50 WATT. 



notion of a degree being only sixty miles appeared by 

 its consequences to disprove his proposition, and in- 

 stead of making any further experiments himself, 

 waited until Picard's more accurate measurement be- 

 came known to him accidentally in 1 682, and enabled 

 him to demonstrate his doctrine. In like manner, 

 Lavoisier, who discovered no gas, and made no original 

 experiments of the least value in pneumatic chemistry, 

 is universally admitted to have discovered the true 

 theory of combustion and calcination, by reasoning on 

 the facts which others had ascertained. Watt's happy 

 inference from the facts discovered by Warltire and 

 Priestley was just as much entitled, and for the same 

 reasons, to be regarded as the discovery of the com- 

 position of water. 



The latter years of Mr. Watt's useful and honour- 

 able life were passed in the bosom of his family and 

 the society of his friends, although he ever gave the 

 due attention to the extensive concerns of the house 

 in which he was the principal partner. He had been 

 married as early as 1764 to Miss Miller, his cousin, 

 and had by her a daughter who predeceased him, and 

 a son, James, who still survives, inheriting the scien- 

 tific tastes, the extensive knowledge, the masculine 

 understanding, and the scrupulous integrity of his 

 father. With the late Mr. Robinson Boulton and Mr, 

 Gregory Watt, he was admitted into the partnership, 

 the concerns of which he has extended, and, for the 

 last quarter of a century, almost exclusively conducted. 

 By his second wife, Miss Macgregor, whom Mr. Watt 

 married 1776, he had one son, Gregory, who unfortu- 

 nately died in October, 1804, at the age of twenty- 

 seven, after giving an earnest of brilliant talents and 

 accomplishments. This loss was, no doubt, a severe 

 blow to his family, and the father shared fully in their 

 sorrow. But he bore it like a man : and I feel great 

 satisfaction in correcting an error into which my illus- 

 trious, friend and colleague M. Arago has fallen through 



