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In 1832, [[English people|English]] [[civil engineer]] and inventor [[William Gravatt]], who was commissioned to examine a scheme for the [[South Eastern Railway, UK|South Eastern Railway's]] route from London to [[Dover]], became frustrated with the slow and cumbersome operation of the "Y" level during the survey work, and devised the more transportable, easier-to-use "dumpy" level,<ref>{{cite book|title=Surveying|author=Saikia|publisher=PHI Learning|date=30 Oct 2010|isbn=8120339851|display-authors=etal}}</ref><ref>{{cite web|url=http://www.craig-telescope.co.uk/life_gravatt.html|title=William Gravatt|publisher=craig-telescope.co.uk|accessdate=2012-05-31}}</ref> so called because of its shorter appearance.<ref>{{cite book |title=Oxford English Dictionary |location="dumpy", adj, 2 |quote=Gravatt's Improved Level, commonly called (from its appearance) the Dumpy Level.}}</ref>
The telescope of the historic "Y" level is held in two brass arms, which are part of the mount and the telescope could be easily removed to allow sighting reversal though 180 degrees or an axial rotation of the telescope; both to compensate for optical collimation errors. Because the telescope is not fixed to the level adjusting mechanism, the "Y" instrument is assembled and disassembled for each sighting station. However, the dumpy level is permanently secured to its two support arms and the levelling mechanism, thereby reducing measurement uncertainty and considerably reducing the time taken to set up the instrument. The Dumpy uses the same basic principle of level sighting.
==Survey operation==
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