94 RESPONSE IN THE LIVING AND NON-LIVING 
the wire and the surroundine 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 1s 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 cireuit. 
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, 1s seen in (é). 
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— 
