INORGANIC RESPONSE 105 
whether the E.M. effect of mechanical stimulus is in- 
stantaneous, or,” again, whether the effect disappears 
immediately. We first take a galvanometer record of 
the sudden introduction and cessation of an E.M.F. on 
the circuit containing the vibration-cell (fig. 60, a). 
We then take a record of the E.M. effect produced by 
a stimulus caused by a single torsional vibration. In 
order to make the conditions of the two experiments 
as similar as possible, the disturbing E.M.F., from 
a potentiometer, is pre- 
viously adjusted to give a 


deflection nearly equal to 
(Qa) 
that caused by stimulus. 
(Sy zo)" Ae 60” 
Fic. 60 
(a) Arrangement for applying a short-lived E.M.F. 
(b) Difference in the periods of recovery: (1) from instantaneous E.M.F.; 
and (2) that caused by mechanical stimulus. 
The torsional vibration was accomplished in a quarter 
of a second, and the contact with the potentiometer 
circuit was also made for the same length of time. 
The record was then taken as follows. The record- 
ing drum had a fast speed of six inches in a minute, 
one of the small subdivisions representing a second. 
The battery contact in the main potentiometer circuit 
was made for a quarter of a second as just mentioned 
and a record taken of the effect of a short-lived E.M.F. 
