Tyndall, John, 1820-1893 · New York : Appleton · leaf 100
ss oblique-ly through the top ofthe cylinder c, and alsoobliquely, but opposite-ly inclined, through therotating disk d e. Theair is thus caused to is-sue from c, not verti-cally, but in side cur-rents, which impingeagainst the disk anddrive it round. In this way, by its passage through thesiren,… … 94 SOUND. pair of toothed wheels (seen when the back of the instru-ment is turned toward you). As the disk and its axisturn, these wheels rotate. In front you simply see twograduated dials, Fig. 28, each furnished with an index likethe hand of a clock. These indexes record the number ofrevolutions…
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