Bell's Telephonic Researches 



timbre [characteristic quality] of the sound would 

 be reproduced. The expense of constructing such 

 an apparatus as that shown in figure 3 deterred 

 me from making the attempt, and I sought to 

 simplify the apparatus before venturing to have 

 it made. 



I have before alluded to the invention by my 

 father of a system of physiological symbols for' 



Fig. 4 



representing the action of the vocal organs, and 

 I had been invited by the Boston Board of Edu- 

 cation to conduct a series of experiments with 

 the system in the Boston school for the deaf and 

 dumb. It is well known that deaf mutes are 

 dumb merely because they are deaf, and that 

 there is no defect in their vocal organs to inca- 

 pacitate them from utterance. Hence it was 

 thought that my father's system of pictorial 

 symbols, popularly known as visible speech, 

 67 



