In fig. 7 let Z be the fulcrum knife-edge, X the knife-edge on which the load R is hung, and H the centre of gravity of the weights to the right of Z, viz. the weight, W, of the steelyard acting at its centre of gravity; G, the travelling poise; P, acting at M; and the weights, Q, hung on the knife-edge at V. Then if Z be below the line joining X and H, the steelyard will be "acceler.^ting "

i.e. with the smallest

excess of moment on the left-hand side of the fulcrum, the end C of the steelyard will rise with accelerating velocity till it is brought up by a stop of some sort; and with the smallest excess of moment on the right-hand side of the fulcrum, the end C of the steelyard will drop, and will descend with accelerating velocity till it is brought up by a similar stop.

If Z be above the line XH, the steelyard is " vibrating "; i.e . it will sway or vibrate up and down, ultimately coming to rest in its position of equilibrium. Steelyards, again, arc frequently arranged as counter machines, having a scoop or pan resting on a pair of knife-edges at the short end, which is prevented c

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