KESPONSE IN METALS 83 
still by torsional vibration, a transitory ‘current of 
action ’ will be found to flow in the wire from B to A, 
from the unstimulated to the stimulated, and in the 
galvanometer from the stimulated to the unstimulated. 
Stimulation of B will give rise to a current in an opposite 
direction. 
Experiment to exhibit the balancing effect.—If the 
wire has been carefully annealed, the molecular condi- 
tion of its different portions is found to be approximately 
the same. If such a wire be held at the ‘ balancing 
(0) (c) 


Fie. 50.—Enectric Response In Merans 
(a) Method of block; (6) Equal and opposite responses when the ends A and 
B are stimulated; the dotted portions of the curves show recovery; 
(c) Balancing effect when both the ends are stimulated simultaneously. 
point’ (which is at or near the middle) by the clamp, 
and a quick vibration, say, of 90° be given to A, an up- 
ward deflection will be produced ; if a vibration of 90° 
be given to B, there will be an equal downward deflec- 
tion. If now both the ends A and B are vibrated simul- 
taneously, the responsive H.M. variation at the two ends 
will continuously balance each other and the galvano- 
a 
meter spot will remain quiescent (fig. 50, A,B, R). This 
balance will be still maintained when the block is 
removed and the wire is vibrated as a whole. It is to 
be remembered that with the length ofewire constant, 
G2 
