STRENGTHS OF FARADIC STIMULI 17 
above is divided by 1000 and the quotient gives the gal- 
vanometer deflection per unit. If now the weaker coil 
is set at zero and the stronger at a point such that the 
galvanometer deflection is that called for per unit, it is 
possible, by repeating the original procedure, to divide 
the scale into 1000 parts, each of which represents a 
given galvanometer deflection, and therefore an equal 
decrement in stimulating value. This method has the 
advantage that after one inductorium is calibrated it is 
extremely easy to calibrate others to correspond with 
it, by connecting the calibrated and uncalibrated coils 
in the manner described above and finding the corre- 
sponding points on the two slides. Kronecker, by sub- 
stituting a telephone for the galvanometer, made the 
taking of readings even more simple. 
The method has the disadvantage that it is purely 
arbitrary, depending at the outset on a chance difference 
of stimulating strength occurring in two inductoria; 
for this reason the calibration can only be duplicated 
through access to a coil already calibrated. An ob- 
server, unable for any reason to obtain a Kronecker coil, 
might, it is true, prepare a calibration of his own by 
repeating Kronecker's original procedure, but he could 
not know whether his units represented the same stimu- 
lating values as the corresponding Kronecker units, and 
so could not express satisfactorily the strengths of 
stimuli used by him. 
