This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1841 Excerpt: ...time must be lost; no time being lost under these circumstances, consequently no power can be gained. A pair of scissors consists of 2 levers of this kind united in one common fulcrum. Thus, the point at which the 2 levers are riveted together is the fulcrum; the fingers are the power, and the substance to be cut affords the resistance; the longer therefore the handles, and the shorter the points of the scissors, the more easily you may cut with them. Snuffers are levers of a similar description, so are most kinds of pincers, the power of which consists in the resisting arm being very short compared with the acting one. The common balance is a lever; the fulcrum being the point on which the beam of the scales rests, and the weights in the scales are the two forces. This is one of the most interesting and useful applications of the lever. When equal weights are placed in each scale the beam will maintain its horizontal position, because the distances from the fulcrum when multiplied by the equal weights being in both cases the same, equal products will be the result, and consequently the equal weights will tend equally to move the scales in opposite directions round the pivot, and thus destroy each other's effects, and the whole machine will therefore settle in the same position which it had when the scales were empty. It is evident that the balance will only maintain a horizontal position when the scales have equal weights; for if one weight be greater than the other, the beam will always incline in the direction of the greater weight. Balances are not unfrequently misconstructed for fraudulent purposes, by making the arm from which the substance to he weighed is suspended longer than that from which the weight hangs, and thus a pound weight will be balance...