This section is from the book "The Engineer's And Mechanic's Encyclopaedia", by Luke Hebert. Also available from Amazon: Engineer's And Mechanic's Encyclopaedia.

**Oscillation** Centre of. . That point, in a body vibrating by its gravity, in which, if any body be placed, or if the whole mass be collected, it will perform its vibrations in the same time, and with the same angular velocity, as the whole body, about the same point or axis of suspension. The centre of oscillation may be thus found: suspend the body by the given point, so that it may vibrate freely in small arcs, and count the number of vibrations it makes in a minute ; then will the distance in inches, of the centre of oscillation, be equal to the number 140,850, divided by the square of the number of vibrations. Thus, suppose any irregular body were set in vibration, and made 30 vibrations in a minute, then 140850/302 = 156 1/2 inches. The number 140,850 is obtained by multiplying 39 1/6 inches, the length of a seconds pendulum, by the square of 60, the number of vibrations it makes in a minute.

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