MA CHINES WITH AL TERN A TE RE VERSIONS. I o 9 



and with each other. The combination of these wires, how- 

 ever, is very simple ; the multipliers are divided, as in the 

 Gramme machine, into four series, and those of each series 

 are joined together for tension. One of the similar ends of 

 each series leads to a metallic ring fixed on the axle of rota- 

 tion of the wheel, and the other ends lead to four other 

 rings insulated from each other, and pressed by the rubbers 

 c in communication with the ' terminal binding screws of 

 the four circuits corresponding with the electric lamps. These 

 circuits are completed by a connection with a rubber which 

 presses on the ring, and is common to all the multipliers. 

 The current of the exciting machine, which is placed beside 

 the other, corresponds, however, with 32 electro-magnets of 

 the two crowns of the inducing system, which electro-mag- 

 nets are joined for tension, each being composed of five layers 

 of 32 spires, in wire of 2 millimetres diameter, p is the pulley 

 for the prime mover. 



A remarkable feature of this machine is the small amount 

 of heating it develops. The inducing electro-magnets are 

 seldom higher than 30 C ; the multipliers are indeed a little 

 more heated, but I am unable to state their temperature. 



According to Boistel, the motive power required to drive 

 this machine for 16 lights will be 13 horse-power (German 

 standard).* The velocity of rotation of the division ma- 

 chine will be 500 turns per minute, and that of the exciting 

 machine 1,375 turns. In the form of the machine intended 

 for 8 lights, the force employed is 7 horse-power, and the 

 speed of the division machine 550 turns ; that of the exciting 

 machine [,375 turns. In the form for 4 lights, the force 

 used is 4. horse-power, the division machine making 600 

 and the exciting machine 1,100 turns per minute. 



Boistel thinks that, by some slight modification, the 4-light 

 machine might be arranged for 6 and the 8-light machine 

 for 12 lights. 



* It seems that the "horse-power" used as the unit in Germany is of 80 

 Liiogrammetres instead of 75, which represents that used in France. 



