Clark was born at
Great Marlow in
Buckinghamshire, where his father made pillow lace. He had two younger brothers and attended his local school. When he was aged 11, he was sent to a French academy in
Normandy for three years, where he became sufficiently proficient in the French language that he was able to translate texts from English to French professionally. Returning to England, he spent some time working in a solicitor's office owned by his uncle. He was at one time a mathematical master at Brook Green, then became a Surveyor in the west of England. In 1846 Clark went to London where he met
Robert Stephenson, who appointed him Superintending engineer of the
Britannia Bridge. Clark, in turn, appointed his brother
Josiah Latimer Clark as his Assistant Engineer. When the Britannia Bridge opened on 5 March 1850, Clark published a book
The Britannia and Conway Tubular Bridges (3 vols), and by August of that year he had moved on to become an Engineer with the Electric and International Telegraph Company, where he took out the first of several patents for telegraph apparatus; the
London and North Western Railway used Clark's telegraph between London and Rugby from 1855. Stephenson bequeathed him £2000 which he used to build a telescope on top of his house in
Honor Oak. He was also known for his
astronomy. ==Thames Hydraulic Lift Graving Dock==