VARIOUS GENERATORS OF ELECTRIC LIGHT. 93 



machine much resembles that of De Meritens, although 

 it is less skilfully put together, and reminds me of the first 

 attempts made by the last-named gentleman. 



This machine consists of a Gramme ring, the coils of which, 

 only eight in number, are separated by rather large intervals, 

 rilled up with pieces of iron. This ring revolves vertically 

 between the expanded poles of two oblong horseshoe electro- 

 magnets, having the poles of the same name opposite to 

 each other. In this way the two halves of the ring laterally 



surrounded by these poles are polarized uniformly, the one 

 south, the other north ; and as with this arrangement alter- 

 nately reversed currents are produced, as in De Me'ritens' 

 machines, and as snch currents are unsuitable for the mag- 

 netization of inducing magnets in dynamo-electric machines, 

 it is necessary to put the coils of the revolving ring in com- 

 munication with a reversing commutator, for which four rub- 

 bers are required. These rubbers, which are shown in the 

 figure to the right and left at the front, are constructed, as in 

 the Gramme machines, of bundles of wires arranged like a 

 brush. Fig. 30 indicates the manner in which the wires of 

 the coils are connected with each other and with the com- 



