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it directly with the ordinary water-wheels, for the brake 

 could not be applied without much inconvenience in any of 

 Mr. Kirk's othermills; nor can any inference be made from the 

 power applied to drive them, for the friction, &c., differs too 

 much in each. For instance, measuring the quantity g, the 

 friction of the machinery of eight engines, it was in that be- 

 longing to the turbine 4'74 horse power, when working at the 

 normal speed ; 3-45 at another mill ; and only 2*82 at a third. 

 That of the beetles is probably equally variable. But he sees 

 no reason for doubting the results obtained with the brake, 

 the lowest of which is scarcely exceeded by the best overshot 

 wheels, while the others surpass considerably the usual esti- 

 mate of their performance. The small bulk and weight are 

 decided advantages (except in variable resistances, where the 

 momentum of a large wheel acts as a fly). It seems peculiarly 

 applicable to very high falls, having the special advantage of 

 lessening in size and cost as the fall increases ; and its power 

 of acting with undiminished effect, when totally submerged, 

 fits it for many situations where ordinary water wheels are im- 

 peded at times by back-water. 



