VARIOUS GENERATORS OF ELECTRIC LIGHT. 95 



and the even coils. " By this means," says the Report of 

 the Committee, "the circuits may be combined so as to 

 transmit currents of more or less intensity, varying from 55 

 to 120 volts, or so as to divide the currents between two 

 circuits, each supplying an electric light." 



We may point out that, under these circumstances, the 

 Brush machine is inferior to that of De Meritens ; i, be- 

 cause the iron ring being continuous, the electro-magnetic 

 currents produced by the approach and withdrawal of the 

 magnetic poles lose their energy, as De Me'ritens proved by 

 his earliest experiments ; 2, because the induced currents 

 gain much when the magnetic cores are formed of very thin 

 pieces of iron bound together in bundles ; 3, because the 

 presence of a reversing commutator occasions much loss of 

 current, 



The Brush machine has recently been applied with success 

 to the illumination of the Park, at the city of Cleveland, in 

 America, and if the newspapers of that city may be trusted, 

 it has, in conjunction with the electric lamps of the same 

 inventor, an advantage in economy over the systems tried in 

 England and in France in the proportion of 20 to 5. This 

 machine required only n horse-power to supply 12 lights, 

 having the luminous intensity of 200 Carcel lamps. But we 

 believe these accounts are much exaggerated, inasmuch as 

 these 12 lights imply a machine for division, which is not 

 described by the newspapers we allude to, and which would 

 appear to be confounded with that spoken of above. 



Biirgin's Machine. Biirgin, struck like De Me'ritens 

 with the loss of action in the Gramme ring, resulting from 

 the withdrawal of the iron core from the inducing poles, has 

 sought to cause its approach by making it pass out of the 

 coils at longer or shorter intervals. In order to accomplish 

 this he formed this ring of six separate rings mounted parallel 

 to each other on the same axle, and each having for a mag- 

 netic core a square frame of iron wires (Fig. 31) on the sides 



