94 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



[Mauch, 



iiersliip witii iiim that, in ISOi!, Trevithick, while at Camhonie, took 

 out his patent for tiie high-pressure steam engine. 



About tlieyear 1723, Leupold, a German philosopher, in his comments 

 on Papin's apparatus in the Theatrum Maehiiiarura, had given the tirst 

 idea of the application of steam on the high-pressure principle, but his 

 suggestions remained without any practical results. Watt indeed had 

 made some allusion to ihis principle in his attempts to obtain a locomo- 

 tive power, but at any rate was not able to avail himself of it, even if 

 he understood its application, and to the last day of his life displayed an 

 obstinate prejudice against it. It does not appear that Watt had then 

 read the Theatrum Machinarum, and it is not likely that Trevithick in 

 his Cornish seclusion ever saw it, so that he has tlie merit of invention 

 as much as of application. The introduction of this improvement 

 gave increased powers to steam, and it is of that importance, tliat Stuart, 

 not likely from national sympathy to be over-prejudiced in favour of an 

 Englishman, is even inclined to date the era of the steam engine from 

 this invention. It is certain that independently of its merits, this ap- 

 plication of steam power is already of paramount importance from its 

 great extension. It affords the means of locomotion on all the rail- 

 wavs in the world, propels tlic swarms of American steamers, and is 

 greatly used in manufacturing operations. 



In 1804, Trevithick had the opportunity of trying his engine on the 

 Merthyr Tydvil tramroad as a motive power applied to a carriage. 

 The engine hadan eight inch cylinder, and the piston had a stroke of four 

 feet six inches ; it travelled at the rate of live miles an ho\n', and drew as 

 many waggons as carried ten tons of iron, without requiring any w-ater, 

 for a distance of nine miles.* Stuart says that the great obstacle to its 

 introduction at this time was the supposed want of adhesion, or hold of 

 the wheels upon tlie rails, to effect the locomotion of the engine. 



Trevithick and Vivian erected several of their high pressure engines 

 in Wales and other places, and it was about this time, although we do 

 not know whether before or after the experiment on the Merthyr Tyd- 

 vil tramroad, that Trevithick put into operation the first locomotive en- 

 gine in London. In the great metropolis Trevithick found ample 

 support in his countryman, Davies Gilbert, the Earl of Stanhope, Mr. 

 Isaac Rogers, Mr. Samuel Kehe, Mr. Henry Clarke, and others con- 

 nected with his native county or the cause of science. The engine he 

 used was about the size of an orchestra drum, and which he attached 

 to a phaeton between the back wheels. With this carriage an experi- 

 ment was made in Lord's cricket ground, at Marylebone, several men 

 ofscience alternately steering it, and expressing their perfect satisfaction 

 as to the ease with which it was directed. Erom hence it was steered 

 down the New-road,andGray's-inn-lane,to the coachbuilder's, whence the 

 phaeton was obtained. Thus it passed over ground, since the site of 

 Hancock's experiments, and perhaps ultimately destined to be witness 

 of the final triumph of this branch of locomotion. The next day 

 Trevithick took this same engine and exhil)ited it in a cutler's shop, 

 working the machinery ; which was one of his essays, to show its general 

 applicability. Subsequently he had a temporary tramroad constructed 

 ■within an enclosure on the ground now occupied by Euston-sqnare. 

 This road was of an elliptical form, and on it he ran his locomotive. 

 It was opened to the public as an exhibition, and people crowded to 

 see it, but the second day Trevithick, in one of his usual freaks, re- 

 moved the engine, and, to the great disappointment of visitants, closed 

 thegroinid. This he did under the impression that it was better to let 

 the affair drop, until he saw the opportunity to avail himself of it 

 advantageously. 



Another occupation of his metropolitan career was the tunnel 

 under the Thames, in which he owed it only to his own pertinacity 

 that he disappointed both the public and himself. Ralph Dodd, an 

 engineer of some note of the last ccntiny, was the first to commence 

 operations for a tunnel under the Tliames from Gravesend to Tilbury 

 Fort. His plan was to avail himself of the clialk stratum which he 

 supposed to run under the bed of tlie river, and he expected that the 

 cliaik quarried out would sufficiently pay tlie expenses of working, 

 leaving its subsequent use as a viaduct to afford a handsome income. 

 As was mentioned by a correspondent in one of our late numbers,-]- he 

 obtained an Act of Parliament for his plan in 179'J, with power to 

 raise 30,0Ulil., and to increase his capital incase of need to ,")0,0n01., his 

 estimate being only 1 j,00l)l. The work was commenced, and proceeded 

 for about three years, but was ultimately stopped on account of the 

 expense of drainage. He had gone on the assumption that the chalk 

 would be in one solid stratum, and that he should not be embarrassed 

 by water, having in his estimates allowed only 17801. for this purpose, 

 and treated the expense as merely contingent. He found, however, 

 such great inconvenience from undor-springs rising through fissures in 

 tlie elialk, that as we have said, he was obliged to abandon' the project. 



^ Historical and Descriptive .Anecdotes of the Steam Engine, by R. Stuart p, 460. — 

 Mcholfon's Operative Meclianic, p. 2«». 



t Vol. I,p. S81, 



This tended to throw a damp on such plans, and when Trevithick pro- 

 posed a similar tunnel imder the Thames at Kotherhithe, he found a na- 

 tural rcltictance to support any such utidertakiiig. Several of his friends, 

 however, raised a subscription to enable him to make an experiment 

 on a small scale, and the result was anxiously awaited to justify an 

 appeal to the public for carrying out the entire plan. 



In 1809, therefore, Trevithick was employed in rtinning a small 

 driftway parallel to the bed of the Thames. The committee of sub- 

 scribers justly felt every assurance of the success of the undertaking, for 

 the operation was extremely simple, while they had entire confidence 

 in his skill and ability, from the experience he had gained in similar 

 underground mining works. We have tunnels four miles in length to 

 some of our canals, and abundance of communications in the mining 

 districts under the surface of the earth, and even beneath the sea ; but 

 notwithstanding the ease of such a work, extraneous causes have always 

 hitherto prevented this kind of viaduct from being used under rivers. 

 Trevithick, to save labour and expense, committed the usual funda- 

 mental error of not going deep enough below the bed of the river, the 

 object in his case being a close-run endeavour to keep at the least 

 possible distance from it. Had his experiment been concluded, this 

 would have enabled him to give a plausible original estimate at any 

 hazaid of subsequent increased expense. This error, however, was not 

 prodtictive of much inconvenience to him, nor was it the immediate 

 cause of the abandonment of the enterprise, for he carried his drift- 

 wav to a greater extent without impediment than has been done in any 

 otlier attempt. It was not until he had gone 930 feet* under the river, 

 that he encountered any obstacle, when he got into a hole in the muddy 

 bottom of the river, and at one time a piece of uncooked ship beef, 

 which had fallen from one of the vessels, drifted into the works. 

 Although the Corporation authorities refused to allow him any 

 facilities, he managed to get this hole stopped, and again went on with 

 vigor ; he c.irried on the excavation at the rate of from four to ten feet 

 per day, and soon completed a thousand feet, to the great joy of every 

 one concerned. On arriving at this distance, according to his previous 

 agreement with the committee, Trevithick was to receive a hundred 

 guineas, which, after a verification of the work by a surveyor, were 

 paid to liini. This surveyor was appointed by the subscribers to check 

 Trevithick, and in giving in his report, confirming the measurement, 

 stated that the line had been run one foot out of the perpendicular. 

 This statement Trevithick took iu high dudgeon, and chose to consider 

 it as a deep leflection on his engineeiing skill to have deviated one 

 foot in a thousand. His Cornish blood was excited, and with his 

 usual impetuositv, he set to work to disprove the assertion, without 

 any regard to consulting his own interest, or embroiling himself with 

 the committee. Of all possible contrivances for effecting this object, he 

 adopted the most absurd, which was no less than to make a hole in the 

 roof of the tunnel at low water, and to push through a series of jointed 

 rods to be received b}' a party in a boat, and then observed from the 

 shore. Even had he been successful in carrying out this process, it 

 would have afforded no criterion of the precision of the work, as the 

 set of the current would necessarily have swerved the rod. Trevithick 

 was employed in the driftway in carrying out this contrivance, and as 

 delays of coinse ensued in fitting together the rods, the gidly consequent 

 on the opening in the roof ultimately admitted so much water as to 

 render a retreat necessary. With a moral courage innate to his 

 character, and worthy of a better cause, he sent the men on before him, 

 and very nearly fell a sacrifice to his devotion. It has been already 

 observed that the driftway was parallel to the bed of the river, and 

 consequently curved ; it necessarily happened, therefore, that the enter- 

 ing water would lodge, syphon-like, in the bottom of the curve, at which 

 part, on Trevitliick's arrival, he found so much water as hardly to be able 

 to escape, for as he ascended the slope on the other side, and climbed 

 the ladders, the water rose to his neck. It is needless to say, that this 

 act of rashness was the death-blow to the project, while it added the 

 climax to the manv acts of inconsistency with which Trevitliick's 

 erratic career was disturbed. On a subsequent occasion, being cross- 

 examined as to this occurrence while witness on a trial, he admitted the 

 fact of his ruining the woiks, and his determination iu any similar 

 circumstance to defend his own character at whatever sacrifice to other 

 people. The work thus ended after having readied 1,011 feet, and 

 remains within a hundred feet of its proposed terminus, a melancholy 

 monument at once of his folly and his skill. 



After these events Trevitliick returned to Camborne, and we now 

 approach another of those epochs of his life, in which his labours were 

 again destined to be followed by tlie most extended results. Here we 

 have an instance of the operation of those trains of finite causes, which, 

 while they are someiimes productive of the most unexpected advan- 

 tages, too often baffle all human expectations and arrangements. t 



' Mi'ehanics' Jlimaiint', Vol. I. , ,, . 



t Tf iiiUfictiuiis vf tlw CvfH'ViiU U'olomcal So9ietj-, Mr, Bo»se s Memoir, 



