215 



ilepth on the turbine was not measured. Instead of it, the 

 depth at the overfall is deducted : this is less than the truth, 

 and therefore the powers given are something too high. 



The experiments were made thus. One compartment of 

 the turbine being opened, the beetles of all the engines were 

 suspended, and the revolutions of the wiper beam, per minute, 

 counted. The resistance here is merely the friction of the 

 gearing of the eight engines, = g. Then bring one set of 

 beetles into action, the resistance is ^r + c, and so on. Repeat 

 the same with two and three compartments. With one, how- 

 ever, only four engines could be worked, and with the others 

 it was thought unsafe to try g alone. The results obtained 

 are given in the following table, of which the last column alone 

 requires explanation. It contains the resistance in terms of 

 g and t, multiplied by a coefficient which is the number of 

 revolutions divided by the power, or that which a unit of horse 

 power would produce. 



