SECT. i. ] THE STEAM ENGINE. 41 



investigation, which had made so little progress in the hands of mechanical people. 

 The first chemist who distinguished himself by attempting a full investigation of 

 the theory of vapour, was Mr. John Dalton. He made an accurate series of 

 experiments on the expansive force of steam at temperatures lower than 212, 

 made experiments and ascertained various phenomena relative to the expansion 

 of gases, the mixture of air and vapour, the nature of evaporation and of com- 

 bustion. And though he failed in his attempt to reduce any of these to general 

 laws, yet he gave such an impulse to the inquiry, as rendered it one of universal 

 research among chemical philosophers. The importance of Dalton's inquiries, 

 and even their connexion with the theory of the steam engine, did not appear, 

 at first, to be much noticed. The idea that Watt had done every thing possible 

 to be done respecting the power of steam had stopped inquiry among men of 

 science, and left the manufacturers and capitalists of the country, who were wishful 

 to encourage improvement, to be guided by vain and ignorant projectors, or ruined 

 by pretending knavery. 



1802. WILLIAM SYMINGTON. 



55. In 1801, Mr. Symington was encouraged to proceed with a steam boat, 

 by Thomas, Lord Dundas, of Kerse, who wished that one might be applied to drag 

 vessels on the Forth and Clyde Canal in place of horses ; and accordingly a series 

 of experiments on a large scale, which cost nearly 3000, were set on foot in the 

 year 1801, and completed in 1802. The boat Mr. Symington made was for towing, 

 and it had a steam cylinder twenty-two inches in diameter, and four feet stroke. 

 A complete model of it, with a set of ice-breakers attached, may be seen at the 

 rooms of the Royal Institution in London. This tow-boat proved to be very much 

 adapted for the intended purpose, but no direct practical application of steam power 

 to this object resulted from it. 



1802. TREVITHICK and VIVIAN. 



56. The idea of a high pressure engine had occurred to Leupold, (art. 12.) 

 and to Watt, 1 (art. 26.) but neither of them had reduced their notions to practice ; 

 and it was not till 1802 that this simple mode of applying steam was brought into 

 use by Messrs. Trevithick and Vivian. 2 Their object seems to have been to form 



1 It was generally understood, that, although Mr. Watt patented the high pressure engine, it 

 was not his intention that it should he employed, except in situations where condensing water could 

 not he had. He considered the risk too great, and life too valuable, to be endangered for a saving 

 in the mere original cost of the engine, there being none in respect of the consumption of fuel. 



Repertory of Arts, vol. iv. p. 241. New Series. 



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