METHODS OF ELECTRICAL STIMULATION 59 



magnetized, as is shown by its attracting the 

 head of the Wagner hammer. 



Bring the meniscus into the field. Approach the 

 primary coil to the secondary as in the experiment 

 with the magnet. Withdraw the primary coil. 



The electrometer shows the presence of in- 

 duced currents, as before. These currents are 

 momentary. The first induction current is in- 

 verse, i. e. it runs round the secondary coil in the 

 direction opposite to that taken by the battery cuf- 

 rent in the primary coil. The second induced cur- 

 rent is in the same direction as the primary current. 



Place the coils at right angles to each other. 

 Approach one towards the other. 



No current will be induced. 



Make and break Induction. Close and open 

 the key in the primary circuit, thus making and 

 breaking the primary current. 



The effect is the same as if the primary were 

 suddenly brought up to the secondary coil from 

 an infinite distance and removed again. The make 

 induction current is in the opposite, the break in 

 the same, direction as the primary current. 



Turn the secondary coil on its pivot until the 

 axis is at right angles to the axis of the primary 

 coil. Make and break the primary current. 



No induction will take place provided the 

 angle between the coils is precisely 90. 



