Tyndall, John, 1820-1893 · New York : Appleton · leaf 99
pon itsupper end p a steel cap,finely polished within, whichholds the axis at the top,the pressure both at top andbottom being so gentle, andthe polish of the touchingsurfaces so perfect, that thedisk can rotate with an ex-ceedingly small amount olfriction. At c, Fig. 27, isthe cap which fits on to… … ANALYSIS OF THE SIREN. 93 perforations may be caused to coincide or not coincidewith those of the cylinder underneath, As the disk turnsits orifices come alternately over the perforations of thecylinder, and over the spaces between the perforations.Hence it is plain that ifair were urged into c,and…
Sound
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