298 ELECTRIC LIGHTING. 



towards the neutral line, a fresh deviation of 10 degrees to 

 the right will be obtained. 



It follows from these experiments that the induced cur- 

 rents, caused by the movements of the coil along the magnet, 

 will be the same as if the neutral line represented a resultant 

 of all the magnetic actions of the bar. If this resultant were 

 represented by a line through which the whole magnetic 

 current were passing, there would follow from the approach 

 of the movable coil to this line a current which, according to 

 Lenz's law, would be inverse; and this is in fact precisely 

 what takes place, since in bringing the coil back from the 

 south pole, or from the north pole towards the neutral line, 

 deviations to the right are obtained. Besides, it must follow 

 from the same law, that on withdrawing the movable coil 

 from that line, direct currents should be obtained, and this is 

 found to be the case, since the deviations are to the left. 



It will therefore be understood that, in accordance with 

 these considerations, a small coil movable round a mag-, 

 netized ring, setting out from the neutral line of one of the 

 two semicircular magnets composing the ring, and moving 

 towards the inducer by which the ring is polarized, must give 

 a direct current, and this is precisely what is observed in the 

 Gramme machine. 



Let us now examine what occurs from the passage of the 

 coil just mentioned, before the inducing pole itself, which I 

 shall suppose to be the south pole of the preceding magnet ; 

 but this time, instead of taking the small coil, of which we 

 spoke at first, we shall take a real bobbin of little thickness 

 and capable of sliding along an iron rod, which acts on its 

 magnetic core. In order to know the directions of the cur- 

 rents that we shall observe, we shall begin by examining the 

 direction of the current produced when we bring near the 

 south pole of the magnet the small bobbin, which we shall 

 present by its anterior extremityj that is to say, by the ex- 

 tremity which in the following experiments goes first. Under 

 these conditions we shall obtain a deviation to the right of 



