Tyndall, John, 1820-1893 · London : Longmans, Green · leaf 453
entor, may find aplace here, a is a steel rod polished at its upper end soas to reflect a point of light; this rod moves in a ball 430 LECTURE IX. and socket joint at b, so that it may assume any position.Its lower end is connected with two arms c and d, placedat right angles to each other, the… … to the small disc h^ placed on the axis which carries thedisc/; and, according as this small disc h is placed nearerto or farther from the centre of the disc g, it communicatesa diflferent relative motion to the disc /. The nut andscrew i enable the disc h to be placed in any positionbetween the…
Sound
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