CHAP. VII.] 



ELECTRIC MOTORS. 



655 



right to left, in this case the current of the battery is thrown into 

 the coils E' E', and leaves the coils E E. The armatures next in turn 

 in the direction of the motion come then to be attracted, and the 

 motion will be continued in the same direction until the armatures 

 are opposite the poles F/ E'. At this moment the current leaves these 

 latter coils and passes on to E" E", and it will now be the turn of the 

 next armature to be attracted, and so indefinitely. It is clear that 

 during an entire revolution there will be as many attractions as the 

 number of times the difference between the angles of separation of 

 the electro-magnets and armatures is contained in the circumference, 



FIG. 4'26. Froment's electro-motor with continuous rotation. 



that is, twenty-four times (the difference between J and J being ^ ). 

 These alternate interruptions and passages of the current in the coils 

 of the engine are obtained by means of a distributor, the arrangement 

 and working of which may be easily understood from Figs. 427 and 

 428. This distributor consists of a wheel, R, centred on the' axis of 

 rotation and provided with eight teeth or pegs, equal, that is, in 

 number with the armatures, and moving with them ; this piece is in 

 constant communication with the positive pole of the battery. Three 

 springs, r, ?', r" t fixed to an immovable circular sector, and each 

 connected with the diametrically opposite pairs of the electro-magnets 



