CHAP. IV. THE ALBION MILLS. 137 



which had in the first place been used for pounding wheat 

 into flour, had long since been displaced by water-mills 

 and windmills ; and now a new agency was about to be 

 employed, of greater power than either the agency 

 of steam. Fire-engines had heretofore been employed 

 almost exclusively in pumping water out of mines ; but the 

 possibility of adapting them to the driving of machinery 

 1 laving been suggested to the inventive mind of James 

 Watt, he set himself at once to the solution of the 

 problem, and the result was the engines for the Albion 

 Mills the most complete and powerful which he had 

 until then turned out of the Soho manufactory. They 

 consisted of two double-acting engines, of the power of 

 50 horses each, with a pressure of steam of five pounds 

 to the superficial inch the two engines, when acting 

 together, working with the power of 150 horses. They 

 drove twenty pairs of millstones, each four feet six inches 

 in diameter, twelve of which were usually worked to- 

 gether, each pair grinding ten bushels of wheat per hour, 

 by day and night if necessary. The two engines working 

 together were capable of grinding, dressing, &c., com- 

 plete, 150 bushels an hour by far the greatest perform- 

 ance achieved by any mill at that time, and probably not 

 since surpassed, if equalled. But the engine power was 

 also applied to a diversity of other purposes, then alto- 

 gether novel such as hoisting and lowering the corn 

 and flour, loading and unloading the barges, and in the 

 processes of fanning, sifting, and dressing so that the 

 Albion Mills came to be regarded as among the greatest 

 mechanical wonders of the day. The details of these 

 various ingenious arrangements were entirely worked 

 out by Mr. Rennie himself, and they occupied him nearly 

 four years in all, having been commenced in 1784, and 

 set to work in 1788. Mr. Watt was so much satisfied 

 with the result of his employment of Rennie, that he 

 wrote to Dr. Robison, thanking him for his recommenda- 

 tion of his young friend, and speaking in the highest 



