70 ELECTRIC LIGHTING. 



copper /, which separate the polar pieces T T, a channel 

 through which a current of cold water was made to circulate. 



The commutator of the apparatus is placed at the end of 

 the axle of the coil, from which the current is collected by 

 means of two springs pressing against it. The bobbin turns 

 also in bearings placed in the cross pieces F, which support 

 it at its extremities, and suitable lubricating apparatus con- 

 stantly supply the rubbing surfaces with oil. 



Under the influence of the movement given to the mag- 

 neto-electric machine M, the induced current excited m the 

 armature o presents itself at the two binding screws / q, 

 which are connected with the two ends of the wire of the 

 electro-magnet A B, and the bobbin turning in F supplies 

 the induced currents required to produce the light. 



Although this machine has been used in the illumination 

 of one of the Scottish lighthouses, it is to electroplating that 

 it has especially been applied, and at the present time it 

 does not appear to us that it could have competed with any 

 of the new machines. A long description of it is given in 

 our Expose des applications de relectrtcite tome //., p. 226. 



Of course the bobbin of the magneto-electric machine re- 

 volves with a less velocity than the bobbin of the dynamo- 

 electric machine. 



In another arrangement of a machine of this kind less 

 generally known, doubtless, on account of its greater bulk 

 Wilde mounted a series of magnetic cores, surrounded by 

 induction coils, on an iron disc revolving in front of powerful 

 electro-magnets ; and instead of a second induction machine 

 set apart for the excitation of the inducing electro-magnets, 

 he borrowed some of its own coils from the induced system 

 itself. But two reversing commutators were always required 

 to rectify the two currents, and it is by little more than the 

 suppression of these commutators that the Wallace Farmer 

 and Lontin machines, which we shall presently study, are dis- 

 tinguished from Wilde's. It is curious that this machine did 

 not at once attract more attention, and that it should be 



