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mill, wliich consisted ol'a 1 a rge circular vat, about tli irt y 

 inches deep, having a central step fixed in the bottom, to 

 carry the axis of a vertical shaft. The moving power 

 was applied to this shaft by a crown cog-wheel placed 

 on the top. At the lower part of the shaft, at right 

 angles to it, were four arms, upon which the grinding- 

 stones were fixed, large blocks of stone of the same kind 

 1 icing likewise placed in the vat. These stones were a 

 very hard silicious mineral, called "Chert," found in 

 abundance in the neighbourhood of Bakewell, in Derby- 

 shire. The broken flints being introduced to the vat 

 and completely covered with water, the axis was made 

 to revolve with great velocity, when the calcined flints 

 were easily reduced to an impalpable powder. This 

 contrivance of Brindley's proved of great value to Wedg- 

 wood, and it was shortly after adopted throughout the 

 Potteries, and continues in use to this day. 



Being thus extensively occupied in the invention and 

 erection of machinery driven by one power or another, 

 it was natural that Brindley's attention should have been 

 attracted to the use of steam power in manufacturing 

 operations. Wind and water had heretofore been almost 

 the exclusive agents employed for the purpose ; but far- 

 srring philosophers and ingenious mechanics had for cen- 

 turies been feeling their way towards the far greater 

 j ( wer derived from the pent-up force of vaporised water ; 

 and engines had actually been contrived which rendered it 

 probable that the problem would ere long be solved, and 

 a motive agent invented, which should be easily con- 

 tn.llaMr. and independent alike of wind, tides, and water- 

 falls. Reserving for another place the history of the 

 successive stages of this great invention, it will be suffi- 

 cient for our present purpose merely to indicate, briefly, 

 the direction of Brindley's labours in this important field. 

 It appears that Newcomen had as early as the year 1711 

 erected an atmospheric engine for the purpose of drawing 

 water from a coal-rnine in the neighbourhood of Wolver- 



