154 



PH YSIOLOGICA L PH YSICS. 



[Chap. XV. 



only will be described. It is that of Dr. C. Spamer. 

 It is small and compact, and seems well fitted for all 

 purposes of faradisation. It is represented in Fig. 81, 

 the lid being removed. 



This apparatus shows well the conditions to be 

 fulfilled in such an instrument. (1) The extent of 

 action of the cell can be regulated by the extent of 

 immersion of the plates. (2) The induced currents of 

 the coil can be regulated as to strength. This is done 

 for the secondary coil by altering its position in 

 reference to the primary, and for the primary coil by 

 the position of the soft iron core. The regulation of 

 the number of induced currents is managed by 

 adjusting the Wagner hammer, which is the inter- 

 rupter of the primary circuit. (3) There should be 

 binding screws connected both with the primary coil, 

 to permit the use of the extra current (page 44) if 

 desired, and with the secondary coil, to permit the 

 use of the induced currents of that coil. 



The description of the 

 apparatus is as follows : 



The interior of the 

 case is divided by a par- 

 tition into two halves, the 

 right of which contains 

 the drawer for the acces- 

 sory apparatus, and above 

 it the interrupter, the ter- 

 minals, marked -f- and 

 (positive and negative 

 pole) for the leading wires, 

 and the plugging arrange- 

 ment which serves to put 

 in circuit the primary or 



secondary current. The plug being inserted in p, as 

 shown in the figure, the primary or extra current is 

 obtained, in s the secondary current. 



Fig. 



81. Electro-induction 

 paratus. 



