94 RESPONSE IN THE LIVING AND NON-LIVING 



the wire and the surrounding liquid being perfect and 

 invariable. 



On now vibrating the end A of the tin wire by means 

 of the ebonite clip holder, a current will be found to 

 flow from B to A through the wire that is to say, 

 towards the excited and from A to B in the galvano- 

 meter. 



The next modification (c) is to transfer the galvano- 

 meter from the electrolytic to the metallic part of the 

 circuit, that is to say, it is interposed in a gap made by 

 cutting the wire A B, the upper part of the circuit being 

 directly connected by the electrolyte. Vibration of A 

 will now give rise to a current of response which flows 

 in the metallic part of the circuit with the interposed 

 galvanometer from B to A. We see that though the 

 direction of the current in this is the same as in 

 the last case, yet the galvanometer deflection is now 

 reversed, for the evident reason that we have it inter- 

 posed in the metallic and not in the electrolytic part of 

 the circuit . 



The next arrangement (d) consists simply of the 

 preceding placed upside down. Here A and B are held 

 parallel to each other in an electrolytic bath (water). 

 Mechanical vibration may now be applied to A without 

 affecting B, and vice versa. 



The actual apparatus, of which this is a diagram- 

 matic representation, is seen in (e). 



Two pieces, from the same specimen of wire, are 

 clamped separately at their lower ends by means of 

 ebonite screws, in an L-shaped piece of ebonite. The 

 wires are fixed at their upper ends to two electrodes 



