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7
Wednesday Nov. 23 - 1881.

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Center of a diaphragm arranged so as to be vibrated by the voice, [[strikethrough]]and[[/strikethrough]] which dips into the mercury. The following diagram will make this arrangement clear. [[drawing of arrangement]] The vibration of the rod attached to the diaphragm produces waves upon the surface of the mercury, and these waves set the carbon contact pieces into a corresponding motion. The battery circuit passes through the thin carbon contacts to the mercury, and back to battery though primary circuit of induction coil.  Telephone is placed in secondary circuit as usual, an may be in primary in place of induction coil.
[[left margin]] Experiment S.T. [[/left margin]]
An arrangement similar to the above (with the exception that the upper carbon contact piece was rigid, instead of attached to a spring as shown above) was tried this afternoon. The articulation heard from the telephone when a person spoke into the mouth piece of this arrangement dipping into the mercury, was quite loud, but not distinct, & very few of the words spoken could be understood.  The contacts were adjusted in various ways, but all with the above results, articulation very poor.
Noted by S.T. Nov. 23 - 1881. - [[underline]]over[[/underline]]

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