1816.) Dr. John Robison. 177 
chemistry, to which, however, he was now bending his attention. 
He had the advantage of being 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 University. Mr. 
Watt, who at that time exercised the profession of a mathematical 
instrument maker, was employed in fitting up the. astronomical 
instruments bequeathed to the Observatory by the late Dr. Macfar- 
lane, of Jamaica. Mr. Robison, 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 ordinary man would have been of no value, gave rise 
to the improvement of the steam-engine. A mode] of the common 
engine, 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 impos- 
sible to supply it with steam, and it was in the attempt to obviate 
this difficulty, and in trying to produce a more perfect vacuum, 
that the idea of condensing the steam in a separate vessel first oc- 
curred to him. At the same time, by a curious coincidence, his 
experiments led him to conclusions concerning the great quantity 
of heat contained in steam, that were only to be explained on the 
principle of latent heat. Mr. Robison lived in a state of great in- 
timacy with Mr. Watt, and was so much acquainted with the first 
steps of this invention that his evidence on the subject of the origi- 
nality of it was afterwards of great use in ascertaining the justness 
of his claim. 
There could not be a better school for philosophical invention 
than Mr. Robison enjoyed at this time, and accordingly he used 
always to say that it was not till his second residence at Glasgow 
that he applied to study with his whole mind. 
Dr. Black was elected Professor of Chemistry in the University 
of Edinburgh in the summer of 1766; and on leaving Glasgow 
recommended Mr. Robison as his successor. He was accordingly 
made choice of, and began his first course of chemical lectures in 
October, 1766. He was appointed for one year only; but his 
success assured his continuance without any other limit than such 
as depended on himself. 
He had also the charge of the education of the late Mr. Mac- 
dowal, of Garthland, and of Mr. Charles Knowles, a son of the 
Admiral. But of the particulars, during four years, about this 
time, I have been able to obtain little information. 
The friendship of Admiral Knowles had been all along exerted 
toward Mr. Robison with an extraordinary degree of zeal and 
assiduity, and was now ‘the méans of procuring for him a very 
Onlooked-for preferment, which removed him from his academical 
