THE MEASUREMENT OF MAKE SHOCKS 97 
ing make shocks, but it is not a complete solution, since 
it offers no means of determining in advance what the 
value of K will be under any given set of conditions. 
The next step was to study a large series of experiments 
with reference to the conditions upon which the values 
of K depend. 
It became apparent at an early stage of the investi- 
gation that make shocks, unlike breaks, are modified in 
intensity by changes in the voltage of the primary cur- 
rent. This observation suggested the grouping of all 
the experiments according to the primary voltage used 
in performing them. After this had been done the 
values of K for the different experiments of any group 
still differed widely, but now wherever the value of K 
was large the value of Z was also large and vice versa. 
This suggested at once a possible dependence of the 
value of K upon that of Z. To test this possibility the 
experiments of each group were plotted, values of K 
against values of Z. The resulting curve in each case is 
a straight line, having the simple equation 
K = aZ. (2) 
Fig. 1 8 gives the curve for coil B obtained by plotting 
the experiments at 2 volts. The value of a given by 
this curve is 18. Substituting in equation (i) the value 
of K given in equation (2), we have 
M 
(3) 
