300 ELECTRIC LIGHTING. 



which we have spoken, while exposing the l-atter to the 

 action of the inducing pole. On proceeding thus the follow- 

 ing effects are observed : 



i. At the first moment, when the inducing pole is being 

 brought near the iron rod, but at a distance sufficient to 

 allow the coil to pass between it and this pole, there is pro 

 duced in the coil, placed on one side, an induced current 

 which results from the magnetization of the rod, and gives a 

 deviation of 39 degrees to the right. The deviations on this 

 side correspond then with inverse currents. 



2. When the coil, placed as in the first series of experi- 

 ments, is moved from right to left, it produces, from the 

 moment it cornes near the inducing pole, a current of 22 

 degrees to the left, which is, therefore, a direct current, and 

 by continuing the movement beyond the inducing pole a 

 new current is obtained in the same direction of 30 degrees 

 to the left. 



The effects produced by the passage of the coil before the 

 inducer are therefore in the same direction with or without 

 an iron rod, but are much more energetic with the iron rod.* 



* The effects produced in this experiment should be carefully noted, for 

 they prove that the magnetic actions are not so simple as is generally sup- 

 posed. In fact, the results which we have just pointed out cannot be esta- 

 blished unless the movable coil is placed on the part of the induced iron rod, 

 intermediate between the inducing pole and its free extremities. Beyond 

 this intermediate part the currents produced are in the opposite direction, 

 which proves that in this case the iron rod has become a true magnet regu- 

 larly constituted. Of course, if the rod is exposed to the inducing pole at 

 one of its extremities, the magnet has only two poles and one neutral line ; 

 but if it is exposed to this inducer at its centre, it forms- a magnet with a 

 consequent point, and has therefore two neutral lines. If, however, the iron 

 rod, instead of being at a distance from the inducing pole, is in contact with 

 it, the effects are quite different. The currents produced by the movement 

 of the coil towards the magnet are always inverse, and those which result 

 from its withdrawal are direct. This shows that the resultant of the mag- 

 netic forces is then concentrated at the inducing pole, which plays the part 

 of a neutral line, as if the two magnetic pieces formed but one. This effect 

 is always produced, on which side soever of the magnetic pole the iron rod 

 is applied. If, however, under these conditions, the rod is separated from 

 the magnet by a magnetically isolating substance, the effects without being 



