In late 1762 he married Bagnall's sister Elizabeth, and the marriage was witnessed by another canal engineer, Hugh Henshall.
[1] Construction of the Trent and Mersey Canal began in 1766, and when its engineer James Brindley died in 1772, Henshall was given the post.
He appears to have still been involved in running Henshall's carrying company, and the Chester Canal decided that he was not giving sufficient attention to their business, and so dismissed him.
The superintendent of the company, James Perry, oversaw the work, but although he was a good manager, he had no experience of canal construction and so Clowes' task was both difficult and onerous.
[3] There were major problems with the construction of the tunnel, as parts of it passed through Fuller's earth, which swelled up when it got wet, causing the ground to move.
The leaks from above proved very difficult to seal, and the problem of springs was not finally resolved until 1790, when Robert Mylne found a solution.
He was paid one and a half guineas (£1.57) a day, plus expenses, and worked for two years, completing both the tunnel and a reservoir at Gads Green.
Next he was asked by the Leeds and Liverpool Canal to assess their summit level, as they thought Whitworth had made errors.
[2] The Worcester and Birmingham Canal continued their attempts to entice him by flattery, and in January 1792 he became their consultant, for which he received 29 guineas (£30.45) per day.
His work on the Shrewsbury Canal included the 970-yard (890 m) Berwick Tunnel, with a wooden towpath cantilevered from the side wall, and an aqueduct at Longdon on Tern, which was swept away by floods in 1795 and replaced by Thomas Telford with a cast iron design, one of the first to use this material.
[6] Clowes was at Middlewich, Cheshire, when he died in late 1794, and was buried in St. Bartholomew's churchyard, Norton le Moors, North Staffordshire on 1 January 1795, next to his first wife, where his memorial can still be seen.