METHODS OF ELECTEICAL STIMULATION 61 



The secondary coil is made of many turns of 

 fine wire, because the object of the inductorium 

 is to transform the low electromotive force of the 

 cell into the high electromotive force of the in- 

 duced current. In the induction coil, as in other 

 transformers, the electromotive forces in the 

 primary circuit are to those produced in the 

 secondary circuit approximately as the number 

 of turns of wire in the primary is to the number 

 in the secondary circuit. 



If the induced current is to be passed through 

 conductors of low resistance, the high internal 

 resistance of the secondary coil, due to its great 

 length of fine wire, will be of importance. 



Place a dry cell with simple key in the pri- 

 mary circuit of an inductorium (posts 1 and 2). 

 Connect the secondary coil with a galvanometer. 

 Note the excursion of the needle with a break 

 induction current. Eeplace the secondary coil 

 with one of fewer windings (the primary coil of 

 a second inductorium will serve). Let the dis- 

 tance between primary and secondary coil be the 

 same as before. 



The excursion of the needle with a break in- 

 duction current will be increased, or at least not 

 proportionately diminished. 



If, on the other hand, the induced current is 

 to be passed through nerve, muscle, or skin, the 



