Tyndall, John, 1820-1893, Making of America Project · New York, Appleton · leaf 305
3rd Series ... 12 10 4th Series ... 9 8 The number 12, it will be observed, is common to bothsyrens. I now open the two series of 12 orifices each,and urge air through the instrument; both sounds flowtogether in perfect unison ; the unison being maintainedhowever highly the pitch may be exalted.… … TONES OF THE DOUBLE SYEEN. 291 disc, or to retreat from them, and that this places it in ourpower either to raise or to lower, within small limits, thepitch of the upper syren. This change of pitch instantlyannounces itself by beats. The more rapidly the handle isturned, the more is the tone of the…
Sound
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