SECT, i.] THE STEAM ENGINE. 31 



equal elastic force, the temperature of the latter was about thirty-five degrees 

 lower, but that the difference of temperature was not constant ; it seemed to be 

 greater or less as the elastic force was greater or less. 



1782. MARQUIS DE JOUFFROY. 



34. The idea of employing the steam engine to propel vessels, which had 

 been suggested by Hulls, (art. 14.) was first tried in practice by the Marquis De 

 Jouffroy, who, in 1782, constructed a steam boat to ply on the Saone, at Lyons; 

 it was 140 feet long and 15 feet wide, and drew 3*2 feet of water. He made 

 several experiments with it, and it was in use fifteen months on the Saone. * 



35. In 1785 M. Perronet gave a very full description, in the French Ency- 

 clopaedia, of an atmospheric engine erected near Saint Guilain, in Hainault : this 

 description is remarkable for its clearness and practical details, and not less so 

 from its being introduced by stating Papin to be the inventor of the steam engine 

 in a most unqualified manner ; though admitting the first to have been constructed 

 in England. 



1788. PATRICK MILLER. 



36. About this time various competitors for the application of steam to navi- 

 gation appeared, (1785-88.); in America, two rivals, James Rumsey of Virginia, 

 and John Fitch of Philadelphia. In Italy the application of steam power to vessels 

 was proposed by D. S. Serratti, and in Scotland by Mr. Miller of Dalswinton, who 

 afterwards, on the sight of a model of a steam carriage invented by Mr. William 

 Symington of Falkirk, was so much pleased with the model, that he desired Mr. 

 Symington to make him a small steam engine, to work a twin or double boat on 

 Dalswinton Loch. The engine having been accordingly executed, and put on 

 board the boat, the experiment was made at Dalswinton in the autumn of 1788, 

 and it succeeded so well, that Mr. Miller commissioned Mr. Symington to pur- 

 chase a gabert, or large boat, at Carron, and to fit up a steam engine on board of 

 it, to make a trial on a larger scale. Every thing being completed, the trial was 

 made on the Forth and Clyde canal, in the summer of 1789, Messrs. Miller, 

 Stainton, Taylor, &c. being on board ; and the result answered their most sanguine 

 expectations ; but most unaccountably, after having thus established, at a consider- 

 able expense, the practicability of employing the power of steam in navigation, 

 Mr. Miller seems to have neglected it entirely. 2 



1 Dictionnaire de Physique, art. Chaloupe a Vapeur. 



- ' Short Narrative of Facts relative to Steam Navigation,' Edinb. Phil. Journal. 



