124 MOTIVE POWER AND DISPOSITION'

of Robison’s ‘ Mechanical Philosophy/ Mr.Watt states—My attention was first directed,in the year 1759, to the subject of steam-engines, by the late Dr. Robison, then a stu-dent in the university of Glasgow, and nearlyof my own age. He, at that time, threw outan idea of applying the power of the steam-engine to the moving of wheel-carriages, andto other purposes; but the scheme was soonabandoned, on his going abroad.” Mr. Watt,it appears, soon after made an experimentwith steam acting by its expansive force, butrelinquished the idea of constructing an engineupon this principle : “ I, however,” says he,described this engine, in the fourth articleof my patent, in 1769; and, again, in the spe-cification of another patent, in the year 1784,together with a mode of applying it to themoving of wheel-carriages.”

For many years subsequent to this, the im-provement of the steam-engine, acting by con-densation, seems to have wholly occupied thescientific world ; and the use of steam, actingby its elastic force, entirely abandoned or neg-lected. Mr. Hornblower had a patent, for theapplication of steam, acting both by its expan-sive force, and by condensation ; but it is toMessrs. Trevithick and Vivian that we owe theintroduction of the steam-engine, acting solelyby the expansive force of the steam. In