Chap. 2.. PHILOSOPHY.

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moves, is all united in the point, which in relation to thepower of gravity is called'the center of oscillation. Let thecylinder A B C D (in fig. 6 o.) whose axis is E F, be fixed tothe point E. AndTupposing the point E to be that on whichthe cylinder is suspended, let the center os oscillation besound in the axis E F, as has been explained above a . Let G'be that center: then I fay, that the force, wherewith this cy-linder turns round the point E, is so united in the point G, that.a sufficient force applied in that point shall stop the motion ofthe cylinder, in such a manner, that the cylinder should im-mediately remain without motion, though it were to be loos-ened from the point E at the fame instant, that the impedi-ment was applied to G: whereas, if this impediment had beenapplied to any other point of the axis, the cylinder would’turn upon the point, where the impediment was applied. Ifthe impediment had been applied between E and G, the cy-linder would so turn on the point, where the impedimentwas applied, that the end B C would continue to move onthe same way it moved before along with the whole cylinder;but is the impediment were applied to the axis farther off fromE than G,. the end AD of the cylinder would start out of itspresent place that way in which the cylinder moved. Fromthis property of the center of oscillation, it is also called thecenter os percussion. That excellent mathematician, Dr.BRooKTaylor, has farther improved this doctrine concerning thecenter of percussion, by shewing, that is through this pointG a line, as G H I, be drawn perpendicular to E F, and lying

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