ELECTRICITY AT THE WORLD'S FAIR. 



737 



method of operation will be clearly understood from the diagram- 

 matic sketch A (Fig. 6) and the illustration (Fig. 7) showing a 

 diagram of the connections of the motor and generator circuits. 

 Considering the latter first, M is the motor and G the generator. 

 The armature A of the generator is wound with two sets of coils, 

 B and B', brought out through the shaft and connected with the 

 contact rings 6 b and b' &'. The field magnet of the motor con- 

 sists of the iron ring R, also wound with two sets of coils, C C 



FIG. 7. DIAGRAM OF TESLA MOTOR CONNECTIONS. 



and C' C', the diametrically opposite coils being connected to- 

 gether in series. The generator coils B and the motor coils C' C' 

 it will be seen are included in one circuit L, and the remaining 

 generator coils B' and the motor coils C C in another circuit L'. 

 The armature of the motor consists simply of a disk of iron cut 

 away at the sides, which becomes a magnet by induction when 

 the motor field is energized. Turning to Fig. 6, B and B' repre- 

 sent the coils of the generator armature and C and C' those of 

 the motor field as in Fig. 7. When the generator coils are in the 

 position shown in the first diagram the coil B is generating no 

 current and B' is generating its maximum amount. The coils C 

 of the motor field, which are included in the circuit of B', are 

 therefore traversed by their greatest current and produce mag- 

 netic poles in the iron ring R at N and S. As the generator arma- 

 ture revolves, B is brought to a position in which it is generating 

 current, and when this movement amounts to one eighth of a revo- 

 lution the circle will be in the position shown in the second dia- 

 gram of the figure. Each of the pair of coils C and C' will now tend 

 to set up poles in the ring R of the motor ninety degrees from each 

 other, and as their action is equal and opposite, the position of the 

 poles will be determined by the resultant of the magnetic forces 

 acting on the ring, and the poles will therefore be shifted around 



VOL. XLIII. 53 



