ELEMENTARY EXPERIMENTAL PHYSIOLOGY 83 



The experimenter can thus apply a regular series of induced 

 shocks at any given rate. 



3. A Rapid Series of Induced Shocks (Neef's Hammer). Connect 

 up an induction coil with the screw terminals marked F, inserting 



3? -Elect TO- 



FIG. 89. End of Coil showing Neef's hammer. 



the wires into the binding-screws in the pillars at the end of the 

 primary coil, so as to bring the Neef's hammer into action (Fig. 89). 

 (Note. Some of the coils are of a different pattern and have only 



r.c 



FIG. 90. Diagram to show the action of Neef's hammer. 



one pillar. In this case connect the second wire to the upper 

 lateral terminal.) Introduce a mercury key into the primary cir- 

 cuit and a friction key into the secondary circuit as before (Fig. 86). 



