. Annual report of the Board of Regents of the Smithsonian Institution . Fig. 18.—Valve of pneumatic sound box. 228 ANNUAL EEPOET SMITHSONIAN INSTITUTION, Fig. 19.—Parsons sound box. but by means of which sound records of the Berliner type can bemost effectively reproduced. In this machine the record does notvibrate a diaphragm, but it vibrates a very finely adjusted valvewhich controls the flow of a column of air under pressure. As theair passes through the valve there are given to it minute pulsations, Avhicli correspond to the undulations in thesound record, so thatsound waves identi
. Annual report of the Board of Regents of the Smithsonian Institution . Fig. 18.—Valve of pneumatic sound box. 228 ANNUAL EEPOET SMITHSONIAN INSTITUTION, Fig. 19.—Parsons sound box. but by means of which sound records of the Berliner type can bemost effectively reproduced. In this machine the record does notvibrate a diaphragm, but it vibrates a very finely adjusted valvewhich controls the flow of a column of air under pressure. As theair passes through the valve there are given to it minute pulsations, Avhicli correspond to the undulations in thesound record, so thatsound waves identicalAvitli those originallyrecorded are set up inthe surrounding air andtravel to the ear of thehearer. In the apparatus joiisee here (fig. 15), a one-sixth horsepower electric motor drives an aircompressor. The air, after passing through an oil separator or filter,enters a reservoir, which helps to insure a regular flow of air to thevalve. From the reservoir the air passes through a dust collectorbefore it reaches the valve, as the very fine adjustment of the latteris apt to be interfered with if particles of dust or oil get into it. The sound box, asyo
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Keywords: ., bookauthorsmithsonianinstitutio, bookcentury1800, bookdecade1840
