WATT (JAMES)


Autograph letter signed ("James Watt") to John Rennie, sending a detailed abstract of his assistant John Southern's observations on Rowland & Pickering's lock machine for canals, which he was unable to see for himself, expressing his own scepticism about the machine ("As long experience of the fallacy of Theoretical reasoning has made me very sceptical as to the success of new contrivances..."), and noting that the technology should not be tested on "an extensive scale" until fully reviewed and offering alternative solutions to the "probable defects" in the raising and lowering mechanism, 3pp with integral address panel, seal and docket, 4to, (258 x 200mm.), Soho, 25 August 1797
|JAMES WATT ADVISES HIS PROTÉGÉ AND FRIEND JOHN RENNIE ON CANAL ENGINEERING: Rennie's acquaintance with James Watt began in 1783 when he procured an introduction during a study tour and subsequently joined Boulton & Watt, masterminding the revolutionary design of the Albion flour mill in Blackfriars. By 1791, Rennie was self-employed and in 1796 was asked by the Ellesmere Canal Company to assess the prototype for Rowland & Pickering's boat lift, patented in 1794, to be installed at Ruabon. As his friend and mentor, Watt would be an obvious choice for Rennie to turn to for advice, particularly as Watt had begun his own career working on several canal projects in Scotland, the last and most significant being the survey of the Caledonian Canal between Fort William and Inverness in 1774. It would appear that, following Watt's advice given here, Rennie's final report was unfavourable, for this branch of the Ellesmere canal was never built and Rowland & Pickering were later reimbursed the sum of £200 of the £800 they had expended on a prototype never to be used. However, the principle employed by Rowland & Pickering was later successfully used on several continental canals. For a detailed account of the machine and this project see Richard Dean, 'The Machine', a Boat Lift Mystery Solved? (www.pontcysyllte-aqueduct.co.uk).Provenance: Bonhams, Papers & Portraits: The Roy Davids Collection Part II, 29 March 2011, lot 359.