74 Sir Is a ac Newton’s Book!

then the strength of the forces is to be estimated by lines letfall from the center of the lever to the directions, wherein theforces act. To balance the levers in fig. the weight orother force at F will bear the fame proportion to the weightat E, as the distance C E bears to C G the perpendicular let fallfrom the point C upon the line, which denotes the directionwherein the force applied to F acts: for here, if the lever beput into motion, the power applied to F will begin to move inthe direction of the line F G; and therefore its first motion willbe the fame, as the motion of the point G.

z 6 . When two weights hang upon a lever, and the point,by which the lever is supported, is placed in the middle be-tween the two weights, that the arms of the lever are bothof equal length ; then this lever is particularly called a ba-lance ; and equal weights equiponderate as in common scales*When the point of support is not equally distant from bothweights, it constitutes that instrument for weighing, whichis called a steelyard. Though both in common scales, and thesteelyard, the point, on which the beam is hung, is not usu-ally placed just in the fame straight line with the points, thathold the weights, but rather a little above ( as in fig. 2.8.)where the lines drawn from the point C, whereon the beamis suspended, to the points E and F, on which the weights arehung, do not make absolutely one continued line. If thethree points E, C, and F were in one straight line, those weights,which equiponderated, when the beam hung horizontally,would also equiponderate in any other situation. But wefee in these instruments, when they are charged with weights,

which