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THE POPULAR SCIENCE MONTHLY. 



of Boulton & Watt, at Soho, near Birmingham, for a long time fur- 

 nished the greater proportion of all the steam-engines made in the 

 world. 



In the new firm, Boulton took charge of the general business, and 

 Watt superintended the design, construction, and erection, of their en- 

 gines. Boulton's business capacity, with Watt's wonderful mechanical 

 ability; Boulton's physical health, and his vigor and courage, offset- 

 ting Watt's feeble health and depression of spirits ; and, more than 

 all, Boulton's pecuniary resources, both in his own purse and in the 

 wealth of his friends, enabled the firm to conquer all difficulties, 

 whether in finance, in litigation, or in engineering. 



39. Watt had, before meeting Boulton, conceived the idea of 

 economizing some of that power the loss of which was so plainly 

 indicated by the violent rush of the exhaust steam into the con- 

 denser, and had described the advantages that would follow the use 

 of steam expansively, by means of a " cut-off," in a letter to Dr. Small, 

 of Birmingham, dated Glasgow, May, 1769. He had also planned a 

 " compound engine." 



This invention of the expansion of steam, which, in importance, 

 was hardly exceeded by any other improvement of the steam-engine, 

 was adopted at Soho in 1776, but the patent was not obtained until 

 1782. 



Pig. 16. Watt's Steam-Engine, a. d. 1780. 



During this interval, Watt invented the crank and fly-wheel, but, 

 as the former had been first patented by Wasborough, who is sup- 

 posed to have obtained a knowledge of it from workmen employed 

 by Watt, the latter patented several other methods of producing 



