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had over fourty calls.  We went first to the senate chamber & then to the Academy room the same occupied by that body last year.  Father commenced to speak immediately after we had taken our seats.  He gave some results of his experiments on sound made in his connection with the light house branch at Sandy Hook & elsewhere.  Explained [[hurriedly?]] the various instruments used as fog signals in the light houses.  Bells, whistles, &c. showed us a drawing of an [[strikethrough]] false [[/strikethrough]] artificial ear constructed in order to guard against a false estimate of the distance at which the sound of a fog signal could be heard used to list these signals.  This ear consisted of hollow tube flair out at one end like a trumpet over the small end and a small piece of    ________of stretched & upon this membrane was scattered the sand wh would danse at the
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sound of the wistle or bell to test the distance at which the latter could be heard.  The instrument was carried farther & farther off until a distance was attained at which the sand ceased to danse.  It was necessary to have such an instrument as a steady test unaffected by the imagination of interested parties.  The results attained were tested by the human ear & found to agree perfectly.  In order to use the instrument it was necessary that the trumpet or tube should not be in unison with the signal bell or wistle & the membrane streched lighter over the end of the tube otherwise they would themselves become sonorous.  Sound is vibration of the atoms of the air.  The distance at which it is heard is in proportion to the number of atoms moved and the square of the ^[[insertion]] [[?]] of [[/insertion]] vibrations. Mentioned that sound was best heard not in the direction
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