PULSATION AND TETANUS. 



35 



the clamp on the left. In order to use this hammer for 

 the production of inductive currents, the one coil, A, of 

 the apparatus (shown in fig. 10, p. 31), must be inserted 

 between the two clamps shown on the right. 1 



Wagner's hammer in a more simple form may be 

 permanently connected with coil A. In this case it is 

 best to place the second coil B on a sliding-piece which 

 is so arranged that it can be moved along a groove to a 



FlG. 13. THE SLIDING INDUCTIVE AITAli-ATCS. 



(As used by du Bois-Reymond.) 



greater or less distance from coil A. This enables the 

 operator to regulate the strength of the inductive current 

 generated in it. Fig. 13 represents an apparatus of this 

 sort. The secondary coil, in which the inductive currents 

 originate, is in this case indicated by i ; the primary coil, 

 through which the constant currents pass, by c ; b is the 

 electro-magnet ; h the armature of the hammer ; / is 

 a small screw, at the point of contact of which with the 



1 In order to set Wagner's hammer itself in motion, these damps 

 must be connected by a wire through which alone the connection 

 from the point to the coils of the electro-magnet is made. 



