74- Sir Is a ac Newton’s Book!

then the ftrength of the forces is to be eftimated by lines letfall from the center of the lever to the directions, wherein theforces aCt To balance the levers in fig. 17, the weight orother force at F will bear the fame proportion to the weightat E, as the diftance 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 firft motion willbe the fame, as the motion of the point G.

3 6 . When two weights hang upon a lever, and the point,by which the lever is fupported, 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 fcales-When the point of fupport is not equally diftant from bothweights, it conftitutes that inftrument for weighing, whichis called a fteelyard. Though both in common fcales, and thefteelyard, the point, on which the beam is hung, is not ufu-ally placed juft in the fame ftraight line with the points, thathold the weights, but rather a little above ( as in fig. 18. )where the lines drawn from the point C, whereon the beamis fufpended, to the points E and F, on which the weights arehung, do not make abfolutely one continued line. If thethree points E, C, and F were in one ftraight line, thole weights,which equiponderated, when the beam hung horizontally,would alfo equiponderate in any other fituation. But wefee in thefe inftruments, when they are charged with weights,

which