But Trevithick did not confine himself to the steam pumping-engine. The improvements which he and others had made and were making in that most important machine necessitated improvements in other parts of the mine. The ore must be drawn more rapidly to the surface, and the mode of sending it up the shafts must be improved. He was equal to the occasion: the steam whim solved the former, and the wrought-iron kibble (formerly a bucket, constructed of wood) the latter difficulty. About this period an amusing incident occurred which is worth recording, as exhibiting Trevithick's force of character in other than merely professional matters. His remuneration would appear to have consisted partly of a fixed salary, partly of the profits incident to the supply of machinery, and partly of royalties payable upon instruments of his invention. Now one of his engines was supplied to a mine called Wheal Abraham, whose shareholders, on somewhat fanciful and possibly unfair grounds, appear to have unnecessarily delayed satisfying Trevithick's just claims; whereupon, one night, the engineer and his men took the matter into their own hands, and (to the astonishment of the staff of the mine next morning) removed the huge engine bodily. We now approach a very interesting episode in Trevithick's career--namely, the invention of his 'Camborne common road-locomotive.'[146] The idea of this may possibly have suggested itself to him (as doubtless other causes suggested similar ideas to Murdock, and to others before and after Trevithick) from his having to transport one of his portable engines from mine to mine, as required--sometimes at a considerable cost. To such a practical genius as his the idea doubtless occurred, 'Why not, with all this available power, make the engine move herself?' However this may be, the curtain now rises on an amusing little group in Trevithick's house; Davies Gilbert acting as stoker, and Lady De Dunstanville of Tehidy (on whose estate most of the great Camborne Mines were situated) playing the part of engine-man to a little model locomotive which ran round the table. The original working model of 'the Trevithick high-pressure locomotive,' the first working model for which was made in 1797, is still to be seen at the South Kensington Museum, in the machinery department; but it was not till Christmas Eve or (according to other authorities) Christmas _Day_, 1801, that the 'puffing devil,'[147] as it was locally termed by the astonished Cornish folk, made its first performances on the roads round Camborne, Tuckingmill, and Tehidy, carrying its ten or a dozen passengers uphill faster than a man could walk. The success, though not complete, was sufficient to determine Trevithick, with his brother-in-law Andrew Vivian--who found the money and shared in the speculation--to proceed forthwith to London in order to obtain a patent (his first), which was accordingly secured on the 24th March, 1802. Smiles points out, in his 'Lives of the Engineers,'