Tyndall, John, 1820-1893 · London : Longmans, Green · leaf 83
depression,and, holding the axis up-right, bring down upon 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 thedisc can rotate with an ex-ceedingly small… … AK\LYSIS OF THE SYREJf. 63 work of the figure. Turning the disc d e slowly round, itsperforations may be caused to coincide or not coincidewith those of the cylinder underneath. As the disc turnsits orifices come alternately over the perforations of thecylinder, and over the spaces between the…
Sound
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