Tyndall, John, 1820-1893 · London : Longmans, Green · leaf 129
four, ordouble the former number. Attaching two strings of thesame length to the same fork, the one parallel and theother perpendicular to the direction of vibration, andstretching both with equal weights; when the fork iscaused to vibrate, one of them divides itself into twice thenumber of ventral… … Dr. Young, by illuminating that point, and watching theline of light which it describes. This is well illustratedby a flat burnished silver wire, twisted so as to form aspiral surface, from which, at regular intervals, the lightflashes when the wire is illuminated. When the vibrationis steady the…
Sound
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