Tyndall, John, 1820-1893 · New York : Appleton · leaf 51
. By the act of reflection the diver-gent beam is converted into this splendid luminous conetraced out upon the dust of the room. The point of con-vergence being marked and the lamp extinguished, I placemy ear at that point. Here every sound-wave sent forth bythe clock and reflected by the mirror… … trie light. At this great distance the ticking of thewatch is distinctly heard. The hearing is much aided byintroducing the end f of a glass funnel into the ear, thefunnel here acting the part of an ear-trumpet. We know, REFLECTION OF SOUND BY MIRRORS. 45 moreover, that in optics the positions of a…
Sound
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