THE MEASUREMENT OF MAKE SHOCKS 105 
used, can be correctly determined only if the constant 
is accurately known. 
By transposition of the equation 
M 
L 
we obtain the formula for the constant 
M 
-i_i. w 
E'Z m I (7) 
By taking advantage of the fact above noted, that 
the value of Z m for the inner secondary positions is inde- 
pendent of C, we can obtain Z m for any given experiment 
M 
by taking the product of X / for these positions. 
Li 
Since the value of Z TO is assumed to be constant through- 
out the experiment we can apply this value to the solu- 
tion of equation (7), using the data obtained at the outer 
M i 
secondary positions to give and - From four experi- 
JLt L 
ments at 2 and 4 volts were obtained by this method the 
following values of C: 8.16, 8.0, 6.8, 9.0, 8.0, 9.8, 8.0, 
5.2, 8.0. The average of these is 7.9. The nearest round 
number, 8, was taken as a sufficiently close approximation 
to the constant, and was applied to three other experi- 
