Masterpieces of 'Science 



might prove a means whereby we could teach 

 the deaf and dumb to use their vocal organs and 

 to speak. The great success of these experiments 

 urged upon me the advisability of devising 

 method of exhibiting the vibrations of sound 

 optically, for use in teaching the deaf and dumb. 

 For some time I carried on experiments with the 

 manometric capsule of Koenig and with the 

 phonautograph of Leon Scott. The scientific 

 apparatus in the Institute of Technology in 

 Boston was freely placed at my disposal for 

 these experiments, and it happened that at that 

 time a student of the Institute of Technology, 

 Mr. Maurey, had invented an improvement upon 

 the phonautograph. He had succeeded in vibrat- 

 ing by the voice a stylus of wood about a foot in 

 length, which was attached to the membrane of 

 the phonautograph, and in this way he had 

 been enabled to obtain enlarged tracings upon a 

 plane surface of smoked glass. With this appa- 

 ratus I succeeded in producing very beautiful 

 tracings of the vibrations of the air for vowel 

 sounds. Some of these tracings are shown in 

 Fig. 4. I was much struck with this improved 

 form of apparatus, and it occurred to me that 

 there was a remarkable likeness between the 

 manner in which this piece of wood was vibrated 

 by the membrane of the phonautograph and the 

 manner in which the ossicula' [small bones] of 

 the human ear were moved by the tympanic 

 membrane. I determined therefore, to con- 

 struct a phonautograph modelled still more 

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