Power by Dynamo- electrical Machines. 521 



plus sign. Accordingly the equations assume the following 

 form for the second machine: — 



In forming these equations it is presupposed that the second 

 machine is similar to the first. If the second machine is dif- 

 ferent from the first, the constants occurring in the equations, 

 and which depend on the nature of the machine, would have 

 different values from those which hold for the first machine ; 

 and this would have somehow to be indicated, for instance by 

 prefixing indices to letters. 



The four equations (III.), (IV.), (V.), (VI.) can now be 

 used to make the calculations for the joint action of the two 

 machines. 



§ 2. Determination of the Current-strength. 



If the two machines are connected, as in the transmission 

 of force, by conductors which contain no further electromotive 

 force, the effective electromotive force in the whole circuit is 

 represented by the difference E x — E 2 . Hence, if R is the 

 resistance of the whole circuit, we may write 



R^Ei-Es (2) 



If we replace E x and E 2 in this, by their values from (IV.) 

 and (VI.), we get 



-(°+wr;)w+ v 2)]h • (3) 



which equation is to be used for determining i. 

 As the first directly obvious solution we get 



fcaO (4) 



After this has been determined we may divide the equation 

 by i, and after removing the members which have no denomi- 

 nator to the left hand, we get the following equation: — 



B+p(y 1 +v 2 ) + a(v^+v^ 



This equation we imagine divided by the magnitude on 



