William Gravatt

[1][2] 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.

[3] 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 and a copy of the Difference machine, distinguishing himself in a number of papers submitted to the Institution of Civil Engineers.

[1][2] Born in Gravesend, Kent on 14 July 1806, he was the son of Colonel William Gravatt, the Assistant Inspector of the Royal Military Academy, Woolwich.

However, company directors Robert Marten and Richard Harris insisted Gravatt take them in to inspect the damage, accompanied by two miners as crew for a dinghy.

Whilst in the workings, Marten attempted to move forward in the dinghy, and after striking his head on the tunnel, tipped the boat over in 12 feet (3.7 m) of water.

"[1] In 1832 during a break in work on the Thames Tunnel due to water ingress, Donkin recommended Gravatt as Engineer to the Calder and Hebble Navigation.

Palmer in examining the original scheme for the South Eastern Railway's route from London to Dover, during the works Gravatt devised the more transportable dumpy level, which is now universally employed.

After gaining passage of their Act of Parliament in 1836, on Brunel's recommendation, the newly incorporated Parrett Navigation Company engaged Gravatt as their engineer on the Westport Canal in June 1836.

[2] Living in an apartment at 34 Parliament Street, his neighbours included the portrait photographer Richard Beard, who in 1852 came to take pictures of the instrument for the Illustrated London News.

[1][2] During his career, Gravatt collected a number of gifts, including: a pair of calipers made by Troughton; Donkin's chronometer by Hardy; a specimen of Babbage's original difference engine.