THE MEASUREMENT OF MAKE SHOCKS 103 
The make shock formula shows that make stimuli do 
not vary directly with the intensity of the primary 
current as break stimuli do. Although make shocks 
increase absolutely with every increase in primary inten- 
sity, other conditions remaining uniform, the increase 
is relatively slight when primary intensities of consid- 
erable magnitude are compared. For example, if with 
coil B a 2 volt primary current be increased from 0.5 
ampere to i .o ampere, the make stimuli will be increased 
only 5 per cent, while break shocks under the same cir- 
cumstances would be doubled. 
This peculiarity of relation of make shocks to primary 
currents of high intensity shows itself very strikingly in 
many experiments in which minimal muscular contrac- 
tions are used as indicators of stimulation strength. In 
the outer parts of the field of the inductorium, where the 
values of are small, primary currents of high intensity 
.L* 
must be employed to give shocks sufficient to elicit 
visible response. I have often found when studying 
make shocks, especially with primary currents of low 
voltage, that as the secondary coil was pushed out to a 
point where primary currents of o.i or 0.2 ampere failed 
to elicit response, no increase of primary intensity up to 
the limits of my apparatus would raise the stimulus to 
the threshold. This frequent failure of relatively enor- 
mous primary currents to give detectable make stimuli 
