STRENGTHS OF FARADIC STIMULI 21 
account of the factor of primary current strength and 
provides for its regulation. It does not, however, take 
account of the influence upon the strength of stimulus 
of variations in tissue resistance, since the quantity 
measured by the galvanometer, namely the voltage, is 
independent of the resistance. Nor does it consider the 
effect of the method of application of the stimulating 
electrodes. But so long as these two factors remain 
constant the Edelmann faradimeter gives accurate re- 
sults for break shocks, and expresses them in terms 
such that the stimuli used by one worker can, save for 
the factors above mentioned, be duplicated by others. 
The importance of taking secondary resistance into 
account was brought out by Hoorweg* in 1893. He 
demonstrated the effect of variations in resistance in 
modifying stimulation strengths, and emphasized the 
necessity of working out some method by which to 
ascertain this effect. At his suggestion Giltay f de- 
signed an electrodynamometer by which the variations 
in strength of stimulus due to varying secondary re- 
sistances can be read directly. This apparatus fulfils 
admirably the purpose for which it was designed. It 
is, however, of little practical use in physiology, since 
its readings, to be comparable, must be made with the 
* Hoorweg: Die medicinische Elektrotechnik und ihre physikalischen 
Grundlagen, Leipzig, 1893. 
t Giltay: Annalen der Physik und Chemie, 1893, Bd. 50, S. 756. 
