508 BIOGRAPHICAL ACCOTiNT 



him before he left Glasgow ; but at that time he had not stu- 

 died chemistry, to which, however, he was now bending his 

 attention. He had the advantage of beino' initiated in it 

 by the author of the discovery just mentioned, and the new 

 views struck out by his master, did not fail to interest him 

 in a study, which, from that time, came to occupy a new place 

 in physical science. 



Mechanics had always been his favourite pursuit, and his 

 turn to whatsoever was connected with it, had brought him to 

 be acquainted with Mr Watt before 1758, when he left the 

 Universit}'. Mr ^Vatt, who, at that time, exercised the pro- 

 fession of a mathematical instrument maker, was employed in 

 fitting up the astronomical instruments bequeathed to the Ob- 

 servatory by the late Dr Macfarlane of Jamaica. Mr Robi- 

 soN, on his return, found him still residing in Glasgow, and 

 exercising the same profession, and their former intimacy was 

 naturally renewed. In 1764, an occurrence such as to an or- 

 dinary man would have been of no value, gave rise to the im- 

 provement of the steam-engine. A model of the common en- 

 gine, Newcomen's, which belonged to the Natural Philosophy 

 Class, was put into Mr Watt's hands in order to be repaired. 

 As the model worked faster than the large engines, it was found 

 impossible to supply it with steam, and it was in the attempt 

 to obviate this difficulty, and in trying to produce a more per- 

 fect vacuum, that the idea of condensing the steam in a sepa- 

 rate vessel first occurred to him. At the same time, by a cu- 

 rious • coincidence, his experiments led him to conclusions 

 concerning the great quantity of heat contained in steam, 

 that were onlv to be explained on the principle of latent 

 heat. IVIr Robison lived in a state of great intimacy with 

 Mr Watt, and was so much acquainted with the first steps 

 of this invention, that his evidence on the subject of the 



originality 



