302 ELECTRIC LIGHTING. 



trary way, the two currents which result from these two 

 consecutive actions are in the same direction, and conse- 

 quently supply a single current during the whole movement 

 of the magnet. Again, the movement in the opposite 

 direction of the magnet, having for its effect at the beginning 

 a demagnetization in the direction opposite to that produced 

 in the first case, the retrograde current resulting from the 

 retrograde movement must be in a direction the reverse of 

 that of the first. 



If we now return to the effects produced by our magnet, 

 acting on our coils moving perpendicularly to their axes, it 

 will be understood from the preceding that displacement of 

 the magnetic polarity of the core must immediately be pro- 

 duced by the inducing magnet having for its effect the in- 

 version of the contrary polarity of this core before and be- 

 hind the points successively influenced, it must follow that 

 the different parts of the core of the coils will successively 

 constitute a series of magnets with inverted poles, analagous 

 to those the effects of which we have already analysed, and 

 which are able to produce those currents in the same direction, 

 whose presence we have proved. These currents will change 

 in direction according as the coils move from right to left, or 

 from left to right. (See my article on the electrical actions 

 in operation in light-producing machines, in the journal La 

 Lumicre Electriqite of the ist November, 1^79.) 



NOTE B. 



." 



ON THE DUTY OF GRAMME MACHINES ACCORDING TO THE 

 RESISTANCE OF THE EXTERNAL CIRCUIT. 



WE reproduce below an interesting paper of Hospitaller's, 

 which shows the importance of the remark made at the con- 

 clusion of this work. 



