20 INDUCTION SHOCKS 
to the single coil on which it is worked out. One very 
important feature of a wholly satisfactory calibration 
must be its general applicability, so that any properly 
constructed inductorium can be calibrated in any labo- 
ratory to give results comparable with those obtained 
from other calibrated instruments. 
Moreover, it is not to be forgotten that no method 
of calibration thus far described takes into account the 
effects of strength of primary current, of tissue resistance, 
or the method of applying the stimulating electrodes, 
all of which are important, and at the same time de- 
terminable, and therefore to be included in a complete 
calibration scheme; nor do any of them consider the 
strength of make shocks, all being available only for 
breaks. 
A device which is superior in certain respects to any 
thus far described for measuring stimuli is the "fara- 
dimeter " of Edelmann. In this apparatus a galvanom- 
eter in the secondary circuit registers the voltage of the 
induced current. The galvanometer readings give cor- 
rect indications of the values of stimuli only when a 
current of definite, fixed amperage is broken in the 
primary circuit. It is necessary, therefore, to have a 
source of currents specially selected to give this amper- 
age, and by means of an ammeter in the primary cir- 
cuit to insure that it is maintained. The Edelmann 
method is an advance over others in that it takes 
