108 ELECTRIC LIGHTING, 



Gramme, is formed of the two vertical crowns of electro- 

 magnets, / /, P i', fixed parallel to and in front of each other, 

 and turning between them is the induced system constructed 

 of as many galvanometric frames, G G, as there are electro- 

 magnets in each of the two crowns. They are, of course, 

 insulated from the cast-iron frame B B, on which they are 

 mounted by means of ebonite plates, and they are so wound 

 that a north pole is always between two south poles, and 

 vice versa. It will readily be understood that the electro- 

 magnets placed opposite to each other on the two supports 

 are of opposite polarities, and that consequently a galvano- 

 metric frame, when it comes between two consecutive cores 

 of this double inducing system, will be affected in four dif- 

 ferent directions first on the two faces of the multiplier, 

 and secondly on the two parts opposite to the galvanome- 

 tric frame. 



The induced system is formed of a bronze wheel, on the 

 circumference of which are fixed the 16 galvanometrie mul- 

 tipliers, G G, already mentioned ; these multipliers are wound 

 on two wooden supports fixed between two plates of copper 

 pierced with holes and having the shape of enlongated 

 sectors. Each multiplier is composed of 23 rows of spires, to 

 the number of 1 7 in each row, and the wire has a diameter of 

 1 8 tenths of a millimetre. They have, however, no iron 

 cores, and present exactly the appearance of a galvanometric 

 frame. They are fixed by their sides on the copper wheel, 

 and are fitted with such exactness that one would suppose 

 that the wheel was provided with two large metallic circum- 

 ferences externally presenting circular notches corresponding 

 with each multiplier. The holes in the metallic sides are for 

 the purpose of admitting air to cool the enclosed multipliers, 

 a precaution neglected in France, but always taken in the 

 machines constructed abroad. 



The central part of the wheel of the induced system is 

 occupied by a thick circular plate D, whereon are fixed the 

 wires by which the coils are connected with the collector c 



