THE MEASUREMENT OF MAKE SHOCKS IOI 
ever the break stimulus Z& may compare with the make 
M 
stimulus Z m , changing the value of by moving the 
44 
secondary coil does not affect the relationship between 
them. To illustrate, if we suppose the ibtfefcli ^stimulus 
to be twice as intense as the make stimulus v/Jien tfrq 
secondary coil is at zero, the break will cbntinufe to be 
twice as intense as the make wherever the secondary 
coil is placed, provided, of course, that all other condi- 
tions remain constant. 
Since the difference between the two formulae is wholly 
in their denominators, we may expect careful analysis 
of these to yield a full understanding of the conditions 
upon which depend the relationships between make and 
break stimuli. The denominator of the make shock 
formula will always be larger than that of the break 
formula, but the amount of difference between the two 
will vary greatly according to the relative values of- 

and - This can best be shown by a concrete case. Let 
hi 
us first compare the values of Z 6 and Z m in a hypotheti- 
cal experiment with coil B in which a primary current of 
0.0005 ampere at 20 volts is employed. The expression 
for Z b is M 
L 
2000 
