William Gravatt FRS (14 July 1806 – 30 May 1866), was a noted English civil engineer and scientific instrument maker. Apprenticed as a mechanical engineer in London from aged 15, after interview he worked with Sir Marc Isambard Brunel on the Thames Tunnel, and then designed bridges for the Calder and Hebble Navigation. Whilst surveying the route for the South Eastern Railway to Dover, he devised the more transportable dumpy level, which is now universally employed. He then supervised the northern engineering team under Isambard Kingdom Brunel on the Bristol and Exeter Railway, where the deployment of his "curve of sines" theorem speeded construction. Dismissed from the project in 1841, after losing money during the railway mania period, Gravatt helped to construct both the Craig telescope