THE AUDITORY APPARATUS 123 



for the reproduction of quality of tone as well as of pitch. 



This consists of a small induction coil, placed below or 

 behind the diaphragm. In an open circuit a current passing 

 through the primary would induce a current in the secondary 

 winding. In a closed circuit anything altering the resistance 

 of the primary circuit would react in a precisely similar 

 way upon the secondary. In this manner, or by means of 

 this device, not only is the note received at B of the same 

 pitch as that sounded at A, but the same quality of note, as 

 well as the very complex modification and superposition 

 of notes upon which articulate speech depends, is preserved. 



A microphone is capable of a great variety of forms. 

 One of the earliest of them consisted of two or more pieces 

 of carbon, resting loosely against each other. Great resis- 

 tance is encountered at the loose contacts, and any vibration 

 in the instrument makes rapid alterations in that resistance, 

 and therefore equally rapid alterations in the total resistance 

 of the circuit. 



The vibrations which set in motion the drum of the external 

 ear differ in no respect from those which excite the diaphragm 

 of the telephone. We have only to imagine the middle 

 ear responding to them as a microphone responds, the 

 perilymph to be the primary and the endolymph the 

 secondary winding of the induction coil to formulate what 

 would appear to be a very reasonable theory. 



There is little value, however, in new ideas unless they 

 conform to natural laws and find some support in the 

 accepted work of others. 



Now, we cannot say that the middle ear is a microphone, 

 in an electrical sense, nor show that alteration of resistance 

 is produced within it by sound waves. It is probably 

 mechanical in its action, and vibrations, we may suppose, 

 are transmitted mechanically as far as the fenestra ovalis, 

 where they are communicated to the perilymph. The peri- 

 lymph is a liquid, and liquids are incompressible. But it 

 is not only a liquid, it is a neuro-electrically charged liquid 

 and assuming it to be the primary winding of the induction 

 coil we should expect it to be the part to which current 

 or charge is applied, and to be of greater sectional area 



