INORGANIC KESPONSE 135 
o 
through a wider range. For accurate quantitative 
measurements it is preferable to wait till the recovery 
is complete. We 
may accomplish this 
within the lmited 
space of the record- 
ing photographic 
plate by making 
the record for one 
minute; during the 
rest of recovery, the 
clockwork moving 
the plate is stopped 
and the galvano- 
meter spot of light 
is cut off. Thus the 

Fic. 84.—A Srconp Set or REcoRDS WITH A 
DIFFERENT SPECIMEN OF TIN 
The amplitudes of vibration are increased by 
steps of 10°, from 20° to 160°. (The deflec- 
tions are reduced by interposing a high ex- 
ternal resistance.) 
next record starts from a point of completed recovery, 
which will be noticed as a bright spot at the beginning 
of each curve. 

Fie. 85.—Errect oF SupERpost- 
TION oN TIN 
A single stimulus produces the feeble 
effect shown in the first response. 
Superposition of 5, 9, 13 such 
stimuli produce the succeeding 
stronger responses. 
With stimulation of high intensity, a 
tendency will be noticed for 
the responses to approach a 
limit. 
Threshold of response.--- 
There is a minimum intensity 
of stimulus below which there 
is hardly any visible response. 
We may regard this point as 
the threshold of response. 
Though apparently ineffective, 
the subliminal stimuli produce some latent effect, which 
may be demonstrated by their additive action. The 
