CHAPTER VIII 
THE PREPARATION OF A CALIBRATION SCALE FOR 
BREAK SHOCKS 
IN previous chapters the methods of obtaining the 
individual factors making up the expression for break 
stimulation strength have been discussed in detail. To 
show how these methods are put into practice in pre- 
paring an inductorium for quantitative use is next in 
order. The first step is the determination of the mutual 
inductions by the method hitherto described, for a 
series of positions, preferably not more than 2 cm. 
apart, along the scale. If the instrument to be cali- 
brated is without the iron core these measurements 
should be taken from the zero position outward; if an 
iron core is present there is no advantage gained by 
determinations of mutual induction for secondary posi- 
tions in the region where the secondary coil overlaps 
the primary. Having determined these values, each is 
divided by L, the product of the cross section by the 
number of turns of the secondary coil. The mean 
cross section must be determined with great care, a 
rather difficult procedure in completed inductoria, and 
one which ought to be carried out in connection with 
their manufacture. 
55 
