Tyndall, John, 1820-1893 · New York, Collier · leaf 49
cingthe end / of a glass funnel into the ear, the funnel hereacting the part of an ear-trumpet. We know, moreover,that in optics the positions of a body and of its imageare reversible. When a candle is placed at this lowerfocus, you see its image on the gallery above, and Ihave only to turn the… … Fio. 7. place, the person on whom the light falls distinctly hearsthe sound. When the ear is assisted by the glass funnel,the reflected ticks of the clock in our first experiment
Sound
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