WATT. 373 



Crinan ; in the difficult and laborious investigations 

 for the improvement of the harbours of Ayr, Greenock, 

 and Glasgow; in improving the navigation of the 

 Forth and the Clyde ; in the Campbelton Canal, and 

 in the surveys and plans preliminary to the Grand 

 Caledonian Canal; beside several bridges of great 

 importance, as those of Hamilton and Rutherglen. At 

 Dr. Roebuck's Mr. Watt had early received much 

 kindness, and many valuable lessons in chemical 

 science. He was here, too, introduced to Dr. Black. 



The various works which have been mentioned occu- 

 pied his whole time from the disappointment experienced 

 in 1769 respecting the steam engine, of which during 

 that long interval he never despaired, to the year 1774, 

 when he acceded to the proposal of Mr. Boulton, of 

 Soho, near Birmingham, that he should be taken in Dr. 

 Roebuck's place as partner in the patent, and in 1775 

 he settled there in this new business. An extension of 

 the patent for twenty-five years from this time was 

 obtained from Parliament, in consequence of the 

 national importance which all men saw belonged to 

 the invention ; and the partners constructed many 

 engines upon the terms of receiving one third of the 

 fuel saved by the improvements. It is a convenient 

 mode of illustrating the effect of the invention in 

 saving fuel, to observe what were the gains of the 

 partners under this stipulation. On one mine, that 

 of Chasewater, in Cornwall, the proprietors com- 

 pounded for 2400/. a year, instead of paying the third 

 of the fuel saved. That saving then must very con- 

 siderably have exceeded 7200/. a year. But there 

 seemed some difficulty in carrying bargains of this kind 



