num, NEW YORK, APRIL 65, 1879. [NEW 8ERIES.] [POSTAGE PREPAID.] NEW ACOUSTIC APPARATUS. fixed focus, and are available under certain conditions only. plane mirror, the office of which is to determine the position BY GEO. M. HOPKINS. of the reflector in relation to the direction of the sound. A… … coasting off Brazil he heard the bells of to be better for this purpose. The ACOUSTIC APPARATUS. Fig. 2. San Salvador from a distance of 110 miles, engraving shows but one of the applica- tions of the reflector. It would be a by standing before the mainsail, which happened at the time to assume the…
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