Gassendi, Pierre

G G Gaillot, Jean-Baptiste-Aimable Born Died Saint-Jean-sur-Tourbe, Marne, France, 27 April 1834 Chartres, Eure-et-Loire, France, 4 June 1921 Aimable Gaillot specialized in celestial mechanics and eliminated notable residuals in the orbits of the jovian planets; his values for the masses of these planets were the most accurate ones then available. His parents were Jean Baptiste Gaillot and Marie Catherine Gillet. Gaillot was recruited in 1861 by Urbain Le Verrier, director of the Paris Observatory. His career was spent entirely in the Service des calculs (Bureau of computation), of which he became the head in 1873. Gaillot remained devoted to Le Verrier, even after the latter’s forced resignation (1870). In this way, he was able to complete the revision of Le Verrier’s planetary theories and was active in several geodetic campaigns. Gaillot was appointed astronome adjoint in 1868 and astronome titulaire in 1874. When Moritz Löewy was chosen as the new director of the Paris Observatory, he called upon Gaillot to be his deputy director, a position Gaillot held until his retirement in 1903. Another of Gaillot’s important contributions was his compilation of nearly 400,000 meridian observations of stars (gathered between 1837 and 1881) into the eight-volume Catalogue de l’Observatoire de Paris (1887). He also served as editor of numerous volumes of the Annales de l’Observatoire de Paris, founded by Le Verrier. Gaillot, however, was chiefly engaged in the refinement of the orbits of the planets. These were successively introduced into the Connaissance des temps (the French nautical almanac) after 1864. Originally, the orbits of Jupiter, Saturn, Uranus, and Neptune displayed residuals on the order of 10 arc-seconds. By a laborious procedure, Gaillot successively derived new orbital elements and masses for these planets, whose final results differed by at most a few arc seconds. For example, Gaillot reduced the discrepancies in Saturn’s mass from one part in a hundred to one part in a thousand, as compared with modern values. Gaillot completed this work in 1913 when he was almost 80 years old. Solange Grillot Selected References Baillaud, B. (1921). “Gaillot (Jean-Baptiste-Aimable).” Comptes rendus de l’Académie des sciences 172: 1393–1394. © Springer-Verlag Berlin Heidelberg 2007 Lévy, Jacques R. (1972). “Gaillot, Aimable Jean-Baptiste.” In Dictionary of Scientific Biography, edited by Charles Coulston Gillispie. Vol. 5, pp. 223–224. New York: Charles Scribner’s Sons. Poggendorff, J. C. “Gaillot.” In Biographisch-literarisches Handwörterbuch. Vol. 4 (1904): 473–474; Vol. 5 (1926): 407. Leipzig and Berlin. Galilei, Galileo Born Died Pisa, (Italy), 15 February 1564 Arcetri near Florence, (Italy), 8 January 1642 Although Galileo Galilei (universally known by his first name) is best remembered in the history of astronomy for his telescopic discoveries, his greatest contribution was his approach to physics, which led to the work of Christiaan Huygens and Isaac Newton. Galilei’s father Vincenzio was a musician who made significant contributions to musicology and influenced the son’s experimental approach. In 1581, Galilei enrolled at the University of Pisa to study medicine, but soon switched to mathematics, which he also studied privately. In 1585, he left the university without a degree, turning to private teaching and research. In 1589 he became professor of mathematics at the University of Pisa, and then from 1592 to 1610 at the University of Padua. During this period, Galilei research focused primarily on the nature of motion. He was critical of Aristotelian physics, favorably inclined toward Archimedean statics and mathematics, and innovatively experimental, in so far as he pioneered the procedure of combining empirical observation with quantitative mathematization and conceptual theorizing. Following this approach, he formulated, justified, and to some extent systematized various mechanical principles: an approximation to the law of inertia, the composition of motion, the laws that in free fall the distance fallen increases as the square of the time elapsed and that the velocity acquired is directly proportional to the time, the isochronism of the pendulum, and the parabolic path of projectiles. However, he did not publish any of these results during that period, indeed not publishing a systematic account of them until the Two New Sciences (Leiden, 1638). 400 G Galilei, Galileo The main reason for this delay was that in 1609 Galilei became actively involved in astronomy. He was already acquainted with Nicolaus Copernicus’s theory of a moving Earth and appreciative of the fact that Copernicus had advanced a novel argument. Galileo also had intuited that the geokinetic theory was more consistent in general with the new physics than was the geostatic theory. In particular, he had been attracted to Copernicanism because he felt that the Earth’s motion could best explain why the tides occur. But he had not published or articulated this general intuition and this particular feeling. Moreover, Galilei was acutely aware of the considerable evidence against Copernicanism: The Earth’s motion seemed epistemologically absurd because it contradicted direct sense experience; astronomically false because it had consequences that could not be observed (such as the similarity between terrestrial and heavenly bodies, Venus’s phases, and annual stellar parallax); mechanically impossible because the available laws of motion implied that bodies on a rotating Earth would, for example, follow a slanted rather than vertical path in free fall, and would be thrown off by centrifugal force; and theologically heretical because it contradicted the words and the traditional interpretations of Scripture. Until 1609, Galilei judged that the antiCopernican arguments far outweighed the pro-Copernican ones. However, the telescopic discoveries led Galilei to a major reassessment. In 1609, he perfected the telescope to such an extent as to make it an astronomically useful instrument that could not be duplicated by others for some time. By this means, he made several startling discoveries that he immediately published in The Sidereal Messenger (Venice, 1610): that the Moon’s surface is full of mountains and valleys, that innumerable other stars exist besides those visible to the naked eye, that the Milky Way and the nebulas are dense collections of large numbers of individual stars, and that the planet Jupiter has four satellites revolving around it at different distances and with different periods. As a result, Galilei became a celebrity. Resigning his professorship at Padua, he was appointed philosopher and chief mathematician to the Grand Duke of Tuscany, moving to Florence the same year. Soon thereafter, he also discovered the phases of Venus and sunspots. On the latter, he published the Sunspot Letters (Rome, 1613). Although most of these discoveries were made independently by others, no one understood their significance as Galilei did. This was threefold. Methodologically, the telescope implied a revolution in astronomy in so far as it was a new instrument that enabled the gathering of a new kind of data transcending the previous reliance on naked-eye observation. Substantively, those discoveries significantly strengthened the case in favor of the physical truth of Copernicanism by refuting almost all empirical astronomical objections and providing new supporting observational evidence. Finally, this reinforcement was not equivalent to a settling of the issue, because there was still some astronomical counterevidence (mainly, the lack of annual stellar parallax and the possibility that Venus’ phases could support a Tychonic view); because the mechanical objections had not yet been answered and the physics of a moving Earth had not yet been articulated; and because the theological objections had not yet been refuted. Thus, Galilei conceived a work on the system of the world in which all aspects of the question would be discussed. This synthesis of Galileo’s astronomy, physics, and methodology was not published until his Dialogue on the Two Chief World Systems (Florence, 1632). This particular delay was due to the fact that the theological aspect of the question got Galilei into trouble with the Inquisition, acquiring a life of its own that drastically changed his life. As it became known that Galilei was convinced that the new telescopic evidence rendered the geokinetic theory a serious contender for real physical truth, he came increasingly under attack from conservative philosophers and clergymen. They argued that Galilei was a heretic because he believed in the Earth’s motion and the Earth’s motion contradicted Scripture. Although Galilei was aware of the potentially explosive nature of this issue, he felt he could not remain silent, and decided to refute the biblical argument against Copernicus. To avoid scandalous publicity, he wrote his criticism in the form of long private letters, in December 1613 to his disciple Benedetto Castelli and in spring 1615 to the dowager Grand Duchess Christina. Galilei letters circulated widely, and the conservatives became even more upset. Thus in February 1615, a Dominican friar filed a written complaint against Galilei with the Inquisition in Rome. An investigation was launched that lasted about a year. As part of this inquiry, a committee of Inquisition consultants reported that the key Copernican theses were absurd and false in natural philosophy and heretical in theology. The Inquisition also interrogated other witnesses. Galilei himself was not summoned or interrogated partly because the key witnesses exonerated him and partly because Galilei letters had not been published, whereas, his published writings contained neither a categorical assertion of Copernicanism nor a denial of the scientific authority of Scripture. However, in December 1615 Galilei went to Rome of his own accord to defend his views. He was able to talk to many influential Church officials and was received in a friendly manner; he may be credited with having prevented the worst, in so far as the Galilei, Galileo Inquisition did not issue a formal condemnation of Copernicanism as a heresy. Instead, two milder consequences followed. In February 1616, Galilei himself was given a private warning by Cardinal Robert Bellarmine (in the name of the Inquisition) forbidding him to hold or defend the truth of the Earth’s motion. Galileo agreed to comply. And in March, the Congregation of the Index (the cardinals in charge of book censorship) published a decree, which, without mentioning Galilei, declared that the Earth’s motion was physically false and contradicted Scripture, that a 1615 book supporting the Earth’s motion as physically true and compatible with Scripture was condemned and permanently banned, and that Copernicus’s 1543 book was banned until appropriately revised. Published in 1620, these revisions amounted to rewording or deleting a dozen passages suggesting that the Earth’s motion was or could be physically true, so as to convey the impression that it was merely a convenient hypothesis to make mathematical calculations and observational predictions. For the next several years, Galilei kept quiet about the forbidden topic, until 1623 when Cardinal Maffeo Barberini became Pope Urban VIII. Since Barberini was an old admirer and patron, Galileo felt freer and decided to write the book on the system of the world conceived earlier, adapting its form to the new restrictions. Galilei wrote the book in the form of a dialogue among three characters engaged in a critical discussion of the cosmological, astronomical, physical, and philosophical arguments, but determined to avoid the biblical or theological ones. This Dialogue was published in 1632, and its key thesis is that the arguments favoring the geokinetic theory are stronger than those favoring the geostatic view, and in that sense Copernicanism is more probable than geostaticism. When so formulated, the thesis is successfully established. In the process, Galilei’s managed to incorporate into the discussion the new telescopic discoveries, his conclusions about the physics of moving bodies, a geokinetic explanation of the tides, and various methodological reflections. From the viewpoint of the ecclesiastic restrictions, Galilei must have felt that the book did not “hold” the theory of the Earth’s motion, because it was not claiming that the geokinetic arguments were conclusive; that it was not “defending” the geokinetic theory, because it was merely a critical examination of the arguments on both sides; and that it was an hypothetical discussion, because the Earth’s motion was being presented as a hypothesis postulated to explain observed phenomena. However, Galilei enemies complained that the book did not treat the Earth’s motion as a hypothesis but as a real possibility, and that it defended the Earth’s motion. These features allegedly amounted to transgressions of Bellarmine’s warning and the Index’s decree. And there was a third charge: that the book violated a special injunction issued personally to Galilei in 1616 prohibiting him from discussing the Earth’s motion in any way whatever; a document describing this special injunction had been found in the file of the earlier Inquisition proceedings. Thus Galilei was summoned to Rome to stand trial, which after various delays began in April 1633. At the first hearing, Galilei was asked about the Dialogue and the events of 1616. He admitted receiving from Bellarmine the warning that the Earth’s motion could not be held or defended, but only discussed hypothetically. He denied receiving a special injunction not to discuss the topic in any way whatever, and in his defense he introduced a certificate he had obtained from Bellarmine in 1616 G that only mentioned the prohibition to hold or defend. Galilei also claimed that the book did not defend the Earth’s motion, but rather suggested that the favorable arguments were inconclusive, and so did not violate Bellarmine’s warning. The special injunction surprised Galilei as much as Bellarmine’s certificate surprised the inquisitors. Thus it took 3 weeks before they decided on the next step. The inquisitors opted for some out-ofcourt plea-bargaining: They would not press the most serious charge (violation of the special injunction), but Galilei would have to plead guilty to a lesser charge (unintentional transgression of the warning not to defend Copernicanism). Galilei requested a few days to devise a dignified way of pleading guilty to the lesser charge. Thus, at later hearings, he stated that the first deposition had prompted him to reread his book; he was surprised to find that it gave readers the impression that the author was defending the Earth’s motion, even though this had not been his intention. He attributed his error to wanting to appear clever by making the weaker side look stronger. He was sorry and ready to make amends. The trial ended on 22 June 1633 with a sentence harsher than Galilei had been led to believe. The verdict found him guilty of a category of heresy intermediate between the most and the least serious, called “vehement suspicion of heresy”; the objectionable beliefs were the cosmological thesis that the Earth moves and the methodological principle that the Bible is not a scientific authority. The Dialogue was banned. He was condemned to house arrest for the rest of his life. And he was forced to recite a humiliating “abjuration.” One of the ironic results of this condemnation was that, to keep his sanity, Galilei went back to his earlier research on motion, organized his notes, and 5 years later published his most important contribution to physics, the Two New Sciences. Without the tragedy of the trial, he might have never done it. Maurice A. Finocchiaro Selected References Biagioli, Mario (1993). Galileo Courtier. Chicago: University of Chicago Press. Clavelin, Maurice (1974). The Natural Philosophy of Galileo, translated by A. J. Pomerans. Cambridge, Massachusetts: MIT Press. Drake, Stillman (1978). Galileo at Work. Chicago: University of Chicago Press. Fantoli, Annibale (1994). Galileo: For Copernicanism and for the Church, translated by G. V. Coyne. Vatican City: Vatican Observatory Publications. (2nd ed. 1996.) Finocchiaro, Maurice A. (1980). Galileo and the Art of Reasoning. Boston: D. Reidel. ——— (trans. and ed.) (1989). The Galileo Affair: A Documentary History. Berkeley: University of California Press. Galilei, Galileo (1890–1909). Opere. 20 Vols. National Edition by A. Favaro. Florence: Barbèra. ——— (1974). Two New Sciences, translated and edited by S. Drake. Madison: University of Wisconsin Press. ——— (1989). Sidereus Nuncius, or the Sidereal Messenger, translated and edited by A. Van Helden. Chicago: University of Chicago Press. ——— (1997). Galileo on the World Systems, translated and edited by M. A. Finocchiaro. Berkeley: University of California Press. Koyré, Alexandre (1978). Galileo Studies, translated by J. Mepham. Hassocks, Sussex: Harvester Press. Wallace, William A. (1984). Galileo and His Sources. Princeton, New Jersey: Princeton University Press. 401 402 G Galle, Johann Gottfried Galle, Johann Gottfried Born Died Pabsthaus, (Sachsen-Anhalt, Germany), 9 June 1812 Potsdam, Germany, 10 July 1910 December 1839 to March 1840, he discovered three new comets. On 23 September 1846, Galle received a letter from the Parisian astronomer Urbain Le Verrier with his prediction of a position for the hypothetical trans-Uranian planet. A half-hour search on the following night yielded his discovery of an uncharted eighth-magnitude object with a tiny disk – the giant planet Neptune. Galle also enjoyed a solid reputation as an experienced computer. Beginning from his student years, he contributed to the Berlin astronomical ephemeris. In 1847, he published his first catalog of the orbital elements of comets; he later expanded this catalog several times. The last edition of 1894 contained the orbital elements for 414 comets. In 1872, Galle made a very useful proposal to use the minor planets to determine the Sun’s parallax. He organized international campaigns for the observations of selected asteroids from different locations in order to measure an asteroid’s distance from the Earth, which enabled the estimation of the Earth’s distance from the Sun. This method gave the most accurate values for the astronomical unit prior to radar observations of the planets. By chance, Galle was involved in meteoritics; he carefully investigated the large rain of meteorites at Pultusk, Poland, on 30 January 1868. In 1840, Galle won the Lalande Prize of the Paris Academy of Sciences. Today, he is remembered for his discovery of Neptune and commemorated by the naming of minor planet (2097) and craters on the Moon and Mars for him. Mihkel Joeveer Selected References Johann Galle, astronomer at Berlin and Breslau, discovered the planet Neptune and three comets, composed noted catalogs of the orbital elements for comets, and elaborated a new method to measure the solar parallax. Galle was the eldest of seven children born to Marie Henriette and Johann Gottfried Galle, who earned a living distilling wood to obtain tar and turpentine. After successful studies at the Wittenberg Gymnasium, he matriculated at Berlin University in 1830 to study practical and theoretical astronomy. In 1835, the director of the Berlin observatory, Johann Encke, invited Galle to fill the post of his assistant. In 1845, he obtained his doctorate in astronomy from Berlin University, and was appointed as director of Breslau (now Wrocaw, Poland) Observatory in 1851. In 1856, Galle married Cäsilie Eugenie Marie Regenbrecht. Their elder son, Andreas (1858–1943), was an astronomer and geodesist, their younger son, Georg, a physician. Galle remained professionally active into very old age; he served as a professor of astronomy and observatory director at Breslau until 1897. At the Berlin Observatory, Galle had at his disposal the highquality 9-in. refractor. In June 1838, while measuring the diameter of Saturn, he discovered the crepe ring of Saturn. His search for comets was remarkably successful; in the brief interval from Anon. (1911). “Johann Gottfried Galle.” Monthly Notices of the Royal Astronomical Society 71: 275. Ashbrook, Joseph (1965). “The Long Career of J. G. Galle.” Sky & Telescope 30, no. 6: 355. Chant, C. A. (1910). “Johann Gottfried Galle.” Journal of the Royal Astronomical Society of Canada 4: 379–385. Franz, J. (1910). “Johann Gottfried Galle.” Astronomische Nachrichten 185: 309–312. Wattenberg, Diedrich (1963). Johann Gottfried Galle, 1812–1910: Leben und Wirken eines deutschen Astronomen. Leipzig: Johann Ambrosius Barth. Gallucci, Giovanni Paolo Born Died Salò, (Lombardy, Italy), 1538 Venice, (Italy), circa 1621 Tutor, writer, translator, and cartographer, Giovanni Gallucci studied in Padua and moved to Venice, where he spent the rest of his life. The range of his activity embraces both scientific and humanistic fields. In his most important work, Theatrum Mundi et Temporis (Theater of the world and time; Venice, 1588), Gallucci presents a general treatment of celestial phenomena, including both astronomical and astrological aspects. He declares the definite intention to clear his discussion of any trace of superstition in order to avoid a conflict with the Catholic Church, which some years before had condemned astrology. Gamow, George [Georgiy] (Antonovich) The most noticeable peculiarity of Gallucci’s book is given by the 48 maps of Ptolemaic constellations. The maps are represented in trapezoidal projection, and show the brightest stars of each asterism and the corresponding mythological figure. The stars’ positions are drawn from Nicolaus Copernicus’ De Revolutionibus Orbium Coelestium. The set of maps of Theatrum renders this work one of the first celestial atlases of the modern age. Davide Neri Selected References Ernst, G. (1998). “Gallucci, Giovanni Paolo.” In Dizionario biografico degli italiani. Vol. 51, pp. 740–743. Rome: Instituto della Enciclopedia italiana. Thorndike, Lynn (1941). A History of Magic and Experimental Science. Vol. 5, pp. 151, 155; Vol. 6, pp. 158–160. New York: Columbia University Press. Tooley, R. Vss. (1979). Tooley’s Dictionary of Mapmakers. Tring, England: Map Collector Publications, p. 234. Warner, Deborah J. (1979). The Sky Explored: Celestial Cartography, 1500–1800. New York: Alan R. Liss, p. 91. Gambart, Jean Félix Adolphe Born Died Sète, Hérault, France, May 1800 Paris, France, 23 July 1836 Jean Gambart became in 1819 an assistant at the Marseilles Observatory, and in 1822 its director. From this underequipped and poorly situated institution, he discovered 13 comets between 1822 and 1833, including the famous one on 9 March 1826 that was independently detected by Wilhelm von Biela 10 days earlier. It was Gambart who calculated the period of this comet to be less than 7 years. A lunar crater is named for him. Selected Reference Poggendorff, J. C. (1863). “Gambart.” In Biographisch-literarisches Handwörterbuch. Vol. 1, col. 842. Leipzig: J. A. Barth. Gamow, George [Georgiy] (Antonovich) Born Died Odessa, (Ukraine), 4 March 1904 Boulder, Colorado, USA, 20 August 1968 Russian–American theoretical physicist George Gamow was among the very first to take seriously the idea of a hot, dense early Universe and to consider the processes that might occur in it, including nuclear reactions and (as a mentor to Ralph Alpher and Robert Herman) the production of thermal radiation that was eventually detected. G Gamow began his education in Odessa but moved to the University of Petrograd (later Leningrad and now Saint Petersburg), where his initial study of relativistic cosmology with Alexander Friedmann was frustrated by the latter’s death. He received a Ph.D. in 1928 for work on aspects of quantum theory. Gamov held fellowships at Copenhagen (1928–1929, 1930–1931) and Cambridge (1929–1930) and a professorship at Leningrad (1931–1933) before leaving the Soviet Union for good. He held a professorship at George Washington University from 1934 to 1956 and at the University of Colorado from 1956 until his death. Gamow’s first major contribution was the understanding of quantum-mechanical tunneling (barrier penetration) required for α particles (helium nuclei) to get out of nuclei like uranium and thorium as these decay to lead. This was a near-simultaneous discovery with that made by Eugene U. Condon and Ronald Gurney. Within the next few years, Robert Atkinson and Friedrich Houtermans recognized that the same sort of tunneling would allow nuclei to come together and fuse, beginning the modern study of energy production and nucleosynthesis in stars. While at George Washington University, he collaborated with Edward Teller on the Gamow–Teller selection rules (which describe another kind of nuclear decay called β) and developed the Gamow functions describing nuclear shapes. In papers in 1940/1941 he, along with Mario Schoenberg, considered the possibility of repeated β decays and inverse β decays in stellar interiors and the neutrinos emitted by the process as a stellar coolant, affecting the subsequent supernova explosions of massive stars. The energy at which a nuclear reaction operator is also called the Gamow peak. As early as 1935, Gamow considered how heavy elements might be built up from light ones by repeated additions of neutrons alternating with β decays, instead of trying to bring more and more massive nuclei together. In 1946, he suggested that the early hot, dense Universe might be an appropriate site for the buildup of heavy elements in this way. In subsequent work with Alpher and Herman, the Universe was described as arising from a primordial substance, “ylem,” which was in fact pure neutrons. Only very gradually did it become clear that neutron addition could not build up heavy elements, because there are no stable nuclei with either five or eight particles. (Thus you make hydrogen and helium, a tiny amount of lithium, and nothing else.) To trace the synthesis of heavy elements in stars (see Fred Hoyle) and to reconsider the early universe nuclear reactions starting with an equilibrium distribution of protons, neutrons, electrons, and so forth, rather than pure neutrons, was left to others. Meanwhile, in 1949, Alpher and Herman published a prediction that processes in the early universe should have left a sea of microwave radiation (the Cosmic Microwave Background Radiation [CMBR]) as their signature. They estimated a temperature of about 5 K for that radiation; when it was found by Arno Penzias and Robert Wilson in 1965, the actual temperature was 2.7 K. Gamow conceivably did not take the prediction very seriously at the time, and he advised a potential graduate student with an interest in microwave spectroscopy to look elsewhere for a thesis project. Even after the discovery, at a 1967 conference, he was heard to mutter, “I lost a nickel; you found a nickel. Who’s to say it’s the same nickel?” In the early 1950s, Gamow also developed an interest in molecular biology and how heredity might work. He is generally thought to have come very close to the idea of the double helix at the same time James Watson and Francis Crick were developing it. A 1954 paper was one of the first suggestions for how the four nucleotides in DNA might code in triplets for the 20 amino acids widely used 403 404 G Gan De by living creatures. Gamov founded a discussion group in the field that had precisely 20 members at any time, so that each could carry the name of an amino acid, and carefully arranged things so that his came first in the alphabet. Gamow was an outstanding popularizer of science. Among his 30 books, the most widely influential were probably Our Friend the Sun (which begins “The sun is much, much larger even than an elephant”) and the “Mr. Tompkins” series, which explained quantum mechanics and relativity by imagining a Universe in which Planck’s constant was a large number and the speed of light a small one, so that everyday objects displayed quantum mechanical and relativistic effects. His sense of humor carried across into his science, with the neutron process named URCA after the Casino in Rio de Janeiro, where money vanished as steadily as the energy carried away by the neutrinos. Gamow produced a spoof paper purporting to distinguish how the Coriolis force affected the chewing of cud by cows in the Northern Hemisphere and Southern Hemisphere. He failed to get Mr. Tompkins on the author list of one of his papers, but scored a success when he and Alpher were about to submit a paper on the synthesis of the elements from ylem. He looked at “Alpher and Gamow,” decided that “something was missing,” and added Hans Bethe in the middle, with a footnote explaining that the middle author appeared in absentia.” The footnote was lost from the published version, and “Alpha, Beta, Gamma” have been famous ever since in the astronomical community not just as the three kinds of radioactive decay (or the first three letters of the Greek alphabet) but as an early key paper in cosmology. It is only a few paragraphs long. Gamow was elected to the United States National Academy of Sciences, the Soviet Academy of Sciences, the Royal Danish Academy, and the International Academy of Astronautics. He was a fellow of the American Physical Society and several others. Douglas Scott Selected References Alpher, Ralph A., H. Bethe, and G. Gamow (1948). “The Origin of Chemical Elements.” Physical Review 73: 803–804. Alpher, Ralph A., R. Herman, and G. Gamow (1948). “Thermonuclear Reactions in the Expanding Universe.” Physical Review 74: 1198–1199. Gamow, G. (1938). “Nuclear Energy Sources and Stellar Evolution.” Physical Review 53: 595–604. ______ (1939). Mr. Tompkins in Wonderland. Cambridge: Cambridge University Press. ______ (1946). “Rotating Universe?” Nature 158: 549. ______ (1954). “Possible Relation between Deoxyribonucleic Acid and Protein Structures.” Nature 173: 318. ______ (1953). The Moon. New York: H. Schuman. ______ (1970). My World Line: An Informal Autobiography. New York: Viking Press. Gamow, G. and M. Schoenberg (1940). “The Possible Role of Neutrinos in Stellar Evolution.” Physical Review 58: 1117. Gamow, G. and E. Teller (1939). “The Expanding Universe and the Origin of the Great Nebulae.” Nature 143: 116–117. Harper, E., W. C. Parke, and G. D. Anderson (eds.) (1997). The George Gamow Symposium. Astronomical Society of the Pacific Conference Series. Vol. 129. San Francisco: Astronomical Society of the Pacific. Kragh, Helge (1996). Cosmology and Controversy: The Historical Development of Two Theories of the Universe. Princeton, New Jersey: Princeton University Press. McConnell, Craig Sean (2000). “The Big Bang-Steady State Controversy: Cosmology in Public and Scientific Forums.” Ph.D. diss., University of Wisconsin-Madison. Gan De Flourished China, 4th century BCE According to tradition, Gan De was a native of the state of Chu—he was also said to be a native of the state of Qi or Lu—in the Warring States period (475–221 BCE). He wrote treatises entitled Tianwen xinzhan (New astrological prognostications of the patterns of the heavens), in eight volumes, and Suixing jing (Canon of the planet Jupiter), but both are lost. Fortunately, some paragraphs from these works were quoted in later books. We can therefore study some of Gan De’s achievements in astronomy from the surviving quotations. These achievements can be summed up in two statements. First, independent of Shi Shen (another astronomer of his time), Gan De observed stars and obtained their latitudes and differences in right ascension. He then composed a star atlas including the Chinese constellations. Later on, there appeared a new atlas called Gan Shi xing jing (Gan’s and Shi’s classic of stars), which was based on Gan’s atlas and Shi Shen’s atlas; it greatly influenced the development of astronomy in China. Recent research has shown that the polar distances and right ascensions of the stars found in Xing jing were probably measured around the year 70 BCE, not during the Warring States Period as traditionally thought. Second, Gan developed the concept of the synodic period of a planet and obtained such periods for Mercury (136 days), Venus (587.25 days), and Jupiter (400 days) (versus present values of 115.9, 583.9, and 398.9 days, respectively). There is some discussion that Gan De may have observed the brightest satellite of Jupiter. Li Di Selected References Chen, Meidong (1992). “Biography of Gan De.” In Zhongguo Gudai Kexuejia Zhuanji (Scientific biographies of ancient Chinese scientists), edited by Du Shiran. Vol. 1, pp. 25–26. Beijing: Science Press. Pan, Nai (1989). Zhongguo hengxing guance shi (History of observations of fixed stars in ancient China). Shanghai: Xuelin Press, pp. 48–72. Qutan Xida (Tang dynasty). Kaiyuan Zhanjing (Canon of astronomy and astrology from the Kaiyuan period 713–741). Photo-offset ed. Beijing: China Book Store, 1983. Gaṇeśa Born Died Nandigrāma (Nandod, Gujarat, India), 1507 probably after 1560 Gaṇeśa was the founder of a fifth school of astronomical thought during the late period of Indian astronomy. The brief remarks in Gaṇeśa’s and his commentators’ works tell us that he was born into a Brāhmaṇa family belonging to the Kauśika gotra (a form of exogamous kin-group). His father was the noted astronomer Keśava; his mother was Lakṣmī. Gaṇeśa appears to have spent his entire life in Nandigrāma. The number of noted astronomers and astrologers in Gaposchkin, Sergei [Sergej] Illarionovich his family indicates that this practice was their hereditary profession or “caste.” Gaṇeśa learned this profession from his father and composed his earliest known astronomical work (according to legend) when he was 13. More than a dozen works are ascribed to him, including treatises and commentaries on mathematics, prosody, and other subjects as well as those on astronomy, astrology, and astronomical instruments. By far the most important of Gaṇeśa’s compositions were the Grahalāghava or Siddhāntarahasya (Brevity [in] Planet [computations]) of 1520 and the Laghutithicintāmaṇi (Wishing-Gem of Lunar Days) of 1525. The former belongs to the class of astronomical handbooks, or kara ṇas, that provided concise and simple rules for computing planetary positions and astrologically significant phenomena such as eclipses and conjunctions. These requirements were fulfilled with great ingenuity in the Grahalāghava. Remarkably, the work employs no trigonometry; the trigonometric solutions to problems of planetary motion are all replaced by algebraic approximations. The Grahalāghava is also unusual because of the direct relationship of its selection of astronomical parameters to observation. Instead of adhering strictly to the traditions of any one of four principal astronomical schools, Gaṇeśa chose parameters for his handbook from more than one school, where they agreed most closely with his own observations. This new combination of parameters subsequently formed the basis of a fifth astronomical school that bore Gaṇeśa’s name. The Laghutithicintāmaṇi also illustrates Gaṇeśa’s interest in, and talent for, ingenious mathematical devices to simplify the labor of routine astronomical computations. It consists of a set of tables for the use of calendar-makers, whose task was to list the dates and times of the beginnings of the several different time-units in the Indian calendar, many of which had ritual or astrological significance. The tables of the Laghutithicintāmaṇi supply all the necessary information for this purpose, with a mere 18 verses of directions for their use. The convenience and simplicity of the methods in the Grahalāghava and the Laghutithicintāmaṇi made the new “Gaṇeśa School” highly popular in the 16th century and thereafter, especially in the northern and western parts of India. Some scholars of classical Indian astronomy, however, have complained that the influence of these works undermined astronomers’ understanding of the relevant theoretical models, as their practical tasks were reduced to the application of fewer and simpler algorithms, thanks to Gaṇeśa’s ingenuity. Gaṇeśa’s other astronomical works, chiefly on observational instruments and astrology, did not have the same impact, although his detailed and insightful commentaries on the mathematical and astronomical works of Bhāskara II were widely known. Kim Plofker Selected References Chattopadhyay, Anjana (2002). “Ganesa.” In Biographical Dictionary of Indian Scientists: From Ancient to Contemporary, p. 438. New Delhi: Rupa. Dikshita, Sankara Balakrshna (1981). Bhāratīya Jyotish śāstra (History of Indian Astronomy), translated by Raghunath Vinayak Vaidya. Vol. 2, pp. 130–139. New Delhi: India Meteorological Department. Pingree, David (1972). “Ganeśa.” In Dictionary of Scientific Biography, edited by Charles Coulston Gillispie. Vol. 5, pp. 274–275. New York: Charles Scribner’s Sons. G ______ (1978). “History of Mathematical Astronomy in India.” In Dictionary of Scientific Biography, edited by Charles Coulston Gillispie. Vol. 15 (Suppl. 1), pp. 533–633. New York: Charles Scribner’s Sons. Gaposchkin, Sergei [Sergej] Illarionovich Born Died Yevpatoriya, (Ukraine), 12 July 1889 Chelmsford, Massachusetts, USA, 17 October 1984 Russian–American stellar astronomer Sergei Gaposchkin devoted his professional career to the study of variable stars, especially eclipsing binary and spectroscopic binary stars. The son of a day laborer and one of 11 children, he completed his elementary school education before traveling to Moscow in 1915 to work in a textile factory. In 1917, he was called for military service and Gaposchkin returned to his hometown to enlist. His military service in the Tsar’s army, spent as a sergeant on the Galician Front (then part of the Austro–Hungarian Empire), ended with the collapse of the Russian autocracy. After walking for several months from the front back to his military depot in the Crimea to turn in his rifle, Gaposchkin spent a few months serving in the police force in his hometown, continuing his studies at night when possible. When both his parents and his older siblings died in a typhus epidemic, Gaposchkin was appointed guardian for his remaining brother and sisters. But in October 1920, on a coasting trip from Yevpatoriya to the Sea of Azov, the sailing vessel in which he and his companions were transporting flour was blown off course and 405 406 G Garfinkel, Boris weathered a ferocious storm that carried them to Bulgaria. Finally they sailed down to Constantinople, where they sold the remains of their goods and were trapped by the collapse of the White Armies when the Russian Revolution ended. Without papers or funds, Gaposchkin worked as a gardener and odd-jobs man until a Russian émigré society helped him to travel to Berlin, Germany, where he enrolled in the German Institute for Foreigners, to learn German to fulfill the educational requirements for joining the university. By 1928 he matriculated at the Kaiser Wilhelm University, where he completed his Ph.D. in astronomy in 1932. During the 1920s, Berlin was a vibrant and highly cultured city that attracted many prominent scientists, among them Albert Einstein, one of his professors in the Physics curriculum of the Kaiser Wilhelm University. Other professors whose lectures he attended included Ludwig Bieberbach, Paul Guthnick, August Kopff, and Max Planck. During this period he met colleagues such as W. Becker with whom he formed lifelong friendships. In 1931/1932 Gaposchkin made a survey of variable stars at the remote Sonneberg Observatory, as part of his duties as an assistant at the Babelsberg Observatory near Berlin. During the time he spent at the Babelsberg Observatory, he lived in a single room in the nearby town of Nowawes. But in 1933, with the rise to power of Adolph Hitler, Gaposchkin lost his position and believed that he was scheduled to be sent to a concentration camp at Sonneberg. He was also unable to return to the Soviet Union because he had left Russia during the civil war. By chance he heard from a colleague about the meeting of the Astronomisches Gessellschaft to be held in Göttingen that August. In hopes of finding another position outside Germany, Gaposchkin bicycled to the meeting where he met many scientists, among them Cecilia Payne (later Cecilia Payne-Gaposchkin), who would argue his case with the director of the Harvard College Observatory, Harlow Shapley. Within a few months, he received a position as research assistant at the Harvard College Observatory, left Germany on a stateless passport, and passing through Britain, took the Georgic to Boston, arriving on 27 November 1933. Sergei and Cecilia (who was UK born) married in 1934, and both became American citizens as soon as possible. Two of their three children, Peter and Katherine (Haramundanis), have been involved in astronomy, the latter coauthoring an introductory textbook with her mother. Gaposchkin spent the rest of his working life at the Harvard Observatory, with occasional extended trips for observing to McDonald Observatory in Texas, USA, and Mount Stromlo Observatory, Australia. During the 1940s, he observed fairly regularly at the Agassiz Station of Harvard Observatory in Harvard, Massachusetts. Gaposchkin was also a gifted artist, working primarily with pencil and watercolors; his sketches of profiles were exceptionally good, and his small landscapes and meticulous Christmas cards, delightful. Gaposchkin’s work in astronomy, much of it done with Cecilia Payne-Gaposchkin at the Harvard College Observatory, was focused on variable stars. His particular specialty was eclipsing binaries, the subject of his Ph.D. dissertation at the University of Berlin. Eclipsing binaries, along with visual binaries, are a source from which the masses of individual stars can be determined. Though somewhat eclipsed by his more brilliant wife, he was fascinated by variables and novae all his life. Gaposchkin published numerous papers on individual variables, and invented the “flyspanker,” a small piece of glass on a wand with graduated ink spots, which he and his assistants could use in making estimates of variable stars when adequate comparison stars were wanting. His systematic methods for making observations on photographic plates enabled the Gaposchkins to complete several large investigations of variable stars including that of the Milton Bureau program of Harvard Observatory and a systematic analysis of variables in the Small Magellanic Cloud in which he and his assistants made over a million observations. Additionally, he translated the seminal work Moving Envelopes of Stars by Viktor V. Sobolev (Harvard University Press, 1960) from Russian, made visual estimates of the brightness of the Magellanic clouds, and drew a unique picture of the visual Milky Way from observations made on his trip by sea to Australia. Gaposchkin’s correspondence can be found in the Russell Papers, Princeton University; Otto Struve Papers, University of Chicago; and Jesse Greenstein Papers, California Institute of Technology. A three-volume, self-published autobiography of Gaposchkin can be found at Harvard and in a few other collections. Katherine Haramundanis Selected References Gaposchkin, Sergei I. (1932). “Lebenslauf.” Die Bedeckungsveranderlichen. Berlin: Der Universitatssternwarte zu Berlin-Babelsberg. (Inaugural Dissertation zur Erlangung der DoktorWurde, Veroff.) ______ (1960). “The Visual Milky Way.” Vistas in Astronomy 3: 289–295. ______ (1974-1978). Divine Scramble. Arlington, Massachusetts. Haramundanis, Katherine Gaposchkin (2001). “Cecilia and Her World.” In The Starry Universe: The Cecilia Payne-Gaposchkin Centenary, edited by A. G. Davis Philip and Rebecca A. Koopmann, pp. 23-24. Schenectady, New York: L. Davis Press. Payne- Gaposchkin, Cecilia, and Sergei, Gaposchkin (1938). Variable Stars. Harvard Observatory Monographs, no. 5. Cambridge, Massachusetts: Harvard College Observatory. ______ (1966). “Variable Stars in the Small Magellanic Cloud.” In Smithsonian Contributions to Astrophysics. Vol. 9 Washington, DC: Smithsonian Institution. Garfinkel, Boris Born Died Rjev, Russia, 18 November 1904 West Palm Beach, Florida, USA, March 1999 Russian American dynamicist Boris Garfinkel formalized the Ideal Resonance Problem in orbital theory. Selected Reference Jupp, A. (1988). “The Critical Inclination Problem–30 Years of Progress.” Celestial Mechanics 43: 127–138. Gascoigne, William Born Died Middleton, (West Yorkshire), England, circa 1612 Marston Moor near Long Marston, (North Yorkshire), England, 2 July 1644 William Gascoigne was the first to use crosshairs in telescopes and invented the wire micrometer. Gascoigne was the eldest child of Henry Gascoigne and Margaret Jane Cartwright, prosperous Gascoigne, William members of the gentry from Thorpe-on-the-Hill, near Leeds in Yorkshire. Gascoigne’s family was likely Catholic. He spent most of his life in Middleton, although John Aubrey claims that he was trained by the Jesuits in Rome. After Gascoigne’s death his papers passed to another prominent Yorkshire Catholic family, the Towneleys. Gascoigne quickly learned astronomy with little formal training. After a brief and uninspiring stay at Oxford, he pursued advanced astronomical studies on his own. Like his contemporary Jeremiah Horrocks, Gascoigne repudiated ancient authority and even disagreed with Philip Lansbergen’s tables. Gascoigne was determined to make new calculations based on fresh observations. Gifted in the construction and use of astronomical instruments, he made his own Galilean telescope by 1640 and described it in a letter to one of his correspondents, William Oughtred. Gascoigne also invented his own methods for grinding glass and apparently had “a whole barn full of machines or instruments.” Gascoigne’s role in positional astronomy went unnoticed for decades. He was the first to discover the use of crosshairs in observational astronomy. He thought of the idea when he observed spider hairs in his telescope. His and others’ early crosshairs were usually made of hair or textile thread. By 1640, Gascoigne had introduced crosshairs (telescopic sights) into the focal plane of the “astronomical” telescope: A telescope with a convex eyepiece was necessary for Gascoigne’s inventions. He also applied the telescope and telescopic sights to positional measuring instruments (arcs) such as the quadrant and sextant, and the wire micrometer and the micrometer’s application to the telescope. Gascoigne was also the first to invent and apply the wire micrometer to the telescope. Consisting of two parallel hairs (or metal bars), screws with turning parts, and some type of internal scale, micrometers measured small angular distances and apparent diameters of planets. Gascoigne’s micrometer consisted of two thin pieces of metal mounted parallel to each other on screws that opened and closed the two blades. The number of revolutions needed to attain a required opening was shown on a scale and the fractions of a revolution on a dial that was divided into a 100 parts. Unlike later micrometers, Gascoigne used two screws on both sides of his device—each screw moved its own reticule either toward or away from the center axis in the field of view. In a 1640 letter, Gascoigne informed Oughtred that he had “either found out, or stumbled” onto an invention “whereby the distance between any of the least stars, visible only by a perspective glass, may be readily given 1/4 to a second.” Gascoigne later described this new mechanical device as “a ruler with a hair in it, moving upon the centre of a circular instrument graduated with transversal lines and two glasses.” He told Oughtred that he had shown his “internal” scale “and its use in a glass” to others who were impressed by the invention because they thought that all possible means for taking measurements had been exhausted. Gascoigne also corresponded with William Crabtree, another north country astronomer and friend of Horrocks. News between Horrocks and Gascoigne, who never corresponded directly, filtered through Crabtree, and the three rarely met, though they maintained a fruitful and rewarding correspondence. Gascoigne was killed while fighting on the Royalist side in the Battle of Marston Moor. G A small group of his friends, including Oughtred and Christopher Towneley, kept most of his papers, letters, and records of his inventions, but did not immediately publicize his work. Knowledge of Gascoigne’s invention of telescopic sights was even more limited than his micrometer work because he had not shared these results with Oughtred. Consequently, it was forgotten until his papers came to Christopher Towneley’s nephew Richard. In 1665, Richard Towneley reintroduced Gascoigne’s work, although Robert Hooke and Christopher Wren had already begun experimenting with telescopic sights by the same year. In the summer of 1671, John Flamsteed visited Towneley and viewed the papers. Flamsteed was impressed with Gascoigne’s manuscript of a treatise on optics that Gascoigne had intended to send to the press. Unfortunately, the treatise has not survived. In the late 1660s, priority disputes broke out between the English and French over who first discovered micrometers and telescopic sights. In 1717, William Derham responded to the French claims of having discovered telescopic sights in the Philosophical Transactions of the Royal Society. Derham felt he was “Duty bound, to do that young but ingenious Gentleman, Mr. Gascoigne, the Justice, to assert his invention to him.” He also claimed that Richard Towneley sufficiently proved that the invention of the micrometer was Gascoigne’s and not Adrien Auzout’s or Jean Picard’s, adding that “Gascoigne was the first that measured the Diameters of the Planets, &c. by a Micrometer,” and “he was the first that applied Telescopick Sights to Astronomical Instruments.” Voula Saridakis Selected References Brooks, Randall C. (1991). “The Development of Micrometers in the Seventeenth, Eighteenth and Nineteenth Centuries.” Journal for the History of Astronomy 22: 127–173. Chapman, Allan (1982). Three North Country Astronomers. Manchester: Neil Richardson. ——— (1990). Dividing the Circle: The Development of Critical Angular Measurement in Astronomy, 1500–1850. London: Ellis Horwood. Derham, William (1717). “Extracts from Mr. Gascoigne’s and Mr. Crabtrie’s Letters, proving Mr. Gascoigne to have been the Inventor of the Telescopick Sights of Mathematical Instruments, and not the French.” Philosophical Transactions 30: 603–610. Gaythorpe, S. B. (1929). “On a Galilean Telescope Made about 1640 by William Gascoigne, Inventor of the Filar Micrometer.” Journal of the British Astronomical Association 39: 238–241. McKeon, Robert M. (1971). “Les débuts de l’astronomie de précision- I. Histoire de la réalisation du micromètre astronomique.” Physis 13: 225–288. ——— (1972). “Les débuts de l’astronomie de précision - II. Histoire de l’acquisition des instruments d’astronomie et de géodésie munis d’appareils de visée optique.” Physis 14: 221–242. Rigaud, Stephen Jordan (ed.) (1841). Correspondence of Scientific Men of the Seventeenth Century. Vol. 1. ( Reprint, Hildesheim, Germany: Georg Olms, 1965.) Saridakis, Voula (2001). “Converging Elements in the Development of Late Seventeenth-Century Disciplinary Astronomy: Instrumentation, Education, Networks, and the Hevelius-Hooke Controversy.” Ph.D. diss., Virginia Polytechnic Institute and State University. Thoren, Victor E. (1972). “Gascoigne, William.” In Dictionary of Scientific Biography, edited by Charles Coulston Gillispie. Vol. 5, pp. 278–279. New York: Charles Scribner’s Sons. 407 408 G Gasparis, Annibale de Gasparis, Annibale de Born Died Bugnara, (Abruzzo, Italy), 9 November 1819 Naples, Italy, 21 March 1892 Annibale de Gasparis was a professor, observatory director, and specialist on minor planets, of which he discovered seven. He was the son of Angelo de Gasparis and Eleonora Angelantoni. In 1838 he moved to Naples in order to attend the courses in the Scuola di ponti e strade (School of bridges and roads), an engineering university, but in 1840 he became alunno (student) at the observatory of Naples. In 1846 the University of Naples honored de Gasparis with a degree “ad honorem” for his studies on the orbit of the minor planet (4) Vesta, which had been discovered by Heinrich Olbers in 1807. In 1848, de Gasparis married Giuseppina Russo, and they had nine sons, of whom three died in infancy. On 19 April 1849, de Gasparis discovered a new asteroid, one that he named Igea Borbonica (Borbonica in honour of Ferdinand II of the Borbones, then king of the two Sicilies). The grateful king awarded de Gasparis a life annuity. When the Borbones were dismissed, the asteroid’s name–and the life annuity–disappeared. De Gasparis continued his research on minor planets and discovered (11) Parthenope and (13) Egeria (1850), (15) Eunomia (1851), (16) Psyche (1852), (24) Themis (1853), (63) Ausonia (1861), and (83) Beatrix (1865). For these discoveries the Royal Astronomical Society made de Gasparis a member (in 1851) and awarded him a Gold Medal. In 1858 he became Professor of Astronomy in the University of Naples, and in 1864 he became director of the astronomical observatory of Naples. De Gasparis published about 200 scientific papers on mathematics, celestial mechanics, astronomy (especially on Kepler’s problem), and meteorology. In 1861 he was appointed senator of the Kingdom of Italy. He was member of the Société Philomatique (Paris); Royal Astronomical Society (London); and the Academies of Naples, Modena, Turin, and many others. On his death de Gasparis was widely mourned for his humane qualities as well as his research. Ennio Badolati Selected References Amodeo, Federico (1924). Vita matematica napoletana. Naples: Tipografia dell’Accademia Pontaniana. Cianci, C. (ed.) (1955). Annibale de Gasparis. Rome: Tipografia Nardini. Mancini, C. (1892). Obituary. Rend. Acc. sc. of Naples, ser. 2, 6: 65. Gassendi, Pierre Born Died Champtercier, (Alpes-de-Haute-Provence), France, 22 January 1592 Paris, France, 24 October 1655 Among the most celebrated philosophers of his century, Pierre Gassendi was one of three surviving children born to Antoine Gassend and Françoise Fabry, a humble farm family from the south of France. Educated initially by his uncle Thomas Fabry, Gassendi later studied at Digne (1599–1606) and Aix (with Philibert Fesaye, 1609–1612) before being appointed canon and finally Principal of the Collège of Digne in 1612. After receiving his doctorat in theology from Avignon in 1614 (under Professor Raphaelis), Gassendi was ordained priest and accepted the chair in philosophy at Aix, which he held from 1616 to1623. Here Gassendi lodged with Joseph Gaultier, then the most noted astronomer in France. During this time Gassendi also visited Paris (April 1615) where he first met Nicolas-Claude Fabri de Peiresc, his later patron. Gassendi traveled widely in his middle years, living in Provence (1625–1628) and Grenoble (1628–1634), visiting Paris and the Netherlands (1628–1630), and later dividing his time between Provence (1634–1641) and Paris (1641–1648). Gassendi’s final years were spent in Provence (till 1653) and Paris, where he revised his major works, among them the Animadversiones (later called Syntagma, 1658). Gassendi is best remembered as a Mechanical Philosopher. As the traditional counterpoint to René Descartes, Gassendi was an Epicurean atomist and mitigated skeptic who opposed the corpuscularism and dogmatism of the Cartesians. Stridently antiAristotelian, Gassendi sought to rehabilitate the ancient atomism of Epicurus but also drew on the skeptical philosophies of Sextus Empiricus, Michel de Montaigne, and Pierre Charron. As an empiricist, Gassendi sought a “science of appearances” based on sense experience and probability, thus opposing Descartes’ rationalism and innate ideas. Arguing that the inner nature of things could not be known, Gassendi insisted that appearances were beyond doubt and sufficient for establishing the New Science. Descartes retorted that this was the philosophy of a “monkey or parrot, not men.” Gassendi’s principal scientific interest was astronomy. A skilled observer, Gassendi was a mainstay of the French école provençale and a founding member of the école parisienne (or Paris Circle). An early Gassendi, Pierre but prudent Copernican, Gassendi was an active and able observer eager to coordinate and compare telescopic observations. Over the course of his career he owned a number of instruments, among them five Galilean telescopes of good quality, as well as several quadrants (5-, 2-, and 1.5-ft radii). One of his first telescopes came from Galileo Galilei, though his best lenses were made by Johannes Hevel (Hevelius) (1648, 4.5 ft.) and Eustachio Divini (1653). When visiting Aix, he also had access to Peiresc’s five telescopes. Like others of his generation, Gassendi used mainly Galilean not Keplerian telescopes, which did not come into wide use until after his death. Gassendi corresponded with astronomers all across Europe. During his second trip to Paris (1628–1632) he visited the famous Cabinet Dupuy where he made lifelong friendships with Marin Mersenne, François Luillier (a patron with whom he lived), Gabriel Naudé, Claude Mydorge, and the young astronomer, Ismaël Boulliau. During this time, he also met Hevelius, who was then visiting Paris with his mentor, the astronomer Peter Krüger. Thereafter, Gassendi actively contributed astronomical observations to the correspondence networks of Peiresc, Mersenne, Boulliau, and Hevelius, an overlapping network that included Galilei, Christian Severin (Longomontanus), Philip Lansbergen, Gottfried Wendelin, Maarten Van den Hove (Hortensius), Wilhelm Schickard, Christopher Scheiner, and dozens of other scholars, including Thomas Hobbes, Gui Patin, Willibrord Snel, and Samuel de Sorbière. Significantly, Gassendi was among the first in France to maintain a journal of astronomical observations (1618–1655), though many of his manuscripts, letters, and observations remain unpublished. Gassendi’s interest in astronomy was linked from the outset to the “optical part of astronomy.” He recognized that practical astronomy was based on observation, and as a skeptical philosopher, his theoretical oncerns ran deep. If all knowledge is based on observation— and all appearances are true—then the “play of light” was serious business. These interests are evident throughout Gassendi’s career, from his early years (Parhelia sive soles, 1630), his middle years (De Apparente, 1642), and in his posthumous publications (Syntagma, 1658). Halos, coronas, rainbows, and the “Moon illusion” were crucial tests for establishing an empiricist epistemology. That meant rethinking the foundations of astronomy and optics—disciplines where light and vision converged. Gassendi’s international reputation was tied to the transit of Mercury (7 November 1631), a “rare and beautiful phenomenon” with important theoretical implications. In his Admonitio ad astronomos (1629) Johannes Kepler had advised astronomers to observe the transit in order to confirm Mercury’s elongated elliptical orbit and unequal motions. Further, transit observations would be useful for establishing the dimensions of the Solar System, perhaps even the Copernican theory itself. But sky conditions throughout Europe were poor, and Gassendi was all but alone in tracing Mercury’s path. Gassendi’s method was based on the principle of a camera obscura. Projecting the image of the Sun through a telescope on to a screen, Gassendi marked times of ingress and egress, while an assistant noted the solar altitude. Some of the results were unexpected. In his Mercurius in sole visus (Paris, 1632) Gassendi admitted that he almost mistook Mercury for a sunspot, due to its unexpectedly small diameter (some 20″). Only three other astronomers observed the transit, Johann Cysat, J. -R. Quietan, and an anonymous Jesuit in Ingolstadt, but their observations were imprecise and of little use. Gassendi’s observations showed that the tables of Severin erred by over 7°, the Prutenic by 5°, and the Rudolphine by 14 min. G Gassendi’s interest in astronomy was never more focused than in his collaborations with Peiresc, particularly during the years 1631– 1637. Among the publications that resulted from their research, largely on the “optical part of astronomy,” was Gassendi’s De Apparente magnitudine (Paris, 1642). Here Gassendi defended his atomist views in optics and vision against a cross section of four carefully selected combatants: against the Aristotelian views of two friends, F. Liceti and G. Naudé; against the polite but vague views of Jean Chapelain; and finally, against his friend Boulliau, who defended Kepler’s punctiform analysis. For his part, Gassendi proposed a “materialist” theory of light, pointedly combating the “mathematicians”—those content to describe light as geometrical rays rather than to explain light, as Gassendi proposed, as physical body. Similar themes underlie Gassendi’s Solstitialis Altitudo Massiliensis (1636). Peiresc’s death in 1637 marked a turning point in Gassendi’s career. Suffering from depression, Gassendi recovered slowly, thereafter devoting several precious years to writing his friend’s biography, Vita illustris (Paris, 1641), a classic of the genre. During this difficult interlude, Gassendi obtained another patron, L. -E. de Valois, the new Governor of Provence (1638). Among his closest friends, Valois was Gassendi’s most prolific correspondent (some 350 letters). But Valois was less interested in science than Gassendi’s earlier patrons; his letters were often short and officious, and, significantly, Valois placed greater demands on Gassendi’s time. Upset by the loss of Peiresc—who died having published nothing— Gassendi’s sense of urgency increased with the onset of his own illness, a lung ailment (1638) that finally took his life. Unsettled, he departed for Paris (1641–1648). But conflict, both public and private, continued. Antoine Agarrat, Gassendi’s longtime assistant in astronomy, soon joined forces with Jean-Baptiste Morin in their ongoing pamphlet war, and charges of heresy soon followed. Gassendi’s years in Paris (1641–1648) were nevertheless highly productive. In 1641, Mersenne asked him to supply a critique of Descartes’ Meditations, and there, in the Fifth set of Objections, Gassendi fleshed out differences between Cartesianism and Gassendism. In addition, Gassendi continued to publish works on astronomy, including Novem stellae circa Jovem visae (Paris, 1643) and several works on motion, providing one of the first modern statements of the principle of inertia. Now famous throughout Europe, Gassendi was appointed Professor of mathematics at the Collège Royale, but he was soon forced to discontinue his lectures due to poor health. In 1647 Gassendi published his Institutio astronomica, a “modern” textbook rivaled only by Kepler’s Epitome and Descartes’ Principles. Here Gassendi provided an introduction to astronomy and a comparison of the Tychonic and Copernican models (Book III). Publicly, Gassendi viewed the Tychonic model as a cautious compromise. Privately, his commitment to Suncentered cosmology was discreet but unswerving. Following Mersenne’s death in 1648, Gassendi again departed Paris for the healthier climate of Provence. Distracted by controversy and discomforted with pain, Gassendi wisely enlisted friends to defend his views (and orthodoxy) against Morin, thus freeing himself to focus on his writing. But as the controversy escalated, Morin predicted Gassendi would die the following year. The prophecy proved false. The following February, accompanied by Luillier and François Bernier, Gassendi climbed the highest peak of Puy-deDome (1650). The exercise confirmed Pascal’s barometric experiment and gave living proof against judicial astrology. 409 410 G Gauss, Carl Friedrich Gassendi’s last years were spent in Paris. Departing Provence in April 1653, Gassendi took residence on the second floor of the Hôtel de Montmor. After the decease of his third patron, Valois, Gassendi enjoyed the support of “Montmor the Rich.” Together they established the famous Académie Montmor. During this time Gassendi published several works, among them his biography of Tycho Brahe (1654) and a treatise on the eclipse of August 1654. Robert Alan Hatch Selected References Centre international de synthèse (1955). Pierre Gassendi, sa vie et son oeuvre. Paris: A. Mitchel. Humbert, Pierre (1936). L’oeuvre astronomique de Gassendi. Actualitiés scientifiques et industrielles, no. 378; Exposés d’histoire et philosophie des sciences, edited by Abel Rey, no. 6. Paris: Hermann et cie. Quadricentenaire de la naissance de Pierre Gassendi, 1592–1992: Actes du Colloque international Pierre Gassendi, Digne-les-Bains, 18–21 mai 1992. 2 Vols. Digne-les-Bains: Societe scientifique et litteraire des Alpes de Haute Provence, 1994. Gauss, Carl Friedrich Born Died Braunschweig, (Niedersachsen, Germany), 30 April 1777 Göttingen, (Germany), 23 February 1855 Carl Gauss is best known for his formulation of the statistical method of least squares. In astronomy, his simplification of the process by which orbits are determined from observations made possible the postconjunction recovery of the first asteroid (1802). The cgs unit of magnetic field intensity, still generally used by astronomers, is named for him. Gauss was the son of Gebhard Dietrich Gauss (1744–1808) and Dorothea Benze (1743–1839). After attending the gymnasium and subsequently the Collegium Carolinum at Braunschweig, he studied philology and mathematics at Göttingen (1795–1798) and received his Ph.D. in 1799 from the University of Helmstedt. The stipend from the Duke of Braunschweig (since 1792) allowed him to live and work at Braunschweig as a private mathematician. The fame resulting from Gauss’s successful computation of the orbit of (1) Ceres laid the ground for his astronomical career. Having declined a call to Saint Petersburg in 1802, he got involved with plans to establish an observatory at Braunschweig. In parallel to his theoretical work, Gauss had started on practical observing quite early, which he continued until 1851. In 1803, he spent several months at the Seeberg Observatory at Gotha to improve his practical proficiency and to enlist János von Zach’s help as an advisor for the Braunschweig project. Political developments and finally the death of his sponsor, Duke Carl Wilhelm Ferdinand (from fatal injuries received in the Battle of Jena in 1806), put an end to this endeavor. In 1805, Gauss married Johanna Osthoff (1780–1809); in 1810 he married Minna Waldeck (1788–1831). He was the father of six children. Gauss was appointed University Professor and Director of the observatory at Göttingen in 1807. The layout of the new observatory there, finished in 1816, was essentially modeled after GothaSeeberg. His earlier experience with astronomical geodesy led to the additional responsibility of director of triangulation for the Kingdom of Hannover (1818–1847). Already a Fellow of the Royal Society (London), Gauss was one of the first foreign associates elected by the Astronomical Society of London established in 1820. A member of the academies at Göttingen, Saint Petersburg, Berlin, and Paris, he received many other international honors including knighthood in the Danish Dannebrog Order. The mathematical method developed during Gauss’s work on the Ceres recovery problem led to his famous Theoria Motus (Theory of the motion of the heavenly bodies moving about the Sun in conic sections, 1809). It remained a basic tool for theoretical astronomy for one and a half centuries. His continuing work on orbit determination, especially on problems encountered with the second known minor planet, (2) Pallas, led to important results in the field of perturbation theory. The General disquisitions about an infinite series (Disquisitiones generales circa seriem infinitam, 1813), containing the mathematical theory of the hypergeometric series and a general investigation of convergence criteria, was a result of these activities. There followed a tract on numerical quadrature (Methodus nova integralium valores per approximationem inveniendi, 1814) and, in 1818, the “Determination of the attraction which a planet exerts on a point of unspecific position . . .” (Determinatio attractionis, quam in punctum quodvis positionis datae exerceret planeta . . . ). Throughout the first two decades of the 19th century, Gauss’s authoritative computations of the orbits of all newly discovered solar-system bodies were of particular importance. Later, other computers (such as Freidrich Bessel and Johann Encke) took over some of these chores. Geddes, Murray Gauss’s papers as well as his personal library are held at the Staatsund Universitaetsbibliothek at Goettingen. Wolfgang Kokott Selected References Bühler, Walter K. (1981). Gauss: A Biographical Study. Berlin: Springer-Verlag. Brendel, M. (1929). Über die astronomischen Arbeiten von Gauss. Vol. 11 of Carl Friedrich Gauss Werke. Berlin: J. Springer, pt. 2, sec. 3, pp. 3– 254. (Still the standard account of Gauss’s contributions to astronomy. This official edition of Gauss’s Works was published in 12 volumes by the Göttingen Academy [Koenigliche Gesellschaft der Wissenschaften zu Goettingen] Leipzig, 1863–1933.) Dunnington. G.W. (1955). Carl Friedrich Gauss, Titan of Science. New York: Exposition Press. Gauss, C. (1809). Theoria Motus corporum coelestium in sectionibus conicis solem ambientium. Hamburg. (Gauss’s most influential and enduring contribution to theoretical astronomy. Publication of this work, originally written in German, was delayed at the behest of the publisher who wanted a Latin text suitable for an international market. The Theory of the Motion was later retranslated into German and translated into several other languages. The first English translation [by Charles Henry Davis] was published in 1857 at Boston; it was reprinted in 1963 [Dover, New York]). Gauss, H. W. (tr.) (1966). Gauss: A Memorial. Colorado Springs. (A translation of the 1856 summary of his life and work by Sartorius von Walthershausen.) Trotter, Hale F. (1957). Gauss’s Work (1804–1826) on the Theory of Least Squares. Princeton. (A good summary of Gauss’s theory of least squares, originally published in the Theoria Motus as well as several other tracts, is found in this English translation from the French.) Watson, James C. (1868). Theoretical Astronomy relating to the motions of the heavenly bodies. Philadelphia: J. B. Lippincott and Co. (Independent of the original text, the Gaussian Method [rendered more suitable for a wider audience by later authors, e. g. Encke] was the standard tool presented in the textbook literature of the 19th and 20th centuries—exemplified in this text.) Gautier, Jean-Alfred Born Died Geneva, Switzerland, 19 July 1793 Geneva, Switzerland, 30 November 1881 Jean-Alfred Gautier was a professor of astronomy and mathematics, observatory director, and a prolific author of astronomical articles. The son of François Gautier and Marie De Tournes, he received his basic education in Geneva, then studied science and humanities at the University of Paris, earning his Licentiate in Science in 1812 and in Letters the following year. Gautier’s first and only major work, which was in effect a doctoral dissertation, was a historical essay on the problem of three bodies published in Paris in 1817. He then spent a year in England where he established lasting friendships with many scientific notables, including John Herschel. Gautier returned to Switzerland in 1819 to serve as Professor of Astronomy at the Geneva Academy. He strove to improve the Geneva Observatory and eventually secured funding for a new one, which was completed in 1830. Unfortunately, he began to have problems with his eyes at this time, to the extent that he could not carry out observations himself; so with characteristic modesty, he gave up the chair of astronomy and directorship of the observatory to one of his former pupils, Emile Plantamour. G Gautier was married twice but had no children. Two nephews, Emile and Raoul, continued to pursue interests similar to those of their uncle. Gautier was one of the first associate members of the Royal Astronomical Society and the earliest foreign member of the Cambridge Philosophical Society. Apart from Edward Sabine and Johann Wolf, Gautier had independently recognized, in 1852, that periodic variations in terrestrial magnetism correlate with the sunspot cycle. The majority of his 200 papers and reviews were commentaries on others’ work in almost every field of astronomy, and appeared in the publications of the Société de physique et d’histoire naturelle de Genève: Bibliothèque universelle des Sciences or Archives des Sciences Physiques et Naturelles. They are conveniently listed in the cumulative index of the latter journal for the period 1846–1878. Gautier’s correspondence is in the Bibliothèque publique et universitaire in Geneva. Peter Broughton Selected Reference Gautier, R. and G. Tiercy (1930). L’ Observatoire de Geneva. Geneva-Kundig. “Jean Alfred Gautier.” Monthly Notices of the Royal Astronomical Society 42 (1882): 150–152. Geddes, Murray Born Died Glasgow, Scotland, 1909 Glasgow, Scotland, 23 July 1944 Murray Geddes, along with his family, immigrated to New Zealand at an early age. Later, he obtained an MS in physics and took up a career in teaching. His avocational studies of the Aurora Australis in collaboration with Norwegian physicist Carl Störmer showed that southern auroral displays were far more common than had previously been understood and at times exceeded the Aurora Borealis. Geddes photographed the aurora to determine the auroral height, study auroral forms, and strengthen the correlation of auroral activity with sunspots. Recognizing from studies of Antarctic exploration historical records that New Zealand provided the only inhabitable landmass from which auroral studies could be carried out consistently, Geddes organized a corps of 700 auroral observers to assist in these studies. He also made useful contributions to the study of zodiacal light. He was an assiduous meteor observer and discovered comet C/1932 M2, for which Geddes received both the Donohoe Medal of the Astronomical Society of the Pacific and a Donavan Prize and Medal from Australia. Geddes had been appointed director of the Carter Observatory shortly before being called to active duty as a naval reservist. He died while serving in the New Zealand Navy in the North Sea during World War II. Thomas R. Williams Selected References Anon. (1944). “Lieutenant Commander M. Geddes, R.N.Z.N.V.R.” Southern Stars 10: 64–65. Thomsen, I. L. (1945). “Murray Geddes.” Monthly Notices of the Royal Astronomical Society 105: 88–89. 411 412 G Geminus Geminus Born Died possibly Rhodes, (Greece), circa 10 BCE circa 60 Geminus concerned himself largely with dividing mathematics (which then included astronomy) into several divisions and subdivisions. The belief that Geminus was from Rhodes is largely based on his astronomical works, which use mountains on Rhodes as reference points. However, Rhodes was the center of astronomical research at the time; it is conceivable that Geminus simply referenced these points from prior knowledge, and it is thus distinctly possible that he was not a native of the island. He was either a direct pupil or a later follower of Posidonius and is considered a Stoic philosopher. Geminus is mentioned in works by Simplicius and is accused of simply rewriting Posidonius. There is enough of Geminus’ original work surviving for this accusation to be untrue. Geminus’ primary contribution to astronomy included some philosophical musings. He said that astronomy dealt with facts and not causes, and proceeds from hypotheses. He gave several examples of such reasoning in relation to astronomy in his works, which included a commentary on Posidonius’ Meteorologica and a work that was clearly his own, Isagoge (Introduction to astronomy). In it he made some interesting contributions to astronomy. In particular, he introduced the concept of mean motion, and represented the motion of the Moon in longitude by an arithmetical function. In addition, the work mentions the zodiac, the solar year, the irregularity of the Sun’s motion, and the motions of the planets. In dealing with the zodiac, Geminus discussed the 12 signs, the constellations, and the axis of the Universe. He spoke of eclipses, the lunar phases, and the calendar. Ian T. Durham Selected References Heath, Sir Thomas L. A Manual of Greek Mathematics. Oxford: Clarendon Press, 1931. New York: Dover, 1963. Neugebauer, Otto (1975). A History of Ancient Mathematical Astronomy. 3 pts. New York: Springer-Verlag. Smith, David Eugene (1923). History of Mathematics. Vol. 1. Boston: Ginn and Co. (Reprint, New York: Dover, 1958.) Swetz, Frank J. (1994). From Five Fingers to Infinity. Chicago: Open Court. Worthern, T. D. (1991). “Inclusive Counting as the Source of the Misunderstanding about the Luni-Solar calendar of Geminus prior to the Octaeteris.” Bulletin of the American Astronomical Society 23: 898. (Paper abstract.) Gemma, Cornelius Born Died Louvain, (Belgium), 28 February 1535 Louvain, (Belgium), 13 October 1578 or 12 October 1579 Cornelius Gemma was the son of Gemma Frisius and Barbara, and followed in his father’s footsteps. His first teacher was M. Bernhardus, the supervisor of a school in Mechelen, where Gemma stayed at least during the years 1546–1547. Around 1549, at the age of 14, he matriculated at the Faculty of Arts at Louvain University, and 3 years later, on 26 March 1552, he was promoted. By 1561, Gemma called himself “medicus” in the title of his Ephemerides, which he published from 1560 onward for 5 consecutive years. Although Gemma was nominated regius professor at the university in 1569, as the successor to Nicolas van Biesen (Biesius), he was only promoted to doctor of medicine on 23 May 1570. On 9 November 1574, he was nominated ordinary professor (professor ordinarius) and succeeded Charles Goossens (Goswinus) of Bruges. Around 1561, Gemma married the daughter of Judocus (Josse) Van der Hoeven. They had four children: a boy and a girl died of the plague in the same year as their mother. Their son Philippe was born around 1562 and became bachelor of medicine in 1583. Raphaël was baptized in November 1566 and died in January 1623. Gemma was in contact with notable people of his time: Antoine Mizauld, Jean Charpentier (Carpentarius), Tadeá Hájek z Hájku, and Benedictus Arias Montanus, with whom he was very close. Gemma was known as a physician, a professor, an astronomer, a philosopher, a poet, and an orator. His writings consist of an astronomical and a philosophical–medical part. In 1556, Gemma completed his father’s De Astrolabo catholico by adding a preface, a dedication to the Spanish king Philip II, a carmen panegyricum on his father’s death, and 18 chapters. His Ephemerides meteorologicae were published during 5 consecutive years (1560–1564); they mostly include meteorological predictions, but they lack the fundamental basis of daily observations. Gemma’s desire to investigate the nature of the phenomena made him revert to the common theories of antiquity. However, after having linked the effects and their causes and having discovered the discrepancies between the data of the Alphonsine tables and the positions of the stars, he expressed his clear preference for the Copernican theory and the Prutenicae tabulae over the Ptolemaic and the Alphonsine tables. Gemma took a major interest in two celestial phenomena that characterized the second half of the 16th century: the new star of 1572 and the comet of 1577. In his writings on both celestial phenomena, he attributed great importance to astrology, and he gave a detailed account of its role in medicine and its influence on human affairs. Gemma’s De Naturae divinis characterismis (1575) was largely inspired by and devoted to the new star of 1572. He supposed that the star emerged from the invisible depths of space, to which it would eventually return. This amounted to a denial of the principle of circular motion of the heavenly bodies, and likewise to a considerable increase of the volume of the world, exceeding the sphere of the fixed celestial bodies. Regarding the 1577 comet, Gemma believed that the comet was not located at the border of the Earth’s atmosphere (as it should be following the Aristotelian doctrine), but in Mercury’s heaven (De prodigiosa specie naturaque cometae, 1578). This meant that neither his opinions concerning the new star nor those concerning the comet were in agreement with traditional cosmology, although he used elements of this system (e. g., he discussed “Mercury’s heaven” from a geocentric viewpoint). Gemma also wrote a report on the reform of the Julian calendar. In 1578, Pope Gregorius XIII sent a book by Aloïs Lilius, on the reform of the calendar, to the leaders of the University of Louvain with the request that it be studied by the mathematicians of the Gentil de la Galaisière, Guillaume-Joseph-Hyacinthe Jean-Baptiste Le Alma mater. Pierre Beausard and Cornelius Gemma were charged with this task. Although they died of the plague before they were able to present their report, the report carrying the signature of both scholars has been found and was transferred to Rome. Gemma’s philosophical–medical works contain his De arte cyclognomica tomi III and his De naturae divinis characterismis … libri II. His De arte cyclognomica (1569) shows his clear preference for the heliocentric theory, because it corresponded better with the observations. However, Gemma did not explicitly reject the geocentric theory because, in his opinion, it corresponded better with the Bible. Astrological concerns are clearly present in Gemma’s writings. He favored christianized Neoplatonism and had close contacts with cabalists such as Guillaume Postel (1505–1581) and Guy le Fèvre de la Boderie (1541–1598). According to Gemma’s view, astrology was within the purview of cosmological semiotics; this is explained in detail in his De naturae divinis characterismis (1575). An earlier version of his theory can be found in his De Arte cyclognomica. Gemma considered the world to be a living body, all parts of which are connected to each other and mutually influence each other. It was impossible to see the observation of the heavens as unrelated to the observation of the Earth’s nature and human society. All the phenomena occurring in one of these three “worlds” were connected with phenomena occurring in the other worlds, and thus became “signs” that required investigation and deciphering by the “cosmocritical art.” Fernand Hallyn and Cindy Lammens Selected References Hallyn, Fernand (1998). “La cosmologie de Gemma Frisius à Wendelen.” In Histoire des sciences en Belgique de l’Antiquité à1815, edited by Robert Halleux, pp. 145–168. Brussels: Crédit Communal. ——— (2002). “Un poème sur le système copernicien: Cornelius Gemma et sa ‘Cosmocritique. ’” Les cahiers de l’humanisme 2. Ortroy, Fernand van (1920). Bio-bibliographie de Gemma Frisius, fondateur de l’école de géographie, de son fils Corneille et de ses neveux les Arsenius. Brussels: Lamertin. Gentil de la Galaisière, GuillaumeJoseph-Hyacinthe Jean-Baptiste Le Born Died Coutance, (Manche), France, 11 September 1725 France, 22 October 1792 G. J. Le Gentil was one of the astronomers to advocate observations of the Venus transit of 1761. As a young man, Le Gentil considered priesthood; however, he broke from his studies one day to hear a lecture by Joseph Delisle. This piqued his curiosity about astronomy so much that he soon became a fixture at the Paris Observatory, working under the tutelage of Jacques Cassini. By 1753, with his religious studies behind him, Le Gentil was recognized as a professional in astronomy. Especially notable were his writings on the difficulty of determining the initial contact of Mercury as it transited the Sun. This, he reasoned, made it nearly impossible to use G the transit as an effective tool to determine the distance between the Sun and the Earth–the Astronomical Unit–though Edmond Halley had believed it possible some decades earlier. Halley had also pointed out that a transit of Venus would provide a better opportunity. Le Gentil believed that Halley’s calculations were based on tables that were not sufficiently accurate to determine the exact times and positions for observation. His work on this problem led him to favor the values produced by Cassini. This placed him in favorable light when the French government began to consider sending its astronomers throughout the world to observe the 1761 transit. For his destination, Le Gentil chose Pondicherry, an area of India controlled at that time by France. He departed for India on 26 March 1760; 3 months later, arriving on the island of Mauritius, he learned that the Indian Ocean was full of British warships, and that Pondicherry was locked in a war with British land forces. Undeterred, Le Gentil talked his way onto a supply ship going there, only to learn, off the Indian coast, that the town had been captured several months earlier. The ship’s captain then returned to Mauritius. Heavy seas and far-from-perfect skies gave him terrible views of the event, and his calculations were worthless. Despite his disappointment, Le Gentil wrote to the Academy of Sciences requesting permission to explore the islands in the Indian Ocean. Thus began a program of natural history, navigation, and geography, mapping the coasts of the islands, doing anything he felt would contribute to the scientific knowledge of the area. When the transit of 1769 was approaching, Le Gentil decided to stay in the area to make up for his previous failure. His calculations suggested that the best observational site was in Manila. In August 1766, after a grueling 3-month voyage, he arrived in Manila, only to learn that the governor wanted no visitors, especially one wanting to establish an astronomical observatory. Le Gentil then sailed for Pondicherry, by now reclaimed by France. He was given permission to set up an observatory in what had been a gunpowder warehouse during the war. He woke on transit day to find gathering clouds, and it remained overcast throughout the day. Le Gentil was devastated. He waited for the next ship out in October 1769, but contracted a life-threatening fever and missed his ship. Still very ill, he took the ship in March 1770, selecting a Europe-bound ship at Mauritius, which had to return to port after nearly sinking in a storm. Le Gentil finally obtained passage on a Spanish warship, reached Spain, and traveled by land to France, more than 11 years after leaving. On arriving home, Le Gentil discovered he had been declared dead, his chair at the academy was occupied by another member, and his heirs had divided up his estate. Eventually, he retrieved some of his property, his place in the academy, and married a wealthy heiress, from whom he had a daughter. His memoirs of his adventures were a popular and financial success. Francine Jackson Selected References Delambre, J. B. J. (1827). Histoire de l’astronomie au dix-huitième siècle. Paris: Bachelier. Maor, Eli (2000). June 8, 2004: Venus in Transit. Princeton, New Jersey: Princeton University Press, esp. pp. 85–86, 105–107. 413 414 G Gerard of Cremona Proctor, Richard A. (1875). Transits of Venus: A Popular Account of Past and Coming Transits, from the First Observed by Horrocks A.D. 1639 to the Transit of A.D. 2012. New York, R. Worthington. Gerardus Mercator > Kremer, Gerhard Gerard of Cremona Born Died Cremona, (Italy), circa 1114 Toledo, (Spain), or Cremona, (Italy), 1187 Gerard’s principal contributions were his translations of Arabic texts on astronomy and other sciences. Gerard received his basic education in his native town of Cremona. Then, interest in deeper learning, especially the work of Ptolemy, led him to (before 1144) Toledo, where he studied Arabic and devoted himself to translating into Latin some of the Arabic translations of Greek treatises, Arabic commentaries on them, and original Arabic works dealing with astronomy, mathematics, philosophy, medicine, and other sciences. Gerard is said to have translated 76 works, including the Almagest (1175) by Ptolemy, the Toledo Tables ascribed to al-Zarqāli, Physics by Aristotle, and different works by Abū Ibn al-Haytham, Ibn Sina, Jabir ibn Aflah, al-Farghani, al-Kindi, Masha’alla, and others. Some traditional ascriptions that he is credited with are wrong (e. g., the Theorica planetarum ascribed also to Gerard Sabionetta). However, like other translators (e. g., Adelard of Bath, Hermannus of Carinthia, Johannes Hispalensis, Plato of Tivoli, Robert of Chester), he mediated the knowledge of the achievements of Greek and Arabic science to Medieval Europe—several of his translations were printed in the 16th century—and he thus stimulated its subsequent development. Gerard was buried at Saint Lucy Church in Cremona. Alena Hadravová and Petr Hadrava Alternate name Gerardus Cremonensis Selected References Carmody, Francis J. (1956). Arabic Astronomical and Astrological Sciences in Latin Translation: A Critical Bibliography. Berkeley: University of California Press. Grant, Edward (1994). Planets, Stars, and Orbs: The Medieval Cosmos, 1200–1687. Cambridge: Cambridge University Press. McCluskey, Stephen C. (1998). Astronomies and Cultures in Early Medieval Europe. Cambridge: Cambridge University Press. Pedersen, Olaf (1981). “The Origins of the ‘Theorica Planetarum.’” Journal for the History of Astronomy 12: 113–123. ______ (1993). Early Physics and Astronomy. Rev. ed. Cambridge: Cambridge University Press. Gerardus Cremonensis > Gerard of Cremona Gerasimovich [Gerasimovič], Boris Petrovich Born Died Poltavian Kremenchug, (Ukraine), 31 March 1889 Leningrad (Saint Petersburg, Russia), 30 November 1937 Boris Gerasimovich, Soviet astrophysicist, was active in a broad range of research areas but became a tragic victim of the 1936– 1937 purges that were a horrific reality in the USSR of the period. Pulkovo Observatory, of which he was director, suffered more than any other scientific institution, largely due to local circumstances. Gerasimovich completed his university education at Kharkov University in 1914, where he had studied under Aristarkh Belopolsky and Sergei Konstantinovich Kostinsky. He held the position of Privatdozent (lecturer) from 1917 to 1922, and was appointed professor at Kharkov University from 1922 to 1931, during which time he was the most senior astronomer at the university observatory. Between 1926 and 1929, Gerasimovich spent a fruitful period in the United States, conducting research, along with the staff of the Harvard College Observatory, and visiting his colleague Otto Struve at Yerkes Observatory. In 1931, Gerasimovich returned to Pulkovo Observatory, where he became director in 1933. Gerasimovich’s scientific work, represented by about 170 publications in several languages, addressed many problems in astrophysics and astronomy. He recognized early the crucial importance of interstellar absorption in the calibration of the Cepheid period–luminosity relation, and gave a quantitative explanation of observed variations in Be stars based on a hypothesis of rotation coupled with an expanding shell. He was among the first to conduct detailed studies of planetary nebulae, noting that their different forms were the result of interactions between the gravitational pull of the central star and its outward light pressure. His observations, later confirmed, indicated that the masses of these central stars were not large. In 1927, with Willem Luyten, Gerasimovich determined the distance from the Sun to selected galactic (open) clusters. He likewise developed and improved the theory of ionization for stellar atmospheres and interstellar gas by suggesting modifications to the Saha formulae of thermodynamic equilibrium. In 1929, with Otto Struve, Gerasimovich observed the physical conditions of interstellar gas and absorption lines created by this gas. In that same year, with Donald Menzel (with whom he shared the A. Cressy–Morrison Award of the New York Academy of Sciences), he used statistical mechanics to model the sources of stellar energy. He, along with Cecilia Payne-Goposchkin, contributed to an understanding of the temperatures of F stars. Gerasimovich was one of the first astronomers to consider the astrophysical significance of cosmic rays. He studied several types of Gersonides: Levi ben Gerson variable stars extensively, by observing their periods and the forms of their light curves. Gerasimovich took part in several solar eclipse expeditions, and was president of a special commission of the USSR Academy of Sciences to prepare unified expeditions to observe the total solar eclipse of 19 June 1936. He wrote the monograph, Solar Physics, published in Ukrainian (1933) and in Russian (1935). However, the later Stalinist purges in 1936–1937 devastated Russian astronomy and destroyed Pulkovo as an active research institute. Following a stormy campaign against him, both by colleagues who found him difficult and by influential amateurs with their own political agendas, Gerasimovich was accused of crimes related to noncompliance with Marxist–Leninist ideology, and of philosophical errors, including being under foreign influence because he had published papers in non-Soviet journals. While the vituperative campaign was under way, he remained as director of Pulkovo and offered twice to resign. But his credibility was tarnished by the Voronov scandal and by the coerced confession of Boris Numerov, who tragically implicated nearly the entire staff of the observatory. The effect on Russian astronomy was to be felt for decades. The Academy of Sciences commissions appointed to investigate the problems at Pulkovo included the Astronomy Council that met in October 1937 to condemn the arrested scientists. They may have wished to shield Gerasimovich but his principal accuser, Vartan T. Ter-Organezov, was adamant and so effectively criticized the Astronomical Council that it was dissolved in December. Gerasimovich was arrested on 30 June 1937 on the train while returning from Moscow to Leningrad and imprisoned. Following a meeting on 30 November 1937 of the Military Collegium of the Supreme Court of the Soviet Union, he was found guilty and executed that day in Leningrad. For years, his name vanished even from official histories of Russian astronomy. Gerasimovich received awards from the Soviet Union (1924, 1926, and 1936) and from France (1934). A crater on the Moon, and minor planet (2126), are named after Gerasimovich. Katherine Haramundanis Selected References Eremeeva, A. I. (1993). “Political Repression Against Soviet Astronomers in the 1930s.” Bulletin of the American Astronomical Society 25: 1289. (Paper abstract.) ——— (1989). (as Yeremeyeva). “Zhizn’ i tvorchestvo Borisa Petrovicha Gerasimovicha (k 100–letniya so dnya rozhdeniya)” (Life and Creative Work of Boris Petrovich Gerasimovich [on the occasion of the 100th anniversary of his birth]). Istoriko-astronomicheskie issledovaniia 21: 253–301. (Reprint, Glavnaya Redaktsiya Fizika-matematicheskoi Literaturi. Moscow: Nauka, 1989.) Haramundanis, Katherine (ed.) (1984). Cecilia Payne-Gaposchkin: An Autobiography and Other Recollections. Cambridge: Cambridge University Press. Kulikovsky, P. G. (1972). “Gerasimovich, Boris Petrovich.” In Dictionary of Scientific Biography, edited by Charles Coulston Gillispie. Vol. 5, pp. 363–364. New York: Charles Scribner’s Sons. McCutcheon, Robert A. (1989). “Stalin’s Purge of Soviet Astronomers.” Sky & Telescope 78, no. 4: 352–357. ——— (1991). “The 1936–1937 Purge of Soviet Astronomers.” Slavic Review 50, no. 1: 100–117. Struve, Otto (1957). “About a Russian Astronomer.” Sky & Telescope 16, no. 8: 379–381. G Gersonides: Levi ben Gerson Born Died Bagnols, (Gard), France, 1288 probably Provence, France, 20 April 1344 Gersonides left few letters and does not talk about himself in his writings; nor is his life discussed at great length by his contemporaries. He may have lived for a time in Bagnol sur-Ceze. It is probable that his father was Gershom ben Salomon de Beziers, a notable mentioned in medieval histories. Though Gersonides made several trips to Avignon, he most likely spent his entire life in Orange. There is some evidence that he may have followed the traditional occupation of his family, moneylending. With the decline of Spanish Judaism in the 13th century, Provence quickly became the cultural center for Jewish intellectual activity. The popes in Avignon had a lenient policy toward the Jews, whose creative life flourished, particularly in philosophy and theology. Although Gersonides spoke Provençal, his works are all written in Hebrew, and all of his quotations from Ibn Rushd, Aristotle, and Maimonides are in Hebrew as well. He may have had a reading knowledge of Latin; he appears to manifest an awareness of contemporary scholastic discussions. Gersonides might, however, have learned of such discussions in oral conversations with his Christian contemporaries. Although Gersonides wrote no scientific works as such, scientific discussions were included in his philosophical works. Gersonides’ major scientific contributions were in the area of astronomy; his works were known by his contemporaries, both Jewish and Christian. One of the craters of the Moon, Rabbi Levi, is named after him. Gersonides’ astronomical writings are contained primarily in Book 5, part 1 of The Wars of the Lord (Milḥamot ha-Shem), his major philosophical opus, which was completed in 1329. The astronomical parts of The Wars were translated into Latin during Gersonides’ lifetime. Although the astronomy chapters were conceived as an integral part of the work, they were omitted in the first printed edition of The Wars but have survived in four manuscripts. In the 136 chapters of Book 5, part 1 of The Wars, Gersonides reviews and criticizes astronomical theories of the day, compiles astronomical tables, and describes one of his astronomical inventions. With respect to his astronomical observations, what distinguished Gersonides from his Jewish philosophical predecessors was his reliance upon and consummate knowledge of mathematics, coupled with his belief in the accuracy of observations achieved by the use of good instruments. Because of this rootedness in empirical observation, which was bolstered by mathematics, Gersonides believed that he had the tools to succeed where others had failed, particularly in the area of astronomy. That Gersonides clearly considered his own observations to be the ultimate test of his system is explicit from his attitude toward Ptolemy. “We did not find among our predecessors from Ptolemy to the present day observations that are helpful for this investigation except our own”(Wars V.1.3, p. 27), he says, in describing his method of collecting astronomical data. Often, his observations do not agree with those of Ptolemy, and in those cases he tells us explicitly that he prefers his own. Gersonides lists the many inaccuracies he has 415 416 G Gersonides: Levi ben Gerson found trying to follow Ptolemy’s calculations. Having investigated the positions of the planets, for example, Gersonides encountered “confusion and disorder,” which led him to deny several of Ptolemy’s planetary principles (Goldstein, 1988, p. 386). He does warn his colleagues, however, to dissent from Ptolemy only after great diligence and scrutiny. It is interesting to note that Gersonides briefly discusses, and then dismisses, the heliocentric model of the Universe before rejecting it in favor of geocentrism (Wars, Chapter 51; also Commentary on Deuteronomy, 213c). Gersonides is perhaps best known for his invention of the Jacob’s Staff. This instrument, which he called Megalle ‘amuqqot (Revealer of profundities) and which was called Bacullus Jacobi (Jacob’s staff) by his Christian contemporaries, is described in detail in Chapters 4–11 of Wars 5.1. The material contained in these chapters was translated into Latin in 1342 at the request of Pope Clement VI and survives in a number of manuscripts. Gersonides’ instrument was used to measure the heights of stars above the horizon. It consisted of a long rod, along which a plate slides, that could be used to find the distance between stars. Gersonides was interested in other instruments as well, including the astrolabe for which he suggested several refinements, and the camera obscura. The latter instrument was used by him for making observations of eclipses. Gersonides also applied the principle of the camera obscura to make a large room into an observing chamber, taking advantage of the image cast by a window on the opposite wall. Chapter 99 of Book 5, part 1, contains astronomical tables commissioned by several Christian clerics. Besides containing a general explanation of the tables, Chapter 99 contains instructions on how to compute the mean conjunction and opposition of the Moon and Sun; a method for deriving the true conjunction or opposition of the Moon and Sun; a computation of solar time; and a discussion of eclipses, with tables for positions of the Moon for each day. In Book 5, part 2, of The Wars, which was included in most manuscripts, Gersonides deals with technical, albeit nonmathematical, issues in astronomy, such as the interspherical matter (Wars 5.1, Chapter 2); topics concerning the diurnal sphere, the Milky Way, and the movements of the planets (Wars 5.1, Chapters 4–5, 7–9); and how the Sun heats the air (Wars 5.1, Chapter 6). In Book 5, part 3, Gersonides examines a number of additional topics, such as the Aristotelian question of how many celestial spheres are needed to explain the movements of the heavenly bodies (Wars 5.3, Chapter 6), and whether the velocities of the heavenly bodies are related by a commensurate number (Wars 5.3, Chapter 10). In this context, Gersonides addresses Ptolemy’s theory of cosmic distances based on a system of nested spherical planetary shells. He introduces a fluid layer (“the matter that does not keep its shape”) between two successive planetary shells so that motion of one planet would not affect the motion of the planet adjacent to it. Gersonides then computes the planetary distances according to three separate theories (Wars 5.3, Chapters 130–135). Gersonides was also an avid supporter of judicial astrology, which plays an important role in his philosophical views on free will and providence. The treatise, Pronosticon de conjunctione Saturni et Jovis et Martis, was started by Gersonides (possibly at the request of Pope Clement VI) and completed by his Latin translator, Peter of Alexander, and Levi’s brother, Solomon. This work is a prediction based on the conjunction of Saturn and Jupiter to take place in March 1345. Gersonides himself died in 1344, a year before the event in question. In his prognostication, Gersonides predicts a number of calamitous events. The Black Death, which arrived in Europe in 1347, was thus provided with numerous astrological credentials. In short, according to Gersonides the ultimate function of astronomy is to understand God. Astronomy, he claims, can only be pursued as a science by “one who is both a mathematician and a natural philosopher, for he can be aided by both of these sciences and take from them whatever is needed to perfect his work” (Wars V.1.1, p. 23). Astronomy, he tells us, is instructive not only because of its exalted subject matter, but also because of its utility to the other sciences. By studying the orbs and stars, we are led ineluctably to a fuller knowledge and appreciation of God. Astronomy thus functions as the underpinning of the rest of his work. Tamar M. Rudavsky Selected References Dahan, Gilbert (ed.) (1991). Gersonide en son temps. Louvain: E. Peeters. Feldman, Seymour (1967). “Gersonides’ Proofs for the Creation of the Universe.” Proceedings of the American Academy for Jewish Research 35: 113–137. Freudenthal, Gad (1987). “épistemologie, astronomie et astrologie chez Gersonide.” Revue des études juives 146: 357–365. ______ (ed.) (1992). Studies on Gersonides: A Fourteenth-Century Jewish Philosopher-Scientist. Leiden: E. J. Brill. Gersonides. Sefer ha-Heqesh ha-yashar (On valid syllogisms, written 1319). (Translated into Latin as Liber Syllogismi Recti. Recently translated by Charles H. Manekin as The Logic of Gersonides. Dordrecht: Kluwer, 1992.) ______ Sefer Ma’aśeh hoshev (The work of a counter, written 1321). (Edited and translated into German by Gerson Lange. Frankfurt am Main: Golde, 1909.) ______ Sefer Milhamot ha-Shem (The wars of the Lord, written 1329). Riva di Trento, 1560; Leipzig, 1866; Berlin, 1923. (Recently translated into English as The Wars of the Lord by Seymour Feldman. 3 vols. Philadelphia: Jewish Publication Society, 1984–1999.) ______ Perush ʕal Sefer ha-Torah (Commentary on the Pentateuch, written 1329–1338). Venice, 1547; Jerusalem, 1967. Goldstein, Bernard R. (1974). The Astronomical Tables of Rabbi Levi ben Gerson. Transactions of the Connecticut Academy of Arts and Sciences, Vol. 45. New Haven, Connecticut: Connecticut Academy of Arts and Sciences. ______ (1985). The Astronomy of Levi ben Gerson (1288–1344): A Critical Edition of Chapters 1–20. New York: Springer-Verlag. ______ “Levi ben Gerson’s Astrology in Historical Perspective.” In Dahan, Gersonide en son temps, pp. 287–300. ______ “Levi ben Gerson’s Contributions to Astronomy.” In Freudenthal, Studies on Gersonides, pp. 3–20. Goldstein, Bernard R. and David Pingree (1990). “Levi ben Gerson’s Prognostication for the Conjunction of 1345.” Transactions of the American Philosophical Society 80, pt. 6: 1–60. Langermann, Y. Tzvi (1989). “Science, Jewish.” In Dictionary of the Middle Ages, edited by Joseph R. Strayer, pp. 89–94. New York: Charles Scribner’s Sons. ______ “Gersonides on the Magnet and the Heat of the Sun.” In Freudenthal, Studies on Gersonides, pp. 267–284. ______ (1999). “Gersonides and Astrology.” In Levi ben Gershom: The Wars of the Lord, edited by Seymour Feldman, Vol. 3, pp. 506–519. New York: Jewish Publication Society of America. Gilbert, Grove Karl Rudavsky, T. M. (2000). Time Matters: Time, Creation, and Cosmology in Medieval Jewish Philosophy. Albany: State University of New York Press. Touati, Charles (1973). La pensée philosophique et théologique de Gersonide. Paris: Les éditions de Minuit. Gilbert, Grove Karl Born Died Rochester, New York, USA, 6 May 1843 Jackson, Michigan, USA, 1 May 1918 Grove Gilbert was the first individual to articulate a cogent theory of lunar crater formation as a consequence of meteoroid impacts, resulting in structures that were patently different than craters of volcanic origin observed on the surface of the Earth. One of the most respected American geologists of his generation, Gilbert trained in mathematics and classical languages at the University of Rochester, graduating in 1862. After a brief stint as a schoolteacher in Michigan, he spent 5 years sorting specimens as a clerk at Ward’s Scientific Establishment, a scientific factory in Rochester known, in true Humboldtean fashion, as Cosmos Hall. In 1869, Gilbert obtained a position as a volunteer with John Strong Newberry’s Geological Survey of Ohio. Gilbert’s work with Newberry was followed in 1871 by an appointment to Lieutenant George M. Wheeler’s wide-ranging army survey of that wonderland of geology, the American Southwest. Gilbert’s reports on these research expeditions already showed the development of his basic approach. His “systematic geology,” as his biographer Stephen J. Pyne put it, proceeded “by an arrangement of careful, systematic contrasts, in which various geologic regions, or systems, or various geologic processes are compared with respect to their fundamental similarities and differences.” As Gilbert himself described it, he preferred wherever possible to make general statements rather than to draw up mere lists of facts. In 1875, Gilbert joined the US Geological and Geographical Survey of the Rocky Mountain Region led by Major John Wesley Powell, the one-armed veteran of the Civil War who had achieved fame for his daring exploration of the Colorado River as far as the Grand Canyon. It was under Powell’s direction that Gilbert carried out his most important investigations as a member of the Geological and Geographical Survey, and later as a geologist of the US Geological Survey. In 1891, Gilbert’s survey work led him to Coon Butte (also known as Coon Mountain) near Canyon Diablo in northern Arizona, and thence to his study of the Moon. Now known as “Meteor Crater,” Coon Butte consists of an arid plain whose scanty soils lie atop beds of limestone. The plain is described in the following manner: [I]nterrupted by a bowl-shaped or saucer-shaped hollow, a few thousand feet broad and a few hundred feet deep…. In other words, there is a crater; but the crater differs from the ordinary volcanic structure of that name in that it contains no volcanic rock. The circling sides of the bowl show limestone and sandstone, and the rim is wholly composed of these materials. Following the discovery of iron at the site, it was visited by a prominent mineralogist, A. E. Foote, who presented his findings at a meeting of the American Association for the Advancement of Science in Washington on 20 August 1891. Gilbert, present at the G meeting, heard Foote suggest the iron was of celestial origin—the remnant of a shower of meteorites. “I asked myself,” he later wrote, “what would result if another small star should now be added to the Earth, and one of the consequences which had occurred to me was the formation of a crater, the suggestion springing from the many familiar instances of craters formed by collision.” Gilbert’s tests in the field, especially his failure to detect the deflection of a magnetized needle, led him to conclude against the falling star theory. Instead, he decided the crater had been formed explosively by steam—in short, it was a volcanic feature of the type known as a maar. He would never discuss Coon Butte again—publicly at least—though it remained the subject of intensive study by others and would eventually and conclusively be shown to be an impact feature. But it was Coon Butte that led directly to Gilbert’s interest in the craters of the Moon. Indeed, almost immediately after his return to Washington, Gilbert turned the 26-in. refractor of the US Naval Observatory and his geologically trained eye to the Moon. Gilbert found he could not support the analogy invoked by so many earlier writers, for example, Johann von Mädler, Johann Schröter, James Nasmyth, and James Carpenter, between terrestrial volcanoes and the lunar craters with their landslip terraces and central peaks. The terrestrial volcanoes were closely grouped around a certain maximum size, as though constrained by a limiting condition, while the larger lunar craters were widely scattered about a maximum, like aberrant shots deviating from the bull’s eye. Even more significant were the differences in form. Craters of the Vesuvian type, which included 95% of terrestrial craters, were formed by lavas containing considerable amounts of water. As the lava rose, this water was converted into steam, and by the propulsive power of steam the lava was torn to pieces and hurled high into the air. Repeated episodes of this process—intermittent explosions followed by periods of quiescence—formed a conical mountain with a funnel-shaped cavity at its summit. Such craters, however, had little in common with those of the Moon. Gilbert noted that the bottoms of lunar craters are almost invariably lower than the surrounding plain; conversely, the bottom of the Vesuvian crater lies higher than the outer plain. In short, geological features of the Earth known to be of volcanic origin were not at all like the lunar craters. By the process of elimination he was left with the meteoritic impact theory. There were, of course, objections to be overcome, especially the sheer scale of the lunar craters. Gilbert admitted that it was “incredible that even the largest meteors of which we have direct knowledge should produce scars comparable in magnitude with even the smallest visible lunar craters.” Earlier theorists had been forced to suggest that at one time such meteors were much larger than what we now observe. As no evidence had been found that the Earth was subjected to a similar attack, the lunar bombardment had to be assigned to an epoch more remote than all the periods of geologic history—an epoch so remote that similar scars on Earth had been obliterated entirely by the forces of water and wind. With the help of physicist Robert Simpson Woodward (1849– 1924), Gilbert worked out many details of the impact process. “In the production of small craters by small moonlets,” he wrote, “I conceive the bodies in collision either were crushed or were subjected to plastic flow and in either case were molded into cups in a manner readily illustrated by laboratory experiments with plastic materials. The material displaced in the formation of the cup was built into a rim partly by overflow at the edges of the cup, but chiefly by outward mass movement in all directions, resulting in the uplifting of the surrounding plain into a gentle conical slope.” 417 418 G Gilbert [Gilberd], William Central peaks were formed by the recoil. The rays emanating from some of the more prominent and fresher-appearing craters were splash features, consisting of material thrown out from the impact that formed them. Gilbert’s most elegant piece of work was his identification of what he called “sculpture”—a pattern of parallel grooves or furrows and smoothly contoured oval hills whose trend lines all converged on a point located near the middle of Mare Imbrium impact basin. Gilbert’s seminal 1892 paper “On the Face of the Moon” seems startlingly modern. Indeed, he deserves to be called the Champollion of the Moon—after Jean François Champollion, the French Egyptologist who completed the decryption of the famous Rosseta Stone. With the insight of genius, he had presented a unified view of the Moon’s incredibly diverse and hitherto largely unintelligible detail. But Gilbert was too far ahead of his time; for decades his work was virtually ignored until it was validated and extended by Ralph Baldwin and Eugene Merle Shoemaker (1928–1997). It must be noted that Gilbert’s work on lunar cratering theory constituted an extremely small component of his scientific oeuvre. Gilbert was a powerful figure in late 19th-century American science, so important in fact that the National Academy of Sciences [NAS] chose to identify him as the most important American scientist in the first century of that organization’s existence. His NAS biographical memoir is, accordingly, the longest such memoir ever published. Thomas A. Dobbins Selected References Both, Ernst E. (1961). A History of Lunar Studies. Buffalo, New York: Buffalo Museum of Science. Davis, W. M. (1926). “Grove Karl Gilbert.” Memoirs of the National Academy of Sciences 21, no. 5: 1–303. (Vol. 11 of the Biographical Memoirs, National Academy of Sciences). Gilbert, Grove Karl (1893). “The Moon’s Face: A Study of the Origin of its Features,” address as retiring president to the National Academy of Science, November 1892. Bulletin of the Philosophical Society of Washington 12: 241–292. ______ (1896). “The Origin of Hypotheses, Illustrated by the Discussion of a Topographic Problem.” Science, n.s., 3: 1–13. Hoyt, William Graves (1987). Coon Mountain Controversies: Meteor Crater and the Development of Impact Theory. Tucson: University of Arizona Press. Pyne, Stephen J. (1980). Grove Karl Gilbert: A Great Engine of Research. Austin: University of Texas Press. Sheehan, William P. and Thomas A. Dobbins (2001). Epic Moon: A History of Lunar Exploration in the Age of the Telescope. Richmond, Virginia: Willmann-Bell. Wilhelms, Don E. (1993). To a Rocky Moon: A Geologist’s History of Lunar Exploration. Tucson: University of Arizona Press. Gilbert [Gilberd], William Born Died Colchester, Essex, England, 1544 probably London, England, 1603 William Gilbert is best known today for his study of magnets and magnetism, in which he discusses (among other things) the Earth’s magnetic field. Gilbert was the eldest son of Jerome [Hieron] Gilberd, recorder of Colchester. William entered Saint Johns College, Cambridge, and obtained a BA (1561), an MA (1564), and finally an MD (1569). He became a Junior Fellow of Saint Johns in 1561, and a Senior Fellow in 1569. Some authors suggest that he also studied in Oxford, but this is not established. On leaving Cambridge, Gilbert probably undertook a long journey on the continent (likely in Italy). He then settled in London in 1573 to practice medicine. He was elected that same year a fellow of the Royal College of Physicians and was in turn Censor (1581/1582, 1584–1587, and 1589/1590), Treasurer (1587–1591, 1597–1599), Elector (1596/1597), Consilarius (1597–1599), and President (1600) of the College. Gilbert participated in the compilation of the College of Physicians’ Pharmacopoeia. His medical career was very successful, and he was one of the prominent physicians in London. Near the end of his life, he became one of the personal physicians to Queen Elizabeth I (1600–1603). After the death of Queen Elizabeth (24 March 1603), he continued as royal physician to King James I and kept this position until his own death by plague 8 months later. Gilbert’s achievement as a doctor would have been enough to secure his fame, but he is best remembered today for his book De Magnete (written in Latin). In this book, published in London in 1600, he presents investigations on magnets. De Magnete provides a review of what was known about the nature of magnetism, as well as knowledge added by Gilbert through his own experiments. Gilbert is sometimes quoted as the father of experimental research and De Magnete described him as the first exemplar of modern science. Gilbert devoted long sections of his book to a critical examination of earlier ideas about the magnet and the compass. The distinction between earlier discoveries and his own input, however, is not always obvious in the text. Gilbert refuted many folk tales, including the medicinal properties of magnets to cure all sorts of headaches, the effect of garlic to weaken the magnetic properties of the compass needle, or even the possibility of a perpetual motion machine. Gilbert also described as “vain and silly” the idea of “magnetic mountains or a certain magnetic rock or a distant phantom pole of the world.” Relying on many experiments, Gilbert drew analogies between the magnetic field of the Earth and that of a terrella (Gilbert’s word for a spherical lodestone). He studied the magnetic dip (declinatio in Gilbert’s word) near the terrella, and conjectured that “the Earth globe itself is a great magnet” (Magnus magnes ipse est globus terrestris); however, rigorous demonstration of the internal origin of the geomagnetic field was only given by Carl Gauss in 1838. Gilbert also proposed to determine longitude and latitude using magnetic dip and declination (Variatio). De Magnete is divided into six “books.” The progression is remarkable. In book III, Gilbert neglected declination to simplify his task. Then he started book IV by reintroducing this notion: “So far we have been treating direction as if there were no such thing as variation.” This sort of simplification has now become a rather classical scientific approach, but it was not at that time. The final book (VI) concerned stellar and terrestrial motions. In this book, Gilbert departed somewhat from the scientific rigor that characterizes his work. Guided by the fact that magnetic North and astronomical North are so close, Gilbert suggested that the Earth’s rotation was due to its magnetic nature. Gilbert described as “philosophers of the vulgar sort (…), with an absurdity unspeakable” Giles of Rome those that believed the Earth to be stationary. He expected the dipole nature of the Earth’s magnetic field to add support to the Copernican theory. Because of this book, Gilbert is sometimes considered as one of the earliest Copernicans; his ideas influenced Johannes Kepler also. A second book, De mundo nostro sublunari philosophia nova, was published (and coauthored) posthumously in 1651, by one of Gilbert’s brothers. This lesser-known text includes a map (or rather a sketch) of the Moon drawn by Gilbert (before the telescope). Emmanuel Dormy Selected References Gilbert, William (1958). De Magnete, translated by P. Fleury Mottelay. New York: Dover. (Reprint of the 1893 English translation including a biographical memoir.) Martin, Stuart and David Barraclough (2000). “Gilbert’s De Magnete: An Early Study of Magnetism and Electricity.” Eos, Transactions of the American Geophysical Union 81, no. 21: 233–234. Roller, Duane H. D. (1959). The De Magnete of William Gilbert. Amsterdam: Menno Hertzberger. Thompson, Silvanus (1891) “Gilbert of Colchester”, London: the Chiswick Press. Tittmann, O. H. (1909). Principal Facts of the Earth’s Magnetism. Washington, DC: Department of Commerce and Labor, Government Printing Office. Gildemeister, Johann Born Died Bremen, ( Germany), 9 September 1753 Bremen, (Germany), 9 February 1837 Johann Gildemeister of Bremen was a prominent member of János von Zach’s “Himmel Polizei” (“Celestial Police”). Selected Reference Hoskin, Michael (1993). “Bode’s Law and the Discovery of Ceres.” In Physics of Solar and Stellar Coronae: G. S. Vaiana Memorial Symposium, edited by J. Linski and S. Serio, p. 35. Dordrecht: Kluwer. Giles of Rome Born Died Rome, (Italy), circa 1247 Avignon, France, 22 December 1316 Giles’ significance in the history of astronomy lies in his metaphysical investigations into such fundamental physical notions as matter, space, and time. Giles was the most significant theologian of the Order of the Augustinian Hermits in the 13th century. His exact date of birth is uncertain, as is his alleged relation to the noble family of the G Colonna (which is not mentioned in contemporary sources). He entered the Augustinian order at a young age, about 1260. Later, Giles was sent to study in Paris, where he probably was among the students of Thomas Aquinas from 1269 to 1272, and started writing his commentary on Peter Lombard’s Sentences, as well as extensive commentaries on Aristotle’s works. If one can believe the traditional, yet often debated attribution, it was also during this period, around 1270, that he composed De Erroribus Philosophorum, the compilation of the philosophically doubtful and theologically condemnable positions of Aristotle, Ibn Rushd, Ibn Sina, Abū al-Ghazali, al Kindi, and Rabbi Moses Maimonides. This work was very much in agreement with the spirit of the 1270 condemnations issued by Stephen Tempier, the Bishop of Paris. Nevertheless, in 1277, Tempier’s zeal found even Giles’ doctrine suspect on several counts. But Giles’ troubles did not prevent King Philip III from entrusting him with the education of his son, the future Philip the Fair. Giles’ immensely influential political work, De Regimine Principum, dates from this period, and is dedicated to his royal student. By 1281, Giles returned to Italy, where he started to play an increasingly important role in his order. Yet, in 1285, upon the reexamination of his teachings, Pope Honorius IV asked him to make a public retraction of some of his theses condemned in 1277. The retraction regained for Giles his license to teach, and so in effect it enabled him to exert an even greater influence in his order and beyond. As a result, the general chapter of the Augustinian Hermits held in Florence in 1287 practically declared his teachings the official doctrine of the order, commanding its members to accept and publicly defend his positions. After serving in further, increasingly important positions, in 1292 Giles was elected superior general of his order at the general chapter in Rome. Three years later, in 1295, the new pope, Boniface VIII, appointed him archbishop of Bourges. As an Italian archbishop in France, and a personal acquaintance of the parties involved, Giles had a difficult role in the conflict between Philip the Fair and Boniface VIII, but on the basis of his theological–political principles, he consistently sided with the pope. On the other hand, after Boniface’s death, he supported the king’s cause against the Order of Templars. In the subsequent years Giles continued to be active in the theological debates of the time, until his death at the papal Curia in Avignon. Giles’ investigations into the nature of matter, space, and time, although usually carried out under the pretext of merely providing further refinements of traditional positions, in fact opened up a number of new theoretical dimensions, pointing away from traditional Aristotelian positions. For example, Giles’ interpretation of the doctrine of the incorruptibility of celestial bodies does not rely on the traditional Aristotelian position of attributing to them a kind of matter (ether, the fifth element, quintessence) that is radically different from the matter of sublunary bodies (which were held to be composed of the four elements, earth, water, air, and fire). Since matter, according to Giles, is in pure potentiality in itself, it certainly cannot make a difference in the constitution of celestial bodies. Therefore, he argued that what makes the difference is that the perfection of the determinate dimensions of these bodies, filling the entire capacity of their matter, renders their matter incapable of receiving any other forms, and that is why 419 420 G Gill, David they are incorruptible. These determinate dimensions are to be distinguished from the indeterminate dimensions of matter (dimensiones interminatae), the dimensions determining a quantity of matter that remains the same while matter is changing its determinate dimensions in the constitution of an actual body, as in the processes of rarefaction and condensation. The distinction is necessitated by considering that if matter is nonatomic, but continuous, genuine rarefaction or condensation (i. e., diminution or enlargement of the actual, determinate dimensions of the same body without the subtraction or addition of any quantity of matter) can take place only if the changing actual dimensions are distinct from the constant quantity of matter. This interpretation of Ibn Rushd’s notion of dimensiones interminatae as the invariable quantity of matter can be regarded as taking a significant step toward the modern notion of mass. Similar considerations apply to Giles’ metaphysical investigations into the nature of time. Motivated by the Aristotelian argument against the possibility of a vacuum, on the grounds that free fall in a vacuum would have to be instantaneous, in his hypothetical speculations concerning the possibility of instantaneous motion in a vacuum, Giles transformed the Aristotelian notion of time into a more general idea of a succession of instants. This enabled him to distinguish different orders of time, namely, the proper time of the thing moved, which is the intrinsic measure of its successive motion (mensura propria), and celestial time, which is the extrinsic measure (mensura non propria) of the same motion. Thus, it would be possible for a thing instantaneously moved in a vacuum to cover all intervening spaces successively at different instants of its proper time, which, however, being unextended and not separated by time, may coincide with the same instant of celestial time. This more general notion also enabled Giles to distinguish between time that is the mode of existence of material things, and angelic time, which is the mode of existence of nonmaterial, yet not simply eternal beings. Trifogli, C. (1990). “La dottrina del tempo in Egidio Romano.” Documenti e studi sulla tradizione filosofica medievale 1: 247–276. ______ (1990). “The Place of the Last Sphere in Late-Ancient and Medieval Commentaries.” In Knowledge and the Sciences in Medieval Philosophy, edited by S. Knuttila, R. Työrinoja, and S. Ebbesen, pp. 342–350. Helsinki: Luther-Agricola Society. ______ (1991). “Egidio Romano e la dottrina aristotelica dell’infinito.” Documenti e studi sulla tradizione filosofica medievale 2: 217–238. ______ (1992). “Giles of Rome on Natural Motion in the Void.” Mediaeval Studies 54: 136–161. Gill, David Born Died Aberdeen, Scotland, 12 June 1843 London, England, 24 June 1914 Gyula Klima Alternate names Aegidius Romanus Aegidius Colonna [Columna] Selected References Giles of Rome. Opera omnia. Florence: Leo S. Olschki, 1985–. ______ Quodlibeta. Frankfurt am Main: Minerva, 1966. ______ Quaestiones in octo libros Physicorum Aristotelis. Frankfurt am Main: Minerva, 1968. ______ Quaestio de materia coeli. Frankfurt am Main: Minerva, 1982. Del Punta, F., S. Donati, and C. Luna (1993). “Egidio Romano.” In Dizionario biografico degli Italiani. Vol. 42, pp. 319–341. Rome: Istituto della Enciclopedia italiana. Donati, S. (1986). “La dottrina di Egidio Romano sulla materia dei corpi celesti. Discussioni sulla natura dei corpi celesti alla fine del tredicesimo secolo.” Medioevo 12: 229–280. ______ (1988). “La dottrina delle dimensioni indeterminate in Egidio Romano.” Medioevo 14: 149–233. ______ (1990). “Ancora una volta sulla nozione di quantitas materiae in Egidio Romano.” In Knowledge and the Sciences in Medieval Philosophy, edited by S. Knuttila, R. Työrinoja, and S. Ebbesen. Helsinki: Luther-Agricola Society. The career of David Gill, the leading British observer and instrumentminded astronomer of his generation, straddled the introduction of photographic techniques to astronomy. He was born in Aberdeen to David Gill (1789–1878), a clockmaker, and Margaret Mitchell (1809– 1870). He had three brothers and a sister who survived infancy. Gill’s education was at Bellevue Academy in Aberdeen and, briefly from the age of 14, at Dollar Academy near Stirling. At 15, he entered Marischal College of Aberdeen University, where one of his teachers was James Maxwell. As it was intended that he should enter the family firm, Gill underwent practical training in watchmaking in England and Switzerland before joining his father in 1863. Gillis, James Melville While in business, Gill remained an avid amateur astronomer and possessed a 12-in. reflecting telescope. A photograph that he took of the Moon came to the attention of Lord James Ludovic Lindsay (later Earl of Crawford and Balcarres), who offered him a position as Director of his proposed private observatory at Dun Echt (Aberdeenshire). Although recently married to Isobel Black (died: 1920) of Aberdeen, he accepted this post, which meant a drop in income by a factor of five. Primarily responsible for ordering the equipment for Dun Echt, Gill learned a great deal about astronomical instrumentation; he later became the leading expert on the heliometer. With Lord Lindsay, Gill went on an expedition to Mauritius for the 1874 transit of Venus, with the intention of measuring the Astronomical Unit [AU]. The experience and reputation he gained, as well as his increasing reputation as an astronomer, encouraged Gill to leave Dun Echt. He then resided in London from 1876 to 1879 as an independent astronomer without paid employment. During this period, Gill conducted an expedition to Ascension Island for further observations of Mars. For his early work, especially on his efforts to determine the AU, he received widespread recognition. In 1879, Gill was appointed by the Admiralty to the position of Her Majesty’s astronomer at the Cape of Good Hope, South Africa. On arrival, he found the Royal Observatory in a lamentable state and immediately set about its reorganization, using his own money when the Admiralty would not provide. Gill made plans for a definitive measurement of the AU through observations of minor planets and persuaded the Admiralty to order a new heliometer for this purpose. His measurements in 1889 led to a value of the AU that was accepted for 45 years. Gill’s most important enduring contribution to astronomy derived from an accidental discovery. In 1882, he photographed the great September comet of that year (C/1882 R2) using “dry” plates, a recent development. He was amazed to find that these new plates were sufficiently sensitive to record the background stars in large numbers. He realized that, with a suitable camera, these plates would provide an excellent means for surveying the sky and dramatically increase the speed of cataloging the heavens. Gill’s breakthrough revolutionized astronomy, greatly impacting the array of instruments that would soon equip leading observatories. In 1885, Gill commenced the sky survey known as the “Cape Photographic Durchmusterung,” a southern extension of the Bonner Durchmusterung of Friedrich Argelander. Because of opposition to this project from the Astronomer Royal, William Christie, Gill had to finance it himself, and, with his wife’s agreement, he devoted half his salary to the work. The project was completed in 1900, with the measurement of the plates undertaken by Jacobus Kapteyn of Groningen. In the meantime, Gill became involved in the international Carte du Ciel program, defined at the 1887 Paris Astrographic Congress, at which he played a leading role, together with Admiral Ernest Mouchez, Director of Paris Observatory. The many telescopes used for this program had to be of standard aperture and focal length. Gill contributed actively and in meticulous detail to the design of those supplied to the British Empire observatories by Howard Grubb. The Cape Observatory’s share of the work absorbed a major part of the its effort for decades. Gill was acutely aware of the trend toward astrophysical research that had taken root in the 1870s and 1880s and was anxious to make his mark in this area. The Admiralty, interested only in navigation, was not willing to provide equipment for astrophysical investigations, but the Royal Observatory was eventually offered a large (26-in.) refractor G and state-of-the-art spectrograph by Gill’s friend and admirer, Frank McClean. This telescope, completed around 1901, was equipped with a laboratory for making comparison spectra of terrestrial substances. Admiral Sir William Wharton, the Hydrographer of the Royal Navy and Gill’s immediate superior, came to admire Gill’s work and acted favorably on proposals he made from about 1895 onward. One of these was for a radically new type of transit circle that Gill designed in detail and that Troughton and Simms constructed. This telescope, installed in 1901, became the pattern for a new generation of such instruments. The Royal Observatory had been transformed into a model institution by the time Gill retired in 1907. In many ways, it outshone the mother observatory in Greenwich. The number and quality of staff were greatly improved. Gill was able to attract long-term eminent visitors, such as Kapteyn, Willem de Sitter, and amateur astrophotographer, John Franklin-Adams, who made the southern part of his all-sky survey from the Royal Observatory. After his retirement, Gill returned to London. There, he took an active part in the Royal Astronomical Society. He completed his monumental history of the Royal Observatory and became a consultant on instrumental matters to various foreign observatories. Gill died in 1914, survived by his wife. He had no children. Most of Gill’s official correspondence is in the Royal Greenwich Observatory Archives, Cambridge University Library. Categories dealing with instrumental and local matters are located at the South African Astronomical Observatory, South Africa (successor to the Royal Observatory). Ian S. Glass Selected References Eddington, Arthur S. (1915). “Sir David Gill.” Monthly Notices of the Royal Astronomical Society 75: 236–247. Fernie, Donald (1976). “A Scotsman Abroad: David Gill in Search of the Solar Parallax.” In The Whisper and the Vision, pp. 107–149. Toronto: Clarke, Irwin, and Co. Forbes, George (1916). David Gill, Man and Astronomer: Memories of Sir David Gill, K. C. B., H. M. Astronomer (1879–1907) at the Cape of Good Hope. London: John Murray. Gill, Sir David (1913). A History and Description of the Royal Observatory, Cape of Good Hope. London: H. M. Stationery Office. Kapteyn, J. C. (1914). “Sir David Gill.” Astrophysical Journal 40: 161–172. Murray, C. A. (1988). “David Gill and Celestial Photography.” In Mapping the Sky, edited by S. Débarbat, J. A. Eddy, H. K. Eichhorn, and A. R. Upgren, pp. 143–148. IAU Symposium No. 133. Dordrecht: Kluwer. Warner, Brian (1979). Astronomers at the Royal Observatory, Cape of Good Hope: A History with Emphasis on the Nineteenth Century. Cape Town: A. A. Balkema. Gillis, James Melville Born Died Georgetown, District of Columbia, USA, 6 September 1811 Washington, District of Columbia, USA, 9 February 1865 James Gillis, son of George and Mary (née Melvile) Gillis, founded the United States Naval Observatory and served as its second superintendent. Gillis’ education in astronomy was largely self-directed. He was 421 422 G Gingrich, Curvin Henry commissioned in the US Navy and served at sea before being assigned as a Lieutenant to the United States Navy Depot of Charts and Instruments. Working with limited resources from the depot, Gillis published the first star catalog based on American observations (1846). Gillis began the process of ordering instruments for a first-class observatory, and then persuaded the US Congress that a new facility should be provided to house the instruments. Navy political considerations dictated the appointment of Matthew Maury as the first superintendent of the new observatory. Instead, Gillis was assigned for a period of time to the Coastal Survey working with Alexander Bache and Benjamin Peirce. On his own initiative, Gillis persuaded the Navy and Congress to equip an expedition to Chile. The expedition’s goal was to make simultaneous observations of the oppositions of Mars and Venus from US observatories and from Chile. The intent was to improve upon the value of the solar parallax, or distance from the Earth to the Sun. Neither Harvard College Observatory director William Bond nor Maury assigned sufficient priority to the effort; therefore Gillis’s efforts fell short of a new determination of the solar parallax. The expedition, which was in Chile from December 1849 to September 1852, was otherwise quite productive, producing many useful measurements and a new catalog of southern celestial objects. The equipment left in Chile resulted in the establishment of Chile’s first astronomical observatory. When Maury fled to the South and joined Confederate forces in the US Civil War, Gillis was promoted to Commander, and eventually Captain, and became the second Superintendent of the Naval Observatory in 1861. Gillis was a founding member of the United States National Academy of Sciences. Thomas R. Williams Selected References Dick, Steven J. (1983). “How the U. S. Naval Observatory Began, 1830-65.” In Sky with Ocean Joined: Proceedings of the Sesquicentennial Symposia of the U. S. Naval Observatory, edited by Steven J. Dick and Leroy E. Doggett, pp. 167–181. Washington, DC: U. S. Naval Observatory. ______ (2003). Sky and Ocean Joined: The U.S. Naval Observatory, 1830–2000. Cambridge: Cambridge University Press. Gould, Benjamin Apthorp (1877). “Memoir of James Melville Gillis.” Biographical Memoirs, National Academy of Sciences 1: 135–179. College, Northfield, Minnesota, where he spent the remainder of his career. Concurrently, he was admitted to the University of Chicago and earned his Ph.D. in 1912. Thereupon, Gingrich was named full professor of mathematics and astronomy at Carleton. He served in a variety of administrative roles between 1914 and 1919. In 1915, Gingrich married Mary Ann Gross; the couple had one daughter. Gingrich’s research chiefly involved the “older” astronomy of position and motion that best utilized the institution’s refracting telescopes. He determined the positions of minor planets and comets by photographic astrometry, measured binary stars, and derived stellar parallaxes. He also conducted stellar photometry. Gingrich was a guest investigator at the Mount Wilson Observatory (1921–1922) and at the Leander McCormick Observatory of the University of Virginia (1935). He lectured part-time at Chicago’s Adler Planetarium (1931–1933). Gingrich was successively named assistant editor of Popular Astronomy (1910) under Herbert Wilson, associate editor (1912), and editor (1926), upon Wilson’s retirement. For eighteen years, he was assisted by colleague Edward Fath, who succeeded Wilson as director of the College Observatory in 1926. Under Wilson’s and Gingrich’s leadership, Popular Astronomy became the unofficial journal of the American Astronomical Society [AAS]. During the 1930s and 1940s, Gingrich established a close professional relationship with Otto Struve, director of the Yerkes Observatory and editor of the Astrophysical Journal. Struve freely contributed to Gingrich’s journal, for the sake of preservation of the AAS and the astronomical community as a whole. In spite of severe austerities introduced by the Great Depression and World War II, Gingrich continued publication of Popular Astronomy without interruption; the journal celebrated its 50th anniversary in 1943. Afterward, he and Struve were able to witness the reflowering of astronomy in the early postwar period. Gingrich was due to retire from the College on 30 June 1951 but suffered a fatal heart attack less than two weeks beforehand. While the remainder of the year’s issues were fulfilled, Popular Astronomy ceased publication after December 1951 and was never resumed by any other institution. Selected papers and correspondence of Gingrich are preserved in the Carleton College Archives. Jordan D. Marché, II Selected References Gingrich, Curvin Henry Born Died Gingrich, Curvin H. (1943). “Popular Astronomy: The First Fifty Years.” Popular Astronomy 51: 1–18, 63–67. Greene, Mark (1988). A Science Not Earthbound: A Brief History of Astronomy at Carleton College. Northfield, Minnesota: Carleton College. Leonard, Frederick C. (1951). “Curvin Henry Gingrich, 1880–1951.” Popular Astronomy 59: 343–347. York, Pennsylvania, USA, 20 November 1880 Northfield, Minnesota, USA, 17 June 1951 Curvin Gingrich was professor of mathematics and astronomy at Carleton College and third editor of the journal, Popular Astronomy, producing its final twenty five volumes (1926–1951). Gingrich, son of William Henry and Ellen Kindig Gingrich, received his bachelor’s degree (1903) and master’s degree (1905) from Dickinson College, Carlisle, Pennsylvania. Between 1903 and 1909, he taught mathematics at two Missouri colleges and one Kansas university. In 1909, Gingrich was appointed to the faculty of Carleton Ginzburg [Ginsberg], Vitaly Lazarevich Born Moscow, Russia, 4 October 1916 Soviet theoretical physicist Vitaly Ginzburg was one of the three founders of the modern Russian school of theoretical astrophysics (along with Joseph Shklovsky and Yakov Zel’dovich). He has Glaisher, James made important contributions to the understanding of the origin of cosmic rays, of nonthermal radiation from the Sun, supernova remnants, and quasars, and of the nature of compact astrophysical objects. Ginzburg was the son of an engineer father and physician mother (who died when he was 2); an only child, he was largely raised by his mother’s younger sister. He was educated at home for several years, received 4 years of formal secondary schooling, and then (because 7 years of education was thought to be enough in those days) became a laboratory assistant in an X-ray diffraction lab. After a couple of tries, Ginzberg was admitted to Moscow State University through a competitive examination in 1934, receiving a first degree from the physics faculty in 1938; a candidate’s degree in 1940 for work that started out as experimental optics under S. M. Levi, but rapidly developed into theoretical investigations of the quantum theory of Vavilov–Cerenkov radiation (an important source of X-rays and γ rays from astronomical objects) and other topics in quantum radiation theory; and a Doctor’s degree in 1942 for a thesis on the theory of higher spin particles. In 1940, Ginzberg was appointed to a position in the department of theoretical physics of the P. N. Lebedev Physical Institute of the USSR Academy of Sciences, where he has worked ever since, apart from 2 years near the beginning of World War II, when Academy scientists were evacuated to Kazan. The department was headed for many years by Igor Tamm, and then, following his death in 1971, by Ginzburg for the next 18 years. The best known of his younger associates and protégés were probably L. M. Ozernoi, S. I. Syrovatsky, and V. V. Zhelezniakov. As part of his war work, Ginzburg considered the propagation of radio waves in the Earth’s ionosphere, and plasma physics in general. Thus, when he was asked to work out how the hot corona of the Sun might reflect radar signals sent from Earth, the calculation was a familiar one, and led to his first official astronomical paper, pointing out that solar radio emission must come from the corona, not the photosphere, and suggesting possible emission mechanisms for both quiescent and radio burst radiation. The latter is synchrotron radiation in large measure, and credit for recognizing this must be somehow divided between Ginzburg and Shklovsky. Another of Ginzburg’s prescient ideas was the suggestion that the radiation from a compact part of the Crab Nebula (it was not known to be a pulsar in 1965) must arise from some coherent, nonthermal process. He was also an early advocate of nonthermal mechanisms for radio galaxies and in rejecting the idea from Walter Baade and Rudolph Minkowski that Cygnus A was a pair of galaxies colliding. Ginzberg pointed out in early 1965 that the diffuse gas between the galaxies (the intergalactic medium) would necessarily be at temperatures larger than 105 K simply because of the energy sources available to it. Observational evidence showing that this must be true appeared later in the year in the form of observations of the quasar 3C9 by Maarten Schmidt and interpretation by James Gunn and Bruce Peterson. Ginzberg’s association between cosmic rays and supernovae and their remnants was also one of the first serious echoes of the ideas of Walter Baade and Fritz Zwicky in 1934. Ginzburg’s level of recognition was somewhat spotty. He published more than 1,000 papers, and was, for many decades, the most G cited Soviet physicist after Lev Landau (whose textbooks trained generations of physicists in every country). Ginzburg was elected a corresponding member of the Soviet Academy of Sciences (1953) and a full member in 1966 primarily in recognition of work on the Soviet fusion bomb project (which remained secret for many years), for which he received the Order of Lenin and the Stalin Prize in the early 1950s. He was the George Darwin lecturer of the Royal Astronomical Society in 1974, but was not allowed to travel to England to give the lecture. He was also elected the founding president of the International Astronomical Union Commission on High Energy Astrophysics in 1970, but again was generally not able to participate in its meetings. Virginia Trimble Selected References Ginzburg, Vitaly L. (1990). “Notes of an Amateur Astrophysicist.” Annual Review of Astronomy and Astrophysics 28: 1–36. ______ (2001). Physics of a Lifetime. Berlin: Springer. Giovanelli, Ronald Gordon Born Died Grafton, New South Wales, Australia, 1915 Sydney, New South Wales, Australia, 27 January 1984 In 1946, Australian astronomer Ronald Giovanelli theorized that solar flares occur through magnetic field reconnection. Selected Reference Piddington, J. H. (1985). “Giovanelli, Ronald Gordon—AAS Biographical Memoir.” Historical Records of Australian Science 6, no. 2. Glaisher, James Born Died Rotherhithe, (London), England, 7 April 1809 Croydon, (London), England, 7 February 1903 James Glaisher’s early professional years were spent as an observational astronomer at the Cambridge University Observatory, and then at the Royal Observatory, Greenwich. He is principally remembered for his major contributions to meteorology. The details of Glaisher’s early years and education are somewhat obscure. His father, James Glaisher (1786–1855), is said to have been a watchmaker. James Jr. was the eldest of nine children; soon after his birth the family moved from the dockland area of Rotherhithe downriver to Greenwich. There, the Glaishers met William Richardson, an assistant to Astronomer Royal John Pond. Richardson introduced Glaisher, and later his brother John Glaisher (1819–1846), to the observatory. James Glaisher was not 423 424 G Glaisher, James Whitbread Lee at first employed there, but around 1829 received some instruction in the use of instruments prior to his appointment to the Ordnance Survey of Ireland in that year. The combination of wet weather and exposed mountain triangulation points damaged his health and forced his resignation from the survey at the end of 1830. (Thirteen years later Glaisher suffered a long bout of rheumatism after studying the formation of dew on damp grass at night.) Glaisher recovered sufficiently by 1833 to be appointed first assistant to George Airy at Cambridge, where he assumed responsibility for the newly installed great mural circle, making nearly all the observations from 1833 to 1835. He is also credited with observations of Halley’s comet (IP/Halley) with the Jones equatorial from 2 September 1835 to 16 January 1836. When Airy became Astronomer Royal at Greenwich in September 1835, Glaisher remained in Cambridge to reduce his 1835 observations and did not go to the Royal Observatory until February 1836, though his appointment at Greenwich was effective from 1 December 1835. With Airy’s encouragement Glaisher continued in the reduction of earlier Greenwich and Cambridge observations of the stars, Sun, Moon, and planets, leading to the publication of a star catalog and corrections to the elements of the orbit of Venus. Glaisher was elected a fellow of the Royal Astronomical Society [RAS] in 1841, and expected and wished to continue as an established astronomer, but Airy decreed otherwise. The Royal Observatory had established a separate division to make observations of terrestrial magnetism in 1838, intending at first to operate it for only a few years. In 1840, Airy assigned Glaisher to the new facility. However, it was determined in 1843 that there should be a permanent Magnetical and Meteorological Department, independent of the astronomical operations. Glaisher was to superintend this new department until his retirement in 1874. He accepted the challenge of this new career, and although he continued to take an interest in astronomical matters, remaining a fellow of the RAS for 63 years, Glaisher effectively became an atmospheric physicist (in modern terms) from 1840 onward. The main features of this second career are mentioned in brief. Glaisher carried out important researches into the radiation from the ground into space at night. At the same time he transformed a scattered body of amateur weather observers over the country into a national network, regularly reporting observations made with calibrated instruments on a uniform plan. Glaisher initiated a system in which observations were taken at railroad stations at 9:00 a.m. daily and forwarded on the next train to London. The collated nationwide data were published the following day in the London Daily News beginning in June 1849. Two years later, an experimental system of telegraphic transmission permitted same-day publication of the data and weather maps. Between 1862 and 1866, Glaisher made a series of 29 balloon ascents for scientific purposes, which brought him international fame; on 5 September 1862 (without oxygen) Glaisher lost consciousness at about 30,000 feet and probably attained a slightly higher altitude. His pilot/companion on these flights was Henry T. Coxwell. The Royal Society [RS] elected Glaisher as a fellow in 1849, Airy having proposed him for this honor. In 1850, three RS fellows, Glaisher and two wealthy friends of his, Samuel Charles Whitbread and John Lee (proprietor of the Hartwell House private observatory), joined with seven RAS fellows to create the British Meteorological Society (later with a Royal Charter). Apart from his presidency from 1867 to 1868, Glaisher served as secretary of the Meteorological Society until 1873. He published an account of the severe winter of early 1855. His microscopical studies of the shapes of snow crystals (necessarily made at low temperatures), with drawings made by his artist wife, are still often reproduced. The relationship between Glaisher, the assistant, and Airy, his director for over 40 years, was unusual. Airy, only 8 years Glaisher’s senior, had a brilliant academic career; Glaisher was largely selftaught. Both came from modest backgrounds, and had made their way in the world by the single-minded pursuit of knowledge and a fierce determination; both had become opinionated and unyielding in the process. They disliked one another, but admired each other’s better qualities. The end came in 1874, when Airy tactlessly rebuked his colleague for leaving work 10 min early on one occasion. Glaisher promptly handed in his resignation by formal letter, and retired from Greenwich on the adequate pension earned by his long service. In retirement, Glaisher had much to occupy him for a further 29 years. He was a well-known writer and was immersed in the activities of several learned societies and committees of public affairs. Glaisher eventually moved to Croydon, near London, with a private observatory there. In 1843, Glaisher had married the much younger Cecilia, daughter of the Greenwich assistant Henry Belville, who was of French descent; the marriage was not entirely happy, and his wife predeceased him in 1892. There were three children. The eldest son, James Whitbread Lee Glaisher, who was given the names of two of his father’s wealthy scientific friends, shared much of the ability and interests of his father and became a fellow of the Royal Society as a distinguished and prolific mathematician and mathematical astronomer. In the 1860s, a nearside lunar crater at latitude 13.° 2 N, longitude 49.° 5 E was named to honor Glaisher’s achievements as a meteorologist. David W. Dewhirst Selected References Anon. (1903). “James Glaisher, F.R.S.” Observatory 26: 129–132. Glaisher, James (1871). Travels in the Air. London: R. Bentley. Hunt, J. L. (1978). “James Glaisher, FRS (1809–1903).” Weather (Royal Meteorological Society) 33: 242–249. ______ (1996). “James Glaisher FRS (1809–1903) Astronomer, Meteorologist and Pioneer of Weather Forecasting: ‘A Venturesome Victorian.’” Quarterly Journal of the Royal Astronomical Society 37: 315–347. W. E. (1904). “James Glaisher.” Monthly Notices of the Royal Astronomical Society 64: 280–287. Glaisher, James Whitbread Lee Born Died Lewisham, Kent, England, 5 November 1848 Cambridge, England, 7 December 1928 James Whitbread Lee Glaisher was a pure mathematician and mathematical astronomer who served in leadership positions in the Royal Astronomical Society for 55 years. Glaisher, James Whitbread Lee The eldest son of the English astronomer/meteorologist James Glaisher, young Glaisher attended Saint Paul’s School in London and then Trinity College, Cambridge, where, in 1871, he graduated as second wrangler. He won the Campden Exhibition in 1867 and the Perry Exhibition in 1869. In 1871, Glaisher was elected to a fellowship and a lectureship in mathematics at Trinity College and held these positions until 1901. He received a D.Sc. degree from Cambridge in 1887, the first year that the degree was offered at the university. Glaisher became a fellow of the Royal Astronomical Society [RAS] shortly before his graduation in 1871, and was elected to the society’s council in 1874. He was reelected to the council continuously and was in the middle of his 55th year of service when he died. Glaisher served two terms as president of the society (1886–1888 and 1901–1903), several terms as a vice president, and as secretary from 1877 to 1884. He served as president of the Royal Astronomical Society Club (an informal but exclusive dining arrangement) for 33 consecutive years. In 1875, Glaisher was elected a fellow of the Royal Society. Glaisher’s notable service to the RAS notwithstanding, he came under attack as secretary, as did Arthur Ranyard, during a decadelong struggle by professional astronomers who wished to appropriate the RAS as a strictly professional organization. The dissidents, led by William Christie, characterized themselves as “working astronomers” and “practical astronomers” and objected to having their papers screened by anyone who was not so qualified. Efforts were made, at different times, to recall both secretaries and replace them in spite of their obvious qualifications. The recall elections failed in both cases, but after Christie became one of the secretaries, control of the society by the professional astronomers accelerated. Upon the retirement of George Airy as Astronomer Royal in 1881, the position was offered to Glaisher, because of his eminence as a mathematical astronomer, but he turned it down. Instead, the appointment went to Christie. In his mathematical career, Glaisher published approximately 400 papers, mostly on the history of mathematical subjects. He was well known and respected for his history-of-mathematics papers, especially on the history of the plus and minus signs and his Encyclopedia Britannica article on logarithms. Many of his papers provided detailed analyses and uses of various elements of mathematics. Overall, Glaisher’s papers were rated by scholars as generally good, but of uneven quality. In the first 2 years after his graduation from Trinity College, he published 62 papers. Glaisher served as the editor of the Quarterly Journal of Mathematics (1879–1928) and the Messenger of Mathematics (1871–1928). He authored the 174-page report by the Committee on Mathematical Tables for the British Association for the Advancement of Science in 1873. This paper detailed the history of mathematical tables, cataloged existing tables, and updated many other tables as necessary. Glaisher edited the Collected Mathematical Papers of Henry John Stephen Smith. In 1872, Glaisher joined the London Mathematical Society and was elected to the society’s council in the same year. He served on its council until his retirement in 1906. Glaisher served as the society’s president for the years 1884 to 1886. The earliest of many mathematical–astronomical papers that Glaisher wrote was his 1872 paper “The Law of the Facility of Errors of Observations and on the Method of Least Squares” published in the Memoirs of the Royal Astronomical Society. His G interests in astronomy probably came from his father, who served under Airy at Cambridge Observatory (1833–1838) and at Greenwich (1838–1874), until he retired in 1874 after being offended by Airy. In 1900, Glaisher served as president of the British Association for the Advancement of Science. He served on several of the association’s mathematical committees and edited volumes 8 and 9 of its Mathematical Tables. Among his numerous awards and honors, Glaisher received the De Morgan Medal from the London Mathematical Society in 1908, the Sylvester Medal of the Royal Society in 1913, and honorary D.Sc degrees from Trinity College of Dublin (1892) and Victoria University of Manchester (1902). He was an honorary fellow of the Manchester Literary and Philosophical Society, the Royal Society of Edinburgh, and the National Academy of Sciences in Washington. Glaisher was a renowned collector and authority on English pottery. He wrote parts of several books on the subject and left his collection to the Fitzwilliam Museum at Cambridge. His extensive collection was considered one of the finest collections of slipware in the world. Glaisher also collected valentines and children’s books; these also were donated to the Fitzwilliam Museum. Glaisher never married. He died in his college room at Cambridge. None of the referenced works cite the actual cause of death, but state that he was a robust man who loved hiking and bicycle riding, yet suffered from failing health in his last few years. A nearside lunar crater at latitude 13.° 2 N, longitude 49.° 5 E was named in the 1860s to honor the father, James Glaisher, based on a lunar map by Dr. John Lee. James Whitbread Lee Glaisher was named in part to honor Dr. John Lee and Samuel Charles Whitbread, who were friends and fellow founders with James Glaisher of the British Meteorological Society (now known as the Royal Meteorological Society), in 1850. Robert A. Garfinkle Selected References Boyer, Carl B. (1985). A History of Mathematics. Princeton, New Jersey: Princeton University Press. Cajori, Florian (1993). A History of Mathematical Notations. New York: Dover. Forsyth, A. R. (rev. by J. J. Gray) (2004). “Glaisher, James Whitbread Lee.” In Oxford Dictionary of National Biography, edited by H. C. G. Mathew and Brian Harrison. Vol. 22, pp. 412–413. Oxford: Oxford University Press. Glaisher, J. W. L. (1874). “The Committee On Mathematical Tables.” In Report of the Forty-Third Meeting of the British Association for the Advancement of Science Held at Bradford in September 1873, pp. 1–175. London: John Murray. Taylor, R. J. (ed.) (1987). History of the Royal Astronomical Society. Vol. 2, 1920– 1980. Oxford: Blackwell Scientific Publications. Turner, Herbert Hall (1929). “James Whitbread Lee Glaisher.” Monthly Notices of the Royal Astronomical Society 89: 300–308. Godefridus Wendelinus > Wendelen, Govaart [Gottfried, Godefried] 425 426 G Godin, Louis Godin, Louis Born Died Paris, France, 28 February 1704 Cádiz, Spain, 11 September 1760 The Frenchman Louis Godin is part of the history of astronomy mainly for two activities conducted outside of France. First, he participated in a geodesic expedition that measured the degree in lands of the Viceroyalty of Peru; second, he was director of the Academy of the Marine Guard of the Kingdom of Spain, in Cádiz, and of its astronomical observatory. The son of François Godin and Elisabeth Charron, Godin studied astronomy with Joseph Delisle, at the Royal College of Paris. He was selected as a member of the Academy of Sciences without having published anything in 1725. His astronomical and literary career started in the academy by publishing minor works until the institution made him editor of the previously unedited Mémoires de l’Académie des sciences, corresponding to the years 1666–1730, which comprise seven volumes. From 1730, up to the volume for 1735, Godin was also in charge of editing of the Connaissance des temps, the official French astronomical ephemerides. The academy chose Godin as the leader of the expedition to measure three meridian degrees in lands of Ecuador more because of his prestige as an organizer and scholar than as an astronomer. His persistence was to bring the journey to pass. With Godin at the head of the expedition and with members that included Pierre Bouguer, Charles de la Condamine, and Joseph Jussieu, along with draftsmen and helpers, the Kingdom of Spain added the sailors Jorge Juan and Antonio de Ulloa. The tensions within the expedition led Godin to have serious arguments with Bouguer and La Condamine. Helped by the Spaniards, Godin took the measurements on his own, duplicated by the French explorers. The Spanish publication of the data, Astronomical and physical observations taken in the Kingdoms of Peru by order of S.M. (Madrid, 1748), signed by Juan and Ulloa, without doubt collected the most important astronomical work of Godin and illustrates his guidance to the young Spanish sailors, who returned to Spain in 1745 having become observers and mathematical experts. Because of unknown circumstances, Godin decided to stay in Peru upon his companions’ return. In 1743 he accepted the post of head of the mathematics department at the University of Lima, replacing Pedro de Peralta. On 13 October 1745 he was expelled from the Academy of Sciences and replaced by César Cassini de Thury. In Lima, Godin did little. He did not have to teach, like previous professors had, due to a lack of students. He collaborated with the Gaceta of Lima and contributed the plans for rebuilding the city after the earthquake on 26 October 1746. Still in Lima, on 29 August 1747, Godin was named (at the behest of Jorge Juan) director of the Marine Guard Academy in Cádiz, Spain. He arrived in Europe in 1751, by way of Lisbon and Paris, where he spent a year trying to arrange his reinstatement into the academy, which he finally accomplished in 1756. Godin arrived in Cádiz during the summer of 1753 to take charge as director of the academy and the newly created Marine Observatory. On 26 October 1753, he observed a partial solar eclipse and used the observations to verify the geographic coordinates of the observatory. At the same time, he participated in the “friendly literary assembly,” a gathering of sailors, doctors, and learned people, organized by Jorge Juan. Between 1 December 1755 and 10 January 1757, Godin was in Paris, fixing his affairs with the Academy. He then returned to Cádiz, where he became gravely ill. This situation, which caused him to fear for his life, continued until the beginning of the summer of 1759. Godin was able to conduct few astronomical projects before his death. Godin observed comet 1P/Halley in April and May of 1759, prepared a history of the Cádiz Observatory, and did various works for a Celestial History of the 18th Century, which remain unpublished in his personal documents. The subsequent story of those documents is complex. The Spanish Navy claimed them, and, at least part of them, were sent to France, where they were dispersed. In agreement with his troubled biography, Godin’s astronomical publications were scarce, most of them in the Mémoires de l’Académie de sciences, which were written before his voyage to America in 1734. His true contribution to astronomy was, without a doubt, the mark he left in the work by Juan and Ulloa, which was the first complete description to be published on the methods used to measure 3° of longitude in the Equator and to correct observations for atmospheric refraction, and which included the methods to determine the differences in length by using sound. Antonio E. Ten Translated by: Claudia Netz Selected References Grandjean de Fouchy, J. P. “Ëloge de M. Godin.” Histoire de l’Académie de Sciences pour 1760: 181–194. Lafuente, A. and A. Mazuecos (1877). Los caballeros del punto fijo. Barcelona: Serbal/CSIC. Lafuente, A., and M. Sellés (1988). El observatorio de Cádiz (1753–1831). Madrid: Ministerio de Defensa. Ten Ros, A. E. (1988). “Ciencia e ilustración en la Universidad de Lima.” Asclepio 40: 187–221. Godwin, Francis Flourished England, circa 1566–1633 English Bishop Francis Godwin posthumously inspired the latter Renaissance with his tale of in situ “space exploration”: The Man in the Moone (1638). Selected Reference Nicholson, Marjorie Hope (1948). Voyages to the Moon. New York: MacMillan. Goldberg, Leo Gökmen, Mehmed Fatin Born Died 1877 Istanbul, (Turkey), 6 December, 1955 Fatin Gökmen is known for his reinvigoration of astronomical education in 20th-century Turkey. He was the founder and first director of the Kandilli Observatory in Istanbul, and his contributions include astronomical work on observation, the calendar, and instruments. Fatin – “Gökmen” was added in 1936, after the foundation of the Turkish state – came from the district of Akseki in Antalya. His father, Qadi Abdulgaffar Efendi, was a traditional Islamic scholar, and Fatin Gökmen’s early schooling was in the madrasa of his native town. He then moved to Istanbul where he learned classical astronomy and the methods of calendar preparation from the last Ottoman head-astronomer, Hüseyin Hilmi Efendi. He also worked in the famous Sultan Selîm time-keeping Institute (muvakkithane). Fatin Gökmen, encouraged by the Turkish mathematician Salih Zeki, pursued his higher education in the fields of astronomy and mathematics in the Ottoman University’s Faculty of Sciences (Dârülfünûn), which opened on 31 August 1900. After 3 years, he graduated from that faculty with the first rank. Fatin subsequently taught mathematics in various high schools, and was eventually appointed in 1909 as a lecturer in astronomy and probability at the Faculty of Sciences of the Ottoman University. He continued to lecture there until he resigned in 1933, as a consequence of the ongoing reform movement. Fatin Gökmen was a key figure in facilitating the emergence of the modern astronomical observatory in Turkey. The Imperial Observatory, established in Istanbul in 1867 under the directorship of A. Coumbary, was mainly a meteorological center. With the assistance of Salih Zeki, Fatin Gökmen was appointed director of this observatory, and he was also given the task of establishing a new observatory. On 4 September 1910 he began work on setting up such a facility, which was to become the Kandilli Observatory. Fatin Gökmen’s initial work at the Kandilli Observatory was publishing meteorology bulletins in 1911/1912. His work later became more astronomically oriented and continued until his retirement in 1943. Fatin Gökmen first wrote on astronomy for university lectures and was influenced by the analytical methods of the French astronomer Henri Andoyer. This revealed itself particularly in Fatin’s work on positional astronomy entitled Vaz�iyyāt ve vaz�iyyāta �āid mesāil-i umūmiyya. In 1927, he published his work entitled Mathematical Astronomy and the Double-false Theory, compiled from his lectures at the university. His most important essay is on the determination and calculation of the total solar eclipse. Fatin approached the solar eclipse from an analytical perspective and, using geometry, explained the difficulties he encountered with his calculations. Using Andoyer’s methods, he analyzed the solar eclipse of 16 June 1936, and his results were published by the Kandilli Observatory as the L’eclipse totale du soleil du 19 Juin 1936. Besides being an astronomer, Fatin Gökmen also did work in the history of astronomy, particularly regarding observational G instruments. He pursued important research on the subjects of astronomy and the calendar among premodern Turks as a contribution to The Society for the Investigation of Turkish History. In his work entitled L’astronomie et le calendrier chez les Turcs (The astronomy and the calendar of the [early] Turks), he benefited from studying Zīj-i īlkhānī of the great Islamic astronomer Naṣīr al-Dīn al-Ṭūsī. As a result of this study, Fatin concluded that the early Turks had made use of “Hellenic–Chaldean” astronomy, i. e., the geocentric astronomy of Ptolemy; this was in contrast to the conventional view that they had followed Chinese astronomy. As for Fatin’s historical work on observational instruments, he made original contributions in his studies of the quadrant, which he published in his Rubu�tahtası nazariyatı ve tersimi (The quadrant: its theory and design; Istanbul, 1948). In addition to explaining the function of this instrument, he also shed light on the Turkish contribution to it and its transmission to modern times. At the end of the work, Fatin included a glossary of astronomical terms in Turkish and French. In this way he contributed to building a bridge between the old and the new astronomy. Fatin Gökmen also conceived of using a particular quadrant (the Rub�al-muqanṭarāṭ) to make a table of the minimum and maximum values of the variations of the azimuth and the hour angle (up to ±3°) for a certain latitude. He further used the quadrant for finding the precision level required in geomagnetism, maps, and other related items as well as for determining the amount of refraction of light and for solving trigonometric problems. Finally, we should mention that Fatin Gökmen made important contributions to the establishment and development of modern meteorology, geophysics, and seismology in Turkey. Mustafa Kaçar Selected References Anon. (1969). “Gökmen, Fatin.” In Türk Ansiklopedisi (Turkish encyclopedia). Vol. 17, pp. 501–502. Ankara. İhsanoğlu, Ekmeleddin (2002). “The Ottoman Scientific-Scholarly Literature.” In History of the Ottoman State, Society and Civilisation, edited by E. İhsanoğlu. Vol. 2, pp. 517–603, esp. 601–603. Istanbul: IRCICA. İhsanoğlu, Ekmeleddin, et al. (1997). Osmanlı Astronomi Literatürü Tarihi (OALT) (History of astronomy literature during the Ottoman period). 2 Vols. Istanbul: IRCICA, Vol. 2, pp. 720–725. Goldberg, Leo Born Died Brooklyn, New York, USA, 26 January 1913 Tucson, Arizona, USA, 1 November 1987 American astrophysicist Leo Goldberg contributed significantly to our understanding of the physics of gaseous nebulae, stellar abundances, and the physics of stellar mass loss, chromospheres, and coronae. Born to Russian–Polish immigrant parents, Goldberg was 427 428 G Goldschmidt, Hermann Chaim Meyer an orphan at nine, but with financial help from an interested businessman, he was able to attend Harvard University receiving a BS in 1934, an AM in 1937, and a Ph.D. in astrophysics in 1938 for work with Donald Menzel on the quantum mechanics of astrophysically interesting atoms. Goldberg at that time also analyzed the spectra of a number of O and B stars, finding that it was necessary to introduce a new parameter called microturbulence (representing convection on length scales smaller than the photon mean free path) into the analysis. He continued to develop this method over several decades to measure, for instance, how convection varies with depth in the atmospheres of stars. After a brief period (1938–1941) as a research fellow at Harvard University, Goldberg became a research associate at the University of Michigan and McMath–Hulbert Observatory, moving upward to assistant and then full professor, and serving as chair of the department and director of the observatory from 1946 to 1960. He was Higgins Professor of Astronomy at Harvard University (1960–1973), department chair (1966–1971), and director of the Harvard College Observatory (1966–1971) in succession to Menzel. He moved to Kitt Peak National Observatory as director in 1971, retiring in 1977. During the war years, Goldberg and his student Lawrence Aller wrote a well-known and frequently reprinted introduction to astrophysics, Atoms, Stars, and Nebulae. At the University of Michigan, he, Aller, and Edith Muller reanalyzed the spectrum of the Sun using newly available atomic data; their compilation of solar abundances remained the standard for more than 20 years after the 1960 publication. Goldberg had also been involved in the development of new infrared detectors at the University of Michigan. Upon returning to Harvard he also became interested in the possibilities of observation from space, particularly in the ultraviolet, where solar abundances could be measured in both the photosphere and the chromosphere using ions not observable from the ground. Detectors developed partly under his leadership flew on rockets from 1964, on Orbiting Solar Observatories IV and VI, and on Skylab. A parallel laboratory effort with William H. Parkinson and Edmond M. Reeves determined atomic properties and transition probabilities for a number of highly ionized atoms found in stellar winds, coronae, and chromospheres. Taking advantage of the Kitt Peak telescopes during his directorship, Goldberg began work on physical processes in red giant stars, including mass motions, chromospheres, and measurements of angular diameter and limb darkening. He published his last paper, on Betelgeuse, only 2 years before his death. Goldberg had a lifelong interest in international relations within science, chairing the United States committee for the International Astronomical Union [IAU] at the height of the Cold War. He was vice president of the IAU (1958–1964), president (1973–1976), and founder and first president (1964–1967) of its Commission on Astronomical Observations from Outside the Terrestrial Atmosphere (now High Energy and Space Astrophysics). Another long-term interest was the unity of the American astronomical community and the provision of first-rate observing facilities for all astronomers, independent of their affiliation. Thus Goldberg was part of the organizing committee of the Association of Universities for Research in Astronomy [AURA] (1956–1957; board member, 1966–1971) that built and operates Kitt Peak and the other national optical observatories. Moreover, he was an early member of the board of Associated Universities (1957–1966), which operates additional national facilities. Goldberg served as vice president (1959–1961) and president (1964–1966) of the American Astronomical Society. He served on advisory boards for the National Academy of Sciences, Air Force, National Aeronautics and Space Administration, and Department of Defense, receiving medals from the latter two. He edited Annual Reviews of Astronomy and Astrophysics from its inception in 1961 through 1973. Léo Houziaux Selected References Dalgarno, Alexander, David Layzer, Robert W. Noyes, and William H. Parkinson (1990). “Leo Goldberg.” Physics Today 43, no. 2: 144–148. Hearnshaw, J. B. (1986). The Analysis of Starlight: One Hundred and Fifty Years of Astronomical Spectroscopy. Cambridge: Cambridge University Press, esp. pp. 247–249. ______ (1988). “Leo Goldberg (1913–1987).” Journal of the Royal Astronomical, Society of Canada 82: 213. McCray, W. Patrick (2004). Giant Telescopes: Astronomical Ambition and the Promise of Technology. Cambridge, Massachusetts: Harvard University Press. Welther, Barbara L. (1988). “Leo Goldberg (1913–1987): Satellites to Supergiants.” Journal of the American Association of Variable Stars Observers 17: 10–14. Goldschmidt, Hermann Chaim Meyer Born Died Frankfurt am Main, (Germany), 17 June 1802 Fontainebleau, Seine-et-Marne, France, 30 August 1866 Hermann Goldschmidt, the son of Meyer Salomon Goldschmidt and Hindle Cassel, was most noted for his discovery of 14 asteroids. Between 1820 and 1846, Goldschmidt studied painting in Munich under Schnorr von Cornelius and lived in the Netherlands, Paris, and Rome, finally settling permanently in Paris. Here he achieved some success as a painter, perhaps through the efforts of his friend Alexander von Humboldt. In 1847 Goldschmidt was commissioned to copy portrait paintings in foreign collections for King Louis-Philippe’s expanded collection of art at Versailles, and his Romeo and Juliet was purchased by the state from the Paris Salon of 1857. Goldschmidt married Adelaide Pierette Moreau in 1861 and had two children, Hélène and Josephine. Goldschmidt’s painting career helped subsidize his passion for astronomy as an amateur. From a rooftop room in the Café Procope, Paris, Goldschmidt made his first discovery of a minor planet, (21) Lutetia, in 1852. Over the next 14 years his more famous contemporaries, including Urbain Le Verrier and Dominique Arago, named his 14 asteroid discoveries. Goldschmidt was involved in a debate over the system of nomenclature for minor planets in the pages of Astronomische Nachrichten, and was one of the first to have one of his discoveries named for a nonmythological figure, (45) Eugenia, the Empress of France. Goodricke, John Goldschmidt was an assiduous observer of variable stars, comets, and nebulae, and traveled to Spain to observe the total solar eclipse of July 1860. Among his many reports of astronomical findings, his only notable erroneous submission was a mistaken sighting of a ninth moon of Saturn, not in fact discovered until 1898. For his asteroid discoveries and other astronomical contributions, the French Academy of Science awarded Goldschmidt the prestigious Lalande Astronomical Prize eight times, the Cross of the Legion of Honor was conferred upon him in 1857, and in 1862 he was awarded an annual pension for his astronomical work. The Royal Astronomical Society conferred its Gold Medal on Goldschmidt in 1861. Alun Ward Selected References J. C. (1867). “Hermann Goldschmidt.” Monthly Notices of the Royal Astronomical Society 27: 115–117. Mérimée, Prosper (1941–1964). Correspondance générale. Vol. 8, nos. 2575 and 2577. Paris: Le Divan. Goldsmid, Johann > Fabricius, Johann Goodacre, Walter G was far superior in positional accuracy. Goodacre’s map served as the basis of the first detailed lunar contour map, constructed in 1934 by the German selenographer Helmut Ritter. In 1931, Goodacre privately published a book containing a reduced copy of his map and an exhaustive description of the named formations under the title The Moon with a Description of Its Surface Features. Unfortunately, the press run was a short one, and the volume is now exceedingly rare, commanding exorbitant prices by collectors. For his monograph, Goodacre reduced the scale of his 1910 map from 77 in. to 60 in., enhanced it with additional detail, and then divided it into 25 sections to facilitate his discussion of various lunar features. His 41-page introduction to the book is a useful introduction to selenography and includes a discussion of the classification of lunar structures supplemented by six plates containing 36 diagrams and one photograph. The discussion includes historical observers as well as more contemporary authorities like William Pickering. Goodacre’s approach to selenography was pure Baconian empiricism. He wrote: One of the chief sources of pleasure to the lunar observer is to discover and record, at some time or other, details not on any of the maps. It also follows that in the future when a map is produced which shows all the detail visible in our telescopes, then the task of selenography will be completed. In 1928, Goodacre endowed a fund to the BAA for the recognition of outstanding members. The Walter Goodacre Medal and Gift is considered the association’s highest honor; it has been awarded approximately biennially since 1930. In 1883, Goodacre married Frances Elizabeth Evison; their marriage was blessed with two children, though Francis died in 1910. Thomas A. Dobbins Born Died Loughborough, Leicestershire, England, 1856 Bournemouth, Dorset, England, 1 May 1938 Walter Goodacre was the preeminent British selenographer of the early 20th century. His monograph on the Moon was considered a primary resource for selenographers for several decades after its publication. Goodacre was born at Loughborough, but in 1863 the family moved to London, where his father founded a carpet manufacturing business. Walter Goodacre established a branch of the family business in India and visited there frequently for 15 years. He succeeded his father as head of the firm in London, remaining in that position until his retirement in 1929. Attracted to astronomy as a boy, for a time Goodacre directed the Lunar Section of the Liverpool Astronomical Society. As a founding member of the British Astronomical Association [BAA], following the death of Thomas Elger, Goodacre was appointed to the directorship of the BAA Lunar Section, a post he held until 1 year before his death. He served as president of the BAA from 1922 to 1924, and was a lifetime fellow of the Royal Astronomical Society. In 1910, Goodacre issued a 77-in.-diameter lunar map (scale 1:1,800,000) in 25 sections, the first such map to employ rectangular coordinates or direction cosines. Principally based on photographs, it employed 1,400 positions measured from negatives obtained at the Paris and Yerkes observatories by Samuel Saunder, a mathematics master at Wellington College. Although inferior in aesthetic appeal to the earlier maps of Johann von Mädler and Johann Schmidt, it Selected References Both, Ernst E. (1961). A History of Lunar Studies. Buffalo, New York: Buffalo Museum of Science. Goodacre, Walter A. (1931). The Moon with a Description of Its Surface Formations. Bournemouth, England: privately published. Sheehan, William P. and Thomas A. Dobbins (2001). Epic Moon: A History of Lunar Exploration in the Age of the Telescope. Richmond, Virginia: Willmann-Bell. Steavenson, William H. (1939). “Walter Goodacre.” Monthly Notices of the Royal Astronomical Society 99: 310–311. Whitaker, Ewen A. (1999). Mapping and Naming the Moon: A History of Lunar Cartography and Nomenclature. Cambridge: Cambridge University Press. Wilkins, H. P. and Patrick Moore (1958). The Moon. London: Faber and Faber, p. 368. Goodricke, John Born Died Groningen, the Netherlands, 17 September 1764 York, England, 20 April 1786 John Goodricke was a pioneer investigator of variable stars. Goodricke’s family moved to England, where he attended the Braidwood Academy, Great Britain’s first formal school for deaf children. According to an 429 430 G Goodricke, John 1815 report, “he lost his hearing by a fever when an infant, and was consequently dumb: but having in part conquered this disadvantage by the assistance of Mr. Braidwood, he made surprising proficiency, becoming a very tolerable classic, and an excellent mathematician.” Goodricke then entered the Warrington Academy, a dissenting academy. His family settled in York. It is there that his first entry in an “astronomical journal” is dated 16 November 1781. The Goodrickes’ neighbor, Nathaniel Pigott, was an amateur astronomer, and Pigott’s son, Edward, was also enthusiastic about astronomy. Edward Pigott’s personal correspondence indicated that he had a challenge communicating with his deaf friend, although he welcomed the company of a like-minded enthusiast. Communicating side by side in the dark during observations was especially difficult. Pigott, 11 years older than Goodricke, was in many ways his mentor. He encouraged Goodricke to watch for variable stars and introduced him to the variability of Algol (β Persei). Both had become fascinated with the name “Algol” and romanticized its meanings to the ancient world. During this early period, Goodricke used opera glasses and a small perspective glass with a magnification of only 10× or 12× to observe comets and stars, including William Herschel’s recent discovery of a “comet” (later to be named the planet Uranus). Goodricke finally acquired an achromatic telescope with greater magnification, modified it with crosswires, and continued to study Uranus. In his astronomical journal, Goodricke’s entry for 12 November 1782 expresses astonishment at having found a large drop in the brightness of Algol. Only a week before, he had observed Algol as second magnitude. Goodricke was struck by the suddenness of this variation. Following many more observations, he contacted the Royal Society through Edward Pigott. William Herschel himself took the report seriously, then made his own observations and reported them on 8 May to the Royal Society. From that time, Goodricke and Herschel corresponded regularly. Among the correspondence is a draft of a letter written by Goodricke to Herschel on 2 September 1784, dealing with the prediction of an Algol brightness minimum. On this subject, Goodricke also wrote to Anthony Shepherd, Plumian Professor at Cambridge, a letter subsequently read to the Royal Society on 12 May 1783 and published in the Philosophical Transactions as “A series of observations on, and a discovery of, the period of variation of light of the bright star in the head of Medusa, called Algol.” Goodricke’s estimate of the period of Algol was 2 days, 20 h, 45 min. This differs only a few minutes from the modern value. Even with today’s sophisticated telescopes and the statistical analyses of irregularities in the light curves of the stars, this observation of Algol is difficult. Goodricke also conjectured on the cause of the changes in brightness, noting that Algol appeared to have a companion, and that the system eclipsed itself at regular intervals. With his letter to the Royal Society, Goodricke included a table of his observations that contained the dates, times, and number of revolutions. The speculation of a periodic eclipse by a large, dark body remained unproven for nearly a century until the German astronomer Hermann Vogel used spectrographic analysis to confirm that Algol was indeed a binary star. Goodricke’s discovery led to great interest in Algol’s periodicity among other astronomers who sent confirmations of the amateur’s observations to the Royal Society. Some used Goodricke’s paper to argue for the existence of planets outside the Solar System. At the age of 19, Goodricke received Britain’s highest scientific honor, the Royal Society’s Copley Medal. In August 1784, Goodricke began to study Lyra, Capricorn, and Aquarius and compare his measurements with the data found in John Flamsteed’s Atlas. By September, he had concluded that β Lyrae also was a variable star whose light curve could be explained by eclipses occurring at intervals of a little more than twelve days. A month later, Goodricke identified δ Cephei as a variable star system. He noticed that it behaved differently from Algol, brightening much faster than it faded, in a way not easily explained by eclipses. He wrote to Nevil Maskelyne and described the strange quality in the fluctuations of brightness in δ Cephei. In this letter, published in Philosophical Transactions in 1785, Goodricke again credited the assistance of Pigott. News of the young deaf astronomer’s findings made an impact on the British scientific community. Sadly, he would experience few of their accolades. Two weeks after he was elected a fellow of the Royal Society, John Goodricke died after exposure to the cold night air while making his observations. Minor planet (3116) Goodricke is named in his honor. Harry G. Lang Selected References Gilman, Carolyn (1978). “John Goodricke and His Variable Stars.” Sky & Telescope 56, no. 5: 400–403. Golladay, L. E. (1962). “John Goodricke Story Includes Locating of His Observatory; Memorial Fund Will Honor Him.” American Era 48: 33–35, 37. Gore, John Ellard Hoskin, Michael (1982). “Goodricke, Pigott and the Quest for Variable Stars.” In Stellar Astronomy: Historical Studies. Chalfont, St. Giles, Bucks, England: Science History Publications. Lang, Harry G. (1994). Silence of the Spheres: The Deaf Experience in the History of Science. Westport, Connecticut: Bergin and Garvey. Lang, Harry G., and Bonnie Meath-Lang. Deaf Persons in the Arts and Sciences: A Biographical Dictionary. Westport, Connecticut: Greenwood, 1995. Gopčević, Spiridion > Brenner, Leo Gore, John Ellard Born Died Athlone, Co. Westmeath, Ireland, 1 June 1845 Dublin, Ireland, 22 July 1910 As a skilled amateur astronomer and prolific writer, John Gore made significant contributions to variable-star and binary-star astronomy, and to the popularization of astronomy and cosmology. He was among the first to estimate the size of red giant and white dwarf stars. Gore was the oldest son of John Ribton Gore (1820–1894), Archdeacon of Achonry and his wife Frances (née Ellard). He was educated privately and entered Trinity College Dublin in 1863. Gore graduated in 1865 with a diploma in engineering and a special G certificate of merit, standing first in his class in both years. After working as a railway engineer in Ireland for more than 2 years, he joined the Indian government public works department in 1869 and worked on the construction of the Sirhind canal in Punjab. Under the clear Indian skies Gore began to observe double and variable stars with achromatic telescopes of 3-in. and 3.9-in. aperture. The results of this work were published in 1877 as Southern Stellar Objects for Small Telescopes and described objects between the celestial equator and −55° declination. Observing with the naked eye at an altitude of 6,000 ft in the Himalayas, Gore was able to detect previously unrecorded rifts and faint extensions of the Milky Way. While Gore was in India, he was elected a member of the Royal Irish Academy on 12 April 1875. Gore returned to Ireland on 2 years’ furlough in 1877 but never returned to India. He retired from the Indian service in 1879 and drew a pension for the rest of his life. Gore resided at Dromard, near Ballysadare, where his father had been appointed rector in 1867. After the death of his father in 1894, Gore moved to Dublin where he lived in lodgings for the rest of his life. While there is no evidence that Gore studied astronomy as a student at Trinity College, he would have had ample opportunities to visit the observatory of Edward Cooper at Markree Castle Observatory in County Sligo. Markree Castle was only about 10 miles from Dromard. It seems very likely that Gore would have known and consulted August William Doberck (1852–1941), director of Markree Observatory from 1874 to 1883, and his successor Albert Marth (1828–1897). However, for his own observations, Gore never used large telescopes but relied on his naked eyes or on a pair of 6 × 50 binoculars. In January 1884, Gore presented to the Royal Irish Academy his first major paper entitled A Catalogue of Known Variable Stars with Notes and Observations. The catalog contained 190 entries, which were increased to 243 in the revised edition published 4 years later. In 1884, he also presented to the academy A Catalogue of Suspected Variable Stars with Supplementary Notes; this contained details of 736 stars. Between 1884 and 1890, Gore discovered four variable stars: W Cygni, S Sagittae, U Orionis, and X Herculis. From 1890 to 1899 he was director of the Variable Star Section of the British Astronomical Association. W.W. Bryant, in his History of Astronomy (1907), named Gore as one of the three leading observers of variable stars in Britain and Ireland. From 1879 onwards Gore devoted much time and energy to calculating the orbits of binary star systems. In 1890 he presented to the academy A Catalogue of binary stars for which orbits have been computed with notes, containing details of 59 binary systems. Gore may have been among the first to realize the great range in size of stars. In 1894, his friend, the amateur astronomer William Monck of Dublin, suggested that there were probably two distinct classes of yellow stars – one being dull and near, the other being bright and remote. This clue to the existence of dwarf and giant stars was taken up by Gore. Using heliometer parallax measurements by William Elkins, Gore estimated that the red star Arcturus had a diameter about 80 times that of the Sun. Although Arcturus’s size was overestimated because of inaccurate data, Gore’s argument was sound. In 1905, Gore attempted to estimate the density of Sirius B, which was known to have a mass equal to the Sun’s mass. He calculated that 431 432 G Gorton, Sandford the satellite was about 1,000 times fainter than the Sun. Its faintness could be due to either its small size or its low surface luminosity. If Gore assumed its surface luminosity was the same as the Sun, he found it would have a density over 44,000 times the density of water, which he thought “entirely out of the question.” The modern value of the mean density of Sirius B is in the region of three million times the density of water. Between 1877 and 1909, Gore published 12 popular books on astronomy. In 1894 he published his translation of Camille Flammarion’s Astronomie Populaire(Popular Astronomy), which received very favorable reviews. The same year The Worlds of Space appeared. This collection of miscellaneous papers and articles, which included some chapters on life on other worlds, was criticized by H. G. Wells for not being more speculative. Gore contributed to the astronomy volume of the Concise Knowledge Library (1898) in collaboration with Agnes Clerke and Alfred Fowler. In his The Visible Universe, Gore speculated on the origin and construction of the heavens, analyzing a number of cosmologies including those of Thomas Wright, Immanuel Kant, Johann Lambert, William Herschel, Richard Proctor, and others. Gore concluded that our Universe (Galaxy) is limited and cannot contain an infinite number of stars. His reasoning was similar to that of Jean Loys de Chéseaux and Heinrich Olbers with respect to the brightness of the night sky, but Gore concluded that there might well be other “external universes” or galaxies that were invisible. Gore was a regular contributor to Monthly Notices of the Royal Astronomical Society, The Observatory, and the Journal of the British Astronomical Association. He was elected a fellow of the Royal Astronomical Society in 1878 and served on the councils of the Royal Irish Academy and the Royal Dublin Society. Gore was a leading member of the Liverpool Astronomical Society and was chosen as a vice president of the British Astronomical Association on its foundation. He was an honorary member of the Welsh Astronomical Society, a fellow of the Association Astronomique de France, and a corresponding fellow of the Royal Astronomical Society of Canada. Gore was described as a grave, quiet man with few friends but very much liked by those who knew him. He was noted for his quiet wisdom and gracious courtesy. He never married, and, when failing sight restricted his astronomical activities, he presented his library to the Royal Irish Academy. Gore died after being struck by a horsedrawn cab. Gorton, Sandford Born Died England, 1823 Clapton, (London), England, 14 February 1879 Founding editor and publisher of the Astronomical Register, Sandford Gorton was an active member of the Royal Astronomical Society [RAS] and attended its meetings regularly. He realized that there was no medium for amateurs like him to compare observations and exchange notes on techniques, topics that were increasingly excluded from the content RAS meetings. Also, disturbed that the minutes of RAS meetings published in the Monthly Notices of the Royal Astronomical Society failed to report the essential details of arguments, and were instead dry and limited in content to essentially the transactions taken in the meeting, Gorton resolved to cure such ailments by publishing a new journal, The Astronomical Register. This is how Gorton described it in the first issue in January 1863, “the present attempt [will] introduce a sort of astronomical ‘Notes and Queries,’ a medium of communication for amateurs and others …” It was his intent to include a monthly “table of occurrences” or short-term ephemerides, to save time for the “nonprofessional observers.” A printer by trade, Gorton wrote and printed the entire first volume himself. However, he was unable to sustain the burden of printing as the Register grew in size and circulation. Gorton did, however, retain complete editorial control for a number of years, and the results were remarkable. The faithful reporting of the RAS meetings by Gorton and others who followed him as Register editor reveal much of the dynamics of the professionalization of the RAS over the next two decades. After his death, The Astronomical Register continued until 1886. By then, it had, in effect, been supplanted by another publication, The Observatory, created by the RAS professional astronomers in the year of Gorton’s death to serve many of the same functions which Gorton’s Astronomical Register had been intended to serve. Thomas R. Williams Selected Reference Anon. “Sandford Gorton.” Monthly Notices of the Royal Astronomical Society 40 (1880): 194–195. Ian Elliott Selected References Crowe, Michael J. (1986). The Extraterrestrial Life Debate, 1750–1900: The Idea of a Plurality of Worlds from Kant to Lowell. Cambridge: Cambridge University Press, pp. 462–463. DeVorkin, David H. (1984). “Stellar Evolution and the Origin of the Hertzsprung–Russell Diagram.” In Astrophysics and Twentieth-Century Astronomy to 1950: Part A, edited by Owen Gingerich, pp. 90–108. Vol. 4A of The General History of Astronomy. Cambridge: Cambridge University Press. Gore, John Ellard (1893). The Visible Universe: Chapters on the Origin and Construction of the Heavens. London: Crosby, Lockwood and Son. ______ (1894). The Worlds of Space: A Series of Popular Articles on Astronomical Subjects. London: A. D. Innes and Co. Macpherson, Jr., Hector, (1905). “John Ellard Gore.” In Astronomers of To-day and Their Work, pp. 145–155. London: Gall and Inglis. ______ (1910). “John Ellard Gore.” Popular Astronomy 18: 519–525. Gothard, Jenõ [Eugen] von Born Died Herény, (Hungary), 31 May 1857 Herény, (Hungary), 29 May 1909 One of the first astrophysicists in Hungary, Jenõ von Gothard was a respected early contributor to the evolution of astrophysics, especially in the practical aspects of instrument development and application. As the oldest son of István and Erzsébet (née Brunner) von Gothard, Jenõ von Gothard was born into a privileged family. Both his father and his grandfather were interested in avocational science. After completing Gould, Benjamin Apthorp the curriculum at the gymnasium in Szombathely in 1875, Gothard studied at the Polytechnische-Hochschule in Vienna, earning a diploma of mechanical engineering in 1879. While in Vienna, he also studied geodesy and astronomy, gaining experience in the institute’s astronomical observatory. As was the convention in those days, Gothard then visited universities in Western Europe before he settled on a career. He was accompanied, for at least part of that trip, by his friend Miklós Konkoly Thege of Ógyalla, Hungary. When Gothard eventually returned to his family estate at Herény, his intention was to build a physical laboratory. However, on being persuaded by Konkoly Thege, Gothard and his brother, Sándor (Alexander) von Gothard, built an astrophysical observatory at Herény (now suburb of Szombathely). The first observations from the observatory were made from the new dome in the autumn of 1881. After it was completed in 1882, the observatory was equipped with state-of-the-art instruments. Konkoly Thege donated the largest telescope to the new observatory, a Browning silver-on-glass 10.25-in. Newtonian reflector. After a few years of more general observing, the observatory program settled down to the development of photographic and spectrographic techniques and their exploitation in astronomy. Gothard made pioneering studies on application of photographic technique in astronomy. He photographed the first extragalactic supernova, S Andromedae (SN 1885 A), within days of its independent discovery on 19 August 1885 by Countess Berta Dégenfeld-Schomburg at the nearby Kiskartal Observatory. He discovered the central star of the Ring Nebula (M57, a planetary nebula in Lyra) on a photographic plate in 1886. Gothard’s comparison of the spectrum of Nova Aurigae 1892 with the spectra of several nebulae and other celestial objects obtained with the same quartz spectrograph allowed him to identify with certainty several bright lines that appeared both in the spectrum of the nova and in the nebulae, at times giving the nova spectrum the appearance of a Wolf–Rayet star. Similar studies conducted for Nova Persei (1901) with an objective prism, as well as the quartz spectrograph, showed the nova to be passing through several specific stages as it matured. On the basis of these observations Gothard was able to point out that during the nova eruption a gaseous envelope was apparently ejected from the star. Gothard published his astrophysical observations mainly in Astronomische Nachrichten as well as in the Memoirs of the Hungarian Academy of Sciences. Translations of these articles were also published in Astronomy and Astrophysics and Monthly Notices of the Royal Astronomical Society. Gothard published several books in Hungarian about modern observational methods in astronomy. He made several astronomical instruments in his workshop for other institutions, including a transit instrument for the Heidelberg Observatory and a spectrograph for the technical university in Vienna. His wedge photometer served as the model for the photometer marketed by the firm of Otto Töpfer, of Potsdam. Gothard also was a prolific inventor of instruments for photography, a field in which his contributions are recognized more highly than they are in astronomy. In 1895, Gothard was appointed technical director of the Vasvármegye Electric Works, an electrical system then being developed in the county surrounding Szombathely. His duties in G that position, which he prosecuted with great success for several years, made it increasingly difficult for him to pursue astrophysics to the extent he might have desired. His health began to fail in 1899, but Gothard deferred retirement from active employment until 1905, devoting the remainder of his life to travel and rest. He never married. Gothard was elected a fellow of the Astronomische Gesellschaft (1881), and of the Royal Astronomical Society (1883), and a corresponding member of the Hungarian Academy of Sciences (1890). A crater on the Moon is named for him. László Szabados Selected References Anon. (1910). “Eugen von Gothard.” Monthly Notices of the Royal Astronomical Society 70: 299. Harkányi, Baron Béla (1910). “Eugene v. Gothard.” Astrophysical Journal 31: 1–7. Horváth, József (1992). “Jenõ Gothard and Miklós Konkoly Thege.” In The Role of Miklós Konkoly Thege in the History of Astronomy in Hungary, edited by Magda Vargha, László Patkós, and Imre Tóth. Budapest: Konkoly Observatory. Vargha, Magda (1986). “Hungarian Astronomy of the Era.” In A Kalocsai Haynald Obzervatórium Története, edited by Imre Mojzes, pp. 31–36. Budapest: MTA-OMIKK Kiadás. Gould, Benjamin Apthorp Born Died Boston, Massachusetts, USA, 27 September 1824 Cambridge, Massachusetts, USA, 26 November 1896 Benjamin Apthorp Gould founded the Astronomical Journal, copioneered with Lewis Rutherfurd the application of photography to astrometry (the determination of the positions of the stars and planets), headed the effort to use the first successful transatlantic telegraph cable to determine the longitude difference between Boston and Liverpool, and created the first comprehensive catalogs of Southern Hemisphere stars. Along the way, Gould was the first director of the Dudley Observatory in Albany, New York, one of the original members of the National Academy of Sciences established by the US Congress in 1863, and a founder and first director of the National Observatory at Córdoba, Argentina. The eldest of four children born to Benjamin Apthorp Gould, Sr. and Lucretia Dana Goddard, Gould was precocious, reading aloud by age three, composing Latin odes by age five, and giving lectures on electricity by age 10. After primary schooling, he attended the Boston Latin School, graduating at age 16 and entering Harvard College. While studying the classics, Gould became interested in biology and astronomy, taking courses from astronomer Benjamin Peirce. In 1844, Gould graduated from Harvard college at age 19 with a distinction in mathematics and physics, along with 433 434 G Gould, Benjamin Apthorp membership in Phi Beta Kappa. After teaching classical languages for a year at the Roxbury Latin School, he decided to pursue a career in science. Upon the advice of Sears Walker, a family friend and mathematical astronomer, Gould decided to spend time in Europe mastering modern languages and European scientific methods. His 3-year trip from 1845 to 1848 became the defining event of Gould’s life. Family connections provided him with letters of introduction to eminent scholars, with whom he established lifelong correspondence. He worked at the Royal Greenwich Observatory with Astronomer Royal George Airy, and at the Paris Observatory with Dominique Arago and Jean Biot. But Gould found his true intellectual home in Germany, where he worked with Johann Encke at the Berlin Observatory and studied mathematics at the University of Göttingen under the supervision of Carl Gauss. In 1848, armed with a new doctorate in astronomy and fluent in Spanish, French, and German, Gould meandered home via the observatory in Altona. There, he spent 4 months with Heinrich Schumacher, founder and editor of the Astronomische Nachrichten, then the foremost international astronomical research journal. It is still being published, though no longer so important. Upon his return, Gould became depressed with the United States’ lack of adequate research libraries and interest in learning foreign languages. He vowed to improve the state of astronomy at home. In 1849, with his own funds, Gould founded the Astronomical Journal, the first scholarly United States research journal of astronomy in the spirit of the Astronomische Nachrichten and in deliberate contrast to the short-lived popular monthly Sidereal Messenger (1846–1848) published by Ormsby Mitchel of the Cincinnati Observatory. So committed was Gould to his mission of improving American astronomy that in 1851, despite the struggling finances of the Astronomical Journal, he turned down an offer from Gauss of a professorship at Göttingen and its promise of becoming director of the Göttingen Observatory. Meanwhile, through his former Harvard college mentor Benjamin Peirce, Gould had become part of the scientific Lazzaroni, a small group of American scientists who shared similar visions for improving the international standing of American scientific research. Among them was Alexander Bache, head of the United States Coast Survey. In 1852, Bache hired Gould to head the Coast Survey’s telegraphic determination of longitudes, succeeding Walker who was terminally ill. Gould remained with the Coast Survey for 15 years, while continuing to publish the Astronomical Journal and pursuing other astronomical work. Following his German mentors, his work focused on the positions and motions of heavenly bodies, emphasizing mathematical rigor and quantification of sources of error. In 1856, he analyzed the determination of the solar parallax made by four temporary observatories south of the Equator. In 1862, he collated a century of observations of the positions of 176 stars from different observatories into a single catalog, which became widely adopted. In 1866, Gould led the Coast Survey’s effort to determine the longitude difference between the Royal Greenwich Observatory and the Harvard College Observatory using the first successful transatlantic telegraph cables. He also quantified observers’ personal equations and extended Walker’s work in measuring the velocity of telegraph signals. In 1861, Gould married the former Mary Apthorp Quincy, fathering five children. She helped finance a private observatory near Cambridge, from which he made meridian observations of faint stars near the North Celestial Pole between 1864 and 1867. In 1866, Gould experimented with Rutherfurd in applying the new technology of photography to astrometry and using a micrometer to measure stellar positions on a photographic plate instead of at the telescope’s eyepiece. Gould also suffered notable failures. In 1855, he became an advisor to the fledgling Dudley Observatory in Albany, New York; his Coast Survey connection was helpful in providing the observatory with instruments and observers. The trustees agreed to bear the financial costs of the Astronomical Journal, so its headquarters were moved from Cambridge to Albany in 1857, followed by Gould himself in 1858 after he became the Observatory’s first director. Pursuing his vision to establish a world-class German-style research Observatory, Gould traveled to Europe to order equipment. The trustees felt the observatory and its telescopes should be opened to the general public, however, which Gould refused. Annoyed by delays in the equipment and unforeseen expenses, the trustees accused Gould of arrogance and incompetence. The standoff degenerated into a vicious newspaper campaign, at the end of which Gould was forcibly ejected from the director’s house in 1859. This highly public controversy polarized the American astronomical community. Moreover, Gould failed both in 1859 and in 1866 to become director of the Harvard College Observatory. He alienated his former mentor Peirce, who became director of the Coast Survey after Bache’s death, a circumstance that compelled Gould to quit his job of 15 years. Gould’s unyielding and antagonistic behavior and his emotional peaks and valleys have led recent historians to speculate that Gould might have suffered from bipolar (manic-depressive) disorder. The 43-year-old Gould’s astronomical career thus seemed over in 1867, but a saving circumstance intervened. Gould had long been aware that there was no comprehensive precision catalog of Southern Hemisphere stars. In 1865, he had approached the Argentine government through its minister in Washington, to explore the possibility of founding a private observatory in Córdoba, a location free from both coastal hurricanes and earthquakes. Luckily for Gould, the minister was Domingo Fautino Sarmiento, a man zealous to improve his nation’s intellectual attainment. Sarmiento offered to cover much of the expense if Gould would establish a national observatory for Argentina. By 1868, Sarmiento himself had become Argentina’s president, and funds for a national observatory had been approved by the Argentine Congress. In 1870, Gould left for Argentina with his wife and children. What he originally envisioned as a 3-year stint eventually stretched out to 15. Before the observatory’s main instruments arrived, Gould and his assistants cataloged all of the naked-eye stars visible in the Southern Hemisphere. In so doing, they established the existence of Gould’s belt of bright stars that intersected the plane of the Milky Way at an angle of 20°, leading Gould to conclude that our solar system was removed from the principal plane of the Milky Way. After the observatory’s main instruments were installed, Gould and his staff measured the positions of 73,160 stars between −23° and −80° declination in his zone catalogs, and 32,448 in the more precise general catalog. These results were published as the Resultados del Observatorio Nacional Argentino in Córdoba, 15 volumes of which appeared between 1877 and Gould’s death. This massive effort laid the groundwork for the authoritative Córdoba Durchmusterung Graham, George catalog of southern stars, compiled by Gould’s successors, John Thome and Charles Perrine. Gould also acquired 1,099 photographic plates, which he measured after returning to the United States; those results were published posthumously. Gould participated in other observations, including the transit of Venus in 1882. Moreover, he organized the Argentine National Meteorological Office, establishing a nationwide system of 25 weather stations extending from the Andes to the Atlantic, and from the tropics to Tierra del Fuego. Gould’s life in Argentina was also marked with tragedy. His two eldest daughters drowned at a family birthday picnic, and his wife died in 1883 during a brief visit to the United States. Gould never fully recovered. About a month after he returned to the United States for good in 1885, Gould was formally greeted by a banquet at the Hotel Vendôme in Boston that included scores of distinguished scientists, some of whom had formerly shunned him after the Dudley Observatory debacle. In 1886, Gould resumed publication of the Astronomical Journal (suspended since 1861 by the Civil War and Gould’s time in Argentina). He died 2 hours after falling down the stairs of his home. Trudy E. Bell Selected References Anon. (1885). “Dr. Gould’s Work in the Argentine Republic.” Nature 33: 9–12. Chandler, Seth C. (1896). “The Life and Work of Dr. Gould.” Science, n.s. 4: 885– 890. (Reprinted verbatim in Popular Astronomy 4 (1897): 341–347.) Comstock, George C. (1924). “Benjamin Apthorp Gould.” Memoirs of the National Academy of Sciences 17, no. 7: 155–180. (Vol. 10 of the Biographical Memoirs, National Academy of Sciences). Hall, Asaph (1897). “Benjamin Apthorp Gould.” Popular Astronomy 4: 337–340. Herrmann, D. B. (1971). “B. A. Gould and His Astronomical Journal.” Journal for the History of Astronomy 2: 98–108. Hodge, John E. (1971). “Benjamin Apthorp Gould and the Founding of the Argentine National Observatory.” Americas 28: 152–175. James, Mary Ann (1987). Elites in Conflict: The Antebellum Clash over the Dudley Observatory. New Brunswick, New Jersey: Rutgers University Press. Marsden, Brian G. (1972). “Gould, Benjamin Apthorp.” In Dictionary of Scientific Biography, edited by Charles Coulston Gillispie. Vol. 5, pp. 479–480. New York: Charles Scribner’s Sons. Olson, Richard G. (1971). “The Gould Controversy at Dudley Observatory: Public and Professional Values in Conflict.” Annals of Science 27: 265–276. Sersic, J. L. (1971). “The First Century of the Cordoba Observatory.” Sky and Telescope 42, no. 6: 347–350. G Graham had no formal education in mechanics or astronomy and was apprenticed (1688–1695) to Henry Aske, a London clockmaker. The second Astronomer Royal, Edmund Halley, introduced Graham to the already successful London clockmaker Thomas Tompion. Graham later married Tompion’s niece and became a business partner with Tompion from 1695 to 1713. He later succeeded to the business as heir by Tompion’s will in 1713. While he is reported to have manufactured only 200 clocks in his lifetime, Graham is credited with the invention of the deadbeat escapement in 1715, the mercury-compensated pendulum in 1722, and the cylinder escapement for watches, which greatly reduced case size needed for the mechanical movements, in 1725. Among Graham’s astronomical instruments was the zenith sector, an instrument designed to detect the annual parallax through measurements of the positions of one or more stars passing overhead of the observer. Graham manufactured one in 1725 for a prosperous amateur astronomer, Samuel Molyneux, of Kew. He followed this with an improved micrometer screw for a reflecting telescope in 1727. Graham also manufactured, for Halley, an 8-ft. quadrant, an instrument widely imitated. Graham was also credited with the invention of the orrery, a clock-driven machine devised to represent the proper motion of the planets about the Sun. Others say that although Graham’s orrery was one of the first, it was not the first instrument of this type. The device was named after the Earl of Orrery, for whom a copy of the instrument was manufactured by instrument-maker John Rowley. Graham manufactured several simple orreries, devices that showed the movement of the Earth about the Sun, and the Moon about the Earth. A grand orrery would show the movements of all of the planets known at the time about the Sun; it might also show day and night on the Earth, the seasons, and the phases of the Moon. Graham provided monetary support and encouragement to John Harrison in 1728. Harrison’s chronometers were the first timekeeping devices able to keep time on a ship within acceptable limits for measuring its position to within 1/2° after traveling from England to the West Indies. Graham may have manufactured some of the early chronograph movements for Harrison to the latter’s specifications. Graham’s precision instruments were used in measurements that established the exact shape of the Earth and increased the precision of Isaac Newton’s calculations for the proportion of the Earth’s axes. Graham was elected to the Royal Society in 1721, serving on its council the following year. He is buried in Westminster Abbey. Donn R. Starkey Graham, George Selected References Born Died Hethersgill, (Cumbria), England, 1674 London, England, 16 November 1751 George Graham, a British clockmaker, horologist, and preeminent instrument-maker of his time, is credited with the invention of the micrometer screw that allowed him to manufacture zenith sectors and calipers of unmatched accuracy. George Graham’s father, also named George, died shortly after his son’s birth. Raised by his uncle, Battison, Edwin A. (1972). “Graham, George.” In Dictionary of Scientific Biography, edited by Charles Coulston Gillispie. Vol. 5, pp. 490–492. New York: Charles Scriber’s Sons. Hoskin, Michael, (ed.) (1997). The Cambridge Illustrated History of Astronomy. Cambridge: Cambridge University Press. King, Henry C. (1978). Geared to the Stars: The Evolution of Planetariums, Orreries, and Astronomical Clocks. Toronto: University of Toronto Press. Sorrenson, Richard J. (1989). “Making a Living Out of Science: John Dolland and the Achromatic Lens.” History of Science Society Schuman Prize Essay. 435 436 G Grassi, Horatio Grassi, Horatio Flourished Italy, 1619 Horatio Grassi was an Italian Jesuit and mathematician. He is best known for the malignant pamphlet he wrote against Discorso delle comete by Galileo Galilei, published in 1619, where Galilei argued that the comets are not sublunar fires because of their transparency and their small parallax. Grassi’s pamphlet, entitled Libra astronomica ac Philosophica, was also published in 1619 under the name Lothario Sarsio Sigensano, an imperfect anagram of Horatio Grassio Saronensi. Galileo answered him with a still more virulent Il saggiatore in 1623. Margherita Hack Selected Reference Drake, Stillman and C. D. O’Malley (trans.) (1960). The Controversy on the Comets of 1618. Philadelphia: University of Pennsylvania Press. Gray, Stephen Born Died Canterbury, England, December 1666 London, England, 7 February 1736 Stephen Gray was a dyer who corresponded with John Flamsteed on scientific matters. His early 18th-century sunspot observations record the Sun’s recovery from the Maunder Minimum. Gray is better known for his experiments with electrical conduction and induction, for which he won both the first and second Copley Prizes of the Royal Society. Nonetheless, he died destitute. Selected Reference Clark, David H. and Lesley Murdin (1979). “The Enigma of Stephen Gray: Astronomer and Scientist (1666-1736).” Vistas in Astronomy 23: 351-404. Greaves, John Born Died Colemore, Hampshire, England, 1602 London, England, 8 October 1652 John Greaves was Savilian Professor of Astronomy at Oxford University and a noted antiquarian. He is especially notable for his interest in the astronomy of the ancients and in his efforts to preserve astronomical tables and manuscripts. Greaves was the eldest son of the Reverend John Greaves, rector of Colemore in Hampshire, and the brother of Sir Edward Greaves (1608–1680), a physician, and of Thomas Greaves (1612–1676), an orientalist. He married in 1648 and died childless. Greaves entered Balliol College, Oxford, in 1617, graduating with a BA in 1621. He was then elected to a fellowship at Merton College in 1624, receiving his MA in 1628. Greaves had great interest in natural philosophy and mathematics; learned oriental languages; and studied ancient Greek, Arabian, and Persian astronomers as well as George Peurbach, Johann Müller (Regiomontanus), Nicolaus Copernicus, Tycho Brahe, and Johannes Kepler. In 1630, while he held his fellowship at Merton, he was chosen professor of geometry in Gresham College, London. Greaves held the chair from 1630 to 1643. In the late 1630s, Greaves traveled to Constantinople, Alexandria, and Cairo. He took measurements of several monuments and pyramids, and collected Greek, Arabic, and Persian manuscripts. Greaves returned to England in 1640, and was chosen to succeed John Bainbridge as Savilian Professor of Astronomy at Oxford, but was deposed from his position at Gresham on grounds of his absence. In 1642 he was appointed subwarden of Merton. On 30 October 1648, Greaves was expelled by parliamentary visitors from both his professorship and his fellowship on several grounds, including misappropriation of college property and favoritism in the appointment of subordinate college officers. At this time he lost a large part of his books and manuscripts, some of which were recovered by a friend. Greaves retired to London, where he married. Before his death he published several books and prepared several other manuscripts, some of which were published posthumously. In 1645, Greaves proposed a reformation of the calendar by eliminating the bissextile day for the next 40 years, i. e., the intercalary day inserted every 4 years in the Julian Calendar, but his scheme was not adopted. His principal contributions to astronomy consist in his efforts to collect and publish astronomical tables from Arabic and Persian sources. He also collected astronomical instruments that were left by will to the Savilian Library at Oxford and presented in 1659 to the Savilian Observatory by his brother Nicholas in his memory. A list of these instruments was published in 1697. The list includes one astrolabe, three quadrants (one of them a mural quadrant made by Elias Allen), two sextants, three telescopes (one of which was 15 ft. in length with three mirrors), a pendulum clock, a lined globe, and a cone cut to illustrate the formation of a parabola, hyperbola, and ellipse. The instruments were probably used in the observatory on the tower of the schools. During Greaves’s tenure, then, Oxford was better equipped with instruments than Greenwich was. Among his several works, the following deserve mention: Pyramidologia (1646), A Discourse of the Roman Foot and Denarius (1647), Anonymus Persa de Siglis Arabum et Persarum Astronomicis (1649), Astronomica quaedam ex traditione Shah Cholgii Persae, una cum Hypothesibus Planetarum (1650), Lemmata Archimedis e vetusto codice manuscripto Arabico (1659), An Account of the Longitude and Latitude of Constantinople and Rhodes (1705), and Miscellaneous Works edited with biography by Thomas Birch (1737). Through the reports of his journeys, Greaves seems to have been well known to members of the Royal Society, the nucleus of which was formed by a group of scientists who began meeting at Gresham College in 1645. Robert Hooke mentions him in passing in two comments, at least one of which is simultaneously appreciative and critical. Greaves maintained an extensive correspondence with the learned men of his day including Archbishop Ussher and William Harvey. His own contributions to geography and astronomy are minor, but he is emblematic of the scholarly interest of his day in mathematics, geography, and astronomy. André Goddu Green, Nathaniel Everett Selected References Gunther, R. T. Early Science in Oxford. Vol. 2 (1923): pp. 78–79; Vol. 7 (1930): 664– 665; Vol. 11 (1937): 48–49. Oxford: Oxford University Press. Johnson, Francis R. (1968). Astronomical Thought in Renaissance England: A Study of the English Scientific Writings from 1500 to 1645. New York: Octagon Books. Pearce, Nigel D. F. (1921–1922). “Greaves, John.” In Dictionary of National Biography, edited by Sir Leslie Stephen and Sir Sidney Lee. Vol. 8, pp. 481–482. London: Oxford University Press. Greaves, William Michael Herbert Born Died Barbados, 10 September 1897 Edinburgh, Scotland, 24 December 1955 William Greaves was Astronomer Royal for Scotland and a Royal Astronomical Society president. He published the Greenwich Colour Temperature Observations in 1932 and 1952, based on his photographic photometry. In 1763, Green was appointed by the Board of Longitude to accompany Nevil Maskelyne on a voyage to Barbados to make longitude observations as part of the sea trial of John Harrison’s watch H4. During the same voyage, Maskelyne tested the rival lunar distance method of finding longitude. Soon after Green arrived back in England in summer 1764, Bliss died and Green took sole charge of the Royal Greenwich Observatory until the following March when Maskelyne was appointed as fifth Astronomer Royal. Following some ill feeling between Maskelyne and Green, Green left the observatory to join the navy as a purser. Some years later, Maskelyne, who respected Green’s astronomical talents despite their personal disagreements, recommended him as the official astronomer on board Captain Cook’s voyage on the Endeavour, the main purpose of which was to observe the 1769 transit of Venus. Green and Cook successfully observed the transit, and the results were published in the Philosophical Transactions of the Royal Society in 1771. After the ship left Tahiti, Cook went on to explore and chart New Zealand and parts of Australia. In his journal, Cook praised Green for his industry in making useful observations and calculations throughout the voyage and for teaching several of the petty officers to do likewise. Cook named an island off the coast of Queensland as Green Island in his honor. Mary Croarken Selected References Brück, Hermann A. (1983). The Story of Astronomy in Edinburgh from Its Beginnings until 1975. Edinburgh: Edinburgh University Press. Redman, R. O. (1956). “William Michael Herbert Greaves.” Biographical Memoirs of the Fellows of the Royal Society 2: 129–138. G Selected References Howse, Derek (2004). “Green, Charles.” In Oxford Dictionary of National Biography, edited by H. C. G. Matthew and Brian Harrison. Vol. 23, p. 498. Oxford: Oxford University Press. Beaglehole, J. (ed.). (1967–1974). The Journals of Captain Cook on His Voyages of Discovery Cambridge: Cambridge University Press. Green, Charles Born Died Wentworth, Yorkshire, England, 26 December 1734 at sea, 29 January 1771 Charles Green was an assistant at the Royal Greenwich Observatory who observed the transits of Venus in both 1761 and 1769. He was the youngest son of Joshua Green, a Yorkshire farmer. Charles was educated by his brother, the Reverend John Green, who ran a schools in Denmark Street, Soho, London, where Green later served as an assistant master. In 1760/1761, Green became assistant to the Astronomer Royal at the Royal Greenwich Observatory, serving under first James Bradley and later under Nathaniel Bliss. In March 1768, Green married Elizabeth Long and later that year sailed on James Cook’s first voyage of discovery in order to observe the 1769 transit of Venus in Tahiti. He died on the journey home. Green was buried at sea at 11° 57´ S, 101° 45´ W. Green’s first professional experience of astronomy came when he was appointed as assistant to Bradley, who was renowned for his high observational standards. Green would have received a very thorough training under his tutorship. Together they observed the 1761 transit of Venus at Greenwich. Following Bradley’s death in July 1762, Green continued as assistant to Bliss. Bliss was in poor health and spent most of his time away from the observatory. Consequently, most of the observational and calculation work of the observatory was carried out by Green. Green, Nathaniel Everett Born Died Bristol, England, 21 August 1823 Saint Albans, Hertfordshire, England, 10 November 1899 Nathaniel Green drew artistic and yet highly accurate drawings of planets, especially Mars, Jupiter, and Saturn. He was the son of Benjamin Holder and Elizabeth (née Everett) Green. After receiving an education primarily from his uncle, Green entered a career in business, but in 1844 he found that art, specifically painting, was much more to his taste. In 1847, Green married Elizabeth Gould of Cork. As a professional artist, he made his living mainly as a successful art teacher. For a year he gave lessons to Queen Victoria and other members of the royal family. Green was also a successful author of practical manuals on art. He lived in then-rural west London, but also visited and painted in Palestine and Cannes, France, where in later years he spent winters for his wife’s health as well as for the weather conducive to out-of-doors painting. For most of his life Green was also an amateur astronomer. His main contributions were colored drawings of planets: a beautiful series of Mars for the close opposition in 1877 from Madeira. He also compiled a long series of drawings of Jupiter 437 438 G Greenstein, Jesse Leonard from 1859 to 1887. Both series were published in Memoirs of the Royal Astronomical Society. Green also made studies of the Moon and was active as a member of the Selenographical Society during its brief existence. Green’s planetary and lunar drawings were of moderate resolution but carefully made. Responding to criticism that he preferred an artistic drawing to an accurate one, he replied, “I know no difference between the two.” James Keeler apparently agreed, and was supportive of Green’s resistance to inclusion of details at higher resolution than could likely exist in the eyepiece. In his later years, Green was a leading figure in both the Royal Astronomical Society and the British Astronomical Association [BAA] and served as the first director of the BAA Saturn Section and as BAA president for the 1897/1898 session. Richard Baum Selected References Anon. (1900). “Nathaniel Everett Green.” Monthly Notices of the Royal Astronomical Society 60: 318–320. Anon. (1910). “In Memoriam. Nathaniel Everett Green, F.R.A.S.” Journal of the British Astronomical Association 10, no. 2: 75–77. Green, Nathaniel E. (1879). “Observations of Mars, at Madeira, in August and September 1877.” Memoirs of the Royal Astronomical Society 44: 123–140. ——— (1890). “On the Belts and Markings of Jupiter.” Memoirs of the Royal Astronomical Society 49: 259–270. Sheehan, William (1988). Planets and Perceptions: Telescopic Views and Interpretations, 1609–1909. Tucson: University of Arizona Press, esp. pp. 103–109. Greenstein, Jesse Leonard Born Died New York City, New York, USA, 15 October 1909 Duarte, California, USA, 21 October 2002 American astrophysicist Jesse Greenstein discovered and clarified the properties of the largest sample of white dwarfs found up to that time. An outstanding administrator as well as scientist, he coordinated the most successful of the decadal reports, “Astrophysics for the 1970s.” Greenstein went to Harvard University at the early age of 16 and majored in astronomy, obtaining his BA in 1929. He had planned to go to the University of Oxford, but a health problem prevented that, and so he remained at Harvard University. His first research was on the temperature scale for O and B stars. Cecilia Payne-Gaposchkin had found that some O and B stars had abnormally low color temperatures in spite of showing high-excitation lines in their spectra. Greenstein showed that the mean color temperatures were lowest in the directions of the Milky Way. His explanation in terms of atmospheric effect was incorrect: He had found the general interstellar reddening caused by interstellar dust discoverd by Robert Trumpler very soon after. Harvard University conferred his MA in 1930. Greenstein participated in his family’s real estate and other businesses through the earliest years of the depression, simultaneously carrying out some astronomical research. He returned to Harvard University in 1934 and completed his Ph.D. in 1937. Greenstein’s thesis research concerned the interstellar medium and the associated absorption and reddening of starlight. He was particularly interested in the ratio of the extinction of the light from a star to the amount of reddening that the light experienced. Greenstein did calculations on Mie scattering by a distribution of small particles. He observed 38 highly reddened B stars by calibrated photographic spectrophotometry of objective-prism plates obtained with the 24-in. reflector at the Harvard Agassiz Station. The extinction law Greenstein found was λ−0.7. He measured the general absorption in the region of each of the B stars and found the ratio of photographic absorption to color excess to be in the range four to six. While at Harvard, Greenstein and Fred Whipple attempted to explain radio emissions from the Milky Way Galaxy, only recently discovered by Karl Jansky, as thermal radiation from dust grains. They concluded that the radio emissions could not be accounted for in that manner. However, Greenstein maintained his interest in radio astronomy and later strongly supported research in that area. After graduating from Harvard University, Greenstein was fortunate to obtain a National Research Council Fellowship for 2 years. He chose to spend these at the Yerkes Observatory of the University of Chicago. Yerkes Observatory was then entering its great period under director Otto Struve, and its staff was preparing to use the McDonald Observatory in Texas, which was at that time under construction as a joint project of the universities of Chicago and Texas. When his fellowship ended in 1939, Greenstein was appointed to the University of Chicago faculty at Yerkes, where he remained until 1947. During most of that period he was a research associate at the McDonald Observatory. At first, Greenstein worked principally on interstellar matter. With Louis Henyey, he studied the scattering of light by dust; an approximate formula that they developed for the particle scattering function later found applications in radiative transfer studies in astrophysics and atmospheric physics. In other collaborations with Henyey, Greenstein studied the diffuse galactic light by setting a photometer on apparently empty space between the stars. The two astronomers studied spectra of reflection nebulae and emission nebulae, and showed that H-α is widely distributed in the Milky Way, not just in bright nebulae. Greenstein used the new 82-in. reflector at McDonald Observatory to study several stellar spectra. His first work was helping Struve to obtain coude spectra of τ Scorpii for Albrecht Unsöld to use at Kiel, spectra which became a testing ground for many subsequent developments in the analysis of stellar atmospheres. Greenstein analyzed the spectrum of the supergiant Canopus, the second brightest star in the sky, finding its composition to be normal. He observed υ Sagittarii, which he proved has a hydrogen-poor atmosphere. This was the first of many studies Greenstein made of abnormalities in stellar spectra. During World War II, Greenstein remained at Yerkes Observatory, and was engaged with Henyey in optical design work for defense purposes. One noteworthy project was their design of a wide-angle camera for military aerial photography. The Henyey– Greenstein camera was later used by Donald Osterbrock and Stewart Sharpless to take several remarkable photographs of the Milky Way, the zodiacal light, the gegenschein, and the aurorae. The Milky Way really did look like an edge-on spiral with a dust lane! Greenstein, Jesse Leonard Greenstein moved to California in 1948 when he was appointed professor (and chairman of the astronomy department) at the California Institute of Technology (Caltech), ending as the Lee A. Dubridge Professor of Astrophysics. He officially retired at the end of 1979. Greenstein was also a staff member of the Hale Observatories, and remained in that position from 1948 until 1980. Greenstein was asked to go to Pasadena to help Caltech prepare for the operation of the Palomar Observatory, to gather the scientific staff for the Palomar Observatory, and to set up an outstanding astronomy graduate program at Caltech. He had to handle the complications of the joint operation by the Carnegie Institution of Washington and Caltech of the Mount Wilson and Palomar observatories. He was one of only two astronomers on the Caltech faculty, the other being Fritz Zwicky. Soon after his arrival in California, Greenstein had an important collaboration with Leverett Davis. The polarization of starlight by the interstellar medium had just been discovered by William Hiltner and John Hall. Interstellar grains absorbed and reddened the light: To produce polarization required elongated grains, and the grains must be aligned over a large volume of space. Davis and Greenstein suggested that the grains contain small amounts of iron compounds and would be paramagnetic. The grains would be spinning rapidly because of collisions with hydrogen molecules in space. They suggested that an interstellar magnetic field of order 10−5 gauss must exist to align the grains, and the field lie along the spiral arms of the Galaxy. Paramagnetic spinning grains produce magnetic energy dissipation, which in turn leads to a torque, and this makes the grains spin around their shortest axis. Other astronomers studied other mechanisms for producing the grain alignment, but Davis and Greenstein’s basic conclusions about the galactic magnetic field were correct. Planetary nebulae had been observed to have a continuum in the visual spectral region. Recombination of hydrogen had been shown as not being the source of the continuum. Greenstein and Thornton Page considered the possibility that the capture continuum of the negative hydrogen ion might be the source, but that turned out to be too weak. The source was found by Greenstein and Lyman Spitzer, who showed that two-photon emission from the 2s state of hydrogen provided sufficient intensity. The 2s state was populated both by electron capture directly onto the 2s state and by electron collision transfer from the 2p state to the 2s state. The effect was to reduce the size of the Balmer discontinuity and reduce the calculated electron temperatures of the planetary nebulae. After his move to California, Greenstein started very extensive studies of the chemical composition of stellar atmospheres. He continued these studies for more than 10 years and, with many collaborators, published about 60 papers in this field. Much of this work was related to studies of the origin of the elements, and complemented work on nuclear reaction cross sections being done at Caltech. Greenstein studied the isotope ratios 13C/12C and 3He/4He, and the nuclei 6 Li, 7Li, 9Be, and 98Tc. The 13C/12C ratio in most stars seemed about the same as in the Sun. Comet C/1963 A1 (Ikeya) was observed, whose 13 C/12C ratio was also about the solar value. The Li/H ratio was higher in young stars, and 3He/4He was high in some peculiar stars. Detailed interpretation of many of these observations proved more difficult than had been anticipated. An important paper with H. Larry Helfer and George Wallerstein determined hydrogen to metal ratios in two K type giant stars in globular clusters and in one high-velocity field star. The hydrogen to metal ratios were from 20 to 100 times the solar G values. The ratios of other elements to iron were within a factor of five of solar values. Subsequent analyses of several other field giant stars indicated still more extreme metal deficiencies, up to factors of 800 less than the solar abundance. Some stars also showed peculiarities in the abundances of individual elements. Greenstein later commented that, after many years of work, the subject was clearly much more complicated than had been thought when he started. White dwarf stars are faint objects, and in consequence they had been little studied in earlier years. The new equipment at the Palomar Observatory allowed Greenstein to initiate an extensive series of studies on white dwarf stars, their colors, spectra, compositions, magnetic fields, and evolution. A joint paper with Olin J. Eggen listed 166 white dwarf stars, mostly with new spectroscopic and photometric data. Greenstein developed a classification system for white dwarfs; his publications showed the large variations in the characteristics of white dwarfs. Some have hydrogen-rich and metal-poor surfaces, while others have helium-rich atmospheres. Some of his spectra showed unidentified very broad features. Greenstein was interested in other kinds of faint stars, including subdwarfs and brown dwarfs. Working with Lawrence Aller, Greenstein analyzed three G-type subdwarfs and found metal deficiencies ranging from 20 to 100. After the discovery, by Maarten Schmidt, of the large red shift δλ/λ = 0.16 of the quasar 3C273, Greenstein and Thomas Matthews confirmed this by showing that the previously unidentifiable lines in 3C48 could be explained by lines of common elements with a redshift of 0.367. Greenstein and Schmidt showed that the redshifts of quasars could not be gravitational, so that, unless new physics intervened, these sources must be very distant and very bright. Greenstein was fortunate to be permitted to continue observing at the Palomar Observatory for some years after he retired. He had many collaborators, including James W. Liebert, J. Beverly Oke, Harry L. Shipman, and Edward M. Sion. Greenstein continued to make spectroscopic observations of white dwarfs and of many other stars. Greenstein collaborated with a large number of astronomers in the compilation of a spectroscopic atlas of white dwarfs, which was published in 1993. This atlas showed in great detail the incredible variety of white dwarf spectra. It illustrated the refinements that had been made in the classification of these stars, as well as the little-understood peculiarities in individual spectra. Many white dwarfs had previously been classified as of type DC, the C indicating a continuous spectrum showing virtually no lines. Greenstein’s later work reduced the apparent number of DC stars by using improved equipment at the Palomar Observatory. He demonstrated the presence of weak C2 bands or weak He[I] lines in many of these stars. The star G 141-2 shows only a broad H-α line and apparently nothing else. The well-known white dwarf 40 Eri B could be observed in the ultraviolet and showed strong Lyman alpha and a strong line at 1391 Å which could possibly be Si[IV] or possibly molecular hydrogen. Among individual stars, GD 356 is unique; it has both H-α and H-β in emission, and both lines show Zeeman splitting corresponding to a magnetic field, if a dipole, of 20 megagauss. The magnetic star Grw +70° 8247 has an effective temperature of about 14,500 K and is a very small star, with a radius of only 0.0066 solar radius, making it one of the heaviest white dwarf stars known. In other papers, Greenstein studied binary stars with both stars degenerate. In six pairs he found that the components were similar in luminosity and temperature; the white dwarfs are near-twins. There must be many more such pairs to be discovered. 439 440 G Greenwood, Nicholas Greenstein also studied binary stars that contain one normal star and one white dwarf. He concluded that duplicity has not changed the evolution of either the white dwarf or the main-sequence star. Each star evolves in isolation. These binaries are separated by many times the average separation of binaries with two main-sequence stars, so presumably there must be many more of these binaries to be discovered. Greenstein obtained many spectra of other kinds of stars, including the star PC0025 +0047, which is an unusual M-type star and which he observed over a very wide range of wavelengths. It has the strongest water vapor bands and the strongest vanadium oxide bands in any known dwarf star. Its effective temperature must be as low as 1,900 K. It may be an old hydrogen-burning star with a mass of about 0.08 solar masses, or it may be a young brown dwarf. Greenstein’s total scientific output was prodigious, about 380 papers and articles in all. His later papers on white dwarfs list large numbers of these fascinating objects with strange characteristics, which should serve as a starting point for many future investigations. Greenstein served on many national committees, starting soon after World War II ended. He was involved in the first grants committee for astronomy of the Office of Naval Research. He was on the first advisory committee of the National Science Foundation when it was considering its first astronomy grants. Greentein was chair of the National Academy of Sciences Astronomy Survey Committee and produced the second survey (1972) in what has become a series of decadal surveys. He was on National Aeronautics and Space Administration [NASA] committees, where he felt that he helped to bridge the gap between scientists and the NASA management. Greenstein was a member of the Harvard Board of Overseers for 6 years. At Caltech, Greenstein served as the chairman of the faculty board. He resigned from heading astronomy at Caltech in 1972, but continued his observational work. Greenstein received many honors, including election to the National Academy of Sciences, the Gold Medal of the Royal Astronomical Society, the Russell Lectureship of the American Astronomical Society, the Bruce Medal of the Astronomical Society of the Pacific, and an honorary D.Sc. from the University of Arizona in 1987. Greenstein had two sons, one of whom, George (born: 1940), has been on the astronomy faculty at Amherst College since 1971. Peter (born: 1946) is active in music in California. Greenstein was predeceased by his wife Naomi, whom he met at Harvard and married in 1934. Roy H. Garstang Greenwood, Nicholas Flourished England, 1689 Nicholas Greenwood wrote a vernacular introduction to astronomy for seamen. Not much is known about Greenwood’s education or personal history. From his major publication Astronomia Anglicana (London, 1689), it is apparent that Greenwood received a Latinbased education. He was a self-professed “professor of physic” and “student in astronomy and mathem.” Greenwood also wrote at least one ephemeris for the year 1690. Astronomia Anglicana was written in the vernacular so that it would be more readily accessible to English mariners. The book is divided into three major sections. In the first section, Greenwood summarizes the “Doctrine of the Sphere,” which provided introductory material on how to find the parallax for the Sun, Moon, and planets. He followed closely Tycho Brahe’s method of determining the distance, latitude, and longitude of a comet, planet, or new star using the known positions of two fixed stars as outlined in Brahe’s Progymnasmata. In this section Greenwood relies heavily on Christian Severin (Longomontanus) and on the prognosticator Vincent Wing’s Astronomia Britannica (London, 1669) in his explanations. In the second section, Greenwood used the astronomical observations of Brahe, Severin, and Pierre Gassendi to explain the “Theory of the Planets” and how to calculate planetary positions. When he came to the more difficult problem of how to explain the elliptical path of a planet, Greenwood used Ismaël Boulliau as his guide rather than trying to use Johannes Kepler or others, because Boulliau “makes the operation more facile.” Finally, in the third section of his book, Greenwood appended tables of planetary positions calculated according to the method he outlined in Section 2. Apart from the tables, Greenwood included a short discussion of the dating of the Creation, which he places at 3,949 years before the birth of Christ. He also included a list of observations made by several astronomers of solar and lunar eclipses and a list of the latitude and longitude positions of major cities in Europe. Derek Jensen Selected Reference Knobel, E. B. (1915). “Note on Dr. Fotheringham’s Paper on the Occultations in the Almagest.” Monthly Notices of the Royal Astronomical Soceity. 75: 397. Gregoras, Nicephoros Selected References Greenstein, Jesse L. (1984). “An Astronomer’s Life.” Annual Review of Astronomy and Astrophysics 22: 1–35. Gunn, Jim (2003). “Jesse Greenstein, 1909–2002.” Bulletin of the American Astronomical Society 35: 1463–1466. Trimble, Virginia (2003). “Jesse Leonard Greenstein (1909–2002).” Publications of the Astronomical Society of the Pacific 115: 890–896. Weaver, Harold F. (1971). “Award of the Bruce Gold Medal to Professor Jesse L. Greenstein.” Publications of the Astronomical Society of the Pacific 83: 243–247. Born Died possibly Constantinople (Istanbul, Turkey), 1291–1294 possibly Constantinople (Istanbul, Turkey), 1358–1361 After studying under Theodore Metochites, Nicephoros Gregoras ran a monastery school at Constantinople. A very accomplished scholar in many fields, including theology and hagiography, he is remembered as both a historian and an astronomer. The latter reputation comes from his commentary on Ptolemy and his work to Gregory, James reform the Julian calendar in order to fix the date of Easter. Gregoras successfully predicted an eclipse in 1330; it was one of the last acts of Byzantine astronomy. Selected Reference G Selected References Hiscock, W. G. (ed.) (1937). David Gregory, Isaac Newton and Their Circle. Oxford. Lawrence, P. D. and A. G. Molland (1970). “David Gregory’s Inaugural Lecture at Oxford.” Notes and Records of the Royal Society of London 25: 143–178. Mogenet, J. et al. (eds.) (1983). Calcul de l’éclipse de soleil du 16 juillet 1330, Amsterdam: J. C. Gieben. Gregory, James Gregory [Gregorie], David Born Died Born Died Aberdeen, Scotland, 3 June 1659 Maidenhead, Berkshire, England, 10 October 1708 Born into a wealthy family, Newtonian advocate David Gregory was a nephew of James Gregory, inventor of the Gregorian telescope. His father (David Gregorie) became heir to the family estate, owing to the murder of his older brother. David Gregorie had 29 children from two wives, of whom David was the third son from the first wife. Gregory studied at Marischal College, part of the University of Aberdeen, between 1671 (when he was only 12 years old) and 1675, but took no degree. He held an MD and was admitted to the College of Physicians in Edinburgh, practicing medicine. Gregory was awarded MAs by Edinburgh and Oxford universities at the time of his academic appointments. At the age of 24, Gregory was appointed professor of mathematics at the University of Edinburgh where he taught Newtonian theory, one of the first (or possibly the first) university teacher to do so. Unsettled by political and religious unrest in Scotland – in 1690 he refused to swear an oath of loyalty to the English throne before a visiting parliamentary commission – Gregory became Savilian Professor at Oxford University in 1691, supported by Isaac Newton, whom he shamelessly courted. He became a fellow of the Royal Society in 1692, but was not active in the society except in the papers that he submitted for publication. In 1702, Gregory published Astronomiae physicae et geometricae elementa, an account of Newton’s theory. He was a member, with Newton, of the committee of referees appointed to supervise the printing of John Flamsteed’s observations made at the Royal Observatory at Greenwich, which culminated in the forced publication of Flamsteed’s Historia Coelestis (1712). Gregory supported Newton’s claim against Gottfried Leibniz as the inventor of the calculus. Gregory worked on mathematical series, not always successfully: He published a wrong-footed derivation of the catenary, which Leibnitz gleefully showed to be erroneous. He also published on optics. In Catoptricae et dioptricae sphericae elementa (1695), Gregory speculated about the possibility of making achromatic refracting telescopes using two different media. He did so by making an analogy with the human eye. In fact, the eye is far from achromatic, but his idea is on the right lines to make an achromatic lens. David Gregory was mostly a theoretician. Flamsteed, no friend after the Historia Coelestis affair, thought him a closet astronomer. Gregory was taken ill (of consumption or smallpox) on a journey from Bath to London and died at an inn. Paul Murdin Drumoak near Aberdeen, Scotland, November 1638 Edinburgh, Scotland, October 1675 Telescope designer James Gregory was the third son of Reverend John Gregory, Minister of Drumoak in the County of Aberdeen, Scotland, and his wife, Janet Anderson. Gregory attended a grammar school and later graduated from Marischal College. From an early age, Gregory displayed extraordinary mathematical talent. In 1663, Gregory published a treatise, entitled Optica Promota, in which he submitted a novel design for a reflecting telescope. The Gregorian reflector consists of a centrally perforated concave parabolic primary mirror, combined with a smaller concave ellipsoidal secondary mirror. By placing the secondary within the diverging cone of light beyond the focal point of the primary, the secondary mirror reflects a converging beam to the final focal point, located on the opposite side of the primary mirror, where it is magnified by an eyepiece. This relatively compact optical configuration is theoretically sound and provides an erect image suitable for terrestrial use. Unfortunately, the precise figuring of the aspherical conic sections of the mirrors proved to be beyond the capabilities of contemporary opticians. After several abortive attempts were made by London opticians to fabricate a working example, Gregory abandoned the pursuit. The simpler form of reflecting telescope proposed by Isaac Newton, which replaced Gregory’s concave ellipsoidal secondary mirror with a planar mirror inclined at 45° to the optical axis, proved far more practical. The first working example of a reflecting telescope of the Newtonian form was demonstrated in 1668 and presented to the Royal Society of London in 1672. A successful Gregorian reflector was not produced until 1674, when the versatile English polymath Robert Hooke constructed an operative telescope on the Gregorian principle. During the 1730s, optician James Short mastered the art of figuring aspherical mirrors. Short figured many fine Gregorian reflectors with apertures as large as 18 in. Yet, the Gregorian design was largely abandoned during the 19th century in favor of the more compact Cassegrain form, in which a convex hyperboloidal secondary mirror is placed before the focus of the telescope’s concave parabolic primary mirror. Gregorian reflectors were revived in the 20th century, however, as the chosen design for NASA’s Orbiting Solar Observatories [OSOs]. Because the concentration of sunlight (in a converging beam) could be potentially harmful to the secondary mirror of a Cassegrain system, Gregory’s design was adopted for the Solar Maximum Mission and related solar telescopes. In 1664, Gregory traveled to Italy, where he spent the majority of his time at the University of Padua. There, he derived the binomial series expansion and the underlying principles of the calculus independently of Newton. Gregory also published two mathematical 441 442 G Gregory of Tours treatises while in Italy. He returned to Great Britain around Easter of 1668, and was elected a fellow of the Royal Society. Later that year, Gregory was appointed to the Regius Chair of Mathematics at Saint Andrews University, Scotland, where he carried out important mathematical and astronomical work. He independently derived the Taylor series expansions for several trigonometric and logarithmic functions. His observations of the interaction of sunlight with a seabird’s feather anticipated the principle and invention of the diffraction grating. In 1669, Gregory married Mary (née) Jamieson, the widow of Peter Burnet. The couple had three children. On one occasion, Gregory returned to Aberdeen and held a collection outside of church doors to raise money for an observatory – the first in Great Britain. He also collaborated with French colleagues to observe a lunar eclipse in a successful attempt to determine the longitude difference between Saint Andrews and Paris. In 1674, Gregory departed Saint Andrews for Edinburgh University, where he acquired that institution’s first chair of mathematics. Within a year of assuming the post, however, he suffered a stroke that left him blind. He died several days later. His manuscripts are held at the Saint Andrews University Library. Thomas A. Dobbins Selected References Dehn, Max and E. D. Hellinger (1943). “Certain Mathematical Achievements of James Gregory.” American Mathematical Monthly 50: 149–163. King, Henry C. (1955). The History of the Telescope. Cambridge, Massachusetts: Sky Publishing Corp., esp. pp. 67–72. Simpson, A. D. C. (1992). “James Gregory and the Reflecting Telescope.” Journal for the History of Astronomy 23: 77–92. Turnbull, H. W. (1938). “James Gregory (1638–75).” Observatory 61: 268–274. Whiteside, D. T. (1972). “Gregory, James.” In Dictionary of Scientific Biography, edited by Charles Coulston Gillispie. Vol. 5, pp. 524–530. New York: Charles Scribner’s Sons. Gregory of Tours Flourished (France), 6th century Bishop Gregory described a sequence of stars by which to count the hours of night, so that monastic prayers could be said at the designated times. rhetoric, philosophy, and theology, he started his studies in astronomy and mathematics. After this he taught mathematics at Graz, Austria. He then went to assist, and later (in 1612) replace, Christopher Clavius, S. J., as professor of mathematics at the Roman College, where he began by helping Clavius in gathering one of the earliest collections of data on novae. A correspondent of Galilei, Grienberger was a strong supporter of the Copernican system and offers a good example of the dilemma of Jesuit scientists. He was convinced of the correctness of Galilei’s heliocentric teachings as well as the mistakes in Aristotle’s doctrines on motion. But because of the rigid decree of his Jesuit superior general, Claudius Aquaviva, obliging Jesuits to teach only Aristotelian physics, he was unable to openly teach the Copernican theory. He expressed disgust at the Church’s treatment of Galilei, but he also stated that if Galilei had heeded the advice of Jesuits and proposed his teachings as hypotheses, he could have written on any subject he wished, including the two motions of the Earth. Grienberger verified Galilei’s discovery of the four satellites of Jupiter as well as the phases of Venus. In March 1611, he organized an ambitious convocation celebrating Galilei: a festa Galileana. At this gathering of cardinals, princes, and scholars, the students of Clavius and Grienberger expounded Galilei’s discoveries to his immense delight. During the festa the Jesuits provided (“to the scandal of the philosophers present”) a demonstration with very suasive evidence that Venus travels around the Sun. Galilei was much assured by this expression of support, and for his part had been anxious to have this backing of the Jesuit astronomers who later would respond to a request from the Holy Office confirming Galilei’s discoveries. Galilei’s discovery of sunspots created problems with the most intransigent Aristotelians who taught that the Sun was a perfect sphere without blemish. Grienberger confirmed the presence of sunspots, and therefore the corruptibility of the Sun, which contradicted Aristotle, thereby challenging the legislation then in force in the Society of Jesus. Grienberger let it be known that it was only this latter constraint of religious obedience that prevented him from teaching about sunspots and the heliocentric theory. In fact, Grienberger stated that he was not surprised that Aristotle was wrong in these two cases, since he himself had demonstrated that Aristotle was wrong in stating that bodies fall at different velocities. Grienberger conducted a public disputation concerning the opposing positions held by Galilei and Aristotle on floating bodies during which he adopted the position of Galilei, once again demonstrating that he was in complete agreement with Galilei’s theories. Selected Reference Joseph F. MacDonnell Heinzelmann, Martin (2001). Gregory of Tours: History and Society in the Sixth Century, translated by Christopher Carroll. Cambridge: Cambridge University Press. Selected References Grienberger, Christopher Born Died Hall, (Switzerland), 1564 Rome, (Italy), 11 March 1636 Christopher Grienberger was the first important Jesuit to embrace Copernicanism and to support Galileo Galilei. Grienberger entered the Jesuit order in 1590 and after his normal course of studies in Blackwell, Richard J. (1991). Galileo, Bellarmine and the Bible. London: Notre Dame Press. Fantoli, Annibale (1994). Galileo: For Copernicanism and for the Church, translated by George Coyne. Notre Dame: Notre Dame Press. Gorman, Michael John (2003). “Mathematics and Modesty in the Society of Jesus: The Problems of Christoph Grienberger.” In The New Science and Jesuit Science: Seventeenth Century Perspectives, edited by Mordechai Feingold, pp. 120. Dordrecht: Kluwer Academic Publishers. Lattis, James M. (1994). Between Copernicus and Galileo. Chicago: University of Chicago Press. Sommervogel, Carlos (1890–1960). Bibliothèque de la Compagnie de Jésus. 12 Vols. Brussels: Société Belge de Libraire. Grimaldi, Francesco Maria Grigg, John Born Died Isle of Thanet, Kent, England, 4 June 1838 Thames, New Zealand, 20 June 1920 Educated at least in part in the shadow of the Greenwich Observatory, John Grigg developed an active interest in astronomy before age 15, but that interest was not put to action until much later in his life. He married in 1858, immigrated to New Zealand in 1863, and settled in Thames. There Grigg established himself as a music merchant, selling instruments, giving lessons, tuning pianos, and conducting a local chorus. The 1874 transit of Venus revived his latent interest in astronomy and led to the construction of a modest observatory. Grigg was mainly a recreational observer until after his retirement from business in 1894. Thereafter, however, he became intensely interested in observing comets. His location far to the south, together with the low number of observatories in the Southern Hemisphere, favored his emergence as an important comet observer. Grigg was frequently the last person to observe a comet after perihelion if it retreated in southern skies. Grigg made independent discoveries of three comets that are named in his honor: 26P/1902 O1 (Grigg–Skjellerup), C/1903 H1 (Grigg–Mellish), and C/1907. His notice of 26P/1902 O1 was apparently lost in transit to Baracchi in Melbourne, and there are other known observations from that apparition; comet 26P remained lost until rediscovered in 1922 by John Skjellerup. Thomas R. Williams Selected Reference Anon. Obituary. (1921). “John Grigg.” Monthly Notices of the Royal Astronomical Society 81: 258–259. Grīḡōriyōs Bar �Eḇrāyā > Barhebraeus: Gregory Abū al-Faraj Grīḡōriyōs Bar �Eḇroyo > Barhebraeus: Gregory Abū al-Faraj in 1632, studied philosophy in Parma and Ferrara, and studied theology in Bologna. After this he undertook the study of astronomy under another Jesuit, Giovanni Riccioli, who would be his coworker for the rest of his life. Grimaldi held the post of professor of mathematics and physics at the Jesuit college in Bologna for many years. The astronomical work of Grimaldi was closely related to that of Riccioli, who is known especially for his Almagestum novum, published in 1651. Riccioli gave a great deal of the credit to Grimaldi for the remarkable success of this publication. He especially praised Grimaldi’s ability to devise, build, and operate new observational instruments. In 1640, Grimaldi conducted experiments with Riccioli on free fall, dropping weights from a tower and using a pendulum as timer. Grimaldi’s contributions also included such measurements as the heights of lunar mountains and the height of clouds. Grimaldi is responsible for the practice of naming lunar regions after scientists rather than after ideas such as “tranquility.” With Riccioli, he composed a very accurate selenograph. It was much more accurate than any lunar map up to that time. Across the top is written: “Neither do men inhabit the moon nor do souls migrate there.” This selenograph is one of the best known of all lunar maps and has been used by many scholars for lunar nomenclature for three centuries. Astronomers took turns naming and renaming craters, which resulted in conflicting lunar maps. In 1922 the International Astronomical Union [IAU] was formed, and eventually eliminated these conflicts and codified all lunar objects: 35 Jesuit scientists are now listed in the National Air and Space Museum [NASM] catalog, which identifies about 1,600 points on the Moon’s surface. This is not surprising, since recent histories emphasize the enormous influence Jesuits had not only on mathematics but also on the other developing sciences such as astronomy. Grimaldi was one of the great physicists of his time and was an exact and skilled observer, especially in the field of optics. He discovered the diffraction of light and gave it its name (meaning “breaking up”). He also laid the groundwork for the later invention of the diffraction grating. Realizing that this new mode of transmission of light was periodic and fluid in nature, Grimaldi was one of the earliest physicists to suggest that light was wavelike in nature. He formulated a geometrical basis for a wave theory of light in his work Physico-mathesis de lumine (1666). This was the only work published by Grimaldi himself. However, 40 of his articles are published in the Almagestum novum. It was the de lumine treatise that attracted Isaac Newton to the study of optics. Later, Newton and Robert Hooke (both of whom quoted Grimaldi’s works) would use the term “inflexion,” but Grimaldi’s word has survived. There is a prominent crater on the Moon’s eastern limb named for Grimaldi. Grimaldi, Francesco Maria Born Died Bologna, (Italy), 2 April 1613 Bologna, (Italy), 28 December 1663 Francesco Grimaldi was a pioneer in lunar mapping and a leading physicist, the discoverer of diffraction. His parents were Paride Grimaldi and Anna Cattani. He entered the Jesuit order G Joseph F. MacDonnell Selected References Cajori, Florian (1898). History of Physics. New York: Macmillan. Reilly, Conor (1958). “A Catalogue of Jesuitica in the Philosophical Transactions of the Royal Society of London.” Archivum Historicum Societatis Iesu 27: 339–362. Sommervogel, Carlos (1890–1960). Bibliothèque de la Compagnie de Jésus. 12 Vols. Brussels: Société Belge de Libraire. 443 444 G Groombridge, Stephen Groombridge, Stephen Grosseteste, Robert Born Died Born Died Goudhurst, Kent, England, 7 January 1755 Blackheath, (London), England, 18 March 1832 The English retail merchant and amateur astronomer Stephen Groombridge conducted an extensive observation program to catalog all the stars brighter than magnitude 8.5 between declination +38° and the North Celestial Pole. The Groombridge Catalogue of 4,243 stars prepared from his observations is highly regarded as the earliest accurate observations of these stars. Groombridge erected a private observatory at Blackheath, within less than a mile of the Royal Greenwich Observatory. He purchased a state-of-the-art reversible transit circle from a leading instrument maker of the period, Edward Troughton. With this superior facility in hand, in 1806 Groombridge commenced the compilation of a catalog of all stars brighter than eighth magnitude within 50° of the North Celestial Pole. Groombridge refined procedures for making such measures as well as his apparatus, and was diligent in making observations. His convenient observatory was adjacent to and easily accessible from his home. It was not uncommon for Groombridge to leave guests at the dinner table for a few minutes while he opportunistically completed measures for a star that was due on the meridian. Groombridge completed his raw observations in 1816, but reduction of the data was still a burden. He revised and improved reduction procedures by computing tables of standard values, but after suffering a stroke in 1827 was unable to complete the reduction of his observations prior to his death. An intervention by Richard Sheepshanks stopped the posthumous publication of a crudely finished catalog of the Groombridge observations. Astronomer Royal George Airy then edited a proper reduction of Groombridge’s observations using more appropriate procedures. The Groombridge Catalogue was finally published in l838. It remained a standard catalog for nearly half a century. It is a testimony to the inherent quality of Groombridge’s observations that, 80 years later, Groombridge’s observations were once again subjected to reduction by Frank Dyson and W. G. Thackeray of the Greenwich Observatory using even more modern reduction techniques. That second edition of the Groombridge Catalogue was published in 1905. Arthur Eddington relied on the 1905 edition of the Groombridge Catalogue for his studies of the motions of galactic stars, claiming that no earlier star catalogs were satisfactory for that purpose. The Groombridge transit circle is preserved at the London Museum of Science. Thomas R. Williams Selected References Ashbrook, Joseph (1974). “The Story of Groombridge 1830.” Sky & Telescope 47, no. 5: 296–297. Douglas, Allie Vibert (1956). The Life of Arthur Stanley Eddington. London: Nelson, pp. 26–27. Groombridge, Stephen, Frank Watson Dyson, and William Grasett, Thackeray (1905). New Reduction of Groombridge’s Circumpolar Catalogue for the Epoch 1810.0. Edinburgh: Printed for H.M. Stationery Off. by Neill and Co. Anon. “The late Stephen Groombridge, Esq.” Monthly Notices of the Royal Astronomical Society 2 (1833): 145–147. Anon. “Richard Sheepshanks.” Monthly Notices of the Royal Astronomical Society 16 (1856): 90–97, esp. p. 92. Stowe, Suffolk, England, after circa 1168 Lincoln, England, 9/10 October, 1253 Some scholars consider the work of Robert Grosseteste to mark the beginnings of modern experimental science. Although Robert Grosseteste, or “Greathead,” was born into the poorest class of feudal society, he received formal education from his earliest years. Evidence for the first five and a half decades of his life is scanty. We know that he worked in the employ of Bishop William de Vere of Hereford until the latter’s death in 1198. The cathedral school of Hereford was a renowned center for study in the liberal arts, theology, law, and the natural sciences; some of its masters were acquainted with Arabic learning. The period of Grosseteste’s life between 1198 and 1225 is subject to a controversy that has broad implications for understanding his place in history. According to a hypothesis first advanced by Daniel Callus in 1955, upon leaving Hereford, Grosseteste became master of arts at the University of Oxford. When studies were suspended there between 1209 and 1214, he immigrated to Paris. As the University of Oxford reopened, Grosseteste was made head of its schools and subsequently became its first chancellor. In 1986, the late Sir Richard Southern challenged this account, claiming that Grosseteste never studied or taught outside England. Moreover, according to that eminent British historian, Grosseteste’s association with Oxford University began only around 1225. He thus spent his most formative years at provincial schools. Grosseteste, Robert While the Callus account considers Grosseteste to be part of the mainstream of Scholastic education, centered as that was on theological concerns as defined at the University of Paris, Southern’s revisionist interpretation regards him as a somewhat eccentric thinker whose interests were shaped by the English scientific tradition (with forerunners such as Adelard of Bath, Daniel of Morley, and Alfred of Shareshill). For Callus and his followers, then, Grosseteste was a conservative theologian who cultivated some scientific interests on the margin of his career. For Southern, on the other hand, Grosseteste was a scientist turned theologian – a theologian, moreover, whose “English mind” (thus the subtitle of Southern’s book) inevitably led him into controversy with the pope. From 1225 onward, documentary evidence for Grosseteste’s life becomes more abundant. In 1225, he was made deacon at Abbotsley, in the diocese of Lincoln. This was the first step in an ecclesiastical career that would, in 1235, raise him to the level of bishop of Lincoln. Between circa 1229 and 1235, Grosseteste lectured to the Franciscans at their study-house in Oxford. After his appointment as bishop, pastoral care for the people in his diocese became one of Grosseteste’s principal occupations; nonetheless, some of his most important philosophical and theological works date from this period as well. Early in 1253, Bishop Grosseteste learned that Pope Innocent IV had bestowed an important ecclesiastical office in his diocese to one of the pope’s own nephews, unqualified for the job. Furious, Grosseteste refused to obey the pope’s order, a decision that is again subject to vastly different interpretations. In the eyes of Southern, it makes Grosseteste a kind of proto-reformer, and one who failed tragically; for a Catholic scholar such as James McEvoy, Grosseteste’s courageous reaction convinced the pope of the failings of his own curia. Robert Grosseteste was a man of unusually wide-ranging interests. His scientific writings – on astronomy and its practical applications for the calculation of the ecclesiastical calendar, meteorology, comets, the tides, the understanding of natural laws in terms of geometry, and light and optics – were mostly composed before 1235. The method displayed in some of them has won him acclaim as the inventor of experimental science. But once again this claim, made by A. C. Crombie in 1953, is deeply disputed. Grosseteste did not, however, limit himself to science in his early years. Already before 1230, he compiled a highly original index of theological sources that attests to his detailed and broad knowledge of the field, apart from showing acquaintance with works of Greek, Roman, and Arabic provenance. He also wrote extensively on Scripture. Many of these interests and sources–natural science, Arabic learning, scriptural studies, theology, Aristotelian physics–flow together in Grosseteste’s philosophical masterpiece, the short treatise De luce (On light). De luce contains Grosseteste’s principal contribution to astronomy: an account of the origin of the universe through the self-diffusion of light. The treatise begins with the assertion that light is the first form of corporeity. Following an Arabico–Jewish tradition of thought, Grosseteste holds that matter itself is dimensionless, being extended in space only in conjunction with this form of corporeity. At the beginning of the universe, then, light rushed out from a single point, carrying matter with it. Light spread itself instantaneously and equally in all directions, until matter became so thin that no further rarefaction was possible. At this point, the process came to a halt, forming the G sphere of the first firmament. In a series of original mathematical propositions on relative infinities, Grosseteste shows that only an infinite “plurification” of light could yield the finite dimensions of the universe. However, light’s power of self-diffusion was not exhausted by the formation of the outermost sphere, and the matter below it remained susceptible to greater rarefaction. The process of selfpropagation therefore reversed, with light now traveling inward from the first firmament toward the center of the universe. This process came to a standstill when, again, the matter that light carried with itself reached the limits of its possible rarefaction and congealed, as it were, in the second sphere. Since the matter below the second sphere was denser than that below the first, the process of self-diffusion could then start again from the second sphere. Grosseteste himself describes this bellows-like movement as an “assembling which disperses” (congregatio disgregans): As light carried matter with itself, it dispersed it, but only to assemble it into bodies of increasing density whenever the process of dispersal reached its natural limits. This alternating movement of expansion and contraction occurred nine times, engendering the nine celestial spheres of the universe, with the earth at its center. On the one hand, the cosmogony of the De luce sketches the outlines of an ambitious scientific project: that of comprehending the origin and structure of the universe by means of the mathematical laws that govern the self-diffusion of light. On the other hand, De luce has far-reaching theological implications. Standing in the Augustinian tradition of light metaphysics, Grosseteste took literally the biblical statement according to which “God is light” (1 John 1:5). His cosmogony was an attempt, then, to understand the creative dynamism through which God became, and remains, present in the universe. Philipp W. Rosemann Selected References Baur, Ludwig (ed.) (1912). Die philosophischen Werke des Robert Grosseteste, Bischofs von Lincoln. Münster: Aschendorff. (An edition of Grosseteste’s philosophical writings which includes De luce.) Callus, D. A. (ed.) (1955). Robert Grosseteste, Scholar and Bishop: Essays in Commemoration of the Seventh Centenary of His Death. Oxford: Clarendon Press. Crombie, A.C. (1962). Robert Grosseteste and the Origins of Experimental Science, 1100–1700. 2nd ed. Oxford: Clarendon Press. Hyman, Arthur and James J. Walsh (eds.) (1983). Philosophy in the Middle Ages: The Christian, Islamic, and Jewish Traditions. 2nd ed. Indianapolis: Hackett, pp. 474–480. (For an English translation by C. G. Wallis of the treatise on light.) McEvoy, James (1982). The Philosophy of Robert Grosseteste. Oxford: Clarendon Press. (See pp. 455–504 for an update of Thomson’s catalog of Grosseteste’s writings.) ______ (1994). Robert Grosseteste, Exegete and Philosopher. Aldershot: Variorum. ______ (2000). Robert Grosseteste. New York: Oxford University Press. ______ (ed.) (1995). Robert Grosseteste: New Perspectives on His Thought and Scholarship. Turnhout: Brepols. Southern, Richard W. (1992). Robert Grosseteste: The Growth of an English Mind in Medieval Europe. 2nd ed. Oxford: Clarendon Press. Thomson, S. Harrison (1940). The Writings of Robert Grosseteste, Bishop of Lincoln 1235–1253. Cambridge: University Press. 445 446 G Grotrian, Walter Grotrian, Walter Born Died Aachen, (Nordrhein-Westfalen), Germany, 21 April 1890 probably Potsdam, (Germany), March 1954 Potsdam Astrophysical Observatory director Walter Grotrian codiscovered (along with Bengt Edlén) the million-degree temperature of the solar corona. His Grotrian diagrams (of atomic levels) enable one to see the relationships between the spectral lines produced by a particular atom or ion. Selected Reference Keinle, H. (1956). “Walter Grotrian.” Mitteilungen der Astronomischen Gesellschaft, no. 7: 5–9. Grubb, Howard Born Died Rathmines, Co. Dublin, Ireland, 28 July 1844 Monkstown, Co. Dublin, Ireland, 16 September 1931 Howard Grubb and his father Thomas Grubb were noted AngloIrish telescope makers who supplied instruments to many British and other observatories during the 19th and early 20th centuries. Howard Grubb was educated at North’s school in Rathmines, Dublin. He entered Trinity College to study engineering in 1863. However, in 1866 his education was cut short by his father, who asked him to join his optical workshop for the construction of the Great Melbourne Telescope. By 1869 they were partners in a specialized optical business and were advertising for astronomical and photographic work. Thanks partly to influential friends, such as the physicist George Stokes and the Armagh astronomer Thomas Robinson, Grubb secured a contract to supply a 15-in. refractor/18-in. reflector combination telescope to William Huggins, one of the pioneers of astrophysics, a discipline then undergoing rapid development. This led to other contracts for the Royal Observatory, Edinburgh, and for Lord Lindsay’s private observatory at Dun Echt, Scotland. In connection with the latter, Grubb became acquainted with the energetic Scottish-born astronomer David Gill, who was to become the main force behind technical improvements to the firm’s telescope designs and a general booster of Grubb’s work. In 1875, Grubb secured the contract for the construction of what was briefly the world’s largest refractor, the 27-in. Great Vienna Telescope. To accommodate this work he constructed a special factory, the “Optical and Mechanical Works, Rathmines,” which remained the location of his business until 1918. The telescope was installed in Vienna in 1882. The 1880s was a period of great activity for Grubb and saw the construction of many small and medium-sized instruments. With the advent of photography as a major astronomical technique in the late 1880s, Grubb started to develop telescope drive systems that permitted precise tracking over long periods. This required refinements to the drive gearing and regulation of the clockwork. He devised a precision gear-cutting technique and also invented a phase-locked loop system for synchronizing the drive to a regulator clock. With the advent of the Carte du Ciel and Astrographic Catalogue project Grubb received orders for six special telescopes with wide-field lenses. Meeting the specifications of the latter cost him considerable trouble and almost led to a nervous breakdown: The optimization of a large two-component lens for wide fields and blue-sensitive plates is a difficult task that was, at the time, poorly understood theoretically. The 1890s saw the construction of a 24-in. telescope for the Royal Observatory (Cape of Good Hope) and a 26-in. telescope for the Royal Greenwich Observatory. Both these instruments were photographic refractors, made achromatic for the blue light that alone could be photographed with early plates. A 30-in. reflector (mirror by Andrew Common) was mounted on the same stand as the 26-in. reflector. A 28-in. refractor (optics and tube only) was constructed for the Royal Greenwich Observatory. This was Grubb’s largest lens. Besides refracting telescopes, Grubb supplied many other instruments. A large heliostat was made for the Smithsonian Institution in Washington. A number of reflectors were also constructed. The largest of these were 24-in. instruments for the Royal Observatory in Edinburgh, Scotland, and for William Edward Wilson’s (1851–1908) observatory in Daramona, Ireland. In about 1896, Grubb refigured the 36-in. mirror of the Crossley reflector for the Lick Observatory. Up to this time, Grubb himself did much of the precision optical work on his telescopes. He was open about his methods and gave public lectures and demonstrations on the subject. Around 1900 he turned his attention to military optics. The construction of periscopes for submarines, then becoming an important element in naval warfare, came to occupy a large part of his efforts. Nevertheless, telescope construction continued, including a 24-in. photographic refractor for the Radcliffe Observatory in Oxford. Before the outbreak of World War I in 1914, Grubb received contracts for a 26.5-in. refractor for Johannesburg, South Africa, and a 40-in. reflector for Simeis in the Crimea. World War I put a stop to civilian work, and the factory was turned over wholly to military optical production. The resurgence of Irish nationalism at this time caused the removal of the works from Dublin to St. Albans (near London) for security reasons, this being completed as the war ended. The inflation and labor unrest that followed were more than the aging Grubb could cope with, and the business faltered. Work on the telescopes that had been ordered slowed to a snail’s pace. The firm went into liquidation early in 1925. It was purchased by Sir Charles Parsons (1854–1931), the developer of the steam turbine and the youngest son of the telescope-builder William Parsons, third Earl of Rosse. Parsons reconstituted the firm as Grubb Parsons and set up a new factory at Newcastle upon Tyne. Only a few key personnel such as Cyril Young, the works manager from 1910, and J. A. Armstrong, the chief optician, were kept on. Howard Grubb was forced to retire and returned to live in Dublin. The reconstituted company survived until 1985. Grubb married Mary Hester Walker of New Orleans, Louisiana, USA, on 5 September 1871. They had five children. Three of the sons were at various times involved in the business. The oldest, Howard Thomas Grubb, died young, of rheumatic fever. George Rudolph Grubb, Thomas Grubb left for India in 1900, and Romney Robinson Grubb was with the firm and its successor in Newcastle upon Tyne until 1929. Howard Grubb was elected Fellow of the Royal Society [FRS] in 1883 and was knighted in 1887. Ian S. Glass Selected References Chapman, S. S. (1932). “Sir Howard Grubb 1844–1931.” Proceedings of the Royal Society A 135: iv–ix. FitzGerald, W. G. (1896). “Illustrated Interviews. No. L. Sir Howard Grubb, F.R.S., F.R.A.S., Etc., Etc.” Strand Magazine 12: 369–381. Glass, Ian S. (1997). Victorian Telescope Makers: The Lives and Letters of Thomas and Howard Grubb. Bristol: Institute of Physics. Grubb, Howard (27 May 1886). “Telescope Objectives and Mirrors: Their Preparation and Testing.” Nature 34: 85–92. (This was originally presented by Grubb as a lecture before the Royal Institution on 2 April 1886.) Manville, G. E. (1971). Two Fathers and Two Sons. Newcastle upon Tyne: Reyrolle Parsons Group. (A pamphlet.) Grubb, Thomas Born Died Waterford, Ireland, 4 August 1800 Dublin, Ireland, 19 September 1878 Thomas Grubb and his youngest son Howard Grubb were noted Anglo–Irish telescope makers. Their instruments were the mainstays of many British and other observatories around the world during the 19th and early 20th centuries. Thomas Grubb’s interest in astronomy appears to have been stimulated by his acquaintance with Reverend Thomas Robinson, director of Armagh Observatory from 1823 to 1882, who had a finger in every Irish scientific pie. Robinson was to be an indefatigable promoter of both Grubbs. Thomas Grubb was of Quaker descent. His father, William Grubb, was a farmer, and Thomas was born of his second marriage, to Eleanor Fayle. Thomas Grubb’s educational background is unknown. By 1832 he was the proprietor of a foundry in Dublin and had obtained a contract to supply an equatorial mounting for a 13.3-in. Cauchoix lens (at the time, the largest in the world) owned by a wealthy Irish amateur astronomer, Edward Cooper of Markree. The uniquely rigid instrument that Grubb constructed, using masonry and cast iron, can be contrasted with the wooden mounting of the Great Dorpat Refractor of Joseph von Fraunhofer, considered to be the state-of-the-art in telescope design at that time. Shortly thereafter, Grubb constructed a 15-in. speculum-metal reflector for Robinson. This was the first substantial reflector on an equatorial mounting – the earlier instruments constructed by Sir William Herschel having been on simple wooden altazimuth frames. Robinson’s telescope also incorporated, for the first time, Grubb’s mirror support system based on equilibrated levers, essentially the nested triangular support system used in many instruments up to the present day. Parts of this instrument, including the mirror cell, still exist at Armagh. His mirror suspension system was adopted by William Parsons (Lord Oxmantown, later third Earl of Rosse) for G his giant telescopes. Parsons referred to Grubb as “a clever Dublin artist” in the description of his 36-in. telescope. Other early refractors constructed by Thomas Grubb were the Sheepshanks 6.75-in. refractor for the Royal Greenwich Observatory (circa 1839) and the West Point refractor (circa 1841). In addition, he built experimental apparatus for various local and British scientists and scientific expeditions. Grubb was elected member of the Royal Irish Academy in 1839. In 1840, Grubb became “engineer to the Bank of Ireland,” to which he supplied specialized and complex printing machinery for banknote production. The only substantial telescope constructed by Grubb in the following 20 years was the South Refractor – the donor of its lens was Sir James South – of Dunsink Observatory, then the property of Trinity College, Dublin. The project appears to have been started before the lens became available. Anticipating that his firm would make the lens, Grubb constructed a complicated polishing machine, described by Robinson in Nichol’s Cyclopaedia of 1857. In 1854, Grubb described ray-tracing work he had been doing on microscope objectives, perhaps the first known use of this technique. According to M. von Rohr, Grubb was the first person to have properly understood the field properties of camera lenses. Photography was a strong interest at this time, and Grubb was a frequent contributor to the specialized journals on the subject. He held a patent on an achromatic meniscus lens that is said to have been lucrative for him. Undoubtedly the most ambitious instrument constructed by Grubb was the Great Melbourne Telescope completed at his workshops in 1868. Although initiated in the early 1850s, the project took many years to come to fruition. Most of the leading astronomers of the time were members of the steering committee, on which Robinson played a highly active role, eventually securing the contract for Grubb. When the work on the Melbourne Telescope commenced, Grubb found himself almost fully occupied with his Bank of Ireland work, so he called on his 21-year-old son Howard Grubb to leave Trinity College, where the latter was a student of engineering, to take charge of the project. Thrown into the deep end, Howard enjoyed the experience of casting the large speculum mirror blanks, which he was able to relate in graphic detail 30 years later to George FitzGerald (1896). The telescope was ready for operation in Melbourne in midAugust 1869. Although generally recognized as a great engineering achievement as the first large professional equatorial, it did not prove to be an astronomical success. Of the many problems with this project, one was the choice of a focal ratio of f/41 for the Cassegrain focus, which was too “slow” for adequate illumination of the images. Too little attention had been paid to the operational requirements of a large telescope. The expertise required to keep it in order was lacking in Melbourne. Only in recent times has it, or parts of it, contributed to an important astronomical project – the MACHO gravitational lensing experiment. Following the apparent success of the Melbourne project, Thomas Grubb left most of the day-to-day running of the firm to Howard. Many more contracts for the construction of large refractors began to come in and very soon a separate factory devoted exclusively to telescopes was constructed – the “Optical and Mechanical Works” in Rathmines, Dublin. 447 448 G Gruithuisen, Franz von Paula In 1826, Grubb married Sarah Palmer of Kilkenny, Ireland. To this marriage were born five sons and four daughters. Mary Anne married Romney Rambaut, a nephew of Robinson and a member of a family that produced more than one astronomer. His eldest son Henry Thomas Grubb succeeded his father as engineer to the Bank of Ireland, while the youngest, Howard, born in 1844, succeeded his father in the telescope-making business. In his 70s, Thomas Grubb was crippled by rheumatism and, though he took part in business operations, his energy was clearly waning. He is buried in the Mount Jerome Cemetery in Dublin, where the register quaintly lists the cause of his death as “Decline of Life.” Ian S. Glass Selected References FitzGerald, W. G. (1896). “Illustrated Interviews: No. L. Sir Howard Grubb, F.R.S., F.R.A.S., Etc., Etc.” Strand Magazine 12: 369–381. Glass, Ian S. (1997). Victorian Telescope Makers: The Lives and Letters of Thomas and Howard Grubb. Bristol: Institute of Physics. Hart, J. et al. (1996). “The Telescope System of the MACHO Program.” Publications of the Astronomical Society of the Pacific 108: 220–222. Nichol, J. P. (1857). A Cyclopaedia of the Physical Sciences. London: Richard Griffin and Co. Oxmantown, Lord (1840). “An Account of Experiments on the Reflecting Telescope.” Philosophical Transactions of the Royal Society of London 130: 503–527. Robinson, T. R. and Thomas Grubb (1869). “Description of the Great Melbourne Telescope.” Philosophical Transactions of the Royal Society of London 159: 127–161. Rohr, M. von (1904). Die Bilderzeugung in Optischen Instrumenten. Berlin: Springer. Gruithuisen, Franz von Paula Born Died Haltenberg Castle near Kaufering am Lech, (Bavaria, Germany), 19 March 1774 Munich, (Germany), 12 June 1852 Franz Gruithuisen – the last name is of Dutch origin – is chiefly known for his advocacy of a plurality of inhabited worlds and fanciful hypotheses about the Moon and planets, a circumstance that occasioned Carl Gauss to speak of “the mad chatter of Dr. Gruithuisen.” His childhood was spent at Haltenberg Castle, where the Elector of Bavaria employed his father as a falconer. Family circumstances did not permit anything other than the limited education that some training in surgery involved, and at the age of 14 the impecunious Gruithuisen departed for medical service in the Austro–Turkish War of 1787–1791. A year or so later, Gruithuisen found employment as a servant in the court of the Elector Karl-Theodor in Munich, where he obtained a small telescope, which he often turned on the Moon. Gruithuisen soon located all the features that appeared in Johannes Hevel’s and Giovanni Riccioli’s charts. In 1801 Gruithuisen obtained patronage and enrolled as a medical student at the University of Landshut, receiving his Doctor of General Medicine degree in 1808. He translated Hippocrates into German and wrote several medical monographs. Meanwhile, the great comet of 1811 (C/1811 F1) awakened his boyhood interest in astronomy just as the Munich optician Joseph von Fraunhofer began to produce his superior refracting telescopes. In 1812, Gruithuisen, who was personally acquainted with Fraunhofer, bought two: one of 2.4-in. aperture and the other of 4-in. aperture. Inspired by his hero Johann Schröter, and emboldened by the improvements in optical science, he sensed an opportunity to gather fresh evidence on the plurality of inhabited worlds. Thus began a rather aimless survey of the lunar surface, a series of observations that was to make Gruithuisen’s name legendary. “We still have much love for the beautiful Moon,” he wrote in his Selenognostische Fragmente (1821), “and dry reports of observations better hold our attention if we can only think of the possibility of Selenites.” This recalled the ideas of Schroeter and led to the discovery of the “colossal structure, not dissimilar to one of our cities,” that came to be known as the “City in the Moon” (a regular but natural arrangement of ramparts that Gruithuisen first observed on the morning of 12 July 1822). Others sought and found this fabled feature, while Gruithuisen himself went on to look for further evidence of an inhabited Moon. A full account of the “city” and other observations are in his Entdeckung vieler deutlichen Spuren der Mondbewohne … (1824). During the 1830s, Gruithuisen extended his advocacy to Mercury and Venus, even to comets. His 1833 interpretation of the Ashen Light of Venus, as the festival illumination put on by the inhabitants of that planet, vivified the public imagination, although, in Camille Flammarion’s opinion, the ideas were fantastic. In the case of the Entdeckung, Gruithuisen’s ideas probably contributed to his career advancement. For in 1826, 2 years after its publication, he was appointed professor of astronomy at Munich University, where he was relieved of all administrative work and allowed to concentrate on his research, which continued to be a mixture of first-rate observation and wild speculation. Still, in wider scientific circles he became an increasingly marginal figure. In his day, however, the planets, like the surface of the Moon, were imperfectly known, and announcements of intriguing and mysterious appearances were rife. Caught up in a web of preconception, imagination, and inadequate resolution, Gruithuisen interpreted his observations simply in the context of analogy and what was then known. He, “assuredly thought, and published, an uncommon amount of nonsense,” to cite Reverend Thomas Webb. Yet he had great energy, and extensive learning. He was a lynx-eyed observer who used small refracting telescopes to very good effect. He discovered fine details on the lunar surface, and was the first to recognize the bright cusp caps of Venus, features that correspond to the bright polar cloud swirls imaged in ultraviolet by the Mariner 10 and Pioneer Venus space probes. In essence, he was a man who foreshadowed aspects of Percival Lowell’s Martian hypothesis, and William Pickering’s “new selenography.” In the 1830s, as he recoiled from stern opposition to his fantasies, Gruithuisen turned to selenological speculation and, from the accretion ideas of the von Bierberstein brothers (1802) and Karl von Moll (1810 and 1820), concluded an impact origin for the craters of the Moon. Gruithuisen’s place in the observational history of the Solar System has never been adequately appreciated. This circumstance Guillemin, Amédée-Victor is largely due to the fact that the authoritative Astronomische Nachrichten refused to publish his work. Accordingly he founded his own journals – Analekten für Erd und Himmelskunde (1829–1831), Neue Analekten für Erd und Himmelskunde (1832–1836), and Naturwissenschaftlich-astronomischen Jahrbuche (1838–1847). Heinrich Olbers may have referred to him as “that peculiar Gruithuisen.” History defines him as an observer of skill and exceptional visual acuity who, in spite of his flights of fancy, is deserving of closer study. Richard Baum Selected References Baum, Richard (1995). “Franz von Paula Gruithuisen and the Discovery of the Polar Spots of Venus.” Journal of the British Astronomical Association 105: 144–147. Crowe, Michael J. (1986). The Extraterrestrial Life Debate, 1750–1900: The Idea of a Plurality of Worlds from Kant to Lowell. Cambridge: Cambridge University Press. Hermann, Dieter B. (1968). “Franz von Paula Gruithuisen und seine ‘Analekten für Erd und Himmelskunde.’” Die Sterne 44: 120–125. Guiducci, Mario Born Died 1585 1646 Galileo Galilei had been cautioned by the church on his astronomical writings. So his student (and later colleague) Mario Guiducci fronted for him in some discourses. Selected Reference Discorso delle Comete. Critical edition by Ottavio Besomi and Mario Helbing. Rome: Antenore, 2002. Guilelmus de Conchis > William of Conches Guillemin, Amédée-Victor Born Died Pierre, Saône-et-Loire, France, 5 July 1826 Pierre, Saône-et-Loire, France, 2 January 1893 Amédée-Victor Guillemin’s fame is as an author of works on the physical sciences. He trained in scientific and literary studies at Beaune and Paris and taught mathematics from 1850 to 1860. G Guillemin penned articles for a number of political and cultural magazines, and by 1860 he had become the editor-in-chief of a local journal, La Savoie, published at Chambéry. Politically, he was one of the defenders of the Republic. Guillemin wrote a number of books on aspects of physics and industry, and these volumes went through many editions and printings. Among them were Les chemins de fer (originally published in 1862, seven editions by 1884), Les phénomènes de la physique (1868), Le monde physique (originally published as Éléments de cosmographie in 1867 and expressly designed for use in secondary schools; the new edition appeared in five volumes from 1881 to 1885), Les applications de la physique aux science, à l’industrie et aux arts (1874), and a 17-volume compendium of knowledge about the physical world and the heavens, Petite encyclopédie populaire (1881–1891). A number of these books appeared in English translation, occasionally revised by a British author. Guillemin also wrote specifically on astronomy, some of which formed part of his popular compendium: Causeries astronomiques: Les mondes (1861, republished in 1863 and 1864), Le ciel, notions d’astronomie à l’usage des gens du monde et de la jeunesse (1864, five editions by 1877), La lune (1866, seventh edition in 1889), Les comètes (1875, revised edition 1887), Les étoiles, notions d’astronomie sidérale (1879), Les nébuleuses, notions d’astronomie sidérale (1889), Le soleil (1869, revised 1873 and 1883), La terre et le ciel (1888, republished 1897), and Esquisses astronomiques: Autres mondes (1892). English translations of Guillemin’s astronomical books were very popular. In particular, The Heavens: An Illustrated Handbook of Popular Astronomy, edited by Norman Lockyer and revised by Richard Proctor, first appeared in 1866, 2 years after the French original, and went through nine editions by 1883. The Sun was published in London 1 year after its Paris edition, in 1870, and appeared in six editions by 1896. Wonders of the Moon, revised by Maria Mitchell, appeared in 1873 and again in 1886. The World of Comets appeared first in 1877 and was highly regarded as a chronicle of cometary apparitions in an era when there were a number of books on the history of comets, by G. F. Chambers and others. These works were typically lengthy popularizations of past and recent research, emphasizing scientific questions of the day and presenting summaries of current literature. The English translations included many editorial comments, occasionally arguing with the author. What set Guillemin’s works apart, however, were their very large numbers of illustrations, mostly woodcuts, with occasional dazzling chromolithographs. Many of the illustrations presented the viewer with a perspective from the astronomical object itself, such as a view of the rings of Saturn (seen from a supposedly cloudfree planetary surface). Earthbound views of astronomical phenomena often included features of local interest. From edition to edition, illustrations were added and removed, especially the chromolithographs. Guillemin’s astronomical works were the most lengthy and best-illustrated volumes available to the public in the last two generations of the 19th century. The astronomical books of Guillemin did not have the authority of Proctor or Lockyer, the dash of Camille Flammarion, or the judgment of Agnes Clerke, but they held the field between the heyday of the woodcut and the rise of the halftone at the end of the 19th century. The closest that a later generation came to them was the Phillips-and-Steavenson collection, Splendour of the Heavens, after 449 450 G Guo Shoujing World War I. Guillemin’s aim was to stir the imagination, and the richly illustrated books that spilled forth from his prolific pen did just that. Rudi Paul Lindner Selected Reference Meyer, C. (1986). “Guillemin.” Dictionnaire de biographie française. Vol. 17, col. 218. Paris: Letouzey et Ané. Guo Shoujing Born Died Xingtai, Shunde (Hebei), China, 1231 Dadu (Beijing), China, 1316 Guo Shoujing was an important Chinese imperial astronomer who contributed to calendaric reform and developed instruments to that end. In his youth, he studied under his grandfather Guo Rong, who was versed in Chinese classics, mathematics, and water conservancy, and then under Liu Bingzhong (1216–1274), who was learned in philosophy, geography, astronomy, and astrology. Among Liu Bingzhong’s disciples was Wang Xun, who later made the Shoushi calendar with Guo Shoujing. In 1262, Guo Shoujing met Kubilai Khan (ruled: 1260–1294) and was initially appointed as a water conservancy engineer. In 1276, Kubilai Khan ordered him to make a new calendar. At that time, the revised Daming calendar of Zhao Zhiwei of the previous Jin dynasty (1115–1234) was still in use, but its errors had accumulated and a more accurate calendar for the new Yuan dynasty (1271–1368) was needed. Although the Yuan dynasty already had a national astronomical observatory (Sitiantai), a new department for the compilation of the new calendar was established; Wang Xun took charge of calculation, Guo Shoujìng of observation. In 1278 or 1279, the department developed into the Taishiyuan (Imperial Bureau of Astronomy and the Calendar). The Bureau was constructed in Dadu, and Wang Xun was appointed director, with Guo Shoujing as deputy director; their work was supervised by Xu Heng (1208–1281). In 1280, they established the Shoushi calendar, officially promulgated after 1281. Shortly thereafter, both Xu Heng and Wang Xun died, leaving Guo Shoujing to continue to compile the exposition of the Shoushi calendar. In 1283, the Shoushi liyi (Theoretical exposition of the Shoushi calendar) was composed by Li Qian (1223–1302). In 1286, Guo Shoujing was appointed director of the Bureau of Astronomy and the Calendar and completed the monographs devoted to the Shoushi calendar. In 1294, he was appointed Zhi taishiyuan shi (Governor of the Bureau of Astronomy and the Calendar). Among the instruments Guo Shoujing created for the Bureau was the jianyi (simplified armillary). The jianyi is a simplified version of an earlier more complicated armillary sphere used to make observations in the equatorial coordinate system. To this instrument was also attached a device to observe the altitude and azimuth of heavenly bodies. It incorporated both equatorial and hour circles and horizontal and vertical circles. The original jianyi is not extant, but a reproduction made in the 15th century is preserved at the Purple Mountain Observatory in Nanjing. Guo Shoujing also created the gaobiao (high gnomon) along with the jingfu (shadow tally). The gnomon was used in China since Antiquity to observe the Sun’s midday shadow and to determine the winter solstice, which is the fundamental point of time in classical Chinese calendars. Guo Shoujing improved it and made it five times higher than previous traditional gnomons, building it 40 chi (12.28 m) high. A huge gnomon constructed by Guo Shoujing and others still exists in Gaocheng, Dengfeng city, Henan province, which is called Guanxingtai (Astral Observatory). The main difficulty in observing gnomon shadows is that the Sun is not a point source, and the shadow’s penumbra produces ambiguity in determining the shadow’s length. Guo Shoujing overcame this difficulty by using jingfu, which is a kind of pinhole camera. The image of the Sun is projected through the pinhole, which is adjusted so that the shadow of the horizontal bar in the window at the top of the gnomon tower exactly passes through the center of the image of the Sun. In this way, the position of the shadow of the bar indicates the exact length of the gnomon shadow, with the height of the bar considered to be the height of gnomon. Guo Shoujing and his colleagues observed the gnomon shadow using the gaobiao several times around the winter and summer solstices, and determined the time of solstices by the method devised by Zu Chongzhi. This determination led them to use the fairly accurate length for the tropical year of 365.2425 days in the Shoushi calendar. Actually, this value had already been used in the Tongtian calendar (1198) of Yang Zhongfu and was confirmed by Guo Shoujing. Guo Shoujing and his colleagues determined the point of the winter solstice on the celestial sphere, the time when the Moon passes its perigee, the time when the Moon passes its nodes, the right ascensions of lunar mansions, the times of sunrise and sunset at Dadu, and other similar phenomena. They also conducted astronomical observations at 27 different places, and observed the altitude of the North Celestial Pole, the length of gnomon shadows at solstices, the length of daytime and nighttime, and related events. Another of Guo Shoujing’s important determinations is that of the obliquity of ecliptic. His value was quoted by Pierre de Laplace in his L'exposition du système du monde (1796) in order to show that the obliquity of the ecliptic is diminishing. Guo Shoujing and his colleagues compiled the Shoushi calendar (1280), which is the most comprehensive, inherently Chinese calendar. They incorporated several features that were superior to those of their predecessors. Almost all Chinese classical calendars used a grand epoch when the Sun, Moon, and planets were assumed to be in conjunction. The Shoushi calendar abandoned the artificial grand epoch, and used a contemporary epoch with certain initial conditions obtained by observations. Moreover, the Shoushi calendar, like the Futian calendar (eighth century), used 10,000 for the denominator in its fractions, avoiding the typical and problematic Chinese calendar usage of fractions with different denominators. Although it was not the first calendar to use this denominator, it was certainly one step toward decimal fractions. The Shoushi calendar adopted the method of the Tongtian calendar (1198) of Yang Zhongfu in which the length of a tropical year gradually diminishes. Although it is true that the length of the tropical year changes, the values given by the Tongtian calendar and the Shoushi calendar are too large. The idea that the length diminishes was abandoned in the Datong calendar (1368) of the Ming dynasty Guthnick, Paul (1368–1644), which otherwise almost completely followed the Shoushi calendar. The Shoushi calendar also used some new mathematical features, such as third-order interpolation and a mathematical method to transform spherical coordinates. For the latter, the Shoushi calendar employed the method devised by Shen Gua (1031–1095), the famous Northern Song Dynasty polymath and scientist. Although the Shoushi calendar was basically made in traditional Chinese style, the possibility of Indian and Islamic influence was recently pointed out by Qu Anjing. All Chinese calendars before the Shoushi calendar used numerical methods to calculate the contact times during eclipses, but the Shoushi calendar used a geometrical model, which is similar to Indian and Islamic methods that had already been introduced into China. This topic deserves further research. The Shoushi calendar was also introduced into Vietnam and Korea. It was not officially used in Japan, but was well studied in the early Edo period in the 17th century, and played an important role in the development of astronomy in Japan. Alternate name G Yukio Ôhashi is in the Sūgakushi Kenkyū (Journal of history of mathematics, Japan) no. 164 [2000]: 1–25.) (For the possible influence of Indian and Islamic astronomy on the Shoushi calendar.) Qu Anjing, Ji Zhigang, and Wang Rongbin (1994). Zhongguo gudai shuli tianwenxue tanxi (Researches on mathematical astronomy in ancient China). Xi'an: Xibei daxue chubanshe Northwest University Press. (Informative work on classical Chinese calendars, including the Shoushi calendar.) Ruan Yuan (1799). Chouren zhuan (Biographies of Astronomers). (Reprint, Taipei: Shijie shuju, 1962.) (See Chap. 25 for some classical accounts of Guo Shoujing.) Song Lian, et al. (eds.) (1370). Yuan shi (History of the Yuan dynasty). (See Chaps. 52–55 for the Shoushi calendar.) Yamada Keiji (1980). Juji-reki no michi (Way of the Shoushi calendar). Tokyo: Misuzu Shobo. (For the intellectual background of the Shoushi calendar, in Japanese.) Yuan shi (History of the Yuan dynasty). 1370. (See Chap. 164 for the official biography of Guo Shoujing.) Gūrgān Kuo Shou-ching Selected References Chan, H. L. and P. Y. Ho (1993). “Kuo Shou-ching (1231–1316).” In In the Service of the Khan, edited by Igor de Rachewitz et al., pp. 282–335. Asiatische Forschungen, Vol. 121. Wiesbaden: Harrassowitz Verlag. (For a detailed biography of Guo Shoujing in English.) Chen, Meidong (1993). “Guo Shoujing.” In Zhongguo gudai kexue-jia zhuanji (Biographies of scientists in ancient China), edited by Du Shiran. Vol. 2, pp. 667–681. Beijing: Kexue chubanshe (Science Publishing House). ______ (1995). Guli xintan (New research on old calendars). Shenyang: Liaoning jiaoyu chubanshe (Educational Publishing House of Liaoning). ______ (1998). “Guo Shoujing.” Zhongguo kexue jishu shi, Renwu juan (A history of science and technology in China, Biographical volume, in Chinese), edited by Jin Qiupeng, pp. 464-483. Beijing: Kexue chubanshe (Science Publishing House). Gauchet, L. “Note sur la trigonométrie sphérique de Kouo, Cheou-king.” T'oung Pao 18 (1917): 151–174. (On the spherical astronomy of Guo Shoujing.) Ke, Shaomin (1920). Xin Yuan shi (New history of the Yuan dynasty). (The Shousi calendar is recorded in the monograph on the calendar, Chaps. 36–40; for the official biography of Guo Shoujing see Chap. 171.) Li Di (1966). Guo Shoujing. Shanghai: Shanghai renmin chubanshe (People’s Publishing House of Shanghai). Needham, Joseph, with the collaboration of Wang Ling (1959). Science and Civilisation in China. Vol. 3, Mathematics and the Sciences of the Heavens and the Earth. Cambridge: Cambridge University Press. (For Chinese astronomy in general, including the contribution of Guo Shoujing.) Pan, Nai, and Xiang Ying (1980). Guo Shoujing. Shanghai: Shanghai renmin chubanshe (People’s Publishing House of Shanghai). Qi Lüqian. Zhi taishiyuan shi Guogong xingzhuang (Memorial on the Director of the Institute of Astronomy and the Calendar, Mr. Guo). Chap. 50 in Yuan wen lei (Collected works of the Yuan dynasty), edited by Su Tianjue. (Included in the Wenyuange edition of Siku quanshu (The Four Treasuries of Traditional Literature). Compiled in the late 18th century. Reprint, Taiwan Commercial Press, 1983–1986, Ch. 1367, pp. 647–655. (A memorial dedicated to Guo Shoujing written by Qi Lüqian [d. 1329], a successor of Guo Shoujing.) Qu, Anjing(2000). “Zhongguo gudai lifa yu yindu Alabo de guanxi–yi riyueshi qiqi suanfa weili” (A comparative study of the computational models of eclipse phases among Chinese, Indian and Islamic astronomy) Ziran bianzhengfa tongxun 22, no. 3: 58–68. (The Japanese version translated by > Ulugh Beg: Muḥammad Ṭaraghāy ibn Shāhrukh ibn Tīmūr Guthnick, Paul Born Died Hitdorf am Rhein (near Leverkusen), (NordrheinWestfalen), Germany, 12 January 1879 Potsdam-Babelsberg, (Germany), 6 September 1947 German astronomer Paul Guthnick’s name is linked with his pioneering work in the application of photoelectric methods to the measurement of the brightness of celestial bodies. Guthnick was the son of a master plumber, later a wine merchant. After Gymnasium in Cologne, he entered the University of Bonn to study (1897–1901) mathematics, natural sciences, and especially astronomy with Friedrich Küstner and Friedrich Deichmüller (1855–1903). Guthnick received his Ph.D. in 1901 for work with Küstner on the variable-star ο Ceti (Mira) and, for economic reasons, also took teaching degrees in mathematics, physics, and chemistry. From 1901 to 1903 he was an assistant at the Berlin Observatory with Arthur Auwers, and from 1903 to 1906 at the Bothkamp Observatory near Kiel. He returned to Berlin (then under the directorship of Karl Struve) in 1906, and moved with the observatory shortly before World War I to the Babelsberg site. He became professor of astronomy at Berlin University in 1916, succeeded Struve as observatory director in 1921, and married in 1923. Guthnick was elected to memberships or associateships in the Prussian Academy of Sciences, the Accademia dei Nuovi Lincei (Italy), the Royal Astronomical Society (London), and the German Academy of Sciences Leopoldina. A lunar crater is named for him. Guthnick obtained photoelectric light curves for Mars, the Galilean satellites of Jupiter (leading to the suggestion that they 451 452 G Gyldén, Johan August Hugo are synchronous rotators), and Titan and Rhea (again supporting synchronous revolution around Saturn). He also did a great deal of work in connection with the Astronomische Gesellschaft Commission for Variable Stars. (His theories for several classes of variable stars, e. g., for Cepheids or for Mira-stars, sometimes seemed a little bit unorthodox.) Guthnick’s contribution “Physik der Fixsterne” to the encyclopedic handbook Kultur der Gegenwart was much appreciated as a very modern view on the new astrophysics. Guthnick’s development of photoelectric methods (beginning about 1912) was very much influenced by the results of the physicists Julius Elster (1854–1920) and Hans Geitel (1855–1923), who had brought photoelectric measuring methods to a high perfection. Guthnick succeeded in building the first photoelectric stellar photometer, attached to the Babelsberg 31-cm refractor, which enabled him to measure stars down to the eighth magnitude. His idea was to combine spectroscopic and photoelectric observations, and he influenced the instrumental development in close collaboration with the Carl Zeiss firm, Jena. Guthnick’s organizational abilities helped develop the Babelsberg Observatory to a first-rate astrophysical institution of the time. Horst Kant Selected References Beer, A. (1948). “Paul Guthnick.” Monthly Notices of the Royal Astronomical Society 108: 35–37. Dick, Wolfgang R. and Arnold Zenkert (1996). “Der Popularisator und der Forscher: Die Freundschaft von Bruno H. Bürgel und Paul Guthnick.” In Seid nicht “gerecht,” sondern gütig! Beiträge von und über Bruno H. Bürgel, edited by Mathias Iven, pp. 58–79. Berlin: Milow. Guthnick, Paul (1901). Neue Untersuchungen über den veränderlichen Stern O (Mira) Ceti. Nova Acta Leopoldina, no. 79. Halle. ______ (1918). “Ist die Strahlung der Sonne veränderlich?” Die Naturwissenschaften 6: 133–137. ______ (1921). “Physik der Fixsterne.” In Astronomie, edited by Johannes Hartmann, pp. 373–510. Leipzig: B. G. Teubner. (=Die Kultur der Segenwart, 3. Teil, 3. Abteilung, 3. Band) ______ (1924). “Ein neues lichtelektrisches Sternphotometer.” Zeitschrift für Instrumentenkunde 44: 303–310. ______ (1924). “Zwölf Jahre lichtelektrischer Photometrie auf der Berliner Sternwarte.” In Probleme der Astronomie: Festschrift für Hugo von Seeliger, edited by Hans Kienle, pp. 391–402. Berlin: J. Springer. Guthnick, Paul and Richard Prager (1914–1918). Photoelektrische Untersuchungen an spektroskopischen Doppelsternen und an Planeten. 2 Vols. Berlin. ______ (1915). “Die Anwendung der lichtelektrischen Methode in der Astrophotometrie.” Die Naturwissenschaften 3: 53–59. Hoffmeister, C. (1948). “Paul Guthnick zum Gedächtnis.” Die Sterne 24: 125–127. Kienle, H. (1947). “Paul Guthnick.” Astronomische Nachrichten 275: 268–269. Gyldén, Johan August Hugo Born Died Helsinki, (Finland), 29 May 1841 Stockholm, Sweden, 9 November 1896 Hugo Gyldén, director of the Stockholm Observatory, was a leading theorist of celestial mechanics and planetary perturbations. He was born into the family of professor Nils Abraham Gyldén and baroness Beata Sofia Wrede. Gyldén was admitted to the University of Helsinki and earned his doctoral degree in 1861. Gyldén’s academic teacher, Lorenz Leonard Lindelöf, guided the young scholar into celestial mechanics. Gyldén then went to Gotha in Germany (1861–1862) as a postdoctoral student of Peter Hansen, one of the leading researchers in celestial mechanics. There, Gyldén drafted a dissertation on the orbit of the planet Neptune, which had been discovered 15 years earlier. To continue his studies, Gyldén relocated to the Pulkovo Observatory in Russia on a grant from the University of Helsinki. There, he determined the declinations of fundamental stars with the vertical circle. In this work, Gyldén had to take into account refraction caused by the Earth’s atmosphere. In turn, he developed a new model of refraction, and with it drafted improved refraction tables that were widely used afterward. In 1863, Gyldén was appointed a “permanent astronomer” at the Pulkovo Observatory. He married Therese Amalie Henriette von Knebel in 1865; the couple had four children. At the Pulkovo Observatory, Gyldén did not neglect celestial mechanics. He began to develop the theory of perturbations. In actual practice, the necessary calculations became insurmountably lengthy. Gyldén tried to shorten the calculations by the use of elliptic functions. With the help of these and suitable differential equations, he was able to make the series converge faster than before, so that there were not so many terms to be calculated. Gyldén implemented these methods in the 1870s and applied them to the orbits of periodic comets. In 1871, the Royal Swedish Academy of Science offered Gyldén the directorship of the Stockholm Observatory. There, he actively developed the observatory and its instruments while continuing his research on celestial mechanics. Gyldén’s aim was to find Gyldén, Johan August Hugo mathematical forms describing the orbits of the planets, and with the help of these forms to account for their motions during arbitrarily long periods of time. In this way, it would be possible to answer the question of whether the Solar System has a permanent structure. At first, Gyldén replaced the elliptical orbits of the planets with curves of higher order. In these intermediate orbits, as he called them, disturbances caused by other planets were taken into account. Soon, however, Gyldén noticed that an intermediate orbit was not accurate enough. He then tried to find as general a form as possible for the orbits of the planets, which he called absolute orbits. While an ordinary elliptical orbit was determined by six constants, the “orbit constants” of an absolute orbit must be expressed by time-dependent periodical functions. Gyldén hoped to show that no deviation of a planet’s orbit, beyond a certain small value, could ever occur. Gyldén intended to publish his research on orbital theory as a three-volume work; the first volume was printed in 1893. But he fell ill and died before the second volume could be completed; it was published posthumously in 1908. Afterward, it was demonstrated that Gyldén’s notions concerning the existence of absolute orbits are not binding. Nonetheless, his accomplishments in the field of G celestial mechanics are undeniable, and influenced other investigators, such as Marie Andoyer. Gyldén was a delegate to the Astrographic Congress in Paris (1877), at which the Carte du Ciel project was launched. Many scientific societies and academies appointed him an honorary or corresponding member. Gyldén was also a member of the board, and finally the chairman, of the international organization of astronomers, the German Astronomische Gesellschaft. Tapio Markkanen Selected References Backlund, O. (1897). “Hugo Gyldén.” Monthly Notices of the Royal Astronomical Society 57: 222–224. Donner, Anders Severin (1897). Minnestal öfver professor Hugo Gyldén. Helsinki: Ex Officina Typographica Societatis Litterariae Fennicae. Gyldén, Hugo (1893). Traité analytique des orbites absolues des huit planètes principales. Stockholm: F. and G. Beijer. Markkanen, T. S., Linnaluoto, and M. Poutanen (1984). Tähtitieteen vaiheita Helsingin yliopistossa: Observatorio 150 vuotta. Helsinki: Helsingin yliopisto Observatorio. 453