NOTES AND APPENDICES. 297 



movements given to the coil when it is passed from the poles 

 towards the neutral line of the magnet, and from the neutral 

 line towards the poles. This is what will be observed : 



i. When the coil is passed from the south pole towards 

 the neutral line, a deviation of 22 degrees to the right will 

 be obtained, and therefore an inverse current, or one of mag- 

 netization. 



2. On making the reverse movement a new current will 

 be produced, and will cause a deviation of 25 degrees 

 towards the left, and therefore the current will be direct. 



3. If, instead of passing the coil from the neutral line 

 towards the south pole, the first movement is continued by 

 bringing the coil from the neutral line towards the north 

 pole, a current will be obtained in the direction opposite to 

 that produced in the first half of the movement, and if the 

 coil is stopped half-way a deviation of 12 degrees to the left 

 will be obtained. 



4. On bringing the coil back from the last position 



the currents are evoked at one or the other pole of the magnet, or at both 

 together, and whatever may be the position of the coil on the magnet. But 

 the currents produced will be the more energetic as the action takes place 

 nearer to the coil. Thus, by placing the coil at the centre of the magnet on 

 the neutral line, the current due to the increase of magnetization resulting 

 from the approximation of an iron armature to one or other of the two poles 

 will be inverse and of 2 degrees, and that which will result from the removal 

 of the armature will be direct and of the same intensity. By acting simul- 

 taneously on the two poles and developing the armature, these currents will 

 show themselves in the same direction, and will attain an intensity repre- 

 sented by 7 degrees. If the coil is placed at one of the poles, at the south 

 pole for instance, the currents will be of 10 to 12 degrees, when the arma- 

 ture is brought near, or withdrawn from, the south pole ; but they will be of 

 only \ degree when the north pole is acted upon, and but of 9 degrees when 

 the armature acts upon the two poles simultaneously. 



On placing the coil near the north pole, half-way between that pole and 

 the neutral line, we shall have an inverse current when the armature ap- 

 proaches the poles ; but it will be one of only 5 degrees when the north pole 

 is acted upon, and one of only 2 degrees when the south pole" is acted upon. 

 It will become one of 9 degrees when the armature is made to act upon both 

 poles at once, and the effects will of course be reversed when the armature 

 . is withdrawn instead of being brought near. 



