162 



tive force of the other. Further, if for 

 any point E, A E was joined and pro- 

 duced, if necessary, to cut in F the 

 circle on A B as diameter, the values of 

 A E, E F, A F, could be taken with 

 the dividers, and measured on the scale 

 first employed. These lines had the 

 following properties : — 



If R was the resistance of the circuit, 

 then — 



The power employed on ) _ A E, AF 

 the first machine (input) ) 2R 



The power heating the ) _ AE' 

 circuit ------ f 2 R 



The power^™ ou * b H _ AE.EF 

 (employed on J 5-^, 



the second machine - 

 The latter depending on whether E lay 

 within or without the circle upon A B. 

 If E lay within the circle upon A B, 

 work would be given out by the second 

 machine ; that was, it might be employed 

 as a motor. If, on the other hand, E 

 lay upon that portion of the E- cir- 

 cle without the circle upon A B, 

 power must be employed on the second 



