Background: William Murdoch was born in Lugar near Cumnock, East Ayrshire, Scotland, the third of seven children and the first son to survive beyond infancy. A son of John Murdoch, a former Hanoverian artillery gunner and a Millwright and tenant of Bello Mill on the estate of James Boswell in Auchinleck, he was educated until the age of ten at the Old Cumnock Kirk School before attending Auchinleck school under William Halbert, author of a highly regarded arithmetic textbook. Murdoch excelled in mathematics. Murdoch also learned the principles of mechanics, practical experimentation and working in metal and wood by assisting in his father's work.
Context: In September 1779 Murdoch was sent to Redruth in Cornwall as a senior engine erector, responsible for the erection, maintenance & repair of Boulton & Watt engines. These were used for pumping water out of the Cornish Tin mines, and therefore the efficiency and efficacy of the engines was an important factor in the amount of tin, and money, which could be extracted from a mine. At that time steam engines were not simply sold to customers but operated, and maintained by the builders for groups or individuals known as 'adventurers' (shareholders). The engine manufacturers were paid not for a completed engine but through a complex formula calculated on the basis of that engine's performance, as Watt described:  Our profits arise not from making the engine, but from a certain proportion of the savings in fuel which we make over any common engine, that raises the same quantity of water to the same height.  Therefore, Murdoch's skill in getting the most out of his engines directly impacted upon Boulton and Watts profits. This he did so successfully that by 1782 Boulton was writing:  We want more Murdocks, for of all others he is the most active man and best engine erector I ever saw...When I look at the work done it astonishes me & is entirely owing to the spirit and activity of Murdoch who hath not gone to bed 3 of the nights.  Due to the frequent problems which could occur with steam engines Murdoch was kept busy travelling around the area repairing and attempting to improve the performance of the engines under his care.
Question: How long was he there?. Whats the answer?