. The wheel is laid on a base, the same as the arms, in the form of a fork, into which a pulley or block and tackle is placed. The whole assembly is called a machina, and is in fact a crane that can be orientated by ropes fixed to its sides, moved by an ergata, or by vertical winches equipped with blades over which the required pressure is exerted. This system is suitable for heavy weights that, in the case of the Segovia Aqueduct, would not have been essential, being probably replaced by horizontal and vertical winches, moved by hand, easier to construct, carry and handle; this type of winch have always existed, of several different sizes, joined to pulleys (orbiculus) or to block and tackle (trochlea) and derricks, also of various sizes, adapted to the weight or the height in each particular case. In general, such materials and devices have continued being in use practically up until the present time, with very little changes to their shape, until the motor came along to replace traditional human «blood» [natural] traction. 34 ROMAN ENGINEERING At the end of the maromas [ropes] and their driving pulley, the way they worked, systems of three different types were used for holding the pieces in suspension: slings, holivelas and tongs [FIG. 2]. Slings Ashlars could have simply been tied, but leaving them in their final position must have been more difficult, because they would have had to be chocked before the ropes were removed from the stones. The slings, a simple tie on a rope, could have been tied to opposite sides, without occupying the bottom surface. But in this case, for the ropes to catch it would be necessary to use nipples, or projections carved on these faces, to ensure that ropes would not slip. Once the block was put in place and the slings had been removed, the projections were no longer needed and could be chipped off, although this was not always done, because they were also regarded as a form of embellishment. When nipples are removed, all traces of the hoisting process disappear. This could have been the system used for the Segovia Aqueduct, although the fact that these protrusions were eventually removed renders it impossible to be sure they were used. Holivela Wedges This is a set of two or more pieces – one of which serving as a keystone –, joined by a common shaft; they are inserted into a socket, grooved for the purpose on the upper surface of the piece to be raised. Once it is in place, the shaft is removed, the keystone is released and the set of tools is withdrawn. The hewing required are, in this particular case, sockets whose longitudinal section is vertical in the form of a trapezoid, with the short side on the ashlar surface. One of its sides can also be arranged obliquely and the other one vertical, by way of summary: a hole whose base is bigger than its mouth. The holivela wedge is put inside, its trapezoidal form adapting to the two sides, at the widest part of the cut, while the mouth dimensions preventing the instrument from getting out as long as the keystone is not removed [FIG. 3]. An assembled holivela wedge. The specimen shown features three key pieces, of quadrangular section and uniform thickness, in the centre. Its number makes it possible to connect the instrument to cuts of several different sizes. The bolt provides safety and closure to the assembly, besides serving as support for the handle. The bolt also has a small stud nail at the far end to prevent it from slipping out without being removed beforehand (exhibit from the Ròmul Gavarro Collection). Source: I. GONZÁLEZ TASCÓN AND I. VELÁZQUEZ: Ingeniería romana..., p. 247. FIG. 3 A FEW TRACES FROM THE CONSTRUCTION OF SEGOVIA’S AQUEDUCT 35 The system was used particularly for pieces whose surfaces should not show signs of any handling, such as pillars or column heads, although it was also used on ashlars or other blocks. The hewing traces could still be seen on the upper surfaces until they were concealed by the new ashlars. So, where the aqueduct is concerned, no traces are left from this system being used, if indeed it was applied, although its utilisation cannot be completely ruled out. Whatever the case may be, a certain degree of skill was needed to carry out the hewing required, given that the weight of the piece to be lifted was going to be concentrated on just a few centimetres, and the holivela had to be carefully adjusted. Claws or Tongs Ashlars were raised into place by means of what were known as ferrei forfices, a tool that is still used today. These are in fact large tongs or grippers, made of cast iron, in the form of a compass, suspended in such a way that the weight being hoisted was used to prevent them from opening out and ensuring that their ends strongly gripped the load. Small indentations, normally conical, had to be hewed to receive the tips of each pincer, and prevent them from slipping. It was customary to cut the indentations on the top third and in the central zone of the load, on opposing surfaces, with a view to preventing any unwanted swaying, except in the case of the keystones, which did have to swing to the inclination that they had to exhibit over the arch frame, which was achieved by offsetting the indentations for the tong tips [FIG. 4]. This was the system that was mainly used to construct the aqueduct. The indentations can still be observed in nearly all ashlars, which makes one wonder why they do not appear on all of them. First of all, the height where they lie must be taken into account. When they are located «high up», it could be the case that erosion processes might have erased many of these marks, in spite of their depth, especially in the case of pieces cut from less resistant granite. The thickness of the bossage on which the socket was cut out, could have been lowered after the piece was laid in place, causing the marks to disappear. For ashlars located in zones that are not very high, the blocks might have been slid into position with levers, ropes or ramps. However, it should not be forgotten that the current ground level, especially in the Plaza de Azoguejo, is a fill that is several metres above the original river valley floor, so the height to be considered is invariably subjective. New blocks are gradually being added by means of these systems, in such a way that the pillars gain height bit by bit until the cornices are put in place, over which the wooden centring is laid to support the arch keystones, the channel acting as an upper closure for the assembly serving also to add to the general stability. FIG. 4 Raising of an ashlar by means of tongs. The weight of the piece tends to close the tong pincers, making the hoisting feasible. As from A. RAMIREZ GALLARDO: Supervivencia …., p. 29. 36 ROMAN ENGINEERING TRACES FROM BLOCK ADJUSTMENT Once the stone blocks had been raised and placed next to their ultimate position, the final adjustment was made using levers (vectis), which were no more than iron bars equipped with a claw at one end, just like they are today. The pressure is exerted on small and recently-made cuts on the edges of what were referred to as the «waiting surfaces» of the blocks, now finally seated. They are small, around 5 cm. long, their number depending on the length of the ashlar to be seated, and in nearly all cases they can be seen on the top edges of every piece. This procedure was extensively used throughout the aqueduct construction process. It also reveals a preliminary cut, with the necessary prior planning, before the task was carried out. This could have taken place before or after hoisting, although we are inclined to think that it often occurred afterwards. More than one of these marks can be seen when the top block is long – or when it is seated showing its longest side – the marks being arranged in such a way that they are at a distance from the vertical joints, on their sides and symmetrically and evenly distributed, i.e., tailormade, depending on the length of the ashlars being adjusted [FIG. 5]. One of the pillars, in Plaza del Azoguejo. The cuts for the adjustment levers (indicated by the arrows) can be seen in the upper edges of the ashlars. The circle shows one of them with the erosion cortex, which was not removed. It is a very rare case, if not the only one in the whole construction. Such a low cornice, near to the pavement, must mean that there are at least 3 m of pillar lying below street level. The sockets for the tongs, when they are not visible at this height, must be located on other surfaces of the blocks. Photograph: A. ZAMORA. FIG. 5 A FEW TRACES FROM THE CONSTRUCTION OF SEGOVIA’S AQUEDUCT 37 38 ROMAN ENGINEERING Fluting on the ashlar surface. Example obtained from the two sides of the exposed surface of the piece. Photograph: A. ZAMORA. FIG. 6 It is also convenient to refer here to some cases where the cuts are made on the lower edges of some ashlars. It does not seem easy to explain it, other than by regarding it as a possible hewing error. The position of the ashlar might have been reversed, perhaps due to the incorrect positioning of the hoisting socket on the lower third instead of on the top third of the surface. Whatever the case may be these indentations for the tips of the levers would have been rejected cuts. However, sometimes they were used to help to adjust the new blocks. It is a complicated subject that has to be expanded upon, as it might make it possible to indicate the particular worker or workshop who performed that action and why, but there is no time here, because we do not think it is merely a question of using up all the blocks in spite of their defects. Nevertheless, there are very few examples of such cases. DRESSING TRACES: CUTTING THE SURFACES The outer surfaces of ashlars could be defined as of «bossed masonry» type, where the faces that are going to be exposed are only rough hewn, remaining raised above the plane determined by the edges of the block. However, a small zone, in the form of a strip and running parallel to these edges, is smoothed. It is a system that speeds up the cutting process in each case, making it easier while protecting the stones from scratching or breaking during transportation. The finishing touches made to the corners, or the strip cut parallel to the edge, might have been done when the pieces were at the works site, before being hoisted and without the final position of the block having been decided upon. Yet in many cases the strip was only applied to one of the sides, the outer one, the one that forms the edge of the construction, which would appear to indicate that either the piece was dressed once raised and laid in place, or there was free-flowing communication between the workers at the foot of the site and those working on the scaffolding, enabling the pieces to be ordered «made-to-measure». Whatever the case may be, the result of these «strips» seen altogether, must have been to highlight all the external edges of pillars and arches with their colour, lighter due to the polishing process, than the rest of the surface, only rough hewn. Somewhat different from the current appearance of the construction [FIG. 6]. One of the systems used in the ancient world to speed up the cutting process for the concealed faces was known as anathyrosis, smoothing of an outer band, for all the edges, which has to coincide with the position of other similar ones on the next ashlar. The inside of each face was worked in such a way that it became indented, not supported on the face it backed onto, like a sort of «negative» bossage, which rendered it unnecessary to carry out the laborious process of planning the entire face. Of course, once the piece was positioned, none of this system could have been detected without dismantling the construction, as it was hidden by the ashlars placed on either side or at the rear. So, we cannot say that this was the method used for the Segovian Aqueduct, although everything A FEW TRACES FROM THE CONSTRUCTION OF SEGOVIA’S AQUEDUCT 39 would appear to indicate that it was not, that the concealed faces of the ashlars were rough hewn and polished until they rested completely on each other. The reason for our quick reference to this cutting procedure is because of its common use and because it is not possible to state as certain that it was never applied on this construction, as we already said. Additional to the foregoing we could point out that in some zones (the lower parts of the piles on Azoguejo’s northern tip) a number of isolated points remain preserved, featuring that the original surface of one ashlar matches the surface of the ashlar below. This has been interpreted as a result of certain capacity for granite to weld. We understand however that it is simply a case of a larger hardness of the stone in those points, very useful since they reveal the good initial adjustment of surfaces and their different response to erosion. Other traces of cuts on the exposed surfaces can often be seen, either done at site on the ground or when the already adjusted piece was positioned in place. They are traces of «pickaxe», normally in the form of stretch marks running almost parallel from top to bottom, sometimes in groups running in several directions, over the same faces. They form slightly curved arcs, which must have depended on the position and length of the arm that was holding the pickaxe. It does seem possible that the blocks were lying on trestles, or on other ashlars, i.e. at a certain height, because the arcs that are traced are fairly vertical. Furthermore, if they were etched with the pieces in their final positions this would involve less handling, which was undoubtedly sought so that time and labour could be saved, as well as making uniform thicknesses in the bossage easier to obtain, because cutting was possible at sight of the other faces – already adjusted – of nearby pieces [FIG. 7]. DEDICATORY INSCRIPTION As is the case with other monuments from the Roman world, Segovia’s Aqueduct also had a dedicatory inscription, located in the centre of Plaza del Azoguejo, at a widening lying between the two arch arrangements. Bordered by cornices, this zone was clearly intended to be a special one, an outstanding epigraphic area where the construction’s commemorative plaque would have been placed. A few small holes can be observed on the ashlars inside this space, some of which contain traces of the lead that was used to support the pins for fixing the lettering. If we assume that the angle at which these pins sloped had to be the same as the angle for the tracing of each letter and the angle for the holes cut into the granite, we must accept the ability to read the old dedicatory inscription, the last letters of which were still quoted in the 15th Century. It must have featured the name and title of the Emperor, plus the names of the local magistrates who authorised the works and most likely paid for them, following the evergetical customs of Romans. FIG. 7 View of the remains of the strip cut into the outer edges of the ashlars for pillars and arches. The fact that they are hardly detectable today is indicative of the extent to which the monument has been exposed to erosion. Photograph: A. ZAMORA. 40 ROMAN ENGINEERING A FEW TRACES FROM THE CONSTRUCTION OF SEGOVIA’S AQUEDUCT 41 Thus, should it be possible to reconstruct the contents of the lost plaque, we would be able to put a date to the aqueduct [FIG. 8]. The text, probably formed with gold plated letters, must have been the same on either side of the monument, perhaps with a certain degree of variation in the word layout; maybe with the words arranged in three lines; although there is no general consensus concerning this point, it would seem most likely. Eventually, the same letters would always have the same pins, the holes in the granite always faced the same way and were always in the same positions. However, the search was not that simple, given that there have 42 ROMAN ENGINEERING FIG. 8 Marks showing the location of the construction’s dedicatory inscription, which would have been made of goldplated lettering. The cornices are clearly visible, surrounding and highlighting not only the epigraphic field but also the indentations that received the pins for the letters. Several of them still contain remnants of the original lead from Roman Times. Photograph: A. ZAMORA. A FEW TRACES FROM THE CONSTRUCTION OF SEGOVIA’S AQUEDUCT 43 been at least five attempts since 1820 (Gómez de Somorrostro) and none of the results are the same. This is justified because the pins may not be the same ones for the same letters, and the holes may coincide with the joints for the stone blocks, for example, with a change of slant or having been eroded away or removed by the effort to pull out the supports. The height of the letters might also have been modified, depending on the requirements of each ashlar or of each zone, although this does not seem very likely. However, we are given to understand that the fact that the results of the various attempts to read do not coincide, reveals that the use of the naked eye cannot be the method that enables one to obtain sufficiently reliable data. The text proposed after the most recent reading of the pin arrangements for the western side, after a detailed examination of the traces conducted by Dr. Geza Alföldly, points to the last of these new hypotheses. It is as follows: 1st Line: IMP(eratoris)·NERVAE·TRAIANI·CAES(aris)·AVG(usti)·GERM(anici)·P(ontificis)· M(aximi)·TR(ibunicia)·P(otestate)·II·CO(n)S(ulis)·II·PATRIS·PATRIAE·IVSSV 2nd Line: P(ublius)·MVMMIVS·MVMMIANVS·ET·P(ublius)·FABIVS·TAVRVS·IIVIRI· MVNIC(ipii)·FL(avii)·SEGOVIENSIVM 3rd Line: AQVAM·RESTITVERVNT That is to say: «On the orders of the Emperor Nerva Trajano César Augusto Germánico Pontífice Máximo in his second Tribunician Power, Second Consul, Father of the Country, / Publio Mummio Mummiano and Publio Fabio Tauro, Duoviros from the Flavian Municipality of Segovia / Repaired the aqueduct». Should this happen to be the correct reading, it could be the case that: a) Domiciano (81 to 96 A.D.) started the works. During his years of rule a lot of construction activity took place. But he was the subject of damnatio memoriae [his name was deliberately erased from memory], and thus his name should not appear on the dedicatory plaque. However, there is no evidence either to suggest that the pin holes were erased or altered to adapt to any different text. b) Nerva was not in power for long enough (96 to 98 A.D.), and his building activities were minimal. He must surely be ruled out. c) Trajan (98 to 117 A.D.) reconstructed, or completed, or refurbished the monument. According to the aforementioned reconstruction of the text, the plate is telling us that Trajan was responsible for the monument (as restorer), which is consistent with the coin 44 ROMAN ENGINEERING found in one of the foundation pits for one of the monument pillars, during one of the most recent methodical works that were carried out there under the responsibility of the archaeologist Germán Prieto. It is a sestertius minted between 112 and 117 A.D. That is to say, that the pit in question was covered over at an unspecified time, from 112 A.D. onwards. As a result, it would now be possible to think that the monument was probably constructed (or completed) during the first twenty or so years of the 2nd Century A.D. Therefore, Segovia would have been a municipium (town or city) during the period of the Flavios, which is perfectly feasible, although this has not yet been corroborated by other texts. All that remains to be said is that in recent research work we tried to find on the granite, traces of embossment lettering that could be consistent with the ancient presence of letters. By means of detailed photogrammetric, in spite of the centuries of erosion to which it had been exposed. However, the results, if it is indeed possible to obtain any, are not yet available. OTHER TRACES Other traces can also be discerned: quarrying marks, in the zones affected by the first great restoration, between the second desander and the beginning of the slope, on the way to Azoguejo. Pointed arches, general reuse of the stone and mixing it with recently extracted pieces, as well as traces from the alterations, collection points and ducting leading to the city. These seem to be the main aspects of the work, carried out on orders from the Catholic Monarchs, towards the end of the 15th Century. There are also marks from later periods, in the same places and several other zones. Although these marks refer to restoration work and have nothing to do with the original erection of the monument, they must be mentioned, because they indicate, endorsed by other data, the reconstruction of a large part of the layout, and they make it clear that what really matters is the aqueduct as a whole, not the period to which each part belongs or the extent of each refurbishment. And this is the case even from a legal viewpoint (Declared a National Monument by Royal Decree, dated 11th October 1884). There are also many other traces, due, not to the extraction system, but to the improper and particularly harsh use of the ducting. The uncontrolled drawing-off of water, losses in the successive channels, which led to spectacular icicles in winter, the use of all kinds of nails and stakes, constructions built upon the ashlars, or cables, were commonplace for a long time, bringing about a large number of breakage, cuts and scratches. Bird droppings, grease and the soot from nearby chimney stacks, the traffic, or the many 20th Century restoration activities, all of them less excusable than the earlier ones, have all left their mark. All of these come together to remind us that the aqueduct has only managed to survive today thanks to its continual use, including refurbishments, alterations and restoration work. Once the duct has passed Azoguejo and reached the city walls it goes underground. This is the place where cisterns and a castellum aquae (water tower) should have been, i.e.: a distribution system, from which new ducts branched out to the houses, fountains A FEW TRACES FROM THE CONSTRUCTION OF SEGOVIA’S AQUEDUCT 45 or baths. However, although there is clear evidence, sufficient research work has not been done either in this zone or throughout the channel leading from the mountains to the city. It has been possible to study, section by section, the main duct that conveyed the water as far as the Alcázar, when it has been necessary to raise the paving to carry out works on the urban services. However, as is the case with the layout from the source, it has not been possible to find any evidence to suggest that this channel is Roman. Nevertheless, it is clear that it formed part of the age-old urban section of the city within the walls, because this was a public ducting network in everyday use. Let’s finish this short essay with a call for serious, methodical and ongoing research into the monument, a task that has never been undertaken, the results of which we can merely speculate about. The undeniable status of the monument clearly makes such a task worthwhile, and the fact that this has still not been done makes such studies all the more necessary. 46 ROMAN ENGINEERING BIBLIOGRAPHY J. P. ADAM: La construction romaine. Materiaux et techniques. Paris, 1984. et. al. (eds.): Elementos de ingeniería romana. European Roman Public Works Conference (3-6 November 2004, Tarragona). Tarragona, 2004. G. ALFÖLDY: Die inschrift des aquäduktes von Segovia. Ein vorbericht, zeitschrift für papyrologie und epigraphik, no. 94, 1992, pages 231-254. — Die bauinschriften des aquäduktes von segovia und des amphitheaters von Tarraco, Madrider Forschungen, no. 19, 1997. — La inscripción del Acueducto de Segovia. Madrid, Ed. Spanish by JORGE MEIER and THOMAS G. SCHATTNER, 2010. M. ALMAGRO BASCH and L. CABALLERO ZOREDA: «Las excavaciones realizadas a lo largo del acueducto romano de Segovia», in Various Authors: Segovia y la arqueología romana. Barcelona, 1977, pages 33-42. A. BLANCO FREIJEIRO: «Epigrafía en torno al Acueducto de Segovia», in Various Authors: Segovia y la arqueología romana. Barcelona, 1977, pages 131-146. M. A. CHAVES MARTÍN: Arquitectura y urbanismo en la ciudad de Segovia (1750-1950). Segovia, 1998. — «El acueducto en la ciudad. La configuración urbana de Segovia en torno al canal “Madre del agua”», in Various Authors: Monumentos restaurados. El acueducto de Segovia. Madrid, 2002, pages 37-76. A. CHOISY: El arte de construir en Roma. Madrid, 1999. D. DE COLMENARES: Historia de la insigne ciudad de Segovia y compendio de las Historias de Castilla, 3 vols. Segovia, 1994. C. FERNÁNDEZ CASADO: Acueductos romanos en España. Madrid, 1972. M. DE FRUTOS BORREGUERO: Época y conservación del acueducto de Segovia. Madrid, 1992. A. GÓMEZ DE SOMORROSTRO: El acueducto y otras antigüedades de Segovia. Facsimile Edition by Miguel de Burgos (1820). Segovia, 1983. T. GONZÁLEZ ROLÁN and L. A. DE CUENCA: Frontinus. De aquaeductu urbis Romae, Col. Hispánica by Greek and Latin Authors. Madrid, 1985. I. GONZÁLEZ TASCÓN and I. VELÁZQUEZ: Ingeniería romana en Hispania. Historia y técnicas constructivas. Madrid, 2005. T. A. HODGE (ed.): Future currents in aqueduct studies. Leeds, 1991. R. INNOVES and R. MARTIN: Dictionnaire méthodique de l’architecture Grecque et Romaine, 2 vols. Roma, 1985. X. LAFON and G. SAURON: Thèorie et practique de l’architecture romaine. Études offertes à Pierre Goss. Aix en Provence, 2005. R. MARTA: Architettura romana. Tecniche costruttive e forme architettoniche del mondo romano. Roma, 1990. L. J. MUNICIO GONZÁLEZ: «La arqueología y el acueducto», in Various Authors: Monumentos Restaurados. El acueducto de Segovia. Madrid, 2002, pages 201-207. G. PRIETO VÁZQUEZ: «Excavaciones arqueológicas en el acueducto de Segovia. 1998», in Various Authors: Segovia Romana. Segovia Exhibition Catalogue, October 2000. Segovia, 2000, pages 89-136. M. QUINTANILLA: Memoria descriptiva del puente acueducto de la ciudad de Segovia, por el Arquitecto Don Juan José de Alzaga, 1835. Estudios Segovianos, Volume V, 15, Segovia, 1953, pages 311-346. A. RAMÍREZ GALLARDO: Supervivencia de una obra hidráulica. El acueducto de Segovia. Segovia, 1975. J. RIVERA BLANCO: «El Acueducto de Segovia: Restauraciones históricas», in Various Authors: Monumentos restaurados. El acueducto de Segovia. Madrid, 2002, pages 149-199. J. A. RUIZ HERNANDO: Historia del urbanismo en la ciudad de Segovia del siglo XII al XIX, 2 Vols. Segovia, 1982. — La ciudad de Segovia. Segovia, 1986. J. SANTOS YANGUAS et. al.: Epigrafía romana de Segovia y su provincia. Segovia, 2005. VARIOUS AUTHORS: Bimilenario del acueducto. Commemorative Exhibition. Catalogue. Madrid, August-September, 1974. VARIOUS AUTHORS: Segovia y la Arqueología Romana. International Roman Architecture Symposium. Bimilenario del Acueducto. Barcelona, Publicaciones Eventuales 27. Universidad de Barcelona, 1977. VARIOUS AUTHORS: Segovia 1088-1988. Actas del Congreso de Historia de la Ciudad. Segovia, 1991. VARIOUS AUTHORS: Segovia Romana. Segovia Exhibition Catalogue. Segovia, 2000. VARIOUS AUTHORS: Monumentos Restaurados. El Acueducto de Segovia. Madrid, 2002. VARIOUS AUTHORS: Aqua romana. Técnica Humana y Fuerza Divina. Barcelona, 2004. A. ZAMORA CANELLADA: El Acueducto de Segovia. Col. Segovia al Paso 1. Segovia, 1995. — «Huellas de Factura en el Acueducto de Segovia», in J. L. GARCÍA HOURCADE et al. (eds.): Estudios de historia de las técnicas, la arqueología industrial y las Ciencias. Actas del VI Congreso de la Sociedad Española de Historia de las Ciencias y de las Técnicas (La Granja de San Ildefonso, September, 1996). Salamanca, 1998, pages 149-158. — «Roma, desde el Museo de Segovia», in Various Authors: Segovia Romana. Segovia Exhibition Catalogue, October 2000. Segovia, 2000, pages 45-70. R. ALBA Back to Contents A FEW TRACES FROM THE CONSTRUCTION OF SEGOVIA’S AQUEDUCT 47 3 Hydraulic Engineering and Religion in the Roman Empire: Trajan and the Construction of Canals SANTIAGO MONTERO HERRERO Professor of Ancient History. Universidad Complutense de Madrid The construction of channels to divert water courses or lower their discharges, i.e. taking the water away for secular uses, has been considered since the times of Ancient Greece as a serious act of ungodliness1. Two Persian monarchs, Cyrus and Xerxes, committed this act of impiety against rivers denounced later by the Greeks and Romans. Cyrus, on his march to Babylon, reached the River Gyndes, a tributary of the Tigris, which also marked the frontier between the Iranian Plateau and the Mesopotamian flood plains. When he attempted to cross it one of his sacred white horses was dragged away by the river currents and drowned in it. The monarch «was extremely annoyed with the river for having committed such an act and threatened to make it so insignificant in the future that even women would be able to cross it easily without getting their knees wet». Carrying out his threat, he decided to punish the river by excavating 180 channels on each side: «…After the threat, abandoning the expedition against Babylon, he split his army in two and, once it was divided, he marked out in a straight line and running in all directions, 180 channels on each bank of the Gyndes, throughout the length of the river. Once he had plotted the work to be done, he ordered the army to dig the channels. As a large number of people were excavating, the works were completed soon, but they spent the whole summer working in this place. When Cyrus had punished the River Gyndes, dividing it into 360 channels and the following spring came around, he decided to continue with his march on Babylon» (Herodotus I, 189; Translation: A. González). In spite of this, Cyrus was always presented as the «perfect sovereign»2; proof of which lies in the fact that he managed to take the City of Babylon, subduing the river that surrounded it by subjecting it to another civil engineering operation. However, in this case, 49 what is of interest to us is that Herodotus viewed the channelling of the River Gyndes in a negative light, as an act of hybris [exaggerated self-pride] committed against nature and the sacred waters of the river. Xerxes constructed a canal for navigation in the isthmus on the Mount Athos Peninsula when he invaded Greece around 480 BC3. His reason for doing this was to make it easier to move his huge fleet and shorten the duration of the expedition. It must not be forgotten that a few years earlier, his father, Darius I, lost a large number of vessels and men after being surprised by a storm when attempting to go round that peninsula. According to Herodotus, the canal constructed by Xerxes was wide enough to enable two ships to pass simultaneously, but perhaps the most interesting point was his reasons for doing it: «As far as I am concerned on making my own conjectures, Xerxes ordered this canal to be constructed through pride, in order to demonstrate his power and leave a legacy worth remembering: because, although it was possible without any great effort to drag the vessels across the isthmus, yet he ordered a canal to be excavated in the sea that was wide enough to allow two triremes to sail through abreast. And he also ordered the same people who he had ordered to construct the canal, to join one bank with the other, to span the River Strimon with a bridge» (Herodotus VII 24; Translation: A. González). It is clear that the Greek Gods were against this kind of works and they made this known to men through the oracles. When the inhabitants of Cnidus were attacked by Harpagus and they tried to cut off the isthmus to turn the city into an island (since apart from a strip it was surrounded by sea), in the face of the difficulties posed by the works and the numerous accidents that befell the workers, they decided to consult the Oracle of Apollo, convinced that the God in question was against those works. The oracle was as follows: «Do not fortify or excavate the Isthmus / because if Zeus had wanted to do so, he would have made it an island»4. The precedents of Cyrus and Xerxes were borne well in mind by the Roman powers. Over the last centuries of the Republic, and after inheriting hydraulic techniques from the Etruscans, Rome was able to systematically modify rivers throughout their different stretches sectioning the gradients of the sections through which they flowed, creating cuts or opening up new channels running parallel so that the original riverbed was abandoned. However, and even though we have not always heard about it, many of these works were opposed by both the Roman and Italic inhabitants as well as those who lived in the provinces, on the grounds of religious beliefs. Local superstitions and beliefs were undoubtedly obstructions to the construction of hydraulic works and the Roman authorities often found themselves having to stop constructing channels especially in deified water courses, in order to avoid confrontations with the local inhabitants who, supported by local priests, remained faithful to the cult of water deities. This also happened in Italy: remember how the population living on the banks of the Tiber and the senators themselves opposed the modifications to be made to the river course in Tiberius’ times, when plans were made to divert tributaries (like the Clanis) or filling in some lakes. It was necessary – or so it was said – to respect the powers that the river people attributed to their 50 ROMAN ENGINEERING rivers and thus prevent the wrath of divus amnis Tiber once he was deprived of his tributaries5. In Rome and the Italian Peninsula, the emperor often had to confront the superstitious reactions of the inhabitants, frequently supported by the decemviri and the political opposition. However, some Roman emperors, defying the technical risks and, above all, the consequences where religion was concerned, dared to carry out works to divert rivers, join one to another or by-pass the most hazardous stretches. Trajan was one such emperor. The Italian scholar G. Traina maintains that in his epoch technical progress in the field of public works gradually «dispelled» the objections raised by the ancients with respect to major projects. And he points out that this is how the attitude towards these works, like the opening of the Isthmus of Corinth for example, is understood by authors such as Suetonio: «In particolare i piani di Traiano, che disponeva di ottimi architetti, potevano aver influenziato l’ atteggiamento di Suetonio verso i progetti di taglio del Istmo»6. According to G. Traina, Chapter 44 of Caesar’s Vita by Suetonio, which lists the public works projects ordered by the Roman dictator, is a political testament «che trova riscontro nelle imprese dell’optimus princeps»7. Ventures such as the Parthian and Dacian Wars, the draining of the Fucine Lake or the Pontine Dams which were attributed to Caesar, all fall within the spirit of the actions taken by Trajan. However, the undeniable progress made by Roman techniques and engineering at the beginning of the 2nd Century AD did not mean to say that there was not a certain amount of opposition of a religious nature from some of the inhabitants. THE FOSSAE (CANALS) OF NICOMEDIA In January 97 AD, Pliny wrote a letter to the Emperor from Bithynia. There was a large lake 30 km to the east of the City of Nicomedia, which is now known as Sabandja Göl (called Sunonensis by Ammianus Marcellinus XXVI 8, 3), which linked up with the Black Sea and Central Anatolia via the Rivers Melas and Sangarius. The Governor suggested to Trajan that two canals (fossae) be constructed, one to connect the lake to Nicomedia and the other to shorten the route between the two rivers. It would thus not only be possible to irrigate the country, but also the canal would connect Nicomedia, in the Gulf of Ismid, with Central Anatolia and the Black Sea: «When I consider the grandeur of your destiny and your character, it seems to me that it would be most advisable to make this clear with works worthy of both your immortality and your glory and that such works should be both useful and beautiful. There is a very large lake near Nicomedia, across which blocks of marble, the fruits of the earth, wood for homes and timber for construction are all transported by ship as far as a road at a moderate cost and effort. However, from that point they are taken by cart to the sea with great difficulty and at a higher cost... [Probable gap in the text]... this work requiring an important work force. But this will not be lacking in the future, because apart from there being many men working in the fields, there are many more in the city, and there is a certain hope that all of them might understand with great pleasure a task that has to be to the benefit of HYDRAULIC ENGINEERING AND RELIGION IN THE ROMAN EMPIRE 51 them. All that you have to do is send, if you think fit, a surveyor or an architect to study in detail whether this lake is higher than the sea. I have found in these territories one canal excavated by one of their kings, but it is not certain whether it was dug to collect water to irrigate the nearby fields or to connect the lake to the river, because the works were never finished. It is also uncertain whether the work was interrupted by the death of the king or because the works were not expected to be successful. That is why (allow me to be ambitious for your glory) I am all the more in favour of works being completed by you that other kings were only able to begin» (ep. X, 41)8. The emperor replied to the letter with another shorter one, in which he was wary of the technical difficulties involved in the project but without showing opposition to it: «This lake that you speak of could encourage us to link it to the sea, but first it is necessary to study in detail how much water flows into it and from where, so that if it is connected to the sea, it does not empty completely. Can you ask Calpurnio Macro for a surveyor, and I will send you from here an expert in this type work» (ep. X, 42)9. Finally, we have a second letter from Pliny to the emperor, in reply to that one, in which once again he insists on his project: «You Sir, with your extraordinary prudence fear that, once the lake is linked to the river and in this way to the sea, the lake will be emptied, but I believe, from field research, that I have found a way around this danger. Indeed, the lake can be joined by a canal to the river without its waters pouring into it. We will manage to ensure that it is not deprived of its waters when they flow into the river the result being however as if the waters did in fact mix. It would be very easy to transport the load carried by the canal as far as the river via this very small piece of land that will go between them both. This will be done if need be, although I hope it will not be necessary. The lake is quite deep, and a water current now flows in the opposite direction, which, once closed on that side and diverted in the direction that we want it to go, will let flow as much water as it currently contains without causing any damage to the lake. Furthermore, some streams run across the land where the canal is to be excavated, and if they are carefully collected they will increase the discharge that is provided by the lake. Notwithstanding, if there is a preference for making a longer canal and, once excavated more deeply, making it be at the same level as the sea and not letting its waters flow into the river, but into the sea itself, the tide from the sea will hold back the flow coming from the lake. If the lay of the land does not permit any of these solutions, we would still have the option of holding the course of the waters using locks. But the soil expert that you must send, Sir, as you have promised, will examine these and other possibilities much more thoroughly. Because the task is worthy of your grandeur and preoccupation. Meanwhile, I have written to Calpurnio Macro, a clear-headed man, as you advised, so that he can send me the most suitable surveyor possible» (ep. X, 61)10. The canal was probably beyond the technical possibilities of the Romans, because it required, as we are told, the use of catarractae, i.e., locks or sluice gates, made of stone to 52 ROMAN ENGINEERING FIG. 1 Nicomedia-Black Sea Canal Project. regulate the water volumes. Pliny and the emperor himself in his reply to the first letter (ep. X, 42) show their concern for the difference in level between the lake and the sea. However, in my opinion, Trajan’s reply reveals the knowledge or, at least, the information that the emperor had available even then in matters concerning canals, which he could have gleaned from the engineers during his stay in Germany on the Rhine front, where he could have received information, for example, about the canal constructed by Druso (Fossae Drusianae) in 12 BC that linked the Rhine and the Issel, or the project submitted to Nero to connect the Rivers Saône and Moselle (Tac., Ann. 13, 53). It was essential for «libratores» [surveyors] to be involved in the construction of these canals and to regulate river navigation, and their technical knowledge was also indispensable for the construction of aqueducts, canals and other structures to ensure that the water flowed from one place to another11. The problem of all the lake waters flowing into the sea was solved by Pliny with the consideration that the lake was deep enough not to empty with the lowering of the shoreline that was inherent to excavating the canal, and with the observation that the water discharge that would take place through the canal would be neutralised by an emissary outlet. Therefore, the water outflow would remain constant and so would the level of the lake. Pliny considered the idea of the local inhabitants participating in the works (manus), which as we shall see later, was not uncommon [FIG. 1]. Only technicians and experts in hydraulic works were mentioned in the correspondence between the emperor and his governor, yet the project undoubtedly had certain religious connotations. It happened that the God-River Sangarius, referred to by Homer in his Iliad (3.187; 16.719), was the son of Oceanus and Tethys, husband of Metope and father of Hecuba (Hes., Theog. 344; Apollod. III 12, 5). According to a legend, to which reference is made in a scholium, he was originally a man who having offended Rhea was punished by becoming a water current (Schol. ad Apollon. Rhod. II, 722). Furthermore, the River Sangarius had a special significance for Rome. In 189 BC, when the consul Manlio Vulsone used a bridge to cross the river and reached the other side, the Gallic priests of the goddess Sybil came to his meeting from Pessinus announcing in a frenzied chant that the goddess had paved the way to war for the Romans and that she granted them victory and control over that region (Liv. 38, 18, 9). HYDRAULIC ENGINEERING AND RELIGION IN THE ROMAN EMPIRE 53 THE IRON GATES CANAL ON THE DANUBE In the spring of 98 AD, Trajan paid an inspection visit to the Danube Frontier that three years later, as from 101 AD, would be the scenario for the first Dacian War. Resorting to Moesia’s troops he also constructed a canal – in Winter 98 and throughout 99 AD – in order to by-pass the so-called Iron Gates of the Danube, that we learnt about thanks to a marble plaque (AE 1973, 475), dating back to 101 AD, which bears the inscription: Imp(erator) Caesar divi Nervae f(ilius) Nerva Traianus Aug(ustus) Germ(anicus), Pont(ifex) max(imus) trib(unicia) pot(estate) V p(ater) p(atriae) co(n)s(ul) IIII ob periculum cataractarum derivato flumine tutam Danuvi navigationem fecit. («The Emperor Caesar Nervae Traianus Augustus Germanicus, son of the Divine Nerva, maximum pontiff, invested with the tribune’s authority for the fifth time, father of the nation, consul for the fourth time, having diverted the water course of the river to avoid the danger caused by waterfalls, made navigation on the Danube safe».Translation: J. González and J. C. Saquete) [FIG. 2]. After the official title, the inscription proclaims that Trajan, by diverting the river because of the falls or rapids, made it safe to navigate on the Danube. The verb derivato refers to the construction of a new canal in the vicinity of Viminacium, to by-pass the rapids in the scary Iron Gate. It led off from the mouth of a tributary, the Kasajna, and crossed the beds of the Rivers Trstenica and Kosivica; the three currents were regulated by lock gates to prevent the build-up of alluvial deposits. Rivers, in this case the Danube, were an excellent driving force for the economic life of the provinces, and made civil and military communications on the frontier easier. However, it was necessary for the emperor to take the required measures to ensure that the river was permanently navigable. Thanks to the archaeological work carried out, we know that Trajan’s Canal was over 3 km long FIG. 2 Commemorative Inscription for the Trajan Canal on the Danube. 54 ROMAN ENGINEERING and 57 m wide. The marble plaque bearing the inscription was placed on the arch over the road that ran from the Diana Castrum to the canal (101 AD). In the 6th Century, Procopius (de aedificiis IV, 6, 8 et seq.) also makes reference to the diversion of the river, associating it with navigation and not, as has sometimes been speculated, with the construction of the famous bridge. He also added that he did not wish to spend more time discussing these hydraulic works because Apollodorus had already written extensively about it, although it would appear to have been lost in the passage of time. However brief, his testimony confirms the contents of the inscription. It is possible that, as Sasel suggests, Trajan might have constructed two more canals in the zone, one close to Karatas and the other in the vicinity of the town of Sip12. He was able to use the Messian Army to help with this task, under the direction of C. Manlius Felix, the emperor’s praefectus fabrum (officer in charge) in 100 and 101 AD [praef(ectus) fabr(um) imp(eratoris) Caesaris Nervae Trai(ani) Germ(anici) Dacici II: CIL III 726=ILS 1419]. To make troop transport easier, Trajan ordered the road already initiated by his predecessors to be extended along the right bank of the Danube. The works done on this road are commemorated by an inscription dating back to between 100 al 103 AD. The monument takes the form of a large inscription carved into the rock itself, 3.20 m long and 1.80 m high, adorned with two winged dolphins, 6-petalled roses and an open-winged eagle. It is protected by a pediment bearing the modern inscription in embossed form and is known as «Tabula Traiana» «Trajan’s Plaque»: Imperator Caesar divi Nervae filius / Nerva Traianus Augustus Germanicus / pontifex maximus tribunicia potestate IIII / pater patriae consul III / montibus excisis anconibus sublatis viam refecit (CIL III 1699). The decoration features the image of an eagle, figures of genies and one more, which probably depicts the God Danubius. The truth is that this road required highly singular engineering works to be performed, as can be deduced from the expression anconibus sublatis, perhaps the use of wooden beams over water or over land (ancones, elements in the form of bracket arms to support a structure). But what matters to us is the proud tone in which he proclaims that he has cut into the mountains to carry it out (via per montes excisa), another triumph over nature similar to the one to be performed with the construction of the famous bridge spanning the Danube. The improvement made to navigating conditions in the Danube coincided with the creation of the Danube route along the Iron Gates stretch, which was carried out in several stages. It ran along the right bank of the Danube and its purpose was twofold: on the one hand, to enable the military forces in the region to communicate with each other, and, on the other hand, to link the Danubian camps, guaranteeing a regular supply for the troops13. It also served to enable vessels to be towed upstream when there were navigation problems, to which the traces of cuts in the rock to secure the mooring ropes bear witness. A set of inscriptions enables us to know the different stages in the route construction process and the various tasks performed. Trajan, following the work first ordered by Tiberius and then by Claudius, decided to prepare for the Dacian Wars by subjecting the Danubian Path and the fortresses in the region to a major reconstruction process, references to which can be seen on several inscriptions to be found close to the river banks so they could be read from the ships that sailed its waters. One of the plaques, which is situated close to the Tabula Traiana, is dedicated by the lapidarii to Hercules: Herculi HYDRAULIC ENGINEERING AND RELIGION IN THE ROMAN EMPIRE 55 Recreation of the repairs to the original rope towpath in the Danube Gorge, carried out in Trajan’s times, according to Connolly, 1989. FIG. 3 sacrum / lapidarii qui exieru[nt] at (?) ancones facien / dos legionis IIII Fl(aviae) / et legionis VII Claudiae /v(otum) so[lverunt]14. In spite of the challenge that these works amounted to against the river deities and the gods who protected the inalterability of nature and its water courses, the religious element is ever-present not only in the famous Tabula but also in this particular inscription [FIG. 3]. Really, that is the way things had to be, because ever since the Empire established itself, the Danube was not only a frontier river, but also an ancient river deity that Trajan even tried to present to Roman public opinion as a Pro-Roman god. That is what can be deduced from the sestertii minted from 103 AD onwards, on which the bust of the emperor appears on the obverse, and on the reverse there is a woman, the personification of Dacia, sitting on the ground, held by force by a male figure, the god Danubius, naked from the waist upwards holding a reed in his left hand. The figure depicted on the coin wears a pileus (brimless hat) so characteristic of the Dacian nobility, and also wears a cloak with slits in the sides and tight pants typical from Dacians15 [FIG. 4]. Only a few years later, Decebalus, the great Dacian king whom Trajan fought against, also diverted the course of another river, the Sargetias (perhaps the River Bistra that runs close to Hateg), in order to bury in its bed the treasure that according to Lydus’ estimates (de magistratibus II, 228), quoting Crito, amounted to 5 million pounds’ weight in gold and twice that in silver, as well as numerous dishware and goblets16. A Dacian nobleman, Bicilis, betraying his boss, revealed the secret to Trajan, who no doubt re-diverted the course of the river to lay his hands on the treasure. The episode is recalled by Cassius Dio: «Decebalus’ treasure was also discovered, hidden under the River Sargetias which runs beyond his palace. With the aid of some captives, Decebalus had diverted the river course, had dug a hole in the riverbed and had buried in it a large amount of gold and silver and other objects of great value that could withstand moisture; he had then piled stones over this treasure and had covered the spot with earth, before diverting the river back to its original course. He had also ordered the same captives to leave their tunics and other articles of certain value in these caves, and after they had done this he dispersed them to prevent them from discovering anything. However, Bicilis, a colleague of his who knew what had happened, furnished information about these occurrences when he was captured» (68, 14, 1-5; Translation: Pilar González-Conde). 56 ROMAN ENGINEERING Sestertius, depicting the bust of Trajan on the obverse and the god Danubio subjecting Dacia on the reverse. FIG. 4 Scene CIII of the Trajan’s Column frieze depicts a mule train loaded with gold, exactly the same as the one shown on the Arch of Trajan in Benevento next to the scenes of the victory over the Dacians. This news would also be confirmed by a letter from Pliny the Younger to his friend Caninius in which he expressed his delight at the publication in the near future of his book on the war against the Dacians, undoubtedly aimed at exalting the heroic deeds of the emperor Trajan. In a passage of that book, he says: «You will make us see rivers flowing through countryside that were once arid and dry; bridges constructed over currents where none had been seen before («dices immensa terris nova flumina, novos pontes fluminibus iniectos» ep. VIII, 4). The reference to the bridges is clear (it obviously refers to the bridge spanning the River Danube constructed by Trajan), whereas the presence of rivers in the middle of the countryside may allude to the diversion of River Sargetias to reveal the treasure hidden by Decebalus. As far as the actions taken by the Dacian king are concerned, these are reminiscent of the customs of other peoples, who took a similar course of action when they buried their leader, this being the case with Alaric, the Visigoth, buried alongside his treasure on the bed of the River Busento17: «He [Alaric] is greatly missed by his people who loved him greatly. They diverted the course of the River Busento, near the City of Cosenza (this river runs from the foot of the mountain as far as the city with its healthy waters) and made a group of prisoners dig a tomb in the middle of the riverbed. They buried Alaric in this hole, together with a lot of valuables, then they re-diverted the river back to its course and killed all the people who dug the hole so that nobody could ever find the spot» (Jordanes, Get. 158). THE TRAJAN CANAL AND THE TIGRIS During his third and final campaign against the Parthians, in 116 AD, Trajan, while advancing upon Ctesiphont via the River Tigris, wanted to create a canal between the Naarmalca and the Tigris. Some sources indicate that on finding out that at this point the Euphrates flows at a greater altitude than the Tigris, it was feared that the canal would overflow from one and flood the other, so the task was abandoned. Trajan eventually de- HYDRAULIC ENGINEERING AND RELIGION IN THE ROMAN EMPIRE 57 cided to drag his vessels overland using machines that were probably winches and rollers, which was performed successfully. Trajan and Pliny faced the same problem of difference in level years earlier, as we have seen, with the Nicomedia canal construction project. However, other authors mention the excavation of the canal, and there is also a third possibility, that the canal was already constructed and all that Trajan had to do was recuperate its flow. Cassius Dio, Ammianus Marcellinus and Zosimus refer to the episode18: 1) «Trajan intended to connect the Euphrates to the Tigris by canal, so that the vessels would sail down the latter and he would be able to construct a bridge. However, on finding out that the altitude of the Euphrates was much higher than the Tigris, his aim was not carried out, because it was feared that the Euphrates would also be rendered un-navigable if all its currents were drawn downstream through the canal. Having thus borne the ships on rollers overland from one river to the other, this tract being very narrow at this point (all the waters of the Euphrates flow into marshland and then join the waters of the Tigris), he crossed the Tigris, reached Ctesiphont and, taking it, was proclaimed emperor by the soldiers and ratified the sobriquet of Parthian» (Cassius Dio 68, 28, 1 - 2; translation: J. Gil). 2) «From that point they reached a channelled river called the Naarmalcha, which means “King’s River”, which was dry at the time. First it was Trajan and then Severus who strove to excavate an artificial water course in the earth that had built up, so that they could transfer water from the Euphrates to this place, thus enabling the vessels to reach the Tigris» (Amm. Marc. 24, 6, 1; translation: M. L. Harto Trujillo). 3) «They left that place to reach a very large channel that, according to the locals had been constructed by Trajan during his expedition against the Persians. The River Narmalaques discharges into it before flowing into the Tigris. The Emperor [Julian] considered cleaning it and inspecting it, thereby providing the ships with a route to the Tigris and giving the rest of the army bridges to cross, if this were possible» (Zos. III 24, 2; translation: J. M. Candau). It was undoubtedly F. Pashoud who, in two works, paid most attention to the canal19. In view of his conclusions and knowing what his sources were, we can state above all, that it was Zosimus who was right: Trajan’s Canal linked the Naarmalcha to the Tigris; Ammianus mistook, as all publishers accept, the Naarmalcha with Trajan’s Canal, also forgetting that he had already mentioned the Naarmalcha in 24, 2, 6. In fact, Trajan wanted his ships to go from the Naarmalcha to the Tigris via a canal, but, realising that the Euphrates was at a higher altitude than the Tigris, he gave up his project fearing that it would cause the water level in the Euphrates / Naalmarcha to fall to such a low level that navigation would be impossible. Therefore, he had to tow the ships along the narrow stretch that separates the two water courses. Dio’s text confirms the distance as being 30 stadia (5.5 km) that Ammianus indicated, i.e., the distance that separates the Naarmalcha from the Tigris. F. Pashoud later wonders if this canal existed before Trajan reached Mesopotamia. He considers Dio’s text to be ambiguous over this point: he thinks that constructing a navigable canal 5 km long was not a minor task and certainly more difficult than trans- 58 ROMAN ENGINEERING porting the ships overland. He thinks that the canal was not opened by Trajan, believing that it was already there: given that the emperor feared lowering the water level in the Naalmarcha, this was obstructed and dry as Julian found it centuries later. Nevertheless, two points weaken his theory: the name of the canal (Trajan’s Canal) and Libanius’ testimony (Or. XVIII, 244-247), which suggests that this canal was the work of palaios basileus, a term that seems to be used to refer to the Roman emperor. Pashoud is of the opinion that, as the canal gave direct access to Seleucia and to its wharfs, its construction has to be put down to the period when the city was founded by Seleucus Nicator. It must be remembered that Ammianus expressly mentioned the excavation (solo fodiri in modum canalis amplissimi studio curaverat summo). Once again, religion appears to have played a very small role in Trajan’s decisions, although the Euphrates and the Tigris, as river deities, do appear on sestertii minted in 116-117 AD after the Roman emperor’s victories in Mesopotamia20 [FIG. 5]. Trajan’s Canal, according to Pashoud, 1979. FIG. 5 HYDRAULIC ENGINEERING AND RELIGION IN THE ROMAN EMPIRE 59 THE TRAÏANOS POTAMÓS While Trajan was finishing off the operations that enabled him to turn Dacia into a new Roman province, his legate in Syria, Aulo Cornelio Palma Frontoniano proceeded to annex Nabataean Arabia (which included the northern coasts of the Red Sea and the Sinai Peninsula as far as Petra). In order to intensify the economic policy with the eastern countries as from 112 AD, the emperor ordered the then abandoned but formerly navigable canal between the Nile and the Red Sea to be completely re-excavated. The canal started off from the Egyptian town of Babylon, close to Cairo, and flowed out into the Port of Clysma, in the north of the Red Sea21. Trajan undoubtedly used the old canal constructed in Pharaoh Necho’s times (XXVI dynasty) and later by the Persian King Darius I and the Hellenic monarch Ptolemy II Philadelphus, but the works, still visible in some places, must have been huge, because the Nile had to provide sufficient water to make the canal navigable, and it cannot have been simply a question of reopening older works that had fallen into disuse. Whatever the case may be, it was the only canal open between the Nile and the Red Sea during the Roman period. It is referred to by several different names. An ostracon dating back to the year 112 mentions the Potamos Babylonos. Midway through the 2nd Century AD the geographer Ptolemy (4, 5, 54) mentions the Traïanos Potamós also from Babylon as far as Clysma in the Red Sea. The brief news that addresses this waterway does not enable us to conclude that the canal was then either totally or partially navigable, but it is the first non-papyrological reference to the hydronym. One generation later, Lucian of Samosata, in a satirical work written around 180 AD, Alexander or the False Prophet (Pseudomantis, 44), mentions in passing, the voyage of a man sailing up the Nile (anapleusas) as far as Clysma, the port on the Red Sea, where he embarked for India. The only aim of that work must have been to facilitate the trade with Arabia and India. The strategic importance of this waterway is beyond all doubt, because it permitted Roman merchant shipping to travel from the Mediterranean to the routes of the luxurious trading objects of Arabia Felix (Yemen), India and the Far East, and it was frequented throughout the duration of the Empire. It cannot be ruled out either that the canal facilitated the export of heavy loads of grain, wine and textiles obtained in the southern delta and the oasis of El Fayum. Trajan established a permanent military fleet in the Red Sea, the Classis Arabica, to guarantee that the route was protected. The opening of the canal would undoubtedly have aroused a certain amount of religious controversy. Necho continued with the works of previous pharaohs, connected Lake Timsah with the Bitter Lakes by canal. Herodotus (II, 158) informs us that, during the excavations for this project, 120,000 men lost their lives, and the pharaoh had to give up the work halfway through because he was stopped by an oracle announcing that «he was working to the advantage of the Barbarians». It is possible that in Trajan’s time the superstitious considered that those works were to blame for two serious events: the insufficient rise of the Nile22 and the Judaic revolt of 11523. Sijpestejn stresses that Turbo, sent by Trajan to Egypt in 117 AD, carried out the re-construction of the fortress of Babylon and defended the channel from the attacks perpetrated by the Hebrews rising up against Roman power24. 60 ROMAN ENGINEERING The canal in times of Darius I, connecting the Bitter Lakes to the Gulf of Suez. FIG. 6 The Nile is the river deity that appears most often on the different coins minted during the Trajan period, and in the greatest variety of forms [FIG. 6]. THE TRAJAN’S FOSSA Trajan also constructed two major canals in Italy, in Rome. The works must have been carried out between the construction of the Danube Canal and the Nile Canal to the Red Sea. In the year 103, the Tiber caused a disastrous flood, described by Pliny, who witnessed the catastrophe. Little importance has been attached to the fact that C. Plinius Caecilius Secundus was curator albei Tiberis et riparum et cloacarum Urbis [i.e.: conservator of the Tiber, its banks, sewers and city drains drains], incidentally, a post created two years before by Trajan, almost certainly succeeding the famous Julius Ferox between the years 103 and 11025, so his description has a special value. Pliny appears to attribute the flooding of the Tíber entirely to natural causes; it must have been under his management that looking after the city’s sewerage system was entrusted to the curatores [conservators] of the Tíber, with a view to «improving the fight against flooding»26. The effects of those floods must have been disastrous, judging by the many epigraphic testimonies that recall it. The river might have broken the pons Sublicius, the oldest bridge in Rome, which Dionysius of Halicarnassus (III, 45) expressly states «was considered to be sacred». A coin (minted around 105-107 AD) that depicts the bridge may commemorate – as has been postulated – the destruction of the bridge and its subsequent reconstruction carried out by Trajan27. The event was particularly serious if we take into account the fact that, a year before, Trajan had constructed a fossa (canal), which is the current Fiumicino Canal, mentioned by Pliny, and an inscription from the period found in Ostia: HYDRAULIC ENGINEERING AND RELIGION IN THE ROMAN EMPIRE 61 «The Tiber has burst its banks and at the points where they are lower has caused considerable damage to the land. In spite of the drainage from the canal that the providential emperor ordered to be excavated (fossa, quam providentissimus imperator fecit), it covers the valleys, floods the fields and places where the terrain is flat and its waters can be seen instead of the ground» (Plin., ep. VIII, 17). [Imp(erator) Caes(ar) diui] / Ne[ruae fil(ius) Nerua] / Tra[ianus Aug(ustus) Germ(anicus)] / Dac[icus, trib(unicia) pot(estate) ——] / im[p(erator) —- co(n)s(ul) —- p(ater) p(atriae)], / fossam [fecit] / [q]ua inun[dationes Tiberis] / [a]dsidue u[rbem uexantes] / [rivo] peren[ni] instituto arcerentur] (CIL XIV, 88=ILS 5797). «The Emperor Caesar Nerva Trajan Augustus Germanic Dacicus, son of the divine Nerva, invested by the power of the Tribune for the xxx time, proclaimed emperor by xxxx, consul by ..., father of the nation, constructed this canal to prevent the Tiber from flooding the city, which frequently happened, having established a permanent channel of water» (Translation: J. González and J.C. Saquete). Indeed, in the year 100, Trajan ordered construction work to start, to the southeast of the Port of Claudio, for a second port, hexagonal in shape (32 Ha and 5 m deep). The works were completed along with several tanks, 2 km of quays, as well as river facilities in Rome designed to unload and receive the imported goods. At the same time, the emperor gave instructions for an artificial canal to be built, the famous Fossa Traiana (now known as the Fiumicino Canal), which connected the Tiber to the sea, passing close to the port (the engineers constructed for it a narrow canal 20 m wide), so that the vessels could reach the river port of Rome [FIG. 7]. The aim of Fossa Traiana, the bottom of which was paved to enable it to be cleaned and the sediment removed, was, amongst other things, for the new mouth to enable the floodwaters to drain away and keep Rome safe from flooding28. This is what was written on the inscription on the line of a previous one from Claudius (CIL XIV, 85). However, FIG. 7 62 ROMAN ENGINEERING Trajan’s Fossa. the new works were unable to hold back the waters (Plin., ep. VIII, 17, 2: quamquam fossa, quam providentissimus imperator fecit...), and the fatal consequences for the city and its inhabitants were soon to be felt. The overflowing of the Tiber banks as it flowed through Rome was traditionally regarded as a disaster that heralded not only the end of the pax deorum, but also a phenomenon that questioned the legitimacy of Roman power. It is possible that Trajan, following in the footsteps of Tiberius, might have opted for technical solutions, rejecting all religious explanations for the phenomenon. The inscription that commemorates the construction of the fossa revealed how the emperor and the administration dealt with a phenomenon that was obviously natural to which hydraulic engineering provided the answer, and not procuratio prodigiorum ,[Acts of God]. However, that declaration of principles must have been seriously questioned by pontíffs, decemvirates and aruspices when another flooding took place in 103. It appeared that Trajan had once again extracted the waters belonging to another river deity, perhaps the most venerable one of all, the god Tiberinus or Tiberinus Pater29. CONCLUSIONS What can account for Trajan’s interest in constructing canals and diverting rivers in different parts of the Empire? First of all, it is advisable to bear in mind the models adopted by other emperors before him, such as Augustus and, especially, the figure of his father30. Thanks to the finding of a large number of inscriptions, we are well informed about the professional activities and personality of M. Ulpius Traianus, father of the future emperor. A faithful servant to the Flavius family, he was one of the first supporters of Vespasian. Under his orders he participated in the year 69 in the Judean War as his legate before the X Legion. Consul suffectus in the year 70, he went on to become legate in Syria before September 74, this being where he developed a great interest in public works activity. A Greek inscription dated 73-74 AD, discovered on the west bank of the River Orontes31, commemorates the fact that in Vespasian’s times the works for a «Fuller’s Canal» were carried out, as along with dikes to deviate the downstream course, all under the authority of Marcus Ulpius Traianus, the emperor’s legate. The authority of the governor sanctioned the approval of the Roman power, although in this case they were works of a local nature that the imperial power was not responsible for organising and carrying out, for, as it is stated in the epigraphic text, they were responsibility of the «Metropolis of the Antiochians», so perhaps a corvada might have been necessary. Trajan’s father only gave the order, and then he only acted as a supervisor, whereas the municipal authorities controlled the works devised to irrigate the boroughs where the Antiochians worked. Notwithstanding the above, in the year 75, Trajan’s father undertook in his capacity of a legatus [legate], the construction of another major canal on the River Orontes, to the north of Antioch, in which he was directly involved, as the following Latin inscription recalls32: HYDRAULIC ENGINEERING AND RELIGION IN THE ROMAN EMPIRE 63 Imp(erator) / Vespasianus Caesar / Augustus pontif(ex) max(imus) / trib(unicia) pot(estate) VI imp(erator) XII p(ater) p(atriae) co(n)s(ul) VI / desig(natus) VII censor / Imp(erator) Titus Caesar Augusti f(ilius) / pontif(ex) max(imus) trib(unicia) pot(estate) IV / [co(n)s(ul) II]II desig(natus) V censor / [[Domitianus]] Caesar / Augusti f(ilius) co(n)s(ul) III / M(arco) Ulpio Traiano leg(ato) / Aug(usti) pro pr(aetore) Dipotamiae / fluminis ductum millia(!) / passus tria cum pontibus / [pe]r milites legionum IIII / [III Gal]l(icae) IV Scyt(hicae) VI Ferr(atae) XVI Flaviae / [ite]m cohortium XX / [item?] Antiochensium / [facien]da(?) curaverunt / m(ille) p(assus) I. The canal, three miles long, spanned by bridges, was marked with milestones, one of which, discovered in 196533, refers to the works under the name «canal of the country with two rivers», or «double river» if the bilingual expression Dipotamiae fluminis could be translated in this way. The location of the inscription, 7 km from Antioch, suggests that Dipotamia was the name of the plain that constitutes the confluence of the River Orontes and, flowing from the north, Lake Antioch’s emissary. The ultimate aim of the works was probably to make the course of the Orontes navigable as far as the lake. Whatever the case may be, they were major works, because they required the participation of detachments sent by the four legions and the twenty cohorts stationed in the province of Syria. As these, unlike the «Fuller’s Canal», were public works probably associated with the needs imposed by the war against the Parthians, the Roman army got involved in the works. Summarizing, Trajan’s interest in channelling major rivers was, as in many other aspects, just a continuation of the Flavius family’s policy where these matters were concerned34. Furthermore, it is clear that canal construction was extremely expensive, the cost being much higher than constructing bridges and roads. However, the prestige involved made it a highly profitable activity from a political perspective. It is well worth observing here that by constructing canals, Trajan was associating himself with acclaimed monarchs: in Nicomedia with the Kings of Bithynia (Ego per eadem loca invenio fossam a rege percussam,... Hoc quoque dubium, intercepto rege mortalitate an desperato operis effectu... ut cupiam peragi a te quae tantum coeperant reges: ep. X, 41); in Mesopotamia, mistaken with the Naarmalcha (quod amnis regum interpretatur) with the Seleucia kings; in Egypt, with the pharaohs of the 26th Dynasty and Darius I, King of Persia. All in all, let’s remember what Pliny said about the construction of the Bithynia Canal: it was a work «non minus aeternite tua quam gloria digna, quantumque pulchritudinis tantum utilitatis habitura» («no less worthy of the immortality of your name than for your glory»: ep. X, 41). It was a triumph over nature – at times it was just an attempt – but it was also a triumph over religious scruples. 64 ROMAN ENGINEERING NOTES 1. Concerning the sacred nature of the waters in the Roman world, see chapter I of MONTERO, 2012, with bibliography. Also: S. «La sacralità dell’acqua nel mondo romano-italico», Acque minerali nel Lazio, Roma, ed. Quasar, 2000, pages 11-22. Especially concerning canals as a lack of respect for religion: DIOSONO, 2010. See J. L. DESNIER: De Cyrus le Grand à Julien l’Apostat. Le Passage du Fleuve. Essai sur la légitimité du souverain, París, 1995, pages 20 and 41, no. 18. D. BRIQUEL: «Le passage de l’Hellespont par Xerxes», BAGB, no. 1, 1983, pages 22-30, which examines this episode in detail, and observed that the total number of channels, 360, was the same as the number of days in the Babylonian and Persian year and that these «civil engineering» operations undoubtedly had a symbolic duration of one year, as Herodotus’ text points out. See also SAGGIORO, 2010. B. S. J. ISSERLIN et alii: «The Canal of Xerxes on the Mount Athos Peninsula», Annual of the British School at Athens, no. 89, 1994, pages 277-284. See HEROD. I, 75; AP XIV 81; EUS., PE V 26, 2. see J. M. NIETO: Cristianismo y profecías de Apolo. Los oráculos paganos en la patrística griega (siglos II-IV). Madrid, ed. Trotta, 2010, page 77. S. MONTERO: «Ingeniería hidráulica y religión: un enfrentamiento en época de Tiberio», in T. NOGALES and P. FERNÁNDEZ URIEL: Ciencia y Tecnología en el mundo antiguo. Monografías emeritenses, 10. Mérida, Museo Nacional de Arte Romano, 2007, pages 229-240. G. TRAINA: «L’impossibile taglio dell’Istmo (Ps. Lucian., Nero, 1-5)», RIFC, 115, 1, 1987, pages 40-49. G. TRAINA: Op.cit., no. 6, page 47. (1) Intuenti mihi et fortunae tuae et animi magnitudinem conuenientissimum uidetur demonstrari opera non minus aeternitate tua quam gloria digna, quantumque pulchritudinis tantum utilitatis habitura. (2) Est in Nicomedensium finibus amplissimus lacus. Per hunc marmora fructus ligna materiae et sumptu modico et labore usque ad uiam nauibus, inde magno labore maiore impendio uehiculis ad mare deuehuntur ... hoc opus multas manus poscit. At eae porro non desunt. Nam et in agris magna copia est hominum et maxima in civitate, certaque spes omnes libentissime aggressuros opus omnibus fructuosum. (3) Superest ut tu libratorem vel architectum si tibi videbitur mittas, qui diligenter exploret, sitne lacus altior mari, quem artifices regionis huius quadraginta cubitis altiorem esse contendunt. (4) Ego per eadem loca invenio fossam a rege percussam, sed incertum utrum ad colligendum umorem circumiacentium agrorum an ad committendum flumini lacum; est enim imperfecta. Hoc quoque dubium, intercepto rege mortalitate an desperato operis effectu. (5) Sed hoc ipso - feres enim me ambitiosum pro tua gloria - incitor et accendor, ut cupiam peragi a te quae tantum coeperant reges (ep. X, 41). Potest nos sollicitare lacus iste, ut committere illum mari uelimus; sed plane explorandum est diligenter, ne si emissus in mare fuerit totus effluat certe, quantum aquarum et unde accipiat. Poteris a Calpurnio Macro petere libratorem, et ego hinc aliquem tibi peritum eius modi operum mittam (X, 42). (1) Tu quidem, domine, providentissime vereris, ne commissus flumini atque ita mari lacus effluat; sed ego in re praesenti invenisse videor, quem ad modum huic periculo occurrerem. (2) Potest enim lacus fossa usque ad flumen adduci nec tamen in flumen emitti, sed relicto quasi margine contineri pariter et dirimi. Sic consequemur, ut neque aqua viduetur flumini mixtus et sit perinde ac si misceatur. Erit enim facile per illam brevissimam terram, quae interiacebit, advecta fossa onera transponere in flumen. (3) Quod ita fiet si necessitas coget, et - spero - non coget. Est enim et lacus ipse satis altus et nunc in contrariam partem flumen emittit, quod interclusum inde et quo volumus aversum, sine ullo detrimento lacus tantum aquae quantum nunc portat effundet. Praeterea per id spatium, per quod fossa fodienda est, incidunt rivi; qui si diligenter colligantur, augebunt illud quod lacus dederit. (4) Enimvero, si placeat fossam longius ducere et altius pressam mari aequare ec in flumen, sed in ipsum mare emittere, repercussus maris servabit et reprimet, quidquid e lacu veniet. Quorum si nihil nobis loci natura praestaret, expeditum tamen erat cataractis aquae cursum temperare. (5) Verum et haec et alia multo sagacius conquiret explorabitque librator, quem plane, domine, debes mittere, ut polliceris. Est enim res digna et magnitudine tua et cura. Ego interim Calpurnio Macro clarissimo viro auctore te scripsi, ut libratorem quam maxime idoneum mitteret (X, 61). MARTINEZ GÁZQUEZ, 1988. SASEL, 1973, pages 80-85. MIRKOVIC, 1996, page 27; JORDOVIC, 1996, page 257. GABRICEVIC, 1972; PETROVIC, 1986, page 49; figs. 12-13, and MIRKOVIC, 1996, page 8. MONTERO, 2012, page 110. J. MAKKAY: «The Treasures of Decebalus», Oxford Journal of Archaeology, no. 14, 3, 1995, pages 333-345. A. H. KRAPPE: «Les funerailles d’Alaric», AJPh, no. 7, 1939, pages 229-243. (1) Τραϊανὸς δὲ ἐβουλεύσατο μὲν τὸν Εὐφράτην κατὰ διώρυχα ἐς τὸν Τίγριν ἐσαγαγεῖν, ἵνα τὰ πλοῖα δι᾽ αὐτῆς κατελθόντα τὴν γέφυραν αὐτῷ SISANI: 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. ποιῆσαι παράσχῃ· μαθὼν δὲ ὅτι πολὺ ὑψηλότερος τοῦ Τίγριδός ἐστι, τοῦτο μὲν οὐκ ἔπραξε, φοβηθεὶς μὴ καὶ ἄπλουν τὸν Εὐφράτην ἀπεργάσηται ἀθρόου τοῦ ῥεύματος ἐς τὸ κάταντες φερομένου, ὑπερενεγκὼν δὲ τὰ πλοῖα ὁλκοῖς διὰ τοῦ μέσου τῶν ποταμῶν ἐλαχίστου ὄντος (τὸ γὰρ ῥεῦμα τὸ τοῦ Εὐφράτου πᾶν ἔς θ᾽ ἕλος ἐκπίπτει καὶ ἐκεῖθέν πως τῷ Τίγριδι συμμίγνυται) τὸν Τίγριν ἐπεραιώθη, καὶ ἐς τὴν Κτησιφῶντα ἐσῆλθε, παραλαβών τε αὐτὴν αὐτοκράτωρ ἐπωνομάσθη καὶ τὴν ἐπίκλησιν τοῦ Παρθικοῦ ἐβεβαιώσατο. (2) Ventum est hinc ad fossile flumen Naar- malcha nomine, quod amnis regum interpretatur, tunc aridum. id antehac Traianus posteaque Severus egesto solo fodiri in modum canalis amplissimi studio curaverat summo, ut aquis illuc ab Euphrate transfusis naves ad Tigridem conmigrarent. (3) Tutissimumque ad omnia visum est eadem loca purgari, quae quondam similia Persae timentes mole saxorum obruere multorum. Hacque valle purgata, avulsis cataractis undarum magnitudine classis secura stadiis triginta decursis in alveum eiecta est Tigridis. 19. PASHOUD, 1978 and F. PASHOUD: Zosime. Histoire Nouvelle tome II 1re partie (Livre III). Paris, Les Belles Lettres, 1979, no. 68, pages 167 et seq. 20. LIMC Euphrates IV.1, no. 21. 21. The most complete work is by SHEEHAN, 2010, see the description by STRAB, XVII 1, 25; DIOD, I 33, 11. HYDRAULIC ENGINEERING AND RELIGION IN THE ROMAN EMPIRE 65 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 66 PEARL, 1956, page 58; D. BONNEAU: La crue du Nil, divinité égyptienne, à travers mille ans d’histoire (332 av.-641 ap. J.-C.), Paris, Klincksieck, 1964. M. PUCCI: La rivolta ebraica al tempo di Traiano. Pisa, Giardini ed., 1981, pages 61-69. SIJPESTEIJN, 1965, page 82. LE GALL, 2005, page 162. J. LE GALL and M. LE GLAY: El Imperio Romano. El Alto Imperio desde la batalla de Actium hasta la muerte de Severo Alejandro (31 a. C.-235 d. C.). Madrid, Akal, 1995, pages 356-357. MONTERO, 2012, page 110. J. LE GALL and M. LE GLAY: El Imperio Romano. El Alto Imperio desde la batalla de Actium hasta la muerte de Severo Alejandro (31 a.C.-235 d.C.). Madrid, Akal, 1995, page 356. LE GALL, 1952. Cf. R. ÏANSLIK: s.v. M. Ulpius Trajanus (pater), RE, Suppl. X, 1965, coll. 1032-1033. Concerning the inscriptions, D. FEISSEL: «Deux listes de quartiers d’Antioche astreints au creusement d’un canal (73-74 après J. C.)», Syria, no. 62, 1988, pages 77-103. SEG 35, 1483=AE 1983, 927. DENIS VAN BERCHEM published it for the first time in «Une inscription flavienne du musée d’ Antioche», MH no. 40, 1983, pages 185-196. see AE, 1983, no. 927. K.H. WATERS: «Traianus Domitiani Continuator», AJPh, 1969, pages 385-395. ROMAN ENGINEERING BIBLIOGRAPHY G. S. ALDRETE: Floods of the Tiber in Ancient Rome. Baltimore, Johns Hopkins University Press, 2007. Trajan, Optimus Princeps: A Life and Times. Bloomington, Indiana University Press, 1997. D. BONNEAU: «La divinité du Nil sous le principat en Egypte», ANRW II, no. 18, 5, Berlin-New York, Walter de Gruyter, 1995, pages 3195-3215. D. BOSKOVIC: «Aperçu sommaire sur les recherches archéologiques du Limes romain et paléobyzantin des Portes de Fer», MEFR(A), no. 90, 1, 1978, pages 425-463. P. CONNOLLY: Las legiones romanas. Madrid, Anaya, 1989. F. DIOSONO: «Pratiche cultuali in relazione a porti fluviali e canali», M. SERLORENZI and H. DI GIUSEPPE (eds.): I riti del costruire nelle acque violate. Atti del Convegno Internazionale (Roma, Palazzo Massimo, 12-14 giugno 2008). Roma, Scienze e Lettere, 2010, pages 91-105. D. FEISSEL: «Deux listes des quartiers d’Antioche astreints au creusement d’un canal (73-74 après J.-C.)», Syria, no. 62, 1988, pages 77-103. A. GÜRBÜZ and S. A. G. LEROY: «Science versus myth: was there a connection between the Marmara Sea and Lake Sapanca?» Journal of Quaternary Science, vol. 25, pages 103-114. ISSN 0267-8179. 2010. F. G. MOORA: «Three Canal Projects, Roman and Byzantine», AJArch, no. 54, 2, 1950, pages 97-111. B. S. J. ISSERLIN: «The Canal of Xerxes on the Mount Athos Peninsula», Annual of the British School at Athens, no. 89, 1994, pages 277-284. C. JORDOVIC: «The Roman Road in the Iron Gate Gorge», P. PETROVIC (ed.): Roman Limes on the Middle and Lower Danube, Cahiers Portes de Fer. Monographies 2. Belgrade, 1996, pages 257-259. S. KLEMENTA: Flussgotter. Gelagerte Flussgötter des Späthellenismus und der römischen Kaiserzeit, Köln-WeimarWien, 1993. F. KURTA: «Limes and cross: the religious dimension of the sixth-century Danube frontier of the early Byzantine Empire», CTAPNHAP, no. 51, 2001, pages 45-68. J. F. LE GALL: Recherches sur le culte du Tibre. Paris, Presses Universitaires de France, 1952. — Le Tibre, fleuve de Rome dans l’Antiquité. Paris, Presses Universitaires de France, 1953 (= Il Tevere fiume di Roma nell’Antichità. Roma, 2005 – italian translation –). J. MARTÍNEZ GÁZQUEZ: «La escasez de artesanos y las cartas de Plinio a Trajano», Faventia, no. 10, 1988, pages 59-64. M. MIRKOVIC: «The Iron Gates (Djerdap) and the Roman Policy on the Moesian Limes AD 33-117», in P. PETROVIC (ed.), Roman Limes on the Middle and Lower Danube, Cahiers Portes de Fer. Monographies 2, Belgrade, 1996, pages 27-40. S. MONTERO: «Trajano y la adivinación. Prodigios, oráculos y apocalíptica en el Imperio Romano (98-117 d. C.)». Anejos de Gerión IV, Madrid, Servicio de Publicaciones Universidad Complutense de Madrid, 2000. — El emperador y los ríos: Ingeniería, religión y política en el Imperio Romano. Madrid, UNED, 2012. N. MORLEY: «Trajan’s Engines», G&R 47, 2, 2000, pages 197-210. F. PASHOUD: «Le Naarmalcha: à propos du tracé d’un canal en Mésopotamie moyenne», Syria, no. 55, 1978, pages 345-359. O. M. PEARL: «The Inundation of the Nile in the Second Century A.D.», TAPA, no. 87, 1956, pages 51-59. S. PEREA YÉBENES: «Ejército y vida cotidiana en el Egipto romano en tiempos del emperador Trajano a través de un florilegio de cartas conservadas en papiros griegos y latinos», Sautuola, no. 12, 2006, pages 225-255. A. SAGGIORO: «Calpestare acque marine. I ponti si Serse e Caligola e l’abuso contro la natura», S. MONTERO - C. CARDETE (eds.): Naturaleza y Religión en el mundo clásico. Usos u abusos del medio natural (V Spanish-italian Seminar on History of Religions, Madrid, 9-10 October 2008), Madrid, Signifer Libros, 2010, pages 165-184. J. SASEL: «Trajan’s Canal at the Iron Gate», JRS, no. 63, 1973, pages 80-85. G. SEELENTAG: «Der Kaiser als Hafen. Die Ideologie italischer Infrastruktur», J. ALBERS, G. GRASSHOFF, M. HEINZELMANN and M. WÄFLER (hrsg.): Das Marsfeld in Rom. Beiträge der Berner Tagung vom 23/24. November 2007, Pantheon 4, Bern, 2008, pages 103-118. P. SHEEHAN: Babylon of Egypt: The Archaeology of Old Cairo and the Origins of the City. New York, American University in Cairo Press, 2010. N. SHERWIN-WHITE: The Letters of Pliny. A historical and social commentary. Oxford, Clarendon Press, 1985 (1966). P. J. SIJPESTEIJN: «Der Potamos Traianos», Aegyptus, no. 43, 1963, pages 70-83. — «Trajan and Egypt», Studia Papirologica Varia, Papyrologica Lugnono-Batava, 14, Leyde, 1965, pages 106-113. R. SYME: «The Lower Danube under Trajan», JRS, no. 49, 1959, pages 30-60. D. WILKES: «The Roman Danube: An Archaeological Survey», Journal of Roman Studies, no. 95, 2005, pages 124-225. J. BENNET: Back to Contents HYDRAULIC ENGINEERING AND RELIGION IN THE ROMAN EMPIRE 67 4 Roman Roads: the Backbone of the Empire CARLOS CABALLERO CASADO Archaeologist. Editor of El Nuevo Miliario — WHAT A ROMAN WAY IS (AND WHAT IT ISN’T) — SOURCES FOR STUDYING ROMAN WAYS — METHODS OF STUDY — GENERAL LINES FOR A REPORT ON THE RESEARCH INTO ROMAN WAYS IN HISPANIA — PRESENT SITUATION In answer to the popular belief that a Roman road is a cobbled road, and even that every cobbled road is a Roman road, the current appearance of many ways assigned to Romans significantly differs from the appearance corresponding to those ways that ran across the Empire. The term Roman is often applied to roads whose appearance is a result of modern restorations, or even medieval or subsequent layouts. The first paragraphs of this work will aim to provide certain guidelines in order to make it possible to identify, at least along general lines, the ways that are genuinely Roman and, especially, to distinguish them from those that quite clearly are not [FIG. 1]. The Besaya Road, with its characteristic cobbles, assumed to be Roman for a long time. FIG. 1 69 FIG. 2 Elevation profile of the Gran San Bernardo Roman Road (Italy), according to G. GILLANI and G. VIAZZO. The most recent research has led to the conclusion that studying a road cannot be done in isolation from the land through which it runs, in such a way that focusing on a stone cobbled section to determine whether or not it is of Roman origin is not sufficient: instead, it will be necessary to broaden the perspective and find out about the route’s geographical context, the landscape and the historical needs that ultimately gave rise to its construction. For example, one first feature to be investigated in order to find out if a way is Roman will be to ascertain whether or not in the vicinity – not necessarily right on the route, as we shall see later – there are, more or less aligned with the way concerned, a number of Roman settlements. However, this should not be the only criterion to be taken into account. If such a way is really Roman, it will tend to avoid steep slopes and, instead, will go around the topographical difficulties resorting to the use of constant gradients. Serious doubts will thus have to be cast on the major slopes traditionally taken to be Roman, and it will be necessary, before establishing the most favourable layout, prepare a preliminary survey of the land’s topography [FIG. 2]. Following on from the above, a Roman way will, as a general rule, be one that features long straight stretches, alignments that at times run for several kilometres, attempting to find the shortest distance to connect two centres of population [FIG. 3]. Similarly, another feature that is common to all Roman ways, or at least an overwhelming majority of them, is that they steer clear of valley floors and, particularly, zones considered to be exposed to the risk of flooding. Nevertheless, being true that a Roman 70 ROMAN ENGINEERING FIG. 3 Example of a Roman Road with a long straight alignment in France, according to CASTELLVÍ (ed.). ROMAN ROADS: THE BACKBONE OF THE EMPIRE 71 FIG. 4 The layout proposed for the Roman Road between Uxama and Augustobriga near Numancia, according to EDUARDO Note that the road systematically avoids the valley floors. SAAVEDRA. FIG. 5 The Donnaz Tunnel, in Pont-Saint-Martin (Aosta, Italy). 72 ROMAN ENGINEERING way has been recently recorded in Hispania that crosses a floodable zone, this discovery in itself is not enough to suggest that this is the norm and it should rather be taken as just an isolated exception to the rule [FIG. 4]. Furthermore, although it might be thought that what follows is merely stating the obvious, the fact that a Roman way is a Roman way will be established by the presence of characteristically Roman infrastructures along its length, i.e. sewers, containment walls, trenches with the typical roman hewing, tunnels and, above all, bridges. However, in the latter case it should be borne in mind that in the light of the most recent and thorough studies, the list of bridges regarded as Roman on the Iberian Peninsula only contains around four dozen examples, according to Manuel Durán’s catalogue1 [FIG. 5]. Non-Roman Paving at the Puerto de la Fuenfría with longitudinal ribbing. FIG. 6 Finally, Roman roads can also be defined by applying a negative argument: stone roads that are systematically accompanied by peak shaped beacons or wheel-guard milestones might un-mistakenly be categorized as not being Romans, because the utilisation of these signs only dates back to the 16th Century and their use only became widespread in the 18th Century. As a result, no road that has truncated cone-shaped road signs at its sides, or the typical wheel-guard milestones rounded towards the interior, should be regarded as Roman because of their current appearance. Along the same lines, the presence of large ribbed compositions running parallel to the longitudinal centreline, will be revealing their origins to be later than Roman age [FIG. 6]. The network of Roman roads became really extensive throughout the Empire, and was continually undergoing repairs and modifications. This is a logical consequence of the fact that Roman ways were constructed to fulfil at least four main functions: to link the cities that formed part of the Empire; to provide an outlet for the raw materials obtained from certain places, to make army moves easier and, to a lesser extent, or at least not as a prime objective, to spread the Roman civilisation. Under these premises, the road network was clearly made up of ways constructed following the same criteria that we would ask from engineers today, and this has enabled us to detect the remains of these roads in many locations of the Empire. When studying these roads, researchers currently have a large collection of ancient sources of different character available, that enable them to carry out sound research into Roman roads, although the basic ones, as is generally the case with Ancient History studies, are epigraphic and literary in nature. The best-known literary source is Antonino’s Itinerary, a work dating back to the 3rd Century, which contains a series of routes that run through the different provinces of the Empire. The part devoted to the Iberian Peninsula consists of a compilation of 34 routes. However, this does not mean to say that they were the 34 main routes that existed in Hispania. This is because, in view of the peculiar characteristics of the document, there has been much discussion about the function of this Roman literary source without any agreement having been reached about the reason for its existence in the first place. The most widely accepted hypothesis currently held is the one put forward by the Swiss ROMAN ROADS: THE BACKBONE OF THE EMPIRE 73 archaeologist Dennis van Berchem, originally postulated in 1937 and elaborated upon in 1974. This hypothesis, disseminated in Spain on the basis of especially the work done by Gonzalo Arias2, claims that Antonino’s Itinerary was, in fact, a series of «route maps» (i.e. a compilation of itineraries) to help the Roman Administration to collect the annona militaris tax. This would explain the arbitrary way in which the routes contained in the document were selected, and would also account for the strange «detour-type» layouts chosen, on some occasions, to link two cities relatively close to each other, when the second city is reached after passing through other places that would have made the route much longer than was really necessary. The Itinerary also contains in great detail (occassionally, with some errors leading to confusion) the list of intermediate stops between the points of departure and arrival for a specific route, as well as the partial distances between the various possible stops (referred to as mansiones, stationes or mutationes, depending on their importance), these distances logically been given in miles. Another controversy created by Antonino’s Itinerary is the reference to some mansiones appearing in the accusative case or preceded by the direction particle «ad», in contrast to others, being referred to in the nominative case. This matter has also been the subject Geographical interpretation of Antonino’s Itinerary in the vicinity of Titultia, according to GONZALO ARIAS. FIG. 7 74 ROMAN ENGINEERING of debate given that it could be one of the clues to unravelling the mystery surrounding the ultimate aim of the Itinerary. Based on the studies conducted by José Manuel Roldán (1966) and Gonzalo Arias (2004) it has been possible to establish that they refer to places that are not on the route, but lie at a certain distance from it. On the basis of this discovery, Arias himself prepared what he called the «grammatical interpretation» of Antonino’s Itinerary, according to which some of these mansiones would be at considerable distance from the route in which they are referred to. Although this interpretation contains certain aspects that are debatable (in particular that it enables one to interpret the routes in an arbitrary way, in view of the fact that it is not necessary for the mansion concerned to be close to them), it is nevertheless true to say that it is currently the hypothesis that best explains the data included in the Itinerary without having to resort to considering the presence of numerous mistakes in it [FIG. 7]. A later source, probably from the 7th or 8th Century AD was the Anonymous from Ravenna, a text that contains a long list of cities and other noteworthy geographical places, apparently structured with no established order. However, the fact that the Anonymous appears to follow itinerary sources – especially because it reproduces fragments of the routes contained in Antonino’s Itinerary3 – and the hypothesis that it could have been based upon some itineraria picta (an illustrated document, of which the Tabula Peutingeriana -Peutinger Map- is one of the main examples), has meant that the (limited) information provided by the Anonymous from Ravenna is often used to reconstruct routes that might have been used by the Romans. However, the information contained in it is scant, little more than a list of names (many of which are grossly deformed with respect to the original source), just enabling to assume that there was a succession of stops on each route. The Spanish version was the work of Roldán (1975), although there are numerous studies on possible individual routes. A brief mention should also be made, amongst the itinerary sources, to other repertoires whose focus on Hispania and use for studying the ways on the Iberian Peninsula are lesser: these include the Itinerarium Maritimum4, the Guidonis Geographica5, the Itinerarium Burdigalense, etc. Apart from the itinerary sources in the strictest sense, many maps are still preserved included for study among the so-called itineraria picta that, which according to certain interpretations would have been at the service of a cartographic reconstruction of the Roman Empire that was undertaken by Agrippa, for which the Rome’s Pantheon6 would have been the centre of activities. Towards the end of the 20th Century, a map called de Artemidorus of Ephesus was found on the back of a papyrus that contained artistic sketches; this can be regarded as the last known example to date of the Orbis Pictus tradition of which, nevertheless, the Peutinger Map is the most outstanding representation. It is likely that the Peutinger Map is a design from the 2nd Century of our era, of which only one copy remains, dating back to the 12th or 13th Century, that includes the reproduction of many of the Empire’s roads together with the distances – mainly expressed in miles – between the intermediate stops. However, the Peutinger Map is of very little use for reconstructing the network of Roman ways on the Iberian Peninsula, because the segment given over to Hispania was lost and all that is available from the original map is a small strip for the Pyrenees. In 1898, Miller prepared for the rest of the Peninsula, a ROMAN ROADS: THE BACKBONE OF THE EMPIRE 75 FIG. 8 «Nest» of miliarios in Lobios (Orense). thorough reconstruction on the basis of data taken from other sources. However, it is only based on the appearance of the original and on diachronic data regarding the time when the original Tabula was drawn up. A second group of sources comprises those of an epigraphic nature. As far as the Iberian Peninsula is concerned, two sources stand out that could be called epigraphic-itineraries, because of the way they are presented; on the one hand, the Vases from Vicarello, four small cylinders three of which were found in excavations carried out in Baños de Vicarello [Vicarello’s Baths], about 30 km from Rome, midway through the 19th Century. They describe, in a similar way as Antonino’s Itinerary7 will do it at a later date, a road that connected Gades with Rome and ran along the Mediterranean Coast, going, in its Hispanic section, from Cádiz to the Pyrenees. In its comparison with the road described, through the same territory, by Antonino’s Itinerary, the Vases from Vicarello are an essential source for establishing how the network of roads developed in the zone at the beginning of our era. A second source of an epigraphic-itinerary nature would consist of the group composed of the so-called Tabletas de Lépido or Itinerarios de Barro de Astorga. These are fragments of four earthenware tabulae ansatae reproducing roads that supposedly ran across the north of Hispania. However, studies conducted by José Manuel Roldán and 76 ROMAN ENGINEERING Gonzalo Arias have cast serious doubts on their authenticity, so there is currently considerable hesitation about whether any of them should be taken seriously8. At this point of the work, miliarios [milestones] play a crucial role among the epigraphic sources – not of itinerary nature –, for the direct information that they provide about the routes they served (date of construction or repair, distance from a particular point), and also for the indirect data that can be gleaned from them, especially if it can be assumed that they were located in situ, actually on the route itself. By the very nature of their function, it would only be expected that milestones would lie at regular distances from each other, there being perhaps more of them in zones of the Iberian Peninsula where the special characteristics of the land through which the roads passed made it necessary to repair or maintain them more often. Yet this is not the case, in Hispania insofar as the presence of miliarios is concerned there are large gaps. There is a major concentration around the route known as Vía de la Plata [Silver Route] and, particularly, in the far northwest of the Peninsula, especially in the south of the Province of Orense and Northern Portugal, with a major concentration around the City of Braga. Groups of ten or twelve milestones significantly described as «nests» have been located in this zone, probable in situ [FIG. 8]. ROMAN ROADS: THE BACKBONE OF THE EMPIRE 77 Miliarios however are not always found in their original positions, as they were often moved or reused, broken up or found with their inscriptions virtually lost, so it is necessary to study them in great detail, in such a way that the information that they yield can be put to the best use. After their first inclusion in the Corpus Inscriptionum Latinarum (CIL), towards the end of the 19th Century, in Hispanic territory, researchers did not take much notice of miliarios, studied from an epistemological viewpoint, until the last two decades of the 20th Century. As from that time, work began on preparing systematic inventories for specific territories (a special, but not exclusive, reference must be made to those in the Province Tarraconense [Tarragona], by Joaquín Lostal9 and to the Convento Bracarense10). In addition to the bibliographies concerning miliarios, there are several projects currently under way whose development can be followed by consulting their databases via Internet. These include the following: — Corpus Inscriptionum Latinarum, based at what is known as the Centro CIL II at the Universidad de Alcalá de Henares, accessible at http://www2.uah.es/imagines_cilii/ — Hispania Epigraphica, whose headquarters are at the Geography and History Faculty at the Universidad Complutense (http://eda-bea.es/) — Vbi erat lupa, prepared by the University of Salzburg (http://www.ubi-erat-lupa.org/) Finally, a last group of sources for studying Roman ways is formed by itinerary sources from the modern period: route repertoires that, to a certain extent, reproduce ways of Roman origins or are suitable to give insight to the layouts of Roman routes that we would not be able to reconstruct if it were not for the existence of these tracking guides. One of these is the Reportorio (sic) de todos los caminos de España, by Pero Juan Villuga (1546), and the Reportorio de caminos ordered by Alonso de Meneses (1576), which is a recycled reflection of Villuga’s work. Along the same lines, providing interesting data for studying roads, there are works such as the Descripción y Cosmografía de España, by Hernando Colón (1517) and even subsequent works like the Diccionario Geográfico-Estadístico e Histórico de España y sus posesiones de Ultramar, coordinated by Pascual Madoz as from 1848. By way of a supplement, or more of a continuation, to the study of Roman Ways carried out resorting to well-known literary and epigraphic sources, it is inevitably required to resort to archaeology. The method used to conduct archaeological research of roads has made considerable progress since the beginning, especially over the last two decades. Studying the road itself, in isolation from the environment through which it passes, and not assuming that all Roman ways had to be made of cobbledstone, have opened the door to a more diverse perspective of roads, probably more consistent with the real situation. Archaeological research has now given up the old hypothesis according to which the materials that constituted a canonical Roman road were arranged in a strict manner comprising four layers as described by Vitruvius when he spoke of the paving for city streets. The idea that it was Vitruvius who defined the four layers that made up a Roman road was for a long time attributed to Nicolás Bergier, who lived in the 17th Century. However, a recent study conducted by Rodríguez Morales (2010) has set the record straight and 78 ROMAN ENGINEERING has exonerated Bergier from being responsible for spreading Vitruvius’ idea in an erroneous context. Regardless of who it might have come from, the truth of the matter is that the hypothesis that a Roman way is Roman if the rolling course is made of cobbled stone and if it has the four layers described by Vitruvius has been believed, just as much as other more accurate theories worthy of belief, to the point that even today, when that hypothesis has been rejected out of hand by those who study Roman roads, cross sections of roads showing this «Vitruvian» stratigraphy can be seen on all kinds of posters, publications and websites, mainly aimed at the tourist market. The truth of the matter is that should one road be studied in relation to its territory and as an essential part of it, as it is done today, the parameters that were described at the beginning of this work could be used, rather than the physical remains, to establish whether the road is original Roman or not. This change of mentality has been brought about largely by the gradual increase in interdisciplinary studies, in which mainly archaeologists and engineers collaborate with professionals from other areas, plus the contribution made by some researchers who have managed to change the way we approach Roman roads. If we quote only those who have played the greatest role in changing our mentality, mention will have to be made to the Quilicis, in Italy, pioneers in integrating roads into their territories in order to study them11; in France, Pierre Sillières (1995), who is responsible for the considerable progress made in the use of aerial photography, Raymond Chevallier (1997) and Gerard Coulon (2007) and, in Spain, Isaac Moreno (2004). The work by all the aforementioned persons has not only modified the way of associating Roman ways with their territories and the landscapes that surround them, but have also led to a new approach to the way the physical remains are analysed. Until only a few years ago, the way of excavating a road consisted of cleaning the surface until the cobbling was reached (if there was any), whereas nowadays the road tends to be sectioned, this being the only way of finding out what construction method was used, what the infrastructure was and how the ground was prepared. As research has progressed in situ, breakthroughs have also been made in office work. The use of aerial photography has been particularly helpful in identifying long straight alignments that could give clues to the presence of Roman ways. The widespread use of powerful tools, which are now available to the general public, has undoubtedly contributed to this progress. However, this does not mean to say that flights from the past, when many of the current infrastructures had not yet been constructed, should not be re-examined, because it was then much easier to pinpoint a priori, the layouts that ought to be studied as potentially Roman. Likewise, the new technologies do not avoid one of the basic steps when it comes to putting forward hypotheses about the layout of historic routes: reanalysing ancient maps. Occasionally, certain routes are marked as «Roman way» or «Moorish way», a circumstance that often refers to a route that presumably dates back a long time. However, from a statistical perspective this is nothing more than incidental, so researchers of ancient history have to look for other toponymic clues: «old road», «rock carvings», «pavement», «old livestock track» or place names prefixed by «ctra-» will be indicating the presence, at least according to tradition, of roads that are probably very old12. ROMAN ROADS: THE BACKBONE OF THE EMPIRE 79 FIG. 9 Roman roads and centuriation in the vicinity of Bolonia (Italy), according to QUILICI and QUILICI, 1994. Preparing the hypothesis of the ideal Roman way layout. In blue, Roman settlements. In red, proposed route (surroundings of Calamocha, Teruel, Page 491 of the National Topographic Map). FIG. 10 80 ROMAN ENGINEERING If the information obtained from mapping is combined with the data yielded by archaeology, the layout of a Roman way can also be established by the centuriations, which were generally bordered by these roads. Although the study of centuriations in Spain is only well developed in zones close to the Mediterranean Coast13 and in some regions within the Ebro Valley, the constant developments made in the extremely useful discipline known as «Landscape Archaeology» are helping to increase the amount of information available on this subject [FIG. 9]. A combination of all these parameters plus the pinpointing of certain geographical features that Roman routes generally avoided (steep slopes, marshland) and with the distribution of the Roman settlements known, will allow the preparation of a theoretical framework that will enable researchers to select the most likely hypotheses when it comes to the potential layout of a Roman way [FIG. 10]. In this regard, studying the distribution of the farming exploitation villae will be of particular importance, because their implementation on the land was invariably conditioned by the maxim established by Columela14, whereby a Roman villa had to be located nec in uia nec in uia procul, i.e., at a reasonable distance from the road but not too far from it [FIG. 11]. FIG. 11 Villae and Roman road in the vicinity of Warfusee-Abancourt (France), according to R. AGACHE. ROMAN ROADS: THE BACKBONE OF THE EMPIRE 81 FIG. 12 Plan view of the Tripontium mansio (Rugby - GB), according to IRENE GLENDINNING. Finally, when conducting a field study of roads, certain parameters must be taken into account that have already been mentioned, – especially, the distribution of Roman bridges and miliarios whose location is considered in situ –, in addition to the identification of the mansiones. As they were infrequent, very little is known about the mansio from an archaeological viewpoint, although it is known that these buildings were usually quadrangular with several rooms opening out onto an inner courtyard, close to which there was also a thermal building. Known mansiones feature these parameters, especially those beyond the frontiers of Hispania, yet the ones researched on the Iberian Peninsula, such as Mariturri (Álava), Lancia (León), Ildum (Castellón) or Collado Mediano (Madrid), do not always fit exactly into this pattern, although their function as a service facility on a Roman way is beyond any doubt15 [FIG. 12]. The study of Roman roads in Hispania has followed the guidelines set by breakthroughs in the research method that has just been explained. The origins, after certain work was done in ancient times – including an edition by Jerónimo Zurita of Antonino’s Itinerary, from the 16th Century, or the Tratado legal y político de caminos públicos y possadas [Legal and Political Treatise of Public Roads and Inns], published by Tomás Fernández de Mesa in 1755 –, have to be sought in the contributions made by engineers from the last third of the 19th Century, such as Francisco Coello and, particularly, Eduardo Saavedra. Saavedra (1829-1912) was responsible for systematising the study of the Roman road network in Hispania, not only regarding the main source of information, the document Antonino’s Itinerary, but also where the research method was concerned. Thus, it was Saavedra who was the first to structure the thirty-four routes that constitute the Hispanic part of the Itinerario, interpreting the layouts and allocating a different number to each one16. Furthermore, as a good engineer, he applied engineering parameters to the study of a specific section of route, the stretch between Vxama (El Burgo de Osma, Soria) and Augustobriga (Ágreda, Soria)17, and most of his considerations and conclusions about its layout are still valid today. 82 ROMAN ENGINEERING The trail set by the pioneer and enlightening work done by Saavedra was followed by the Blázquez’s (Antonio and Ángel) and by Claudio Sánchez Albornoz, who, under the auspices of the Junta Superior de Excavaciones y Antigüedades (JSEA) [Excavations and Antiquities Board], carried out commendable fieldwork activities based upon exploring Roman ways directly. However, that exhaustive task, often presented in the different volumes published by the JSEA, with certain literary overtones, some even quixotic, gave way – after the JSEA ceased its activities, and, especially, during the period that began when the war ended, in 1939 – to a long and dark period for the study of Roman ways in Hispania, in which there were no outstanding studies of a global nature and hardly any reference was made to the road network in the activities associated with the publication of findings and results obtained when excavating specific archaeological sites. That period of certain abandonment of the research into Roman routes on the Iberian Peninsula, was to be interrupted in the 1960s and the early 70s, with the publication of two works by José Manuel Roldán: a study of the Silver Route, in 197118, which involved applying new research methods to a Roman route in Spain19, and, especially, the volume Itinera Hispana, published in 1975, which compiled for the first time in one single book, the ancient sources used to study Roman Roads in Hispania, i.e. Antonino’s Itinerary, the Tabletas de Lépido, the Vases from Vicarello, the Anonymous from Ravenna, the Guidonis Geographica and the Tegula de Valencia. It also included, in the form of an appendix, an attempt to catalogue the numerous mansiones quoted by the itinerary sources, conducting a location test for each one, on the basis of the state-of-the-art at that time. Perhaps it was because this publication structured the available information in an easily accessible way, the fact is that it paved the way for a renaissance in the study of Roman roads on the Peninsula, particularly during the 1980s, when a large number of monographic works were published governed by territorial criteria on the basis of the current political divisions. A publication also appeared in Cadiz as early as 1963, which paid very little attention to the established standards, called El Miliario Extravagante, under the directorship of Gonzalo Arias Bonet. This periodical publication appeared quite by chance, as a by-product arising from the main aim of the researcher, which was to put together a Historic Atlas of the Iberian Peninsula, yet the work ended up by taking on its own identity and overshadowing its parent project, which remained uncompleted. Based on the author’s own research and the contributions made by «correspondents», a dense network of collaborators making contributions during the journal’s forty years of existence, the project led to a sort of self school, extravagant in the strict sense of the term however making notable breakthroughs in the knowledge about the Hispanic road network. The publication was split into four «periods», the first of which (1963-1968) was embellished with mythical overtones, as it consisted of 14 typewritten issues illustrated by hand, edited in Paris where its exiled and unrepeatable author lived, before being distributed in Spain. On that first stage, which was gradually lost down through the years, Arias made a compilation in 1987 that later, reprinted and updated in 2004, ended up by being a summary of all his work20, with a few innovative considerations, some of which were brilliant and witty, such as the above-mentioned grammatical interpretation of Antonino’s Itinerary, while others were debatable, like the origin of the City of Madrid being put down to its ROMAN ROADS: THE BACKBONE OF THE EMPIRE 83 position at the crossroads of two Roman roads, all of which served to liven up the research debate into the roads [FIG. 13]. However, given that its role as a forum for all those who were devoted to the study of Roman roads in Hispania seemed ideal, once El Miliario Extravagante ceased publication in 2004, several subscribers to the journal decided to take over and brought out a new publication, El Nuevo Miliario21, which, sponsored by the Fundación Juanelo Turriano, is certainly different in nature, although it does try to conserve some of the essential characteristics of El Miliario Extravagante. The large number of studies that were conducted in the 1980s, which led to the holding of the Tarazona Symposium22, gave rise to the development, in the last few years of the 20th FIG. 13 Gonzalo Arias. Photography by GIACOM GILLANI. Century, of studies that became increasingly more specific in nature, brought together not only in the form of monographical works (to the extent that every Autonomous Region has its own detailed study on the subject), but also in scientific meetings. Furthermore, initiatives have emerged that, without being strictly devoted to publicising the results of research into Roman roads, occasionally make contributions that are of great interest to those who are interested in this subject. Such initiatives include two series of periodical meetings, the Congresos de Caminería Hispánica and, especially, the series of Congresos de Obras Públicas Romanas that have been taking place organised by the Colegio de Ingenieros Técnicos de Obras Públicas. At present, in the first decades of the 21st Century, apart from dealing with the layouts of very specific routes23, there has been a certain return to the basics, in view of the fact that projects of a global nature are again being considered that, in the light of the epistemology, had emerged towards the end of the 19th Century. Undoubtedly, the potential for accessing more powerful technologies and the ease with which it is now possible for researchers to exchange information, makes it much easier for them to undertake controversial projects from a broader perspective. It is thus advisable to mention, apart from the epigraphic compilations referred to in the preceding pages, such mapping initiatives as the Tabula Imperii Romani or the Barrington Atlas of the Greek and Roman World, as well as projects that deal exclusively with itineraries, such as the website run by Pedro Soutinho about the Portuguese road network24, the work coordinated by Isaac Moreno 84 ROMAN ENGINEERING about the Roman roads of Castilla y León25 or the Itinera Hispana, which is an update of the old Itineraria Hispana that once again, is being coordinated from the Universidad Complutense by José Manuel Roldán. All in all, this is not the place to get side-tracked into giving details about the Roman ways of Hispania, a task often controversial and always substantial, that would take not just a short work like this one but one or more monographs and that has been the research subject to which more than one erudite has devoted his life. The general impression is that, in spite of all the work carried out, there is still a lot more to do, but as is nearly always the case with research, the tasks still to be done look very exciting. NOTES 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. DURÁN, 2005. Collected in ARIAS, 2004, and in the Appendix to El Miliario Extravagante entitled: «An Extravagant Approach to Roman Roads», 2004. In this sense, reference can be made to C. CABALLERO: La ciudad y la romanización de Celtiberia. Zaragoza, 2003, page 115 et seq., or to A. CAPALVO: Celtiberia. Zaragoza, 1996. ROLDÁN, 1975, page 102 up. ROLDÁN, 1975, page 143 up. This hypothesis can be followed in L. ZAPICO: «Was Antonino’s Itinerary prepared for cartographic purposes?», El Nuevo Miliario, 6, 2006 (See also, Revista de Obras Públicas, 3,289, which is where it was originally published). Further data in Chapter V («Marco Vespasiano Agrippa and his Orbis Pictus») from the book Mina y Gigante, Madrid, 2009. The Vases from Vicarello would be from around the change of era (See ROLDÁN, 1975, page 153). In print, this work was published with an interesting contribution from CARMEN FERNÁNDEZ OCHOA, ÁNGEL MORILLO and FERNANDO GIL, 2012, with the results from the dating of the tablets using thermoluminescence and the interpretation of the itineraries contained in it. This analysis could modify the interpretation that is given to this epigraphic document. J. LOSTAL: Los miliarios de la Provincia Tarraconense. Zaragoza, 1992. A. RODRÍGUEZ COLMENERO, S. FERRER and R. D. ÁLVAREZ ASOREY: Miliarios e outras inscricións romanas do noroeste hispánico. Santiago, 2004. See, amongst others, L. QUILICI, 1992, and L. QUILICI-S. QUILICI, 1994. In this sense, the summary of the mapping sources made by MANUEL TRUJILLO is particularly illustrative: «Fuentes cartográficas para la identificación de los caminos públicos», which can be downloaded from the following website: www.elnuevomiliario.eu See the volume Catastros, hábitat y vías romanas. Valencia, 2006. COLUMELA, De agri cultura, I, 5, 2. Articles on mansiones can be found in Issue no. 5 of El Nuevo Miliario, which contains several works on different mansiones of the Roman Empire. In brackets, it would be advisable to say that Saavedra’s structuring of the routes into independent epigraphs numbered consecutively has an unwanted effect: the fact that many now believe that allocating numbers to the routes is inherent to Antonino’s Itinerary, so nowadays it is possible to read, in some tourist publications and on many posters that mark out Roman routes, how reference is made to them being identified as Route XXIII or XXXI, when the truth is that the numbering came from Saavedra’s work, and it would be completely out of order to resort to Roman numerals. E. SAAVEDRA: Descripción de la vía romana entre Uxama y Augustóbriga, 1864 (re-edited in Soria in 2000). J. M. ROLDÁN: Iter ab Emerita Asturicam. El camino de la Plata. Salamanca, 1971. Apart from giving, to a certain extent, origin to the «Silver Route» myth, about which the author himself reflected for a long time afterwards J. M. ROLDÁN: «El camino de la Plata: ¿iter o negotium?», Gerión, vol. Extra, 2007. G. ARIAS: Repertorio de caminos de la Hispania romana, 2004. www.elnuevomiliario.eu Simposio sobre la red viaria en la Hispania romana. Zaragoza, 1987. In this sense, it is likely that the Silver Route is the one that has generated the most extensive bibliography, See the Exhibition Catalogue Vía de la Plata. Una calzada y mil caminos, held in 2008. Roman Roads in Portugal: http://viasromanas.planetaclix.pt/index.html Roman Roads in Castilla y León: http://www.viasromanas.net/ ROMAN ROADS: THE BACKBONE OF THE EMPIRE 85 BIBLIOGRAPHY G. ARIAS: Repertorio de caminos de la Hispania romana. Ronda, 2004. (ed.): Voies romaines du Rhône à l’Ebre: via Domitia et Augusta. 1997. R. CHEVALLIER: Les voies romaines. Paris, 1997. G. COULON: Les voies romaines en Gaule. Saint-Amand-Montron, 2007. M. DURÁN: La construcción de puentes romanos en España. Santiago, 2005. C. FERNÁNDEZ OCHOA, A. MORILLO and F. GIL SENDINO: «El Itinerario de Barro. Cuestiones de autenticidad y lectura», Zephyrus, LXX. 2012. I. GONZÁLEZ TASCÓN and I. VELÁZQUEZ: Ingeniería romana en Hispania. Historia y técnicas constructivas. Madrid, 2005. I. MORENO: Vías romanas. Ingeniería y técnica constructiva. Madrid, 2004. L. QUILICI (dir.): Tecnica stradale romana. Roma, 1992. L. QUILICI and S. QUILICI (dirs.): Strade romane. Percorsi e infrastrutture. Roma, 1994. G. RADKE: Viae publicae romanae. 1971. J. RODRÍGUEZ MORALES: «Las vías romanas en la erudición moderna: reivindicación de Nicolás Bergier», V Congress on Roman Public Works. Córdoba, 2010. J. M. ROLDÁN: «Sobre los acusativos con “ad” en el Itinerario de Antonino», Zaphyrus, no. 17. 1966. — Itineraria Hispana. Valladolid, 1975. E. SAAVEDRA: Discursos leídos en la Real Academia de la Historia en la recepción pública de D. Eduardo Saavedra. Madrid, 1862. — Descripción de la vía romana entre Uxama y Augustobriga. Soria, 2000. P. SILLIÉRES: Voies de communication de l’Hispanie meridionales. Paris, 1995. G. CASTELLVÍ Back to Contents 86 ROMAN ENGINEERING 5 Design and Construction of Roman Bridges in Hispania MANUEL DURÁN FUENTES Civil Engineer (ETSICCP), Universidad de A Coruña INTRODUCTION The construction of public works, and especially roads and thus bridges, was essential to guarantee the smooth running of the Roman Administration, complex and efficient for those early times. The grandeur of Roman engineering was not based upon the use of innovative techniques and construction types, but on the effective and systematic use of foreign materials and technologies that the Romans themselves gradually improved and applied more extensively. Romans were outstanding builders of masonry bridges, because they managed to perfect them from a formal, aesthetic, material and construction perspective, as can be seen from the works that are still with us today. Bridges were erected to be symbols of the maiestas imperii [grandeur of empire] and the publica magnificentia [public magnificence] of the Roman people, solid and stable, without any concessions to frivolity and with a clear intention to make them long-lasting «forever over the centuries of this world», in the written words of architect Caius Iulius Lacer, constructor of the Alcántara Bridge. In the course of time, this outstanding construction performance has turned Roman bridges into the epitome of strong, long-lasting and beautiful works. HISTORICAL BACKGROUND Many of their construction techniques and systems came from Greece, which was, in turn, closely linked to Egypt from eras prior to the Egyptian Ptolemies. The Pharaohs from this dynasty employed Greek engineers in Egyptian construction work for the tech- 87 nical superiority they had over their former masters thanks to the new technological inventions, according to the German archaeologist Dieter Arnold. Ever since the first dynasties the Egyptians used construction systems and details that many centuries later would be applied to Greek and Roman construction. It was the experienced and renowned Greek architects who were the major figures in transferring the technology to Rome since the times of the Republic, as can be seen from the formal similarities between the two architectures and through the knowledge, mainly thanks to Vitruvius, of the names of some of the individuals involved in Roman works. The first contacts occurred in the 3rd Century BC, in Magna Graecia, in the south of the Italian peninsula and on the island of Sicily, but it was only after the conquest of Greece, at the beginning of the 1st Century BC, when this influence was consolidated, enhanced by the systematic plundering of the latter’s architectural heritage, which often meant transferring the stonework itself to Italy. The sacking of Syracuse, in 212 B.C. by Marcellus, was the first of these acts of pillaging. Strabo states that most of the statues that could be seen in Rome in times of Augustus came from Corinth. A large number of architects, artisans and artists also arrived in Rome, some as hostages from the wars and others of their own free will, and once they began to provide their services to the Army, the Roman Administration or private individuals, they gave new forms to the construction that rapidly established themselves owing to their convincing proselytism. One example of a Greek architect who reached Rome in 146 B.C. from Macedonia as a result of the military actions of Metellus Macedonicus, was Hermodorus of Salamis, to whom a variety of monuments are attributed, constructed with materials and by artisans brought from the Aegean regions (ADAM, 1996, 114-115). Just after he took up his post as Governor, Pliny the Younger sent letters to Trajan from Bithynia in which he asked for an engineer expert in canals or an architect to be sent from Rome. In answer to a request to send a technician to carry on with the works on a theatre in Nicaea, the Emperor wrote back saying «you cannot possibly be lacking in architects. There is no province that does not have expert and talented men; unless you think that it is quicker to send them from Rome, when it is even normal that they come to us from Greece» (PLINY THE YOUNGER, 2005, 510-511). The different works should be designed, according to the Latin author Vitruvius, with the aid of Architecture, given that without this science, based on numerous teachings and instructions, it would not have been possible to complete them with skill, proportion, harmony and beauty. The economic aspect is also present in Roman works, because as Vitruvius wrote «the administration of the materials and land, as well as tight budgets and reasonable costs in performing the works had to be taken into account». He regrets that architects were not penalised for carelessness regarding the final cost of public works, as they were in Greece, and specifically in Ephesus. As a result of a Law passed there, as soon as an architect accepted responsibility for works and submitted his performance quote, his possessions were transferred to the magistrate until the works were completed; if the actual cost was equivalent to the quote submitted, the architect was rewarded with «honours and complimentary statements». If the final cost exceeded the initial price quoted by up to 25%, the difference was paid out of public money and the architect was not penalised. However, if the cost excess was over 25% «the architect had 88 ROMAN ENGINEERING to pay the extra amount with his own goods». Vitruvius wished that a similar law had been in force for private works. Certain uniformity can be observed in the way the different Roman buildings were constructed, that was undoubtedly achieved by adapting the typologies to their objectives. All the typologies that functioned satisfactorily were conserved and developed, while those that failed were modified. All in all, what was good and correct was found out by trial and error, as in any other process of experimentation, although, as has already been pointed out, the constructional precedents reached Rome after having been well tried out and successful. THE ROMAN BRIDGES IN HISPANIA The folded surface of the Iberian Peninsula, its extensive river network and the use of the territory, were the basic determinants for establishing land communications in the past. The construction of works to span water courses has left a rich heritage where typologies are concerned, as well as a variety of materials and construction systems that have been subject to change through the centuries. The rivers on the peninsula are well known for their extremely irregular discharges, especially the ones that flow into the Mediterranean, which alternate between having insignificant or zero discharges at one moment in time, and having very high or even devastating rises in another. Such floodings caused by the meteorological phenomena inherent to the zone accounts for the fact that hardly any Roman bridges are left standing. To carry out the desirable and essential task of preserving the historic bridges as part of a country’s Cultural Heritage, it is first necessary to keep an inventory of the works that remain and then make sure they are listed in a catalogue, including the geographical and historical data concerning each bridge, as well as information about the roads, tracks and surroundings, plus the dimensional and constructive characteristics, and, on the basis of all this, their present status and the measures required to preserve and protect them. An important part of the historical study involves allocating them into a specific construction period, so an identification process will have to be carried out, which in the case of Roman bridges was hardly ever performed until recent times. There is a lack of systematic studies that can define the type of construction for each period or time in history, and the same applies to statistical studies that relate and compare them. Design According to P. Pontones, bridges are «roads over the waters» which have to be connected to the roads on the ground, composed of masonry walls whose pieces have been laid in a particular order, in which openings have been created to enable the water to pass through. The construction of a bridge in a natural environment could have a negative impact on the value of the place, but the harmony and beauty of its structure, shape and composition can have the opposite effect, by bestowing character and uniqueness on the environment concerned and enhance its landscape value. DESIGN AND CONSTRUCTION OF ROMAN BRIDGES IN HISPANIA 89 A Ponte Velha in Vila Formosa (Portugal). FIG. 1 On analysing the masonry used to construct bridges that are known to be Roman, not only in Hispania but also in the rest of the Empire, it has been found that their design was approached in a systematic and practical way, with solutions that had already been tried out while at the same time taking into account the singularity of each one. The simplicity, strength and the structuring of the parts with each other and as a whole, and the aesthetics arising from their functionality and harmony, are clear evidence of the sense of strictness in the construction process, which Fernández Casado so much admired in his faithful defence of such professional behaviour and ideal. Viollet-le-Duc said of Roman architects that «their spirit was too regulatory and their mentality too straight, but they were so good administrators that they found it impossible to build useless structures», and the French engineer Auguste Choisy wrote that «the genius of the Romans invariably knew how to reconcile a passion for major tasks with economic factors; size with devising methods that were easy to carry out» [FIG. 1]. Territorial Location When approaching the design and building process for a bridge, Roman engineers studied and overcame a series of unavoidable preliminary problems, such as selecting the exact construction spot and the materials to be used. A zone on the river that was suitable for laying the foundations and the potential for using nearby materials were excellent starting points, albeit in the case of the materials this was not a deciding factor, given that it would always be possible to transport them from a certain distance although this would make the works more expensive. This economic factor had a greater effect than might have been thought, because the preconceived idea that the resources were almost infinite and not decisive is not correct. When these initial decisions were taken, the type of works in question were also considered, as they could be of a temporary or permanent character. Other basic factors that came into play when selecting the site for a bridge were the road layout, the presence of a settlement by the river or the founding of a new city or colony. The point where the road reached the river was the spot that indicated a more or less extensive zone where the bridge could be constructed and this was later narrowed down on the basis of the way the land lay on the riverbanks and the geotechnical conditions of the ground. As the engineer Eugenio Rivera pointed out «ever since the dim and distant 90 ROMAN ENGINEERING FIG. 2 Upstream view of the Alcántara Bridge. FIG. 3 Bridge over the Guadiana, in Mérida. past, bridges were located at points where rivers were not as wide, which was where the banks are usually firmer». The works in such locations were shorter, more economical and long-lasting, the road layout being adapted to the bridge and not the other way around. This firmness was eagerly sought using specific knowledge, fortunately enabling the engineers to construct in predetermined zones where the geological conditions were the best that could be expected. The Galician bridges of Pedriña and Cigarrosa are good examples, as is the Alcántara Bridge (Cáceres), when it spans the River Tajo, in the most suitable spot from a topographical and geotechnical viewpoint, on a hard Pre-Cambrian shalegreywacke (sandstone) outcrop at the narrowest point along the watercourse. It was the same zone that two thousand years later the engineers who constructed the Alcántara Dam were to choose as the ideal spot for implementing the dam should it not have been for the presence of the Roman bridge [FIG. 2]. However, this right choice has not always been achieved and a lack of good ground conditions has brought about serious deterioration to the masonry, and sometimes the complete disappearance, of bridges that were constructed, for example, on the Peninsula’s Mediterranean watershed, caused by the phenomenon of thermal inversion and the tremendous subsequent floods at the beginning of autumn. The presence of a settlement or the establishment of a new one could have made the constructors reconsider the technical solution. The bridge over the Guadiana, in Mérida, constructed at one of the exits from the city, made it necessary to improve the foundations along some stretches of the riverbed and to construct a very long bridge in view of the layout of the valley at this particular spot [FIG. 3]. Materials When bridges were constructed for warfare and were thus temporary and provisional, wood was the material used because it adapted best to the cutting, transporting and working requirements. The only condition was that there had to be forests nearby. The bridges constructed by Julius Caesar in the war against the Gauls and by Trajan in the war against the Dacians are well known examples of timber bridges. In Spain, the remains of the piers that supported A Pontóriga Bridge in Gallaecia have been preserved, although this was constructed for the exploitation of gold in the Valdeorras area, across the River Sil, not for warfare purposes. DESIGN AND CONSTRUCTION OF ROMAN BRIDGES IN HISPANIA 91 In Hispania the most extensively used material was stone, not only the granites and slates of the west, but also the sandstones, marls and limestones of the south and east. The most easily identified bridges are the ones constructed with dry stone blocks, because the working and bonding had qualities that were favourable. Rubble stone and slate slabs were not used FIG. 4 The Old Odiel Bridge (Huelva). without mortar in the manufacturing process, because their shape and size made them unstable if no binding material was used. This type of masonry was undoubtedly used to construct bridges, not only during the Roman period but also down through the subsequent centuries. The fact that there was no dressing of the stonework and that a timeless technique was used makes difficult to pinpoint the origins of the works constructed in this way. It is necessary to resort to formal and construction comparative analyses FIG. 5 Torre Astura Bridge Aqueduct (Italy). and, above all, to the dating of the mortar utilised through the use of procedures that have made much progress in recent years. Concrete prepared with hydraulic lime was one of the major breakthroughs made in Roman times, but it was only used as a filler in bridge construction, not as the sole material. The Torre Astura Bridge-Aqueduct near Terracina in Italy, is the only one preserved that is constructed mainly with concrete, although the vaults are made of brick. This was another material that was used for both road bridges and aqueducts, and when they were built in this way, identifying them as Roman works is plagued with difficulties, as is the case with those were slate was used. One such example is the Old Odiel Bridge, near Aracena, in Huelva; considered to be Roman. It is difficult to demonstrate this entirely through its manufacturing process, although it does have two features, its typology and the small arch, which are similar to the Roman Sewers in Mérida. However, without absolute proof, this bridge remains undefined in time. Dating the bricks or the mortar by thermo-luminescence would give us a greater insight into its actual construction date [FIGS. 4 and 5]. Applying analytical systems to the identification and dating of historic masonry bridges will be extremely enlightening, in order to get construction dates, regardless of whether they corroborate current datings, or at least to enable us to know the construction period albeit within a broad time range. 92 ROMAN ENGINEERING Formal composition From Roman times and right up to the end of the 19th Century, bridge composition was determined by a variety of circumstances beyond the engineer’s will, such as, amongst others, the lay of the riverbed and riverbanks, the availability of suitable foundation conditions, how the floodwaters drained away and the economic factors. Amongst these un-resolved variables, the drainage was the variable that stood out most owing to its imprecision, in view of the fact that numerical procedures were not available to calculate the discharge of a particular flood. An awareness of low, average and high water levels constituted the basic initial data for the engineer, who, on the basis of his skill and experience, determined the size of the bridge, its gradient, where to position the buttresses and the number of arches to provide. As late as in the 1930s, the engineer José Eugenio Ribera reflected the state of the art when he examined the undermining of the buttresses caused by the high flow rate when drainage facilities were insufficient, a cause for the destruction of many bridges. He did not trust the hydraulic theories of the times, because he did not believe that they could be applied owing to their fantasy, and recommended that engineers relied more on the data obtained from nearby bridges and on the information about the levels reached by the most severe flooding remembered by the local inhabitants. Roman engineers undoubtedly had this type of information, although this did not always mean that they were successful in ensuring that some bridges would last for thousands of years, like the Alcántara or the Bibei Bridge, which have probably never been overtopped by a flood. As Fernández Casado wrote, when referring to the Alcántara Bridge ,«at a first glance it would appear to be disproportionate to the hydraulic conditions of the river, but when this is put into the context of the maximum flood levels, it proves to be perfectly functional». Something similar happens with the Bibei Bridge, which demonstrates that their designers were right in both cases [FIG. 6]. The economic factor was also decisive, since considering one solution or another could make a big difference were expense was concerned. Therefore, they must have examined several solutions varying the number of piles and the shape of the arches, the steepness of the slope and, thus, the size of the bridge, etc., and would have chosen the most economical one from the perspective of resources, materials and labour force. Upstream view of Ponte Bibei (Ourense). FIG. 6 DESIGN AND CONSTRUCTION OF ROMAN BRIDGES IN HISPANIA 93 Improvements to the foundations on the left section of Mérida Bridge. FIG. 7 Construction Once the design stage was completed and the construction stage of a bridge in Roman times commenced, we believe that the basic aim of the builders was to construct a strong, durable and economical bridge that would suitably fulfil its function, would last forever, just like the Empire and, if possible, it should also be beautiful. In order to achieve this, the first question to be solved was to find a suitable place to lay the foundations, a task at which they were not always successful at the first attempt, so they had to perform supplementary works that would improve the geotechnical conditions or otherwise adapt the type of foundation to the prevailing conditions. Solid ground was not found on the left bank of the Guadiana, where the third section of Mérida Bridge was built, so the engineers had to construct an artificial foundation with concrete masses. The fourth pier on the ancient and disappeared Ourense Bridge also had to be directly settled on the alluvial layers or on artificial rubble stone, because it was not possible to reach the granite rock, which we now know lies at a depth of 12 metres. In other zones of the Empire, such as parts of Gaul or Germania, where the terrain was not hard, deep foundations were often laid by driving in piles whose tips were reinforced with metal points, as was the case with the old Treveris Bridge (CÜPPERS, 1969). Vitruvius devoted his attention to it and advised that the driving process be carried out using «stakes made of poplar, olive or oak, scorched, and then hammered in by machine». This pile-driving technique for laying bridge foundations was extensively used from then right up to the present days [FIG. 7]. The search for a strong firm required a great technical and economic effort that in later periods was not always made. This state of affairs has been demonstrated during the recent rehabilitation works carried out on Ponte Vella in Lugo: the original Roman piers were seated on the riverbed rock whereas in the reconstruction of one pier, probably in the 18th Century, it was directly seated on the ruins of the previous construction, namely one vault, without any type of improvement or cleaning [FIG. 8]. Buttresses are the parts most prone to local undermining of the ground on which they are seated and the most exposed to the erosion caused by the action of water. The first problem was overcome by laying the foundations on hard or artificial (concrete) ground 94 ROMAN ENGINEERING FIG. 8 Reconstruction of the left pier of A Ponte Vella FIG. 9 Dovetail joints on A Ponte Vella (Lugo). (Lugo). that could withstand the erosive force of running waters with turbulences caused by their presence in the middle of the river. The second problem was dealt with by controlling the quality and hardness of the materials used and the way they were placed on the works. Piers withstand the pressure from the river water in a way that is directly proportional to their size, shape and to the water velocity, and this is achieved better if they act as one single solid body. Roman engineers managed to do this successfully if they used materials with a stone lining and concrete fill, but not as effectively if they used stone ashlars laid without mortar; in the latter case they improved the binding with construction techniques such as alternating the coursing work with ropes and headers, the use of linkages, possibly of hard timber, in the form of double dovetails, or with metal clamps [FIG. 9]. One characteristic feature of Roman bridges was the cutwater, which although not an invention of that period, was used to the best advantage by the roman engineers. Its function was to reduce the pressure of the water on the pier and to enable the waters to flow past without causing harmful turbulences. A suitable shape for a cutwater is pointed or triangular, a less effective shape being circular, which was the type used for the bridges in Mérida or Lugo, the advantage of circular cutwaters being that floating matter did not get so easily entangled in the construction. From the viewpoint of overall bridge stability, the wider the piers are the better. However, this leads to reducing the outflow capacity with all the drawbacks involved, especially where the risk of undermining is concerned. In the case of the bridges in Hispania, no uniform ratio has been observed between the thickness of the piers and the spans of the contiguous vaults, that ratio ranging from 1:1 to 1:5. The abutments are the bridge components that are subjected to the greatest unbalancing forces insofar as the arch arrangement is concerned, because, unlike the piers, they only receive the support and thrust from one single vault. Their stability depends only on their mass and thus their weight, which combined with the sloping thrust from the vault, manages to make it more vertical the bigger it is, thereby achieving greater stability. The most outstanding characteristic of Roman bridges is the use of arched masonry structures, with all the mastery of those who have understood its correct structural func- DESIGN AND CONSTRUCTION OF ROMAN BRIDGES IN HISPANIA 95 tioning and its great technological development throughout the course of time. Romans only used circular forms, either semi-circular, in most cases, or depressed, a lot less frequent yet just as important, given that this amounted to a major technical breakthrough, since they were not used again until the 18th Century. Romans also developed a variety of systems that improved vault stability, such as FIG. 10 Reinforced interior of a vault on Ponte Freixo doubling the arch rings (Alcántara), (Ourense). partially reinforcing the vault from the back (Ponte Freixo), arranging larger voussoirs at the lower parts of the vaults (Cáparra or Chaves), or erecting longitudinal walls inside the spandrel that bound the lower parts of the vaults together (Ponte Lima). The interior fill made of stonework or mass concrete also served to greatly improve vault stability [FIG. 10]. Bridge arches in Hispania generally have small spans, 80% of them ranging from 6 to 10 m. The Alcántara FIG. 11 Parapets on A Ponte Velha in Vila Formosa (Portugal). Bridge has the biggest arch with an opening of 28.80 m, although the ancient Roman Bridge in Ourense might have had a span of 33 to 34 m. Such a value would have meant that the opening was almost as wide as the 36.65 m for the San Martín de Aosta Bridge, possibly the biggest span ever used on a Roman bridge. The bridge decks in Hispania were mainly horizontal, although a minority were slightly hump-backed bridges. There are none with a mixed gradient, i.e.: a horizontal central section above the arches and a slope at the access points, like the well-known Augustus Bridge in Rimini (Italy), a model Renaissance bridge. The pavement was large, because the road was 6 or 7 m wide, like the Alcántara Bridge, which is 7.80 m or the Lugo Bridge which was 7 m wide. More than 80 % of the bridges in Hispania were wider than 5 m. Hardly any information remains about what the original road pavement, sidewalks and parapet walls were like on Hispanic bridges, because they were elements very prone to being dragged away by flooding or parts being taken away and reused in other constructions. There is no trace of the original carriageway surface, the original sidewalks, and neither is anything known about whether the parapetti [parapets] on some of them are the original ones [FIG. 11]. 96 ROMAN ENGINEERING Cornices on A Ponte Velha in Vila Formosa (Portugal). FIG. 12 As far as adornment was concerned, the simple tastes of Roman engineers prevailed, because, according to Auguste Choisy, unlike the Greeks, they were able to separate the construction from the architecture and their eminently practical personality led them to forget about ornamental embellishments. The rustic bossage of the stonework was the technique most extensively used to obtain an effect of robustness and a play of light and shade that fitted in well with Roman tastes. The decorative elements used most often were the springer or cornice, whose alignments finish off and separate the different parts and, to the naked eye, underline the formal composition of the works. They were generally laid on the springing of arches (separating these from the buttress threads) and on the edge of the facing of spandrels and walls, the external part marking the level of the carriageway. Cornices were placed along the pier shafts to reduce their slenderness when the piers themselves were rather large, as was the case with the Alconétar and Alcántara Bridges. There are three basic types: one single layer of slightly protruding ashlars (straight section of the Mérida Bridge and the Alcántara Bridge), with straight moulding and inverted chamfering (Albarregas, Cáparra, Salamanca and Lugo) and with curved moulding of the mixed type with straight ogee or top (Salamanca, Freixo, Vila Formosa, Segura, Alconétar, Mérida, etc.) [FIG. 12]. IDENTIFYING THE BRIDGES IN HISPANIA As has already been explained at the beginning, the task of identifying, let alone dating, a Roman bridge is rather complex. To make progress in this process, the first stage started by conducting a geometric and construction analysis and a formal study of the stone bridges that are reasonably well preserved and which are generally considered to be of Roman origin. A series of shared construction characteristics were extracted from the stonework, which was the main and virtually the only source for identifying them, although these characteristics were not always a common feature to all of them. The type DESIGN AND CONSTRUCTION OF ROMAN BRIDGES IN HISPANIA 97 of hewing, the bonding and the superb workmanship are the first signs that attract attention and that, in some way, when one has an overall view of the Roman construction, enable one to recognise it. The presence of certain features, such as the notches for the lever and the dove-tail holes, are such singular characteristics of the stonework that the works can almost certainly be regarded as Roman. Summarizing, the presence of some of these characteristics does not serve as conclusive proof that the works are Roman, but the presence of all the singularities does confirm that they are. The characteristic and singularities brought together after a systematic study of Roman bridges in Hispania constructed with stone ashlars are as follows: — Robustness and appreciable formal, constructive and technical quality. — Symmetrical, proportionate, uniform or harmonious formal composition. — Very frequent presence of bossing in the stonework. — Dry-laid ashlars, rubblefree and provided with finely worked joints. — Alternating arrangement for the ashlar layers, with a rope and header bond. — Devices for locking the stonework: – Dovetail joint keys/linkages. – Lead filled metal clamps or pins. — Evidence of holes, on opposite faces, for the tongs. — Evidence of notches on the edge and the bottom of ashlars, for levers to be inserted and used. — Absence of stone quarry marks, although Roman numerals and letters can occasionally be seen, as well as engravings and indentations. — Semi-circular or occasionally depressed circular vaults. — Vaults wider than 4.50 m, frequently ranging from 6 to 7 m, of uniform thickness throughout the rings. — Identical measure of vault opening and width in some cases of culverts. — Presence of cornices for adornment and composition. — Horizontal or slightly humped gradient. It is essential that this type of identification, based on evidence of certain features on the masonry, be supplemented, to the extent that this is possible, with historic, archaeological, geological data and documentary evidence, etc., which can be directly or indirectly associated with the works in question [FIG. 13]. Where Roman bridges are concerned, and in view of their age, very little historic information remains, therefore data of an archaeological nature, not only about the bridge but also regarding its surroundings, are needed, as they could be decisive. A list of the construction details originated in Egypt is given below, as Egypt is the country where Greek architects learnt to put them into practice, before they were taken on and used in Roman construction [FIG. 14]: 98 ROMAN ENGINEERING Notches to facilitate the use of a lever on the ashlars of Ponte Freixo (Ourense). FIG. 13 FIG. 14 Linkage made with sycamore wood in Kom Ombo (Egypt). — Dry-laid ashlars with very fine joints between the stone blocks. — Hewing of notches so that levers can be inserted and used to lay the ashlars. — Use of anathyrosis for dressing the joints between ashlars. — Alternating of ashlar courses with ropes and headers. — Increasing the internal binding of the stone blocks by means of wooden double dovetail links. — Bossing of the exposed faces of ashlars. — Limited use of marks or graphite. TWO IDENTIFICATION EXAMPLES Recently, for distinct reasons, two bridges very different in style and materials and in which greatly differing techniques were used, were studied. Both are found in Hispanic territory but far apart from each other, one in the south of the Bética region and the other in the north of Gallaecia. The first one is on the Cotobro Culvert spanning the stream or rambla of the same name, close to the city of Almuñécar, in Granada, which was built to make it easier – if it proves to be of Roman origin – to reach the Item a Castulone Malacam Road, number 5 on Antonino’s Itinerary, between the mansiones called Saxetanum and Caviclum. It was constructed with hydraulic masonry using irregular local stone and has a semi-circular vault, whose span and width are both 4.90 m. The ring is supported on masonry abutments that were constructed in horizontal layers 30 to 50 cm thick [FIG. 15]. Its identification is not easy because of the type of masonry used, of hard to know origin as it has been carried out in a similar way down through the centuries. However, it has been considered possible that the abutments and the vault are of Roman origin, whereas the rest could be a result of later modifications or reconstructions that gave it its current elevation and gradient. We have based our conclusions on the following arguments: DESIGN AND CONSTRUCTION OF ROMAN BRIDGES IN HISPANIA 99 FIG. 15 Cotobro Culvert in Almuñécar (Granada). — A first argument that would suggest that it is Roman bridge is the fact that it is close to Sexi, the ancient Punic-Roman city, where abundant Roman archaeological remains are found. — The bridge lies on the old road that left Sexi heading west. — The construction process is similar to the technique used for the aqueduct-bridge constructed in the vicinity to supply the city. The span of the upper arches on one of the bridges is the same width (4.90 m) (FERNÁNDEZ CASADO, 2008, 196). — The way the stonework is laid in tiers, ranging from 30 to 50 cm thick, with the upper face evened out to a horizontal plane, is similar to other Roman constructions, such as the interior vaults of the Brigantium Lighthouse (A Coruña), the Segóbriga Baths (Cuenca), the outer walls of the vaulted building in Centcelles (Tarragona), etc., as well as the masonry of the aforementioned aqueduct. — The vault’s span and width are the same. This is a feature of the Roman culverts at San García and San Ciprián along a branch of the road from Milán to León, number 1 in Antonino’s Itinerary, leading to Segasamunclo Mansion, located on the Valdemoros Pass on the outskirts of Cerezo de Río Tirón. Furthermore, the rings on these two culverts are equally 59 cm (two feet) thick which is also the thickness in the Cotobro Culvert. The equality of the span and width is also a feature of the crossing works for Road no. 17 from Bracara to Asturica, at San Lourenço and Ponte do Arquinho, in Portugal. The span of the end arches on Ponte Freixo are also the same size as their width, 4.70 m. Decisive data in this regard will be obtained from the result of the dating test carried out on the binding mortar, using the thermo-luminescence technique. The second bridge on which the masonry was analysed was the Ponte Vella in Lugo. The first remnants identified as being Roman were recognised in 1996, and it was in the 100 ROMAN ENGINEERING summer of 2012 when there was an opportunity to complete the study of most of the original masonry that remained, on the occasion of the rehabilitation works that were being conducted. The construction of a cofferdam left part of the Miño riverbed dry, so it was possible to excavate around the undermined piers and get them underpinned again. It is the bottom part of these piers that FIG. 16 Roman lower body of a pier in A Ponte Vella (Lugo). still retain most of their Roman masonry, these consisting of square stone blocks, the ashlars being locked together with clamps in the form of a double dovetail that we assumed to be of timber as there were no traces left. It was dry-laid, without rubble, the joints being finely worked to guarantee good contact, and with alternating layers of stone blocks laid with a rope and header bond [FIG. 16]. In spite of having found some arch voussoirs when excavating the riverbed around the piers, there is FIG. 17 Roman stonework with a circular positioning line on its not enough data to enable us to bed. know what shape the Roman vaults were. Plotting marks were detected however on the ashlars that permitted to find out the dimensions of the pier body: 7 m width (transverse to the bridge axis) and 4.70 m thickness. The discovery of two ashlars with rounded faces and three others with circular positioning lines carved into their beds, made it possible to know that the original cutwaters were semi-circular, similar to the ones on the Mérida Bridge. A couple of ashlars were also found with one edge chamfered that could well have been from the cornice. This type of springer can be seen on the Roman bridges of Cáparra and Salamanca [FIG. 17]. A large number of loose ashlars found on the riverbed, as well as quite a few from the pier bodies, show evidence of notches to facilitate the use of levers to lay them in place, which as has already been pointed out, is a singular feature of Roman masonry. And finally, reference must be made to the discovery of some marks in the form of letters, an engraving and a rough relief that appears to represent two propitiatory symbols joined together, like a phallus and the fig, similar to the one that appears on the bridge over the Guadiana and on the Los Milagros Aqueduct, both in Mérida. Evidence of all these construction characteristics on the masonry of Ponte Vella in Lugo confirms beyond all doubt that the bridge is of Roman origin. DESIGN AND CONSTRUCTION OF ROMAN BRIDGES IN HISPANIA 101 BIBLIOGRAPHY J. P. ADAM: La construcción romana. Materiales y técnicas. León, Editorial de los Oficios, 1996. «A Pontóriga. Sobre los restos de un antiguo puente romano cerca de Sobradelo de Valdeorras». Boletín Auriense, tomo IX, Ourense, 1979. S. ALVARADO, M. DURÁN and C. NÁRDIZ: Puentes Históricos de Galicia. Santiago, 1989. J. M.ª ÁLVAREZ MARTÍNEZ: El puente romano de Mérida. Monografías Emeritenses 1. Badajoz, 1983. M. H. BALANCE: The roman bridges of the Vía Flaminia. Rome, The British School, 1951. A. CHOISY: El arte de construir en Roma. Madrid, CEHOPU - Instituto Juan de Herrera, [1873] 1999. H. CÜPPERS: Die Trierer Römerbrücken. Mainz, Verlag Phillip von Zabern,1969. M. DURÁN FUENTES: La construcción de puentes romanos en Hispania. 2nd Edition. Santiago, Xunta de Galicia, 2005. C. FERNÁNDEZ CASADO: Historia del puente en España. Puentes Romanos. Madrid, Instituto Eduardo Torroja, 1980. — Acueductos romanos en España. Madrid, Colegio de Ingenieros de C. C. y P., 2008. V. GALLIAZZO: Il ponti romani. Venecia, Edizione Canova, 1995. P. GAZZOLA: Ponte Pietra a Verona. Ponti Romani. I-II. Florence, Leo S. Olschki Editore, 1963. P. MENDES PINTO: Pontes Romanas de Portugal. Lisbon, Associaçao Juventude e Patrimônio, 1998. C. O’CONNOR: Roman Bridges. Cambridge University Press, 1993. A. PEREIRA BRANDÃO: Estradas e pontes romanas. Lisbon, Junta Autónoma de Estradas, 1995. SEVERAL AUTHORS: «Puentes I», «Puentes II» and «Puentes III». Revista O. P. Colegio de Ingenieros de Caminos. Barcelona, 1991. PLINY THE YOUNGER: Letters. Translation by Julián González Fernández. Madrid, Editorial Gredos, 2005. M. VITRUVIUS POLLIO: Los diez libros de Arquitectura. Translation J. L. Oliver Domingo. Madrid, Alianza Editorial, 1997. S. ALVARADO BLANCO: Back to Contents 102 ROMAN ENGINEERING 6 Artifex. Roman Engineering in Spain BERNARDO REVUELTA POL Architect. Managing Director of Fundación Juanelo Turriano INTRODUCTION The course «Roman Engineering. That the greatness of the empire might be attended with distinguished authority in its public buildings», held in Segovia and jointly organised by UNED and Fundación Juanelo Turriano, ended with a visit to the exhibition entitled Artifex. Roman Engineering in Spain, shown in the recently restored Casa de la Moneda [Mint]. This exhibition was first opened at the Madrid’s Museum of Archaeology in 2002, and after being adapted to enable it to travel, it has visited a variety of museums and cultural centres throughout Spain, having been on show at 18 different venues so far. Along with Fundación Juanelo Turriano, the exhibition was organised by the Ministries of Culture and Public Works, in the latter case via CEHOPU, a department of CEDEX whose collection of mock-ups and models supplied the photographs that are featured in this article. The curator of the exhibition and source for most of the texts used to prepare this summary was the Civil Engineer and Professor at Universidad de Granada, Ignacio González Tascón (1947-2006), whereas the author of this article has been responsible for its design and setting up only. The underlying idea behind this exhibition was for it to form part of a larger project whose aim was to feature the entire history of engineering in Spain, examples of which include Felipe II. Ingenious Devices and Machines (1998) and Ars Mechanicae. Medieval Engineering in Spain (2008), also planned in Fundación by the same authors. The text that follows is an abbreviated account of Roman Engineering as seen through the Artifex Exhibition, a view that carries all the limitations and determinants inherent to an exhibition format. Firstly, it has been necessarily foreshortened, which means that certain material of undoubted value has had to be excluded. Secondly, the consideration that an exhibition of 103 such characteristics must have an educational role that makes it useful and appealing to a broad target of the general public, but without compromising its scientific rigour. The secret of its success or failure lies in finding a suitable balance between these two factors. Furthermore, it happens to be the case that the subject matter being dealt with here, engineering, is a dynamic reality, a continuity that reaches out through time and space. Explaining engineering works means that it is necessary to talk about projects, construction, operation, improvements, adaptation to other uses, connections between some works with others, integration into more general systems, etc., which involves certain difficulties, because an exhibition is basically static, although dynamic elements such as audio-visual aids or models in motion can be utilised. In view of all the aforementioned, this exhibition, like the other referred to above, places emphasis on engineering as a process. Therefore, when explaining an arched stone structure, what is stressed is the decisive role of the carpentry work that is essential for constructing the centring, and if it is the arcuationis of an aqueduct that are on display, it should not be forgotten that these are just a small part of a complex water supply system. Although this is self-evident to the well-informed observer, it is not so obvious to other sectors of the public whose initial interest may be limited to the exhibit purely as a monument, not utilitarian, timeless, of Roman works as they have survived until the present time. The exhibition is organised into the following five areas: Area I. Construction: materials and machinery. Area II. Communications: roads, bridges, ports. Area III. The city and its equipment. Area IV. Mining and metallurgy. Area V. Industrial techniques and arts. Area I. Construction: materials and machinery The first image that can be seen in this Area and the one that opens the exhibition is that of a Greek sage, not a Roman one. It is an image that depicts the famous scene in which a soldier is about to kill Archimedes during the taking of Syracuse, an act that caused great displeasure to the Roman military leader Marcellus, who was no doubt looking forward to putting the Greek man’s knowledge at his service. A mathematician and constructor of devices and machines, Archimedes came to epitomise the philosopher of nature who combined his status as a great thinker with practical activities that we would now consider to be inherent to civil engineering. As Professor Alicia Cámara points out in another one of these papers, during the Renaissance, and even afterwards, outstanding engineers were often praised by being compared to Archimedes, of which there are many famous examples, although it is quite probable that the Greek sage would not have been too pleased about this, given that, according to Plutarch, Archimedes considered the work of engineers and other practical activities to be ignoble and only suitable for artisans. Such was the dichotomy between intellectual and practical activities, that has pervaded history, the first manifestations of which include, amongst others and by way of 104 ROMAN ENGINEERING example, the explanation of the origins of mathematics. According to Aristotle, mathematics was created by the Egyptian priest caste, which had spare time to devote to intellectual speculation, whereas Herodotus also states that mathematics arose in Egypt, but for land registry purposes, i.e. the reasons where of a practical nature. Whatever the case may be, the aim was to make it clear that Rome owed much to Greece in the engineering field, as well as in many other areas. It must be pointed out that Roman engineering, in spite of the magnitude of its performance, is not characterised by having made many contributions where purely technical innovations are concerned. Firstly, the extensive and imaginative use of arches and vaults are among the few that we can highlight, albeit not as inventions in themselves, and, secondly, the use of concrete, especially hydraulic concrete. Arches consisting of stone voussoirs supported by one centring assembly during the construction process opened up hitherto unknown potential for architectural and engineering works, as is the case with bridges. It is not known for certain who invented this wonderful idea, although the first known arches with voussoirs where there is no doubt about their construction period date back to midway through the 3rd Century B.C. and seem to have appeared in the regions of Italy that were greatly influenced by the Etruscans. Nevertheless, the idea was successful and rapidly spread not only throughout the Western world but also in the Hellenic kingdoms of the East. The arch construction process, once the piers on which it was to be supported had been put in place, involved the erection of a robust and stable wooden centring, which was laid in a suitable position with the aid of scaffolding and hoisting machines. Exactly the same procedure was used to construct barrel vaults and groined arches, formed by the encounter between two orthogonal barrel vaults and rarely used owing to the difficulties involved in cutting the stone in the shape required and with the precision needed to construct the encounter. The first groined arches performed with blocks of worked stone appeared at a later date – midway through the 3rd Century A.D. – in a far-flung corner of the Empire, in Syria, the first known example of this technique in Italy being the Mausoleum of Theodoric, as late as 530 A.D. However, in Hispania, an exceptional granite construction of this type is to be found in the quadrifons arch in Cáparra (Cáceres) dating back much earlier (6996 A.D.), a scale model of which is on FIG. 1 Model of the quadrifons arch in Cáparra display at the exhibition [FIG. 1]. (Cáceres). ARTIFEX. ROMAN ENGINEERING IN SPAIN 105 The invention of concrete, a doughy product, malleable and easy to mould, that hardens to the consistency of stone in contact with air, is a genuinely Roman achievement. For its fabrication, a wooden coffer work is used, an idea borrowed from the Carthaginians, and lime mortar as a binder which, together with the aggregates and water, made a plain concrete known as opus caementicium. However, the concretes made with lime only cure when in contact with air, so they cannot be used in submerged works, so for these types of works Roman technicians experimented with manufacturing special concretes that could harden while under water. In an empirical way, which still amazes us, they discovered that if they replaced the usual FIG. 2 Model of a crane operated by a treadmill. sand in the lime mortar with some dark ash of volcanic origin that they called pulvis puteolanus [pozzolanic ash], a miracle took place, and they obtained a special mortar that, when poured over the aggregates, was able to set and harden under water. Pozzolanic ash or pozzolan was only used on exceptional occasions, because transporting it from afar made the works more expensive. It is the earliest record of hydraulic concrete in history, and there is no evidence of another case – manufactured artificially – until 1824, when the English inventor Joseph Aspdin patented Portland cement. The Romans used many other construction materials (timber, ceramics, glass, etc.), one of which is particularly worth mentioning because of its singularity, lapis specularis [selenite], a transparent crystalline gypsum that is easy to exfoliate, whose main quarries were in Hispania, close to the city of Segobriga (Saelices, Cuenca) and used, as an alternative to glass, for making the enclosure on ports and windows. We will bring this brief summary to an end by mentioning the auxiliary machines used for construction purposes, such as cranes, lathes or block and tackle to increase the force, bucket wheels, spandrels, draining machines, cocks, Ctesibius’ pumps or Archimedes’ screws, devices already known and used in Greece and Egypt and whose design and construction were tasks commissioned to the mechanicus, the engineer whose job was to construct devices and machines. The descriptions given by Vitruvius have been used to make some of the scale models of these devices, although in some cases it has been possible to study specific examples from their archaeological remains [FIG. 2]. 106 ROMAN ENGINEERING Area II. Communications: roads, bridges, ports The communications that were made possible by the Empire, which provided its «backbone», as Carlos Caballero entitles his paper, are viewed in this exhibition from the perspective of the infrastructures, emphasis being placed on their technical and construction aspects. As far as roads and land vehicles are concerned, we can start by mentioning here the model of the odometer, which according to Vitruvius’ description was a sort of cart that had a device attached to one of its wheels, consisting of gears that enable the user to know automatically when the vehicle had covered one mile, or five FIG. 3 Model of the odometer. thousand feet, which is the equivalent of 1,481 m [FIG. 3]. The most outstanding aspect of bridges, which were extensively dealt with in the paper by Manuel Durán, is the description, by means of a model, of the construction process for the pier of a bridge spanning muddy and not very solid terrain. The model shows a cofferdam consisting of a dual palisade of wooden piles, the inside of which has been filled with well-rolled clayey earth, which makes it possible to create an enclosed waterproof zone from which the water can be extracted by a variety of draining devices. The foundation that will support the pier has been laid on the bottom, this being half-completed in the model. Unfinished stone walls can be seen and these also act as permanent formwork for the concrete filling. On the water there is a raft with a hammer to drive in the row of piles for the next cofferdam [FIG. 4]. FIG. 4 Model of a bridge pier under construction. ARTIFEX. ROMAN ENGINEERING IN SPAIN 107 Model of the centring for the reconstruction of Alcántara Bridge. FIG. 5 Model of a coclea, the Archimedes’ screw or Egyptian snail. FIG. 6 Other interesting models include the one that shows the centring that was designed in 1856 by the engineer Alejandro Millán for the reconstruction of the Alcántara Bridge and the model of a coclea or Archimedes’ screw, a machine for raising liquids, which is still used today. In this case, as in many others, it must be stressed that these machines from Ancient Times are still utilised now with the same mechanical arrangement, albeit constructed with other materials and driven by other sources of energy, which is the main difference [FIGS. 5 and 6]. 108 ROMAN ENGINEERING Model of the hypothetical original state of Tower of Hercules. FIG. 7 The Brigantium Lighthouse or Tower of Hercules is a singular example of the infrastructure used for maritime communications that still remains in Spain. It is the only Roman lighthouse that is still used for navigation aid purposes. The name of its designer is also known, the architectus Gaius Sevius Lupus, from Aeminum [Coimbra], in Lusitania. The Tower of Hercules was originally a rough, 3-storey concrete structure, the first two floors each being about 9.5 m high, the top one being 13.5 m. The three levels were linked only by an external ramp that was supported between the central core, which is the part that survives, and an outer wall. It was abandoned for centuries, until in 1685 the architect Amaro Antúnez carried out some refurbishments that enabled it to be adapted to its former use. As the exterior wall (and thus the ramp) had already disappeared a long time before, an interior wooden staircase was built up to the top of the tower, for which purpose Antúnez had to drill into the concrete vaults. A much more ambitious modernisation project was carried out between 1785 and 1791 by the engineer Eustaquio Giannini, who replaced the humble wooden staircase with a stone one, which is what is used today to reach the top. The outer wall was also covered with granite, leaving a narrow stretch of stone still visible to remind visitors that the ramp had once existed. That was when a smart flashing light was added, thus returning the tower to its former glory and function as a lighthouse. There is a model exhibited of the lighthouse, cut to show the strong outer wall and the ramp used to carry firewood up to the top platform of the tower, where a fire was lit to warn vessels [FIG. 7]. ARTIFEX. ROMAN ENGINEERING IN SPAIN 109 Area III. The city and its equipment This section basically concerns the systems that supplied and distributed water for urban use; these were complex systems that required Roman engineers to make the most of their skill and, as a result, they have left some of the most outstanding Roman works that still survive today. The subject is explained in detail in the papers prepared by Alonso Zamora and José María Álvarez Martínez. By way of an introduction to the subject, a few instruments are exhibited that were used in the essential surveying work required for an aqueduct layout, including the chorobates [water level], an instrument fitted with a water level that we know about thanks to the description given by Vitruvius in his famous treatise. It is composed of a wooden frame 20 feet long (nearly 6 m), meaning that it is heavy and difficult to transport, which it makes up for by being remarkably accurate with its measurements [FIG. 8]. The construction of cisterns that collected and stored rainwater so it could be distributed to nearby homes and public buildings, is one of the simplest water supply procedures that should be mentioned. The best kept records of this type of works in Hispania are for Emporion (Ampurias, Girona), a settlement that did not have a public aqueduct with water supplied by ducts either in the Greek polis period or in the Roman period. Twenty-seven cisterns have been excavated in the Roman urbs, all of which are of the underground type and covered to prevent dirt from entering and the sun’s action from causing the water quality to deteriorate. Roman tanks are easy to distinguish from the Greek ones, which are long and narrow and just covered with one simple stone slab. However, Roman cisterns are much wider and deeper, because their tops covered with lime concrete vaulting enabled them to span greater distances. Furthermore, the vaults transmit horizontal forces to the upper part of the works, so it is possible to dispense with inner diaphragms or ties that were frequently used for Greek cisterns to prevent collapse caused by earth pressure when they were empty. This new type of Roman cistern, wider and deeper, was much more rational and economical, in view of the fact that it was possible to store a much greater volume of water with the same surface area of side wall. Although the use of wells and cisterns in roman cities was widespread, the Romans preferred water to be transferred publicly via aqueductus. These were works of great political significance, generally financed with funds from the aerarium (public treasury). The design was left to the architectus or hydraulic engineer, who could rely for their execution on specialists in different subjects. FIG. 8 Model of a chorobate. 110 ROMAN ENGINEERING Before water could be supplied to towns a suitable source from which to draw it off (caput aquae) was required. Sometimes fontes (springs) were used directly as they rose to the surface, as long as their flow rates were sufficient to guarantee supply, even during the summer months. This was the solution adopted in the city of Gades (Cadiz), which drew off its water supply from the distant but excellent Tempul Springs. However, the Romans resorted more frequently to groundwater as the source, and this was generally drawn off by excavating galleries, which was already an old technique in Roman times. This was the system used for the Segobriga or Sexi (Almuñécar, Granada) Aqueducts. An in-depth working knowledge of the terrain was required to locate the groundwater, hence the importance of the aquilegus, an expert water diviner able to detect hidden springs and to assess the quantity and quality of their waters. Nevertheless, in most cases, the engineers resorted to extracting the water flowing in rivers or streams (fluminus cursus), which was diverted to a brickwork channel, either using a diversion dam or small weir, or by means of an outtake from a reservoir. When looking for water supplies on the Iberian Peninsula, Roman technicians steered clear of the major rivers because of their irregular flows and the seriousness of their floodings, which could easily wash away the works erected on the watercourses. That is why Zaragoza was not supplied with the water from the Ebro, Toledo was not supplied with resources from the Tagus, Mérida did not receive the waters of the Guadiana and Córdoba was not supplied by the Guadalquivir. Instead of using the major rivers, they preferred to tap the waters of minor rivers and streams, whose water discharge was carefully studied. Once the river course had been selected, in order to channel the water to the artificial duct that would convey it to the desired destination – also for irrigation or industrial purposes – the most reasonable economic solution was to erect a saeptum (dam) in the riverbed, generally not very high. These were minor works, sometimes consisting of loose stones secured with tree branches, others were made of masonry or stonework, whose purpose was not to store the water, but to divert it into the channel. The dam that diverts the waters of River Frío into the Segovia Aqueduct is a well conserved example. When the water supply could not be guaranteed all the year round, saepta (dams) were built for regulation, storing the water in the rainy months so that it could be distributed throughout the year. Rather than choosing the beds of large rivers, Roman technicians often preferred sites with natural dips in the terrain, so they could erect the dams in dry conditions and then fill the areas behind them by diverting the water from the nearby rivers or streams into the hollow, thereby creating a reservoir. The importance, diversity and state of conservation of the dams in Hispania was much better than any other region in the Roman world, mainly because of mountainous nature of the Iberian Peninsula and the excellent quarries providing stone for construction work. The smaller Roman dams, not very high, were built with continuous masonry walls. should they exceed some 2 m high, the engineers would find ways of saving on stone and concrete by replacing the thick solid wall with a thinner one, reinforcing the downstream face with buttresses that helped to withstand the water pressure. The Araya Dam, near Mérida, with a maximum of 4 m high, is an example of this wall and buttress type. Considerable progress was made when flat walls were replaced by small arches, which are better able to withstand the water pressure, enabling the designer to increase the gap ARTIFEX. ROMAN ENGINEERING IN SPAIN 111 between buttresses. The Esparragalejo Dam, also close to Mérida and just over 5 m. high, is the best conserved dam of this kind, i.e. multiple arch buttress dams. A third way of lightening dams and saving on materials was devised by replacing the quarry stone and concrete with compacted earth. In these cases a slender wall was erected, to which an earth shell was attached, adjoining the downstream face, which helped to withstand the water pressure when the reservoir was full and the pressure was at its maximum. The Proserpina and Cornalvo Dams are of this type – wall and earth shell –, both being 21 m high and constructed as part of the supply infrastructure for Augusta Emerita (Mérida). Models of these dams can be seen in the exhibition [FIGS. 9 and 10]. In the case of not very high dams, a single opening or a rectangular outlet made in the dam body was the only device needed for the extraction of water from the reservoir, enabling it to flow into the channel. However, major works required the water to flow out of large towers through a series of thick lead pipes located at different heights, controlled by stopcocks. FIG. 9 Model of Proserpina Dam, Mérida (Badajoz). FIG. 10 Model of Cornalvo Dam, Mérida (Badajoz). 112 ROMAN ENGINEERING An aqueduct could only be constructed once the layout (directura) had been defined with great precision, after careful levelling, making sure that the drop was sufficient to enable the water to reach the city by gravity. The water flowed down a specus (masonry channel) from the head catchment as far as the city’s distribution cistern or castellum aquae [water tower]. These channels varied greatly in length depending on the place where abundant drinking water was found. The longest construction of this type in Hispania was the Gades Aqueduct, approximately 75 km long. The specus was invariably covered over in order to prevent pollution, and it ran down a gradient that was sufficiently steep to make up for losses due to friction, and the slope was as uniform as possible. To achieve this, at times it ran underground, but sometimes it was raised above ground, and this was done by means of masonry walls (substructiones), if the height that had to be cleared was limited, or arches (arcuationes), if the excessive height made this advisable. One single row of arches was normally sufficient, but in exceptional circumstances, to span gullies or river valleys, several superimposed levels of arches were erected, which led to the construction of some of the most beautiful engineering works ever constructed, which are often identified as the most characteristic element of Roman aqueducts [FIGS. 11, 12 and 13]. FIG. 11 Model of Segovia Aqueduct (Segovia). FIG. 12 Model of Las Ferreras Aqueduct (Tarragona). FIG. 13 Model of Los Milagros Aqueduct , Mérida (Badajoz). ARTIFEX. ROMAN ENGINEERING IN SPAIN 113 The impurities or limus (silt) that the water entrained was generally removed in the final stretch of the channel, before entering the city. This activity took place in the piscina limaria [settling pool], a decanting or desanding tank, where the hydraulic section was greatly increased, the flow velocity decreasing thus enabling the sand and silt to settle on the bottom. Free of impurities, the water could flow into the large distribution cistern, located at the highest part of the city. Whenever the ducts had to cross dips or deep canyons, the running water channel solution was often given up in favour of the siphon, which ensured that the water was piped at a pressure greater than atmospheric pressure. Flowing from the channel to the siphon required the construction of two transition boxes, where the change of hydrodynamic system took place, from free flow to pressure piping. The most important and largest box is the one for the inflow to the siphon, which has to guarantee that the pressurized pipe is always loaded, so that air bubbles cannot enter that might cause turbulence and even throttle the flow. Furthermore, it has to be equipped with an overflow (ladronera or almenara) to remove surplus water. The outflow box is usually simpler, all that is required for it being to be located at a suitable elevation in order to enable the water to flow into the channel at a suitable velocity. A wide variety of materials were used to construct the siphon piping. Ceramic ducts (tubuli) were used for Sexi; lead piping (fistulae) was the solution adopted for Caesaraugusta (Zaragoza), and even stone blocks with drill holes can be seen in situ for bringing water to Gades, much of which flowed in siphon. The most fragile part of a siphon is the lowest part, where the pressure is at its highest. It has to be absolutely flat and horizontal to prevent air bubbles from being trapped that could throttle the flow. The Romans constructed a carefully levelled «venter» at this part, which generally fulfilled the twofold function of being a bridge and serving to support the siphon piping. The castellum aquae or water distribution cistern was then used to send the water (erogatio aquarum) to the various districts in the city, by means of lead pipes, which conveyed the resources to the public baths and troughs and fountains where the citizens collected their supplies. As the city grew, the water also reached the major public buildings (such as theatres, amphitheatres and circuses), to the industries that required it, to the most luxurious houses (domus) and, sometimes, to the basements of the humbler dwellings with several storeys or insulae. The users paid on the basis of the modulus or bore of the piping contracted, the basic unit being the quinarius, which was a pipe whose inner diameter was 5/4 of a finger (digitus), i.e. around 2.3 cm. To ensure that the resource was fairly shared out, the water pressure had to be more or less similar at all outtakes, so every so often surge tanks (columnarias) were provided to prevent the districts at a lower altitude from receiving more than their fair share of water. The water officials fitted a special pipe called a calix, generally made of bronze, in the intakes in order to prevent abuses and fraud, which often took place by citizens replacing the contracted piping with other pipes with a larger diameter; this pipe was sealed externally with complicated bossage to make forgery more difficult. 114 ROMAN ENGINEERING Roman engineers were always concerned about two aspects of water associated with the health of the cities’ inhabitants: the quality (bonitas) of the drinking water and the advisability of rapidly draining away the waste water beyond the urban zone to prevent disease from spreading. With the latter objective in mind they constructed model sanitation networks, which were not bettered for many centuries. The same careful levelling and measurement processes used by the surveyors to convey water to the city and distribute it to the numerous districts, also served to protect and construct the underground galleries that made up the sewer network that enabled the waste water and sewage to flow away from the city, and with it the filth that it contained. Water from latrines (latrinae) in houses and public places [foricae], also reached the sewer network, arriving in much greater quantities from theatres, amphitheatres or circuses, as they filled up with spectators when shows were on. The sewage system also took away the waste water from polluting industries such as the dye-works (tinctoriae) or the factories where cloth (fullonicae) was milled. Any rainwater collected in the street gutters and the surplus water that flowed out of the troughs, fountains and nymphaeums also ended up in the network. Frontinus, in his famous technical treatise De Aquaeductu Urbis Romae, pointed out the advisability of letting the surplus water that overflowed from the fountains serve, «not only the healthiness of our city, but also to clean the gutters and sewers». Area IV. Mining and metallurgy Although there were mines whose function was not to extract minerals from which metals could be obtained – such as ornamental stone and lapis specularis –, the aim of most of these exploitations was to find and obtain one of the seven metals known to the Romans: gold, silver, lead, copper, tin, iron or mercury. This explains why the subject of metallurgy and mining appear together in this section. The Las Médulas gold mines stand out from the many other Roman mine exploitation, because procedures were used that radically changed the landscape, as can be seen in the audio-visual aid that is shown in the exhibition and as the numerous people who visit this district in the Province of Leon can bear witness. The gold extraction method, which Pliny the Younger called ruina montium or hill destruction, was based upon erosion, or perhaps pressure, caused by water, which was poured in large quantities from tanks through underground galleries. The water for these headwater tanks were supplied by a network of channels simply dug in the ground and that were not covered over in any way. The force of the water knocked over, washed away and decomposed the gold conglomerate «The mountain, cracked open, collapses under its own weight and comes crashing down making a noise difficult for the human mind to imagine» (Natural History, 33.7078). The gold is subsequently decanted, and the small stones removed, in washing channels. It must be pointed out that the amount of gold obtained was minimal if this quantity is compared with the thousands of tonnes of earth moved, although it would undoubtedly have been profitable in the economic context of the period. The mine drain pumping machinery was an essential part of mining technology. One of the models made for the exhibition is a rota (bucket wheel). Very little is known about ARTIFEX. ROMAN ENGINEERING IN SPAIN 115 Model of a draining device (bucket wheel) from the Huelva mines. FIG. 14 Replica of the Ctesibius pump from Sotiel-Coronada. FIG. 15 whether the origins of this device are Hellenic or whether it dates back even further. Vitruvius describes it clearly and the fact that it has been found in many archaeological sites serves as proof that its use in Hispania was widespread. The set of rotae (bucket wheels) found in the Riotinto Mines (Huelva) are a good example of the perfection of Roman mine-draining techniques. They consisted of at least eight pairs of wheels, each one of more than 4 m in diameter, raising the water 30 m. This scale model (1:2.5) is based on the data taken from the remains studied [FIG. 14]. Another singular exhibit is the replica, in the same material – bronze – and identical dimensions, of the Ctesibius pump, which is kept at the National Archaeological Museum in Madrid. The Hellenic sage Ctesibius of Alexandria is considered to have invented the sipho or dual-effect piston pump, i.e. suction-impeller, midway through the 3rd Century B.C. No texts written by the inventor remain, although there are several descriptions of the machine, including articles in the Pneumatica by Hero of Alexandria or De Architectura by Vitruvius. The latter gives an accurate and detailed description of the components that constitute a pump of this type, indicating that the device raises the water to a great height and is cast in bronze. Two identical cylinders, each one with its own piston, converge on a shared chamber that contains the valves that open and close to make the water-raising process continuous. The machine was operated by hand, by means of a wooden lever with a reciprocating movement. In an alternating pace, the water ascended up one or the other of the two pistons, being distributed from the valve chamber. At least two pumps of this kind have been preserved in Spain, one made of lead, found in the lead mines of the Sierra de Cartagena, in Murcia, and the other made of bronze, found in the Sotiel-Coronada Mine, in Huelva. In the Romano Oiasso Museum in Irún there is a valve, identical in every way to those that were cast for this reproduction, that, once completed, was tested to verify that it operates correctly in the way described by Vitruvius [FIG. 15]. FIG. 16 Stages in the casting of bronze using the lost wax procedure. In compliance with the criterion expressed in the introduction concerning the importance of considering engineering as a process, the technique of casting with the «lost wax procedure» is explained, and visitors are taken through the nine steps sequence followed to make a bronze sculpture, for which purpose the head of a nobleman dating back to the 1st Century B.C. is used as the model; this sculpture was found in the necropolis at Cabezo de Azaila (Teruel) and is preserved at the National Archaeological Museum. The stages begin with the head modelled in clay by the artist and this is followed by the preparation of successive gypsum or mortar moulds and countermoulds until the end product emerges. The widespread use of lost-wax bronze casting became an art and technique during Roman times that enabled the artist to make a relatively numerous series of copies in bronze at a reasonable price, from one single sculpture modelled in clay, These pieces, together with the aforementioned Ctesibius pump, were created expressly for the exhibition by the bronze-casters Marisa and Miguel Ángel Codina [FIG. 16]. ARTIFEX. ROMAN ENGINEERING IN SPAIN 117 Area V. Industrial techniques and arts In this final part, and to round off the exhibition, certain industrial or craftsmanship activities are shown that, involving agriculture, fishing or livestock, are of special interest due to their characteristics, as they give us insight into some of the everyday customs of Roman civilisation. Rome, which raised the sumptuous arts to cult status, revealed a liking for the most expensive and exquisite dyes in their clothing and the textiles that they used to adorn their homes. The city of Rome obtained the very best raw materials from among the ones that could be found in each one of the Empire’s provinces and made the most exotic products from the Far East arrive along the silk routes. Numa Pompilius, the legendary king of Rome (c. 715 - c. 672 B.C.) is considered to have set up the first craftsmen’s guilds, including the Collegium tinctorum, where practicing of the profession was structured and legislated. It was split into categories: the infectores, who created the colours, and the offectores, whose job was to re-dye worn or faded garments. The infectores had their own specialities depending on the techniques that were required to handle the different raw materials, such as the flammarii, that dyed red from a blond root and the kermes insect, the crocotarii, that dyed yellow with saffron, or the purpurarii, that dyed purple with sea snails. The social status of the owner of an officina tinctoria [dye-works] was that of a respectable and well-off citizen who had at his service, the workers, often slaves, who carried out the physical work. In Hispania, the main archaeological remains of a Roman officina tinctoria recovered and documented are the Barcino Dye-Works in Barcelona, dating back to the second half of the 2nd Century A.D. Apart from use in the dye-works, tannins were utilised in the manufacture of atramentum, the black ink for writing purposes. The preparation process involved crushing products rich in tannin, such as oak apples or grape skin, boiling them in water, adding iron sulphate or acetate and, once the black ink had been obtained, it was thickened with gum Arabic. Papyrus, amongst other materials, was used for writing on, and this was obtained from an aquatic plant that grows spontaneously in Syria, Palestine, Mesopotamia and along the banks of the River Nile. Although the invention is Egyptian, the Romans also used it to write on. At that time there was considerable trade in papyrus throughout the Mediterranean, it being a major industry in Rome. In about the 2nd Century A.D. papyrus began to challenge parchment (charta pergamena), which was manufactured with different types of skin. Around the 4th Century A.D. papyrus gradually fell into disuse. Glass is a material obtained artificially from three basic ingredients that are melted at high temperatures in special furnaces. Most of the mixture is composed of clean sand abundant in many parts. The second ingredient in importance is a fusion agent – soda or potash – which is needed to lower the melting point and save fuel. In the analyses of Hispano-Roman glass hardly any potash is detected, but there is plenty of soda, which was obtained by burning types of plants frequently found in brine basins in hot zones, known as salsola soda or barilla plants. The third ingredient in glass was limestone, which turns to caustic lime or quicklime into the furnace, used to make sure the glass is not altered by moisture and other corrosive agents. For many centuries only small pieces of 118 ROMAN ENGINEERING glass were manufactured, until midway through the 1st Century B.C., the new technique of blown glass appeared in the Syria-Palestine Region, first blown in the air and, soon afterwards, inside moulds, which made it easy to manufacture on a large scale, jars, bottles, glasses, jugs and other types of containers, such as cinerary urns. Since time immemorial fish was cured, so that it could be consumed without having to depend on irregular catches. The traditional fish preserving process involved drying the fish in the open air or smoking it, although it was also kept in salt and brine or, once cooked, conserved in oil or vinegar. There were many brine factories throughout the Mediterranean, but particularly on the southern coast of Spain – Cádiz, Málaga, Cartagena – the main brine exporter to Rome. Garum, a salted and highly-spiced fish paste was one of the main cured fish products of the period. It could be kept for a long time and was sent by sea to Rome, where it was greatly appreciated. There were important garum factories in Hispania in Sexi, Baelo Claudia (Bolonia, Cádiz), Barcino or Cartago Nova (Cartagena), where they manufactured garum sociorum [garum of the allies] using the scomber, a type of mackerel, a fish that has lent its name to the present Murcian island of Escombreras. With a view to ensuring that the fish remained fresh for the longest possible time, they were kept alive in those factories and fattened until they were killed in large tanks full of salt water that were known as piscina amara or piscina salsa, which are also hydraulic structures. Garum was exported in very distinctive amphorae, via wholesalers who dealt with this product. This visit to Artifex. Ingeniería romana en España would not be complete without mentioning the book of the same title that accompanies it and that is not merely a catalogue of exhibits, since it provides a greater in-depth insight into the exhibition and elaborates upon the matters addressed therein in a different format. ARTIFEX. ROMAN ENGINEERING IN SPAIN 119 BIBLIOGRAPHY ARISTOTLE: Metaphysics. Buenos Aires, Espasa Calpe. 1943. M. J. BERNÁRDEZ and J. C. GUISADO: «Las explotaciones mineras de lapis specularis en Hispania», Artifex. Ingeniería romana en España, Ministerios de Cultura y Fomento. Madrid. 2002, pages 273-298. «La fundición de bronce a la cera perdida», Artifex. Ingeniería romana en España, Ministerios de Cultura y Fomento. Madrid, 2002, pages 299-302. J. FERNÁNDEZ PÉREZ: «Algunas especies vegetales de uso industrial en la época romana», Artifex. Ingeniería romana en España, Ministerios de Cultura y Fomento. Madrid, 2002, pages 315-330. T. F. GLICK: «La tecnología del siglo XVI en España: algunas observaciones», Fundación Juanelo Turriano, 19872012, Fundación Juanelo Turriano. Madrid, 2012, pages 29-39. I. GONZÁLEZ TASCÓN: «La Ingeniería Civil Romana», Artifex. Ingeniería romana en España, Ministerios de Cultura y Fomento. Madrid, 2002, pages 33-176. I. GONZÁLEZ TASCÓN and I. VELÁZQUEZ: Ingeniería romana en Hispania. Historia y técnicas constructivas. Madrid, Fundación Juanelo Turriano, 2005. HERODOTO: Los Nueve Libros de la Historia. Biblioteca Virtual Antorcha, 2006. A. ROQUERO: «Tintorería en la antigua Roma. Una tecnología al servicio de las artes suntuarias», Artifex. Ingeniería romana en España, Ministerios de Cultura y Fomento. Madrid, 2002, pages 353-382. F. J. SÁNCHEZ-PALENCIA and I. SASTRE: «La red hidráulica en las minas romanas de oro del noroeste hispano: Las Médulas», Artifex. Ingeniería romana en España, Ministerios de Cultura y Fomento. Madrid, 2002, pages 241254. MARISA and MIGUEL ÁNGEL CODINA: Back to Contents 120 ROMAN ENGINEERING 7 Ingenious comparisons: the look of the Renaissance* ALICIA CÁMARA MUÑOZ Professor of Art History Universidad Nacional de Educación a Distancia (UNED) «If we come to Spain, we will find traces of them showing how great they were, such as the Alcántara Bridge and the Segovia Aqueduct, that amazing construction that they created just to support a water duct to supply the city»1. Those words by Cristóbal de Villalón in 1539, the year of his Ingenious comparison between old and new, associated the engineering works of Roman Hispania with other conserved works from ancient times that were even more famous, but also wrote about the relocation of St. Peter’s Obelisk, an engineering work admired by all the men of its times. Comparisons were inevitable … Had the same heights of perfection been achieved? ... Had they been exceeded? When considering the way that the Spanish Renaissance looked upon the engineering of ancient times we are going to resort to the testimonies that we have been given by both historians and engineers, and find out that there was a shared view, invariably one of admiration, but also diverse in its historical and scientific rigour. Myth will coexist with history and with the genesis of archaeology, and engineers will seek an emulation of those ancient works whose remains were visible in many places, because they felt an essential and very active part of an empire that had surpassed the ancient ones. Comparison as a method of acquiring knowledge was widely used in the Renaissance. That is why Cristóbal de Villalón felt the need to mediate in the controversy between those who considered that «wise men in science and arts, both speculative and mechanical» of the time went at least one step beyond their ancient counterparts, on the one hand, and those who begged to differ, on the other hand, the latter basing their conflicting 121 Close-up of the device by Juanelo Turriano on the view of Toledo included in G. BRAUN and F. HOGENBERG: Civitates Orbis Terrarum, 1572-1617, on an engraving by JORIS HOEFNAGEL from 1566. FIG. 1 opinion on the history that they read about antiquity, to announce in the prologue that «God should be thanked for each of the two ages for having formed them so well»2. This sort of pact between old and new after having compared them, in which each was equally admirable, satisfied everybody, but most of all it served to elevate the present time, i.e. the 16th Century, to the same level of universal greatness as Roman Antiquity. Furthermore, the term «ingeniosa» [ingenious], which is the word that appears in the title of Villalón’s work, has a host of meanings, because in man’s «ingenio» [ingenuity] lies the ability to invent. In this sense, in Nebrija’s Dictionary, Dictionarium latino hispanicum, the term «ingenium» means not only «nature or natural genius», but also «by the natural condition of every individual». In that dictionary, «ingenero» [engineering] is the action that is developed as a result of ingenium [ingenuity], and is translated by «engendrar adentro» [to breed within]. We can deduce that the term «ingeniero» [engineer] came into existence during the Renaissance to refer to men with natural ingenuity that enables their knowledge to lead to this talent for fathering or creating things3. Sometime later, in 1611, the following appeared in the Tesoro de la lengua castellana by Covarrubias, «we use the term ingeniero [engineer] to refer to he who manufactures machines to defend himself from the enemy, and to attack him … The same machines invented with great skill we call ingenios [devices], such as the device that conveys water up from the River Tagus to Toledo’s Alcazar, invented by Ianelo, another Archimedes… Finally, anything that is manufactured with understanding and that makes it easier to do what, when using force, was difficult and costly, is called ingenio» [FIG. 1]. With respect to the extraordinary value bestowed on an engineer’s expertise in the Renaissance, it should not be forgotten that the seven wonders of the world, which Villalón also wrote about, were large buildings, walls, or the Colossus of Rhodes and, we might add, the eighth wonder of the world, as the Monastery of El Escorial was called years after, owes part of its sobriquet to what we now call engineering, given that it would not have been possible to construct it without the machines and devices used, If it was possible to construct it in six years and its «grandeur surpasses everything that Antiquity enjoyed», as Vander Hammen recalls4, it was thanks to such devices. Now that we are fully focused on ingenios [devices], ingenieros [engineers] and on the ingeniosas [ingenious] comparisons between old and new, we can start to consider how the Spanish Renaissance viewed that old world engineering, of which so many rem- 122 ROMAN ENGINEERING nants are still with us today. One exceptional source are the cities’ historians, a breed that enjoyed unprecedented success in the 16th Century, and even more so in the first half of the 17th Century, when all cities wanted to have their story told, and sought their greatness not only in the saints who protected them, their famous citizens or major historic events, triumphant entries, etc., but also in mythical foundations entrusted to heroes who faded away in the obscurity of time, and in what remained of that ancient world, those public buildings that could turn them into new Romes or new Troys. We are not going to dwell on those archaeological remains and the general appraisal they received and neither are we going to be speaking about antiques collections, what we are going to do is talk about cities and public works, and how historians and engineers viewed those works. Because the second observation platform is the one that concerns itself with the writings and works of the engineers themselves. The vision of those buildings and infrastructures is sometimes lost in the written accounts of the era, whose authors were more preoccupied with reflecting other perceptions of Antiquity. That is why it is necessary to use the testimonies of the engineers, and that is why it is necessary to go back to Vitruvius, whose definition of architect enables us to so often identify the engineers of the Renaissance as men who possessed universal knowledge, but also because his definition of public works requires us to redefine certain traditional parameters used when studying the history of architecture. In the translation of Vitruvius’ work undertaken by Miguel de Urrea, published in 1582, we can read «the public buildings have three different perspectives. One is for defence, another is for religion and the third one is for opportunity or recreation», and he goes on to explain each one of them. Renaissance engineers took care of all of them, especially the ones concerned with defence, essential in a Europe at war, but also the second one, as engineers have been involved in the construction of many churches in the modern era, and of course the third perspective, which translated as being preoccupied with «comfort», the translator going on in detail: «they are ports, markets, gates, baths, theatres, cloisters, and all those other things of that kind, which are usually built in public places», and all of them must be given strength, utility and beauty5 [FIGS. 2 A and B]. FIG. 2 A & B M. VITRUVIUS: De Architectura. Alcalá de Henares, 1582. Front cover and aqueduct. INGENIOUS COMPARISONS: THE LOOK OF THE RENAISSANCE 123 Strength guaranteed that constructions like aqueducts were still being used in the 16 Century. Therefore, it was not in order to talk about conserving them in the same way as historians and clever archaeologists did with other types of works where the only real value was preserving the memory of the past, and that, nevertheless, proved to be excellent sources of materials for new works. A bridge, a road or an aqueduct could not be turned into a quarry. They were still in use. We know that the Segovia Aqueduct was utilised for centuries, and the Mérida Aqueduct brings to mind Ambrosio de Morales who, when Pedro de Esquivel was in that city studying the measurements used by the Romans, he used the distances between the aqueduct arches or openings to find out exactly how long a Roman foot was, discovering that it was somewhat longer than the old Spanish foot. At that time, «the water that now serves the city, comes from one league away via an old Roman building, although some parts of it are destroyed, and repaired in our times»6. Accounts like this reveal to us that in matters concerning public works, another value, no less admirable, was added to the Vitruvian ones of utilitas, firmitas, venustas, namely the value of historic reconstruction of the past under a scientific mentality. th THE HISTORIANS According to historians, in the 16th Century the Spanish monarchy was at its height, because «The Crown and the Empire tightened its control over the land, having taken possession of the Kingdom of Portugal», so Felipe II «with his arms and Empire embraced the entire roundness of Earth». Thus the Spanish Crown had surpassed «all the monarchies of the old days: Medos, Persians, Babylonians, Greeks or Romans»7. An Empire that could outdo all the empires of the past, and especially the Roman Empire, was worth having its history recorded, often resorting to those ingenious comparisons, all the more so where engineering works were concerned. Let’s begin with the false accounts of history that, with scientific pretext, sought to discover the origins of Spain and its cities. Hercules had been the major founder of Spanish cities; however, as Luis Ariz pointed out in his Historia de la ciudad de Ávila, dated 1607, the first thing that had to be found out was which of the forty-three Herculeses was the oldest, the one that was to marry an African woman and whose son founded Ávila. Because as Hernando de Soto wrote in his Emblemas Moralizadas in 1599, there were no less than forty-three Herculeses according to Marco Varrón, and six according to Cicero8. The Tower of Hercules in A Coruña is named after one of those mythical foundations, given that, after slaying the giant Gerion he erected the tower over his skull, and A Coruña was born of this building. It was a tower that was said to have been rebuilt afterwards by Julius Caesar9. Major engineering works were supposed to have been created by demigods like Hercules, but so many Herculeses eventually became too many, and the stories that continued using them proved to be rather unreliable. Perhaps that is why Gómez Bravo, in his history of Mérida in 1638, stressed how tired historians like himself were, as they attempted to write history in a scientific and well informed way, when they found that there were no rivers, mountains or cities where the name of Hercules did not appear, when it would be «simpler and more noble to admit (as Cicero said) 124 ROMAN ENGINEERING FIG. 3 A & B Tower of Hercules. A Coruña. Roman Interior. Exterior from the 18th Century. that we don’t know what we don’t know, rather than causing tiresome for everybody by telling these prefabrications»10 [FIGS. 3 A and B]. Hydraulic works were a source of almost unlimited admiration, and the fact that aqueducts were so visible meant that they featured on the pages of these historical accounts. The Tarragona Aqueducts were among the antiquities that most attracted the attention of Cock, who travelled through Felipe II’s Spain11. Some years before they had been the subject of studies, with scientific archaeological pretensions based not only on measurement and in situ examination of their characteristics, but also on reference to the archives, carried out by Luis Pons d’Icart in 157212. An engraving showing the Les Ferreres Aqueduct illustrates the work by Jeroni Pujades on the Principality of Cataluña, in 160913, contributing to the dissemination of works that did not always use images, often being limited to written descriptions. In Valencia, Cock also referred to «the sewers that Scipio order to be constructed», and also mentioned the temples and inscriptions bearing witness to their great age14. Travellers arriving in Segovia never ceased to admire and depict the aqueduct in images, but the city also had its own historian who gives us great insight into understanding how this magnificent work came to be incorporated into the city’s origins. His name was Diego de Colmenares, «San Juan’s parish priest», who wrote his well-known Historia de la insigne ciudad de Segovia y compendio de las historias de Castilla between 1620 and 1634, which INGENIOUS COMPARISONS: THE LOOK OF THE RENAISSANCE 125 was published in 1637. It includes an image of the aqueduct, apart from the one that appears on the cover, but funnily enough the image inside the book appears to form part of an illustration referring to the Guadalajara Gate in Madrid [FIG. 4]. It is the historical memory of an event that the Madrid historian Jerónimo de la Quintana relates, to prove it wrong, explaining how the Segovia Coat of Arms appeared on this Madrid Gate. According to Quintana it was not true that the Segovians conquered the Villa of Madrid, which was in the hands of «the Moors» in the 11th Century, since in 1083 Segovia was not inhabited, so its inhabitants could not have taken part in the conquest. However, at that time there still existed in living memory witnesses to the fact that to commemorate the deed, King Alfonso VI put the Segovia Coat of Arms not only on the Guadalajara FIG. 4 DIEGO DE ASTOR. The Guadalajara Gate but also on other locations of the city. This Gate depicting the Segovia Aqueduct. 1629. In D. DE COLMENARES: Historia de la insigne ciudad is also refuted by Jerónimo de la Quintana, who de Segovia y compendio de las historias de Castilla. Segovia, DIEGO DÍEZ, 1637, f. 88 vº. states that these coats of arms never appeared on the now disappeared Guadalajara Gate15. However, it re-emerges in the history written by Colmenares, who states that the Segovian Coat of Arms was there until 1542, that it was never again put back on the gate in spite of the repeated requests to do so from the City of Segovia16. Anxious to increase the stature of Segovia and the Segovians, as Quintana was to do for the inhabitants of Madrid, all we can say is that, was although a fruit of rivalry between cities and disagreements between historians, yet this is one of the very few images that remain of the Segovia Aqueduct from the 17th Century. Segovia, just like any other great city, was founded by Hercules, who it was claimed was responsible for «constructing the wonderful Bridge, or Aqueduct, that our Segovian ancestors called the Dry Bridge, in ancient writings and reports. We are aware of the differences of opinion as to who was the designer of that wonderful construction, that in grandeur and antiquity matches the most famous ones on Earth and has outlived them, because the others only live on in name, whereas this one has withstood the test of time through the centuries and remains at its primary function»17. This made such works the object of great curiosity for travellers, because it was not a question of it being just a handful of remains where only the name mattered, as in this case all the stonework remained in place, so Colmenares could claim that it surpassed the most famous wonders of the world. The historian then goes on to make an observation that is astute enough to give us insight into the incipient world of Renaissance scientific archaeology, which cannot go unmentioned. He states that where the sculptures of the Virgin and St. Sebastian now lie, and on the highest pillar «that has been known as Açoguejo» since 1520, there were statues of Hercules «and it is true to say that there used to be statues in those niches 126 ROMAN ENGINEERING Model of the Alcántara Bridge. Artifex Exhibition. Government of Extremadura. FIG. 5 that if the forebears, when they removed them, kept a record (as they should have) of what they had taken away, would add light to our darkness» (the italics are ours)18. It is curious to note that he casts aspersions on any of the works being Roman if they are not in keeping with any of the architectural orders (he mentions: Doric, Ionic, Corinthian, Tuscan and compound), or inscriptions, when, for example, the Alcántara Bridge spanning the Tagus has seven inscriptions, which repeat the name of Trajan. A bridge «so magnificent and splendid that those who have seen the bridges of Rome, and all the famous ones in Europe, have never found one to be as large and wonderfully built», according to Ambrosio de Morales19 [FIG. 5]. All in all, Colmenares found everything about the foundation of this work uncertain, but according to him the stone used was the same, albeit more worn, as the stone used for a statue of Hercules that was conserved, which made him think that it dated back to pre-Roman times. The detailed description he gives of the aqueduct shows that he studied it in depth, from its source until it reaches the Alcazar [FIG. 6]. FIG. 6 ANTON VAN DEN WYNGAERDE. Segovia, 1562. Close-up of the aqueduct. Oxford, Ashmolean Museum. INGENIOUS COMPARISONS: THE LOOK OF THE RENAISSANCE 127 The Celebration of Power, in this case a triumphant entry into the city, becomes a new historical document that has to be added to that construction of Segovian history carried out during the Renaissance, always revolving around the aqueduct. Colmenares tells us that during the triumphant entry of Anna of Austria, the aqueduct was reproduced on one of the ephemeral arches of triumph, depicting the three figures of its possible constructors: Hercules, Hispan and Trajan, and showing them (and he did this using texts) arguing about which one had created the aqueduct. Hercules claimed that as he had founded the city in a high place, from the very start he needed the aqueduct to supply it with water. Hispan, who had been the first king of Spain, was the only one who had had «power and time to create such a major work». Finally, Trajan argued against the other two «the poverty of their FIG. 7 JAN CORNELISZ VERMEYEN, view of the Kingdom, and the roughness of their age: using Segovia Aqueduct, 1525-1550. Engraving. London, British Museum. in his favour the grandeur of Rome». However Minerva, who crowned the arch, «as authoress of arts and sciences, stated in the verses of a Poem that she had created such an outstanding work»20. To cut a long story short, in view of the difficulty involved in knowing who had constructed it on the basis of highly unreliable historical sources, the author of the iconographic program led the admiring spectator of the Celebration to conclude that it was wisdom, personified by Minerva, who was the real constructor of such a wonder. Such well-known humanists as Alonso de Cartagena or Rodrigo Jiménez de Rada had taken part in this debate about the origins of the aqueduct that Colmenares includes in his work, and they considered the aqueduct to be the work of Hispan21. And the truth is, if many others such as Tubal or Tarsis are credited with the mythical founding of the Spanish nation, Hispan can be regarded as the most «credible» candidate, so associating his name with the aqueduct was a way of linking its construction with the origins of the nation22 [FIG. 7]. With respect to the sources provided to us from travellers such as Vermeyen or Van den Wyngaerde, who drew it, Andrea Navagero, in his journey around Spain between 1524 and 1526, also wrote that «it is one of the most notable things in Spain, and the Spanish consider it to be just that, although they base their admiration on absurd reasoning, calling the aqueduct a bridge, and they say that the bridge in Segovia is a great wonder because it is an upside down bridge, as all other ones are built for the water to flow under and this one is constructed for the water to go above». This is one of «the three wonders of Spain». The others are considered to be just as fantastic as this one: a city of fire, that is Madrid («my walls of fire are …» was part of the original text on the 128 ROMAN ENGINEERING FIG. 8 JAN CORNELISZ VERMEYEN: Tríptico de la familia Micault, 1534. Brussels, Musées royaux des Beaux-Arts. first Madrid coat of arms), and a place they call a bridge because the rams grace over the River Guadiana23, so he would probably be referring to Ojos del Guadiana, as though it were some sort of underground river [FIG. 8]. The aqueduct was conserved in Segovia, but without any doubt the best conserved Roman city was Mérida, where very important public constructions could be seen. Praised by Nebrija and compared to Carthage, whose aqueducts were compared to those in the city of Extremadura to make its grandeur known24, according to Bernabé Moreno de Vargas, who published its history in 163325, the city had been founded by Tubal, Noah’s grandson, long before the Romans reached Spain26. «The famous and admirable bridge» spanned the Guadiana there, All that he could say about its age being that «it is the work of the Romans, the Architecture is very strong, and it is very old … I know it was founded when the way was laid, the Military road that we generally refer to as the Silver Route … because as this road was a wonderful construction, it would have been incomplete if bridges had not been built over the rivers». Moreno de Vargas quotes Abraham Ortelio, who on his maps says that it is a Roman bridge, and Antonio de Guevara, who wrote in his biography of Trajan that it was the work of that emperor. However, Moreno de Vargas says that, although he is a «very serious historian», «he was misled over many things» and «he confused eras», although he does agree with him that part of the bridge was the work of Trajan «because its architecture is very similar to the masonry dating back to that period», and he recalls that it was reconstructed after a flood at the beginning of the 17th Century, in 1603, the works being completed in 1610. Once again we find that resorting to comparison, in this case with works that we know for certain are dated back to Trajan’s times, helped to reconstruct the history of ancient buildings. INGENIOUS COMPARISONS: THE LOOK OF THE RENAISSANCE 129 As far as the Roman roads are concerned, he writes that remains of them can be seen in many parts of Spain. He quotes St. Isidore, who said that «these roads were military ways, laid on the ground and cobbled, in such a manner that they were flat». He was familiar with Antonino’s Itinerary27, and of course he keeps referring to the «aqueducts and water ducts», recalling that Esquivel was sent by Felipe II to describe one of the aqueducts, that he had read about in Ambrosio de Morales. The other one, very well conserved «is so outstanding and famous, that they call it of the miracles, as though the works themselves were miraculous». And as its streets were paved with stones, he compares Mérida with «the African Carthage» described by Virgil28, along similar lines as the aforementioned comparisons to the North African city that we have seen. King Felipe II’s visit on his way to Portugal is of particular interest. He took «masters» with him who testified that the antemurale, or vantage point overlooking the River Guadiana, was «the strongest in the world», and considered that the Romans must have had at that spot «a poplar grove or gardens with their fountains, altars and obelisks, some stones being found there that bore witness to this. In this sense, Mérida could compete with the Walls of Babylon, which had trees and orchards on top of them that they called pensiles». The king was only there for fifteen days, during which «he saw and admired the Roman buildings», but this was the one he admired most «because it is made of very large grained stones, well fitted together, that do not have lime, not even for their duration, and what keeps them firmly in place is the way they are locked together and the wonderful way they have been wrought by the craftsman. And as proof of this, it should be known that the Guadiana has been flowing past these walls for more than one thousand years, and although in the winter the river has very fast currents, they have not washed away one single stone. Those masters said that this masonry was from the Emperor Trajan’s times, because that was when architecture was at its height, and that the architecture used for this building has been lost, and now there is nobody who could construct again like he did»29. And as if admiration from one of the monarchs best acquainted with Architecture in his time was not enough to grant universal value to the public works in the City of Mérida, we can go back again to Vitruvius, because this treatiser, almost legendary to Renaissance architects, mentions «the castles, or water storage facilities … referring to the ingenio [device] and its shape, so that by the action of the water, the same water can be raised to the highest point», as could be seen in Mérida. All in all, that this city, like so many others described in the 16th and 17th centuries, was «another Rome in Spain»30. Perhaps one of the most widely recognised «new Romes» was Seville, and the historians set their sights on «Old Seville», i.e., Italica, the birthplace of Trajan, Hadrian and Theodosius as Rodrigo Caro recalls31. Years earlier, Juan de Mal Lara stated that the remains of paved roads from the time of Hercules were conserved in Seville32. This careful look that historians took at the remains from ancient times, even if they did mix them up with Hercules, helped to build-up the «memory of past centuries» of which Argote de Molina spoke in 158833. In that context, the studies that we could already describe as being archaeological, progressed in such a way that the public works, associated with the expansion of the Empire, were well known to the engineers, who enthusiastically read all the writings that had been conserved from the Roman era. 130 ROMAN ENGINEERING THE ENGINEERS Codices and manuscripts of machines were passing through the hands of experts in the 16th Century at the same time as there was a boom in the dissemination of printed works, and their authors appropriated the technical knowledge they inherited from the past to insert it in their own experience, as cultural heritage and even as an expression of social prestige. Recent sources such as Valturio, Taccola and Francesco di Giorgio, and classical ones like Archímedes, Euclid, Philo, Frontinus, Vegetius, Hero or Vitruvius, were the persons continually referred to in the texts of the Renaissance engineers34 [FIG. 9]. In the 15th Century, Luca Pacioli had already referred to Archímedes of Syracuse as a model for engineers and «inventors of new devices» and to Vegetius and Frontinus35 as experts in fortification due to their knowledge of mathematics. In Spain, Cristóbal de Rojas, after studying many other matters related to his profession as an engineer, turned to the question of how to form squadrons, for which purpose he used Vegetius as a reference, although the «art of squadrons stemmed from Homer, and was passed down to other famous Greek Captains»36. When we mention Rome, we are invariably referring to it as the epitome of public architecture, but data we have received from Rojas pursuant to Greece, and other information, often in the words of the engineers, establishing a comparison between the present grandeur and other cultures and empires of old, should make us think about the fact that Rome was not the only benchmark that had to be used, because no matter how little was known about Greece, Egypt or Persia, it would be well worthwhile trying to trace the impact that they had had on the Renaissance culture in which the engineers concerned lived, and on the imperial conception of the Spanish monarchy. It was not possible to make comparisons with Antiquity in matters concerning engineering only when dealing with fortifications, because artillery had changed everything. That is why Lupercio Leonardo de Argensola, in his praise of Cristóbal de Rojas, wrote «what names and titles does the learned Rojas deserve, that from the hidden arts he offers the most difficult part to his country? His strong masonry is not designed to defend as in olden times, against the battering ram or the catapult, but against the awful artillery, that in such a variety of terrible ways, vomits hell every day». The destruction caused by artillery fire was often associated with hell at that time, and military architecture had to adapt to these news arms, bringing about a change that was so radical that anybody could FIG. 9 Cover of the treatise by C. DE ROJAS: Teórica y práctica de fortificación. Madrid, 1598. distinguish a high medieval fortress from a INGENIOUS COMPARISONS: THE LOOK OF THE RENAISSANCE 131 fortress from a later period, with its geometrical shapes that became lower all the time until, with the passage of time, they were practically buried underground and invisible to the human eye. When looking back on classical antiquity, we cannot forget that engineering and architecture occupied the same area, whose common base was mathematics, so Cristóbal de Rojas, in his treatise, wrote that Juan de Herrera was «such an excellent, well versed expert on mathematical sciences, that Spain could pride itself on having such a son as did Sicily with Archimedes and Italy with Vitruvius»37. Archímedes was used as a model for engineers and Vitruvius for architects, but the greatest figures, like Juan de Herrera, possessed the expertise that was needed for both professions. There were certain writings that were always cited as with scientific authority for the new Archimedeses of FIG. 10 FRANCESCO DI GIORGIO MARTINI. Dinócrates. Florence, Biblioteca Nacional. Códice Magliabechiano, II.I.141, h. the times. In this sense, following a 1490. historical tradition, Rojas states that geometry, essential to the engineer, was invented by «Merys King of Egypt (even here this science wanted to take advantage, that a King was its inventor) and later it was the famous Pythagoras who expanded upon it, finding the potency of the right-angled triangle, thereafter backed up by the most erudite Archimedes, dealing largely with proportions, machines and heavy bodies; and above all the excellent Euclid, talented and shrewd, bringing together all the rules and writings that he found»38. Going back to Villalón and his ingenious comparisons, among the architects of antiquity he refers to those who constructed public buildings (according to the Vitruvian classification), such as Archimedes, who thanks to his «instruments of warfare» defended Syracuse from the Romans for three years, or Democrates (he misspells the name somewhat), who «surrounded Alexandria with impregnable city walls», yet he also writes about temples, given that they were public works39. Archímedes and Dinocrates were admirable, but probably the ones mentioned most often in the Renaissance Treatises were Vitruvius and Euclid [FIG. 10]. Juan de Herrera could be fairly compared with them, especially if we take a brief look at his personal library. Among his many books on engineering and history of antiquity, there was one in particular «de la conserbaçión de los aquadubtos, manoescripto, en por- 132 ROMAN ENGINEERING FIG. 11 Bridge in the Third Book by S. SERLIO: Tercero y quarto libro de architectura. Toledo, 1552. tugués». Other titles were: «de los edifiçios del enperador Justiniano, por Procopio, en latín» (two copies) and «las obserbaziones militares y ardides de guerra que usó Zésar, traduzido en castellano por Graçián, manoescrito», «las termas de Diocleçiano, enperador, en latín, con otros muchos deseós de fábricas», «diez libros de Roma tryunphante, de Blondi Flavi, en latín», the Historia natural by Pliny the Younger, from Volume 26 to 37, the Rhetoric by Cicero, comedies by Aristophanes, or Décadas by Tito Livio in Spanish. His library also contained, «triunphos romanos dende Rómulo hasta carlo quinto, en latín» and «títulos de la ciudad romana antigua». Apart from those, he possessed «discurso de Juanelo sobre la nueva reformazión del año», and another discourse by the same author, on exactly the same subject, hand-written in Italian, a «quaderno de diversos epigramas en alabanza del relox de Juanelo», and works that specifically dealt with Antiquity and the History of Spain, such as «Andrés de Poza, de antigüedades de la Cantabria y poblaciones de España» and «letreros e insignias reales de los reyes de Vbiedo, León y Castilla para el alcázar de Segovia, en romanze»40. Francisco de Villalpando, in his translation of the Third and Fourth Book by Serlio in 1552, used the term architects to refer to those that we would now call engineers, because Vitruvius talked about architects. It was they, according to Villalpando, who made victory and conquests possible with their «machines and industries», creating not only the squadrons, but also buildings and sculptures41. Serlio is another writer of treatises that contributed to an awareness of Ancient Times, to which he devotes his Third Book. In this volume he describes and overpraises the values of the Nimes Aqueduct in France, and includes descriptions with prints of works like the Pantheon, other temples, amphitheatres, bridges, etc. [FIG. 11]. INGENIOUS COMPARISONS: THE LOOK OF THE RENAISSANCE 133 FIG. 12 G. MAGGI and I. CASTRIOTTO: Della fortificatione delle città. Venice, 1583. The military architecture treatises, which deal with all engineering matters, not only fortification, contain many references to Antiquity as a model. The treatise by Maggi and Castriotto (one of the treatises quoted by and used by Rojas), contains a debate about whether in Antiquity the layout of the City of Rome was square or circular, after which it opts for the square arrangement after reference is made to several sources dating back to that period, in spite of the fact that as far as new fortifications were concerned, the more circular they were, the better the outer limits functioned42. Once again, the changes imposed by the new weapons of war made it necessary to question the effectiveness of the standard models coming from the Roman Empire [FIG. 12]. Comparisons provide a historical contents even to the most technical treatises and, returning to Cristóbal de Rojas again, we read that the warlike achievements of the Spanish «leave the achievements of old as small»43, and that he would like to be able to write like Julius Caesar, with the eloquence of Cicero and Demosthenes44. He does not hesitate to compare the minor modifications that Juan del Águila made to his small army in Brittany, with the changes that Cornelius Scipio made to his army before taking Numancia. He also compares Gonzalo Fernández de Córdoba and the Duque de Alba with great warriors such as Alexander and Hannibal45. 134 ROMAN ENGINEERING Another subject for reflection where the ancients served as a benchmark for comparison purposes was about matters of public interest being invariably associated with public works. In this context, Vitruvius is once again the prime example, and for his translator into Spanish, Miguel de Urrea, as Vitruvius dedicated his work to the Emperor, he dedicates it to the «Emperor of all the Spanish and best in the world», stating in the epistle to the reader, how useful this work is for the common good46. Diego González de Medina Barba, in his Examen de fortificación, asserted that «the common good must undoubtedly be considered over and above the individual good, and one has to strive to achieve this. Maintaining and defending Empires, Kingdoms, States and Cities that contain, not only one life, one honour and one particular wealth, but a countless number of these, as is plain to be seen, if for defending one life it is so much justified the defence, even if this means injury and death to he who wishes to take this away, that to defend and protect so many thousands of lives, honours and goods, it should be compulsory to find a way of supporting and defending them»47. One historian, Vander Hammen, in his history of King Felipe II, recalls his «marvellous works in the benefit of the common good». There was of course the genius of Juanelo, not to mention «The Mint in Segovia, with his genius for making it water-powered», the Alicante Reservoir for irrigation, or the water device for tilling powder in Pamplona48. So, the common good, the public interest or whatever other term any author might choose to call it, was something that the Ancients also excelled at and was to be found in their own devices, machines and public buildings [FIG. 13]. Yet the engineers knew a lot more about Antiquity that they showed in their treatises and their own works, demonstrating this in other kind of writings. They never ceased to praise such knowledge, even in documents that were not going to be published, as if they were going to be seen by the king. They are sometimes reminiscent of humanists like Alvar Gómez de Castro, who narrated the conquest of Oran and Mazalquivir as if this were a feat carried out by the Romans; the king was visited by «some military tribunes» who later directed the FIG. 13 POMPEO LEONI: Felipe II como emperador. 1568. warfare and under his command there Palacio de Aranjuez. INGENIOUS COMPARISONS: THE LOOK OF THE RENAISSANCE 135 were «maniple officers and centurion officers»49. With the same intentions, the engineer Tiburzio Spannocchi defined the Spanish Armada sent against England as a venture worthy of Ancient Rome, that should have even been announced to the Queen of England by herald, as was done in Rome50. And this was not the fruit of sudden inspiration, because this consciousness of belonging to a profession that went back to Ancient Times and constructed empires was also highlighted on the Latin inscription that appeared on the map of Sicily that Spannocchi entitled «Regiarum Machinarum, atque Menium Opidorum Structurae Potentisimi ispaniarum regis Magistro Supremo»51. It was a language that they were particularly fond of in Felipe II’s times, and although he was a king, not an emperor, he was often regarded as such, and he possessed such a number of kingdoms that he regarded himself as the inheritor of the Roman Empire. As we have pointed out, this ambition was repeatedly fulfilled by the reports that the monarch’s engineers issued about wars and fortifications. According to Juan Bautista Antonelli, the Spanish Empire could be compared not only to the Roman Empire, but also to the Assyrian and Persian Empires52, and another engineer who was forever resorting to comparisons with Ancient Times in his historical writings was Leonardo Turriano. He used Tacitus to argue in favour of the destruction of fortifications that could not be conserved and put forward as examples the Romans and the Greeks (Scipio, Hannibal, Sulla, Severus or Vespasian), so nobody should question the fact that Emperor Charles V destroyed the city fortress in Africa, as the Turks had done with La Goleta. And in the interests of comparison, he brings up the subject of the Arabs, who did likewise in North African cities53. That fact that he used the term «incursion» to refer to the Arabs when they carried out actions similar to the admirable Romans activities could suggest that there was more than one way of viewing other cultures during the Spanish Renaissance. In this context, the admiration that the sage Ambrosio de Morales had for the genius Juanelo Turriano is hardly surprising. Morales left a written record for the coming centuries giving account of how wonderful the machine was that the Cremonese inventor constructed in Toledo. He describes the entire construction process of what he called an aqueduct, which Juanelo had previously made a mock-up, a «model in small size», which he showed to Morales, explaining the arithmetical basics of the invention. In it, he applied an invention from the Treatise of Valturius (the Re Militari Treatise of 1472), although (and this is what we find interesting) «the one invented by Juanelo has new sophistications and subtleties», given that Juanelo «added much more to it in terms of harmony and silence in motion», as well as having fitted into the timbers long tin pipes, all of this and a lot more being of his own invention. And, reflecting the anthropomorphic notion of all that exists, Ambrosio de Morales compares it with a human body, with feet in the river, with the «perpetual uniformity and consistency of the pulse that causes the inhalation that enters through the mouth and moves the heart by the lungs». That is to say, that it operates just like the continuous rhythm of respiration, as though it were alive54. He compares it with works of Roman Times, not only by calling it an aqueduct, wonder, etc., but also because «in a long stretch of a very wide street that the machine had to cross, Juanelo once again built the wonderful wooden bridge that Julius Caesar had constructed during the siege of Marseille»55. Juanelo would outdo the Ancients, even Archimedes, because apart from the famous device he created, he also made an astro- 136 ROMAN ENGINEERING FIG. 14 Engraving representing Juanelo Turriano´s device in Toledo, circa 1650. nomical clock that he took twenty years to imagine and three and a half years to make with his own hands56. Agustín de Rojas also compared him to Archimedes, because if painters were new Apelleses and architects new Vitruviuses, it could be argued that engineers were new Archimedeses. He thus described the Toledo device: «This work is the most outstanding and creative of its kind in the world. Its inventor was Juanelo Turriano, born in Cremona, in Lombardy, who just for this one single work deserves exactly the same glory as Archimedes, of Syracuse, or Archytas of Taranto, who was such a great mathematician that he made a wooden dove fly all around the city, and we can see that for just the invention of this device the timberwork required contains more than the thin wood in two hundred carts, and it supports over five hundred weights of brass, and more than one thousand six hundred pitchers of water»57. Or as Góngora wrote, Juanelo with his device [genius] gave wings to the Tagus to rise up58 [FIG. 14]. It would be impossible to imagine Los veintiún libros de los ingenios y máquinas – written towards the end of the 16th Century or at the beginning of the 17th Century –, a book that devotes so many pages to hydraulic engineering, failing to make any references to the Romans’ engineering. On the subject of aqueducts in particular, the author explains that, to transport the water, «huge arches were constructed to enable the water to flow from one hill to another. And when they saw that one set of arches was not enough, they invented the idea of creating two levels of arches, one on top of the other. They sought a way of creating three levels to reach the water line, as can be seen in Spain, in INGENIOUS COMPARISONS: THE LOOK OF THE RENAISSANCE 137 Italy, in France and even in Africa. Aqueducts are thus buildings that the ancients were very proud of, to the extent that they used great skill and adorned them with cornices, architraves, friezes, column heads, pedestals, figures with facias and moulds all very exquisitely made with different types of arches»59. He goes on to explain in detail how they were made, and this is what is of inFIG. 15 Aqueduct in Los veintiún libros de los ingenios y máquinas. terest to us, that towards the end of the 16th Century, and in view of the fact that aqueducts were still being built (such as the one in Teruel, constructed by Pierre Vedel midway through the 16th Century), the Roman technique was still proving useful to the engineers of the age. In fact, with respect to the drawings he includes, he states that he borrowed most of them from ancient works, although in his manuscript he does not specify the locations. Caños de Carmona is one place that he mentions in Spain, which makes it clear that he is talking about an aqueduct, and «in Segovia, in Mérida and in a host of other places. In Aragón close to Sádaba, ancient spots in Teruel, modern ones in the Kingdom of Valencia, in Monviedro, in Catalonia, in Tarragona and many other places, which I omit because I do not wish to appear long-winded»60 [FIG. 15]. Being able to show that one had an awareness of Imperial Rome was an added value for any engineer who wanted to prosper in the Spanish Court. So, when Giovanni Battista Antonelli, in his unpublished treatise of 1561, dedicated to Juan Marique de Lara, Captain General of Artillery, described how to lodge armies, he said that to do this in an orderly way it was essential to copy the Romans, who invariably did this in the same manner61. Then there was Leonardo Turriano deliberating about whether or not the villa that Antonelli destroyed in Mazalquivir to make the walls could really have been Roman, given that, following Pliny the Younger, there was an absence of «that Roman luxury that are manifest in all the ruins of the buildings that were constructed by the Ancients Latins in these areas, especially as large gold medals bearing the Emperor Claudius on the face and others even older have been found here, which suggest that those buildings were noble»62. And when the excavations were being dug to lay the foundations for the citadel of Jaca, designed by Spannocchi, old medals were found. The Captain General of the Aragón Army then wrote to Felipe II telling him that one of them was of the first ever catholic emperor, who was called Philippus, which meant he was a namesake of the king, and thus they had made a good start to the works63. In this case, it was probably a figment of the imagination, but the message is the same, that the great public works ordered by Felipe II could better the Roman ones, which were becoming increasingly well-known [FIG. 16]. Military engineering also made a major contribution to the development of antiques collection, examples of collectors being Diego Hurtado de Mendoza in Siena, and Vespasiano Gonzaga in Cartagena, who boosted their collections with finds from the classic works that 138 ROMAN ENGINEERING G. B. ANTONELLI: Epitomi delle fortificationi moderne, 1561. Toledo, Museo del Ejército. A Roman camp. FIG. 16 had been uncovered when constructing city walls. These people who knew so much about antiques, and the renaissance engineers, regarded looking back to Antiquity as an intellectual attitude with political intent, because they had a lot to learn, but, above all, much to surpass and with which to compare themselves, given that all of them worked for an empire that looked upon itself and wished to be portrayed as an emulation of the Roman Empire. Studying Roman engineering works that were still in use could also be associated with the birth of archaeology. Many kept inscriptions, eagerly collected once it had been checked that the remains were ancient, because, as Ambrosio de Morales wrote in 1575, «if there are no traces and samples of antiquity at the site, looking for anything else is all in vain; and on the contrary, if evidence of Antiquity is found, this begs the question what once lay there, and what the name of that place was»64. Argote de Molina includes the Roman inscriptions from Úbeda and Baeza in his work Nobleza de Andalucía, in 1588, and Rodrigo Caro included in his works engravings from the medals found in the cities whose histories he wrote. One of the most extensively studied engineering works, apart from aqueducts and bridges, were the Roman roads, travelled along and measured by historians like Antonio de Guevara, Jerónimo Zurita or Ginés de Sepúlveda. All of them tried to find out exactly how long a Roman foot was65 in an imperial Spain that based its power and control over territory on measurement and geometry. Ambrosio de Morales once again proves to serve as a good example, when he indicates the need to know with precision these Roman measurements, using for this purpose not only Vitruvius or Frontinus, but also St. Isidore, and other contemporary authors such as Pedro Apiano, Antonio de Lebrixa (Nebrija), Doctor Sepúlveda or Florián de Ocampo, yet it was the teacher Pedro de Esquivel who solved the problem, in spite of the difficulties involved in finding the equivalents between the Roman measurements and those that were used in the 1570s66. Comparison was the best possible proof of the identity between the Antiquity with the present time, and in this case all the more so because it drew parallels for kingdoms being able to measure their territories, as the Romans had done with their own Empire. INGENIOUS COMPARISONS: THE LOOK OF THE RENAISSANCE 139 NOTES * This work is part of the research project HAR2012-31117. El dibujante ingeniero al servicio de la monarquía hispánica. Siglos Ministerio de Economía y Competitividad. C. DE VILLALÓN: Ingenious comparison between old and new. Hecha por el Bachiller Villalón, dirigida al Illustre y reverendissimo Señor don Fray Alonso de Virues, Obispo dignísimo de Canaria, predicador y del consejo de la cathólica y cesarea magestad. En la qual se disputa quando ovo más sabios agora, o en la antigüedad, y para en prueba desto, se trae todos los sabios e inventores antiguos y presentes en todas las sciencias y artes (Valladolid, 1539). Madrid, Sociedad de Bibliófilos Españoles, 1898, p. 150. «Vean a Puzol, y la gruta de Nápoles, y el Coliseo de Roma y el Septizonio que hizo Severo, y el aguja que está cabe Sant pedro, que según dizen fue traída por la mar de Egypto y subida al Vaticano y enhestada sobre otra que está debajo, y sabemos que el Papa Sixto dava mil ducados por cada passo que se la llevasen hasta ponerla en la plaza de Sant Pedro, y no ovo quien la osasse emprehender». Ibidem, pages 130, 149 and 150. A. CÁMARA: «Military architecture and the engineers of the Spanish monarchy: aspects of a profession (1530-1650)». Revista de la Universidad Complutense, no. 3, 1981, p. 255. L. VANDER HAMMEN Y LEÓN: Don Filipe el prudente, segundo deste nombre, rey de las Españas y nuevo mundo. Madrid, Viuda de Alonso Martín, 1632, f. 125 vº and 126. M. VITRUVIO POLLION: De architectura, dividido en diez libros, traduzidos de Latin en castellano por Miguel de Urrea Architecto, y sacado en su perfectión por Iuan Gracian impresor vezino de Alcalá. Alcalá de Henares, 1582, f. 11 vº. A. DE MORALES: Las antigüedades de las ciudades de España que van nombradas en la corónica con las averiguaciones de sus sitios y nombres antiguos, que escribía Ambrosio de Morales, cronista del rey católico nuestro señor don Felipe II. Tomo IX. Madrid, Benito Cano, 1792, p. 107. BALTASAR PORREÑO: Dichos y hechos del Señor Rey don Felipe Segundo, el prudente, potentíssimo y glorioso monarca de las Españas y de las Indias (1628). ANTONIO ÁLVAREZ OSSORIO and PALOMA CUENCA (eds.). Madrid, Sociedad Estatal para la conmemoración de los centenarios de Felipe II y Carlos V, 2001, p. 126. A. CÁMARA: «History and myth: the city narrated in the Spanish Renaissance». En Imágenes, Palabras, Sonidos, Prácticas y Reflexiones. IV Jornadas de Estudios e Investigaciones. Instituto de Teoría e Historia del Arte «Julio E. Payró». Buenos Aires, 2000, p. 312. S. HUTTER and T. TAUSCHILD: El faro romano de La Coruña. 1991, p. 15. Cited in A. CÁMARA: «Historia y mito…», p. 319. A. CÁMARA: «Historia y mito…», p. 319. A. MOREL FATIO and A. RODRÍGUEZ VILLA: Relación del viaje hecho por Felipe II, en 1585 a Zaragoza, Barcelona y Valencia. Escrita por Henrique Cock, notario apostólico de la guardia del cuerpo real... Madrid, 1876, p. 114. About Enrique Cock, see A. ALVAR EZQUERRA: «Enrique Cock. Humanista, corógrafo de Madrid, cronista de los archeros reales», 2011, http://www.proyectos. cchs.csic.es/humanismoyhumanistas/enrique-cock M. MORÁN TURINA: La memoria de las piedras. Anticuarios, arqueólogos y coleccionistas de antigüedades en la España de los Austrias. Madrid, Centro de Estudios Europa Hispánica, 2010, pages 123-125. Reproduced in M. MORÁN TURINA: La memoria de las piedras..., p.18. Ibidem, p. 248. JERÓNIMO DE LA QUINTANA: A la muy antigua, noble y coronada villa de Madrid, historia de su antigüedad, nobleza y grandeza... Madrid, Imprenta del Reyno, 1629, ff. 87 vº - 90 vº. D. DE COLMENARES: Historia de la insigne ciudad de Segovia y compendio de las historias de Castilla. Segovia, Diego Díez, 1637, f. 89. D. DE COLMENARES: Historia de la insigne ciudad de Segovia... f. 6. Ibídem. A. DE MORALES: Las antigüedades de las ciudades de España que van nombradas en la corónica con las averiguaciones de sus sitios y nombres antiguos, que escribía Ambrosio de Morales, cronista del rey católico nuestro señor don Felipe II. Tomo IX. Madrid, Benito Cano, 1792, pages 344-345. D. DE COLMENARES: Op. cit., p. 554. M. MORÁN: Op. cit., p. 192. According to Kagan, all nations look for a founder linked to Antiquity, and especially to Noah, who would have given his descendents certain qualities that made them see themselves as a nation. R. L. KAGAN: Los cronistas y la corona. Madrid, Centro de Estudios Europa Hispánica and Marcial Pons, 2010, p. 363. Juan de Arfe also mentioned the Segovia Aqueduct and the Mérida Bridge among other famous constructions that were conserved in Spain dating back to Roman times. M. MORÁN: Op. cit., p. 193. M. MORÁN TURINA: La memoria de las piedras... pages 61, 63, 66. B. MORENO DE VARGAS: Historia de la ciudad de Mérida, dedicada a la misma Ciudad. Madrid, Viuda de Alonso Martín, 1633, f. 21 vº-22 vº. Tubal was Noah’s grandson, son of Japhet and responsible for founding cities from Asturias to Cádiz after the Great Flood. See A. CAMARA: «History and Myth», p. 313. B. MORENO DE VARGAS: Historia de la ciudad de Mérida... f. 25. Ibidem: f. 35 - 36 vº. Ibidem: f. 38, 38 vº. Ibidem: f. 39. XVI-XVIII (DIMH). 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 140 ROMAN ENGINEERING 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. R. CARO: Antigüedades y principado de la ilustrissima ciudad de Sevilla y chorographia de su convento iuridico, o antigua chancilleria. Dirigida al excelentissimo señor Don Gaspar de Guzmán, Conde Duque de Sanlúcar la Mayor. Seville, Andrés Grande, 1634. J. DE MAL LARA: Recebimiento que hizo la muy noble y muy leal Ciudad de Sevilla, a la c:r:m: del Rey D. Philippe N.S. Va todo figurado. Con una breve descripción de la Ciudad y su tierra. Seville, Alonso Escrivano, 1570, f. 49 vº. With regard to Seville the book by V. LLEÓ CAÑAL, a pioneer in these studies, is fundamental: Nueva Roma. Mitología y humanismo en the Renaissance sevillano. (1979). Madrid revised edition, Centro de Estudios Europa Hispánica, 2012. A. CÁMARA: Arquitectura y sociedad en el Siglo de Oro. Idea, traza y edificio. Madrid, Ediciones El Arquero, 1990, p. 20. DANIELA LAMBERINI: «La fortuna delle macchine senese nel Cinquecento,» in Prima di Leonardo. Cultura delle macchine a Siena nel Rinascimento. PAOLO GALLUZZI (ed.), Milan, 1991, p.139. LUCA PACIOLI: La divina proporción. A. M. GONZÁLEZ MADRID (intr.) and J. CALATRAVA (translation), Akal, 1991, pages 34-35. C. DE ROJAS: Teórica y práctica de fortificación, conforme las medidas y defensas destos tiempos... por el capitán Christoval de Rojas, Ingeniero del Rey nuestro señor. Dirigida al Príncipe nuestro señor Don Felipe III. Madrid, 1598, f. 101 vº. C. DE ROJAS: Teórica y práctica... Prologue. Ibidem, f. 1 vº. C. DE VILLALÓN: Op. cit., p. 147. He is confusing the name of Democrates with that of Dinocrates, the person responsible for the layout of the City of Alexandria for Alexander the Great, and who is one of the references that constantly appears in works on Antiquity written during the Renaissance when reference is made to that city. L. CERVERA VERA: Inventario de los bienes de Juan de Herrera. Valencia, Albatros Ediciones, 1977, pages 169, 170, 171. S. SERLIO: Tercero y quarto libro de architectura de Sebastián Serlio Boloñés. En los quales se trata de las maneras de cómo se puede adornar los hedificios con los exemplos de las antigüedades. Agora nuevamente traduzido de Toscano en Romance Castellano por Francisco de Villalpando architecto. Toledo, 1552, prologue for the reader. G. MAGGI and I. CASTRIOTTO: Della fortificatione delle città. Venecia, 1583, f. 6. C. DE ROJAS: Teórica... Prologue. C. DE ROJAS: Compendio y breve resolución..., p. 250. C. DE ROJAS: Sumario de la milicia..., pages 309-319. VITRUVIO: Op. cit., f. 3 and 4 vº. D. GONZÁLEZ DE MEDINA BARBA: Examen de fortificación, Madrid, Imprenta del Licenciado Várez de Castro, 1599, pages 3-4. L. VANDER HAMMEN: Don Filipe el prudente. Madrid, 1632, f. 129 vº. Quoted in A. CÁMARA: «La arquitectura militar y los ingenieros de la monarquía española. Aspectos de una profesión (1530-1650). Revista de la Universidad Complutense, no. 3, 1981, p. 267. A. GÓMEZ DE CASTRO: De las hazañas de Francisco Jiménez de Cisneros (1569). Madrid, Fundación Universitaria Española, 1984, pages 257 and 262. A. CÁMARA: «Tiburzio Spannocchi, Ingeniero Mayor de los Reinos de España». Espacio, Tiempo y Forma, no. 2, 1988, pages 77-91. T. SPANNOCCHI: Descripción de las marinas de todo el reino de Sicilia. Con otras importantes declaraciones notadas por el caballero Tiburcio Spanoqui del Abito de San Juan Gentilhombre de la Casa de su Magestad. Dirigido al príncipe don Filipe nuestro señor en el año de MDXCVI. BNE, Mss. 788, s. fol. A. CÁMARA: Fortificación y ciudad en los reinos de Felipe II. Madrid, Nerea, 1998, p. 61. Descripción de las Plaças de Oran y Mazarquivir..., f. 49. En A. CÁMARA, R. MOREIRA and M. VIGANÒ: Leonardo Turriano, ingeniero del rey. Madrid, Fundación Juanelo Turriano, 2010, p. 85. A. DE MORALES: Op. cit., pages 330-336. Ibidem, p. 335. Ibidem, pages 337-338. AGUSTÍN DE ROJAS: El viaje entretenido. Libro II (1604). Madrid, Aguilar, 1964, pages 307-308. «–GALEAZO: ¿Qué edificio es aquel que admira el cielo? –EMILIO: Alcázar es real el que señalas. –GALEAZO: ¿Y aquél, quién es, que con osado vuelo a la casa del Rey le pone escalas? –EMILIO: El Tajo, que hecho Icaro, a Juanelo, Dédalo cremonés, le pidió alas. Y temiendo después al Sol el Tajo, Tiende sus alas por allí debajo». LUIS DE GÓNGORA in Las firmezas de Isabela, (1610) in J. C. SÁNCHEZ MAYENDÍA: «El artificio de Juanelo en la literatura española». Cuadernos Hispanoamericanos, no. 103, 1958, pages 73-93. Los veintiún libros de los ingenios y máquinas de Juanelo Turriano. J. A. GARCÍA DIEGO (ed.), with transcription and a prologue by P. LAÍN ENTRALGO. Madrid, Fundación Juanelo Turriano, Doce Calles, 1996, vol. I, p. 185. Idem, p. 194. G. B. ANTONELLI: Epitomi delle fortificationi moderne (a cura de M. Sartor). Udine, Forum, 2009, p. 353. L. TURRIANO: Descripción... (transcription by D. CRESPO), in A. CÁMARA et alii: Leonardo Turriano..., p. 256. A. CÁMARA: «La ciudadela del rey en Jaca», en Signos. Arte y cultura en Huesca. De Forment a Lastanosa. Siglos XVI-XVII. Catalogue from the Exhibition. Diputación de Huesca, 1994, p. 93. A. 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VANDER HAMMEN Y LEÓN: Don Filipe el prudente, segundo deste nombre, rey de las Españas y nuevo mundo. Madrid, Viuda de Alonso Martín, 1632. C. DE VILLALÓN: Ingeniosa comparación entre lo antiguo y lo presente. Hecha por el Bachiller Villalón, dirigida al Illustre y reverendissimo Señor don Fray Alonso de Virues, Obispo dignísimo de Canaria, predicador y del consejo de la cathólica y cesarea magestad. En la qual se disputa quando ovo más sabios agora, o en la antigüedad, y para en prueba desto, se trae todos los sabios e inventores antiguos y presentes en todas las sciencias y artes (Valladolid, 1539). Madrid, Sociedad de Bibliófilos Españoles, 1898. M. VITRUVIO POLLION: De architectura, dividido en diez libros, traduzidos de Latín en castellano por Miguel de Urrea Architecto, y sacado en su perfectión por Iuan Gracian impresor vezino de Alcalá. Alcalá de Henares, 1582. Back to Contents INGENIOUS COMPARISONS: THE LOOK OF THE RENAISSANCE 143 BOOKS PUBLISHED BY FUNDACIÓN JUANELO TURRIANO JUANELO TURRIANO COLLECTION ON THE HISTORY OF ENGINEERING 2016 Elena and MARTÍNEZ JIMÉNEZ, Javier, Los acueductos de Hispania. Construcción y abandono. SÁNCHEZ LÓPEZ, 2015 Cristiano, Juanelo Turriano, de Cremona a la Corte: formación y red social de un ingenio del Renacimiento. ZANETTI, ROMERO MUÑOZ, Dolores, La navegación del Manzanares: el proyecto Grunenbergh. LOPERA, Antonio, Arquitecturas flotantes. Juan Miguel, Jorge Próspero Verboom: ingeniero militar flamenco de la monarquía hispánica. MUÑOZ CORBALÁN, JUANELO TURRIANO LECTURES ON THE HISTORY OF ENGINEERING 2016 CÁMARA MUÑOZ, Alicia and REVUELTA POL, Bernardo (eds.), «Libros, caminos y días». El viaje del ingeniero. CÁMARA MUÑOZ, Alicia (ed.), El dibujante ingeniero al servicio de la monarquía hispánica. Siglos XVI-XVIII. English edition: Draughtsman Engineers Serving the Spanish Monarchy in the Sixteenth to Eighteenth Centuries. 2015 NAVASCUÉS PALACIO, Pedro and REVUELTA POL, Bernardo (eds.), Ingenieros Arquitectos. CÁMARA MUÑOZ, Alicia and REVUELTA POL, Bernardo (eds.), Ingeniería de la Ilustración. 2014 CÁMARA MUÑOZ, Alicia and REVUELTA POL, Bernardo (eds.), Ingenieros del Renacimiento. English edition (2016): Renaissance Engineers. 2013 CÁMARA MUÑOZ, Alicia and REVUELTA POL, Bernardo (eds.), Ingeniería romana. English edition (2016): Roman Engineering. «That the greatness of the empire might be attended with distinguished authority in its public buildings» OTHER BOOKS 2014 Pedro and REVUELTA POL, Bernardo (eds.), Una mirada ilustrada. Los puertos españoles de Mariano Sánchez. NAVASCUÉS PALACIO, 144 2013 Juan Ignacio, Submarino Peral: día a día de su construcción, funcionamiento y pruebas. CHACÓN BULNES, 2012 Inmaculada, El discurso del ingeniero en el siglo XIX. Aportaciones a la historia de las obras públicas. AGUILAR CIVERA, CRESPO DELGADO, Daniel, Árboles para una capital. Árboles en el Madrid de la Ilustración. 2011 Pepa and REVUELTA POL, Bernardo (eds.), Ildefonso Sánchez del Río Pisón: el ingenio de un legado. CASSINELLO, 2010 CÁMARA MUÑOZ, Alicia CASSINELLO, (ed.), Leonardo Turriano, ingeniero del rey. Pepa (ed.), Félix Candela. La conquista de la esbeltez. 2009 CÓRDOBA DE LA LLAVE, Ricardo, Ciencia y técnica monetarias en la España bajomedieval. José Ramón (ed.), Pensar la ingeniería. Antología de textos de José Antonio Fernández Ordóñez. NAVARRO VERA, 2008 RICART CABÚS, Alejandro, Pirámides y obeliscos. Transporte y construcción: una hipótesis. Ignacio and NAVASCUÉS PALACIO, Pedro (eds.), Ars Mechanicae. Ingeniería medieval en España. GONZÁLEZ TASCÓN, 2006 Glenn; IZAGA REINER, José María and SOLER VALENCIA, Jorge Miguel, El Real Ingenio de la Moneda de Segovia. Maravilla tecnológica del siglo XVI. MURRAY FANTOM, 2005 Ignacio and VELÁZQUEZ SORIANO, Isabel, Ingeniería romana en Hispania. Historia y técnicas constructivas. GONZÁLEZ TASCÓN, 2001 José Ramón, El puente moderno en España (1850-1950). La cultura técnica y estética de los ingenieros. NAVARRO VERA, 1997 CAMPO Y FRANCÉS, Ángel del, Semblanza iconográfica de Juanelo Turriano. 1996/2009 Los Veintiún Libros de los Ingenios y Máquinas de Juanelo Turriano. 1995 MORENO, Roberto, José Rodríguez de Losada. Vida y obra. Back to Contents 145 This book is the outcome of the course held in 2012 at the Centro Asociado de la UNED in Segovia, as a result of the collaboration between the University and the Fundación Juanelo Turriano. Roman Engineering. «That the greatness of the empire might be attended with distinguished authority in its public buildings», is the first work in the series that contains the lectures given by wellknown specialists in these courses at university level. This first publication aims to analyse, amongst other subjects: communication in the Roman Empire; religious matters where hydraulic engineering was concerned; the effects of public works on the citizens’ everyday lives; or water supply in towns and cities. 146