Claims have been put forward by various writers that Murdock ought to be regarded as one of the inventors of the locomotive ; but from a strictly practical point of view this can hardly be conceded, as his experiments led to no results, and those who followed him worked on different, lines. His attention seems to have been directed to the subject of locomotion by steam in 1784 (cf. Muirhead, Life of Watt, pp. 443-5). On 9 Aug. 1786 Thomas Wilson, Boulton & Watt's agent in Cornwall, wrote to Soho : 'Wm. Murdock desires me to inform you that he has made a small engine of ¾ dia. and 1½-inch stroke, that he has apply'd to a small carriage, which answers amazingly.' In all probability this is the well-known model which was purchased a few years ago from the Murdock family by Messrs. Tangye Brothers, and by them presented to the Birmingham Art Gallery, where it is now exhibited, although the dimensions do not quite correspond with those given by Wilson. The true date of its construction is probably 1786. An exact reproduction of the Birmingham model may be seen in the machinery and inventions department of the South Kensington Museum. A section of the engine, carefully drawn to scale, appeared in 'The Engineer,' 10 June 1881, p. 432.
Writing to Watt from Truro on 2 Sept. 1786, Boulton stated that near Exeter he had met a coach in which was William Murdock. 'He got out, and we had a parley for some time. He said he was going to London to get men ; but I soon found he was going there with his steam carriage to show it, and take out a patent, he having been told by Mr. Wm. Wilkinson what Sadler has said, and he has likewise read in the newspaper Symington's puff, which has rekindled all Wm.'s fire and impatience to make steam carriages. However, I prevailed upon him to return to Cornwall by the next day's diligence, and he accordingly arrived here this day at noon, since which he hath unpacked his carriage and made travil a mile or two in Bivers's great room, making it carry the fire-shovel, poker, and tongs. I think it fortunate that I met him, as I am persuaded I can either cure him of the disorder or turn the evil to good. At least I shall prevent a mischief that would have been the consequence of his journey to London.' On the 8th of the same month Boulton again writes to Watt : ' Murdock seems in good spirits and good humour, and has neither thought upon nor done anything about the wheel carriage since his return, because he hath so much to do about the mines.' On the 17th he writes : ' Send all the engines as soon as possible, and he will be better employed than about wheel carriages. He hath made a very pretty working model, which keeps him in good humour, and that is a matter of great consequence to us. He says he has contrived, or rather is contriving, to save the power ariseing from the descent of the carriage when going down hill, and applying that power to assist it in its ascent up hill, and thus balance y e acct. up and down. How he means to accomplish it I know not . . . Wm. uses no separate valves, but uses ye valve piston, something like the 12-inch little engine at Soho, but not quite.'
The originals of these letters hitherto unnoticed are at Soho. They are of considerable importance, as they not only fix the date of the model, but they also go to prove that Murdock made another and larger engine, the Birmingham locomotive being quite incapable of carrying the weight of a set of fire-irons. There is a passage in Trevithick's 'Life of Trevithick,' i. 150, which may possibly refer to the larger model, or perhaps even to a third engine. Writing to Davies Giddy, under date 10 Oct. 1803, Trevithick says : ' I have desired Captain A. Vivian to wait on you to give you every information respecting Murdock's carriage, whether the large one at Mr. Budge's foundry [at Tuckingmill] was to be a condensing engine or not.' As Mr. Trevithick observes, 'this opens up a curious question in the history of the locomotive,' and there appears to be good ground for believing that Murdock made three locomotives : (1) the model now at Birmingham ; (2) the model mentioned by Boulton in his letter of 2 'Sept. 1786 ; and (3) the engine referred to in Trevithick's 'Life,' which, as the context shows, was certainly of considerable size. No. 2 is in all probability the engine which alarmed the vicar of Redruth when Murdock was trying it one night on the path leading to the church (Smiles, Lives of Boulton and Watt, 1874, p. 367). Both Watt and Boulton did all they could to discourage and hinder Murdock from pursuing his experiments, and in a letter from Watt to his partner, dated 12 Sept. 1786, probably in answer to one of those just referred to, he says : 'I am extremely sorry that W. M. still busies himself with the steam carriage. ... I wish W. could be brought to do as we do, to mind the business in hand and let such as Symington and Sadler throw away their time and money ; hunting shadows' (Muirhead, Life of Watt, 2nd ed. p. 445; Mechanical Inventions of Watt. ii. 210).
Apart from the locomotive, Murdock was the author of several improvements in the
