upon a railway (cf. Official Report of Stephenson Centenary, 1881). This pioneer engine was tried at Pen-y-darran during February 1804. On 22 Feb. it carried ten tons of iron, seventy men, and five wagons a distance of 9½ miles at a rate of nearly five miles an hour exclusive of stoppages (to remove obstacles from the tramway). On 2 March 1804 Trevithick wrote to his friend Davies Gilbert [q. v.]: ‘We have tried the carriage with twenty-five tons of iron, and found we were more than a match for that weight. … The steam is delivered into the chimney above the damper … it makes the draught much stronger by going up the chimney.’ Shortly after this the engine went off the road, whereupon, like its predecessor, it was converted into a stationary engine. Imperfect, however, as ‘the first railroad locomotive engine was, with its single cylinder and flywheel, it is obvious that its failure was attributable to the weakness and roughness of the tram-road, rather than to defects in the engine itself’ (Galloway; Thurston). This engine, cumbrous as it looks (it is figured in all books on the locomotive, and a model is at South Kensington), displayed a marked advance upon all previous types, and upon the strength of its performance it has been claimed that Trevithick was ‘the real inventor of the locomotive. He was the first to prove the sufficiency of the adhesion of the wheels to the rails for all purposes of traction on lines of ordinary gradient, the first to make the return flue boiler, the first to use the steam jet in the chimney, and the first to couple all the wheels of the engine’ (Engineering, 27 March 1868; and this view is amply endorsed by later writers on the locomotive, such as Hyde Clarke, Fletcher, and Stretton; cf. Rees, Cyclop. 1819). It is noteworthy that a ‘travelling engine’ of the Pen-y-darran type was built from Trevithick's designs in 1805 by his assistant, John Steele, for the wagon-way at Wylam colliery (where it worked for a short period in May 1805), and there is little doubt that this locomotive supplies the link between the type invented by the Cornish school of engineers and that perfected by the Newcastle school a quarter of a century later (see Mining Journal, 2 Oct. 1858; Gateshead Observer, 28 Aug. 1858 et seq.). In 1808 Trevithick built a new and simpler form of locomotive, the ‘catch-me-who-can;’ this was designed for a circular railway or ‘steam circus,’ which was erected upon the site of what is now Euston Square, where the inventor offered rides to all comers at one shilling a head during the months of July and August. After some weeks, however, a rail broke, the engine was overturned, and the experiment, which had not proved a pecuniary success, was discontinued. This was Trevithick's last essay upon a locomotive model, the perfection of which was left to be achieved by the Stephensons.
From 1803 to 1807 Trevithick was fully occupied in improving a steam dredger used in the Thames estuary. In 1806 he entered into a twenty-one years' agreement with the board of the Trinity House to lift ballast from the bottom of the Thames at the rate of half a million tons a year and a payment of sixpence a ton; but this arrangement seems to have lapsed. About the same time the idea of substituting high-pressure steam in the then existing Boulton and Watt pumping engines, and of expanding it down to a low pressure previous to condensation, seems to have occurred to him (letter of Trevithick to Davies Gilbert, dated 18 Feb. 1806). For this purpose he proposed to substitute a cylindrical boiler of his own design for that in common use. If this idea had been followed up, an engine nearly the counterpart of those now in use would have been produced; but Trevithick was considerably in advance of his age, his suggestions were not adopted, and he lacked the money to push them (Pole, On the Cornish Engine, 1844). An engine on a somewhat similar plan was, however, erected by him at Wheal Prosper mine in the spring of 1812, and proved a success. It was the first ‘Cornish engine’ (as the type has since been denominated) ever erected. In 1809 Trevithick was consulted as to the practicability of an archway or tunnel under the Thames, and set to work upon an experimental driftway; but here, like his predecessors, he seems to have approached too near the bed of the river, and his passage was flooded and submerged after he had accomplished rather more than three quarters of the distance proposed (Law, Thames Tunnel, pp. 4–6; Civil Engineering Journal, ii. 94). His attention was immediately diverted by the vision of an ideal cylindrical boiler of wrought iron, and by a scheme for the manufacture of iron tanks for water cisterns (an idea of great practical utility which he had patented in 1808) for buoys and for marine freight generally. In 1811 at Hayle Foundry he built for Sir Christopher Hawkins a pioneer steam threshing machine (now in the South Kensington Museum), and he was confident of the successful application of steam to all processes of agriculture; but the invention seemed at the time completely stillborn. In 1814 his interest was absorbed in a scheme for the engineering, on Cornish principles, of the famous mines of Peru. Nine of his engines
