NOTES AND APPENDICES. 299 



25 degrees, and when we withdraw the coil we shall obtain a 

 deviation of 22 degrees to the left. As this experiment is 

 the reproduction of Faraday's well-known one, we perceivo 

 that the deviations to the right will represent inverse currents, 

 and that the deviations to the left will represent direct 

 currents. 



Now, if we take the coil in question, and cause it to pass 

 from right to left tangentially before the south pole of the 

 inducer, taking care to produce the movements in two parts, 

 we shall observe : 



T. That in the first half of the motion a current will be 

 produced causing a galvanometric deviation of 8 degrees to 

 the left, and in the second half another current of 5 degrees 

 in the same direction. 



2. That in effecting the movement in the contrary direc- 

 tion, the current will be produced in the inverse direction. 



It may therefore be concluded that the currents resulting 

 from the tangential movement of a coil before a magnetic pole 

 are produced under conditions altogether different from 

 those which result from a movement effected in the direc- 

 tion of the axis of the magnet. These two movements are, 

 in fact, produced not only in two perpendicular directions, 

 but also under different conditions with regard to the manner 

 in which the induction is produced in the various parts of 

 the spiral. In the case of the tangential movement, the in- 

 duction takes place only on one half of the circumference of 

 the spires, and it acts from the two sides on a different end 

 of the coil. It is not thus in the other case ; the relative 

 positions of the different parts of the coil remain in the same 

 condition as regards the inducing pole, and it is only the 

 position of the resultant that varies with regard to the direc- 

 tion of the motion. 



It remains to find what occurs when the coil performing 

 the movements just considered is subjected to the action of 

 a magnetic core, influenced by the inducer, and in this case 

 it suffices to cause the coil to pass along the iron rod of 



