BLACK. 345 



intercourse with Black, one of his earliest patrons ; 

 and although it is as certain that he did not owe to that 

 philosopher's suggestions any of the steps by which his 

 inventions were compassed, as it is that he had him- 

 self no share in Black's great discovery, it cannot be 

 doubted that the knowledge thus acquired of the true 

 nature of heat, of steam, of evaporation, and of con- 

 densation, contributed most essentially to his mighty 

 improvements. As for the gases, it would be difficult 

 to name the branch of art which has not in some 

 manner and to some extent gained by their discovery. 

 So that the great man whose history we are contem- 

 plating, had the satisfaction of seeing the triumphs of 

 his youth bear fruit in every direction, exalting the 

 power and increasing the comforts of mankind as well 

 as extending the bounds of their knowledge and enlarg- 

 ing the range of their industry. He was but twenty- 

 four years old when he made his first discovery, and 

 thirty-four when his second was added. He lived to 

 nearly fourscore. 



It remains to consider him as a teacher ; and cer- 

 tainly nothing could be more admirable than the 

 manner in which for forty years he performed this use- 

 ful and dignified office. His style of lecturing was as 

 nearly perfect as can well be conceived ; for it had all 

 the simplicity which is so entirely suited to scientific 

 discourse, while it partook largely of the elegance 

 which characterized all he said or did. The publica- 

 tion of his lectures has conveyed an accurate idea of the 

 purely analytical order in which he deemed it best to 

 handle the subject with a view to instruction, consider- 

 ing this as most likely to draw and to fix the learner's 



