Sir Proby Thomas Cautley KCB (3 January 1802 – 25 January 1871), English engineer and palaeontologist, born in Stratford St Mary, Suffolk, is best known for conceiving and supervising the construction of the Ganges canal during East India Company rule in India. The canal stretches some 350 miles between its headworks at Haridwar and, after bifurcation near Aligarh, its confluences with the Ganges river mainstem in Kanpur and the Yamuna river in Etawah. At the time of completion, it had the greatest discharge of any irrigation canal in the world.
Proby Cautley was educated at Charterhouse School (1813–18), followed by the East India Company's Military Seminary at Addiscombe (1818–19). After less than a year there, he was commissioned second lieutenant and dispatched to India, joining the Bengal Presidency artillery in Calcutta. In 1825, he assisted Captain Robert Smith, the engineer in charge of constructing the Eastern Yamuna canal, also called the Doab canal. He was in charge of this canal for 12 years between 1831 and 1843. By 1836, he was Superintendent-General of Canals.
In 1840 Cautley reported on the proposed Ganges canal, for the irrigation of the country between the rivers Ganges, Hindan and Yamuna- then called the Jumna, which was his most important work. Cautley began working towards his dream of building a Ganges canal, and spent six months walking and riding through the area taking each measurement himself. He was confident that a 500-kilometre canal was feasible. There were many obstacles and objections to his project, mostly financial, but Cautley persevered and eventually persuaded the British East India Company to back him. This project was sanctioned in 1841, but the work was not begun till 1843, and even then Cautley found himself hampered in its execution by the opposition of Lord Ellenborough.