Page:The Mathematical Principles of Natural Philosophy - 1729 - Volume 1.djvu/66

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As if the unequal Radii OM and ON drawn from the centre O of any wheel, hould utain the weights A and P by the cords MA and NP; and the forces of thoe weights to move the wheel were required. Through the centre O draw the right line KOL, meeting the cords perpendicularly in K and L; and from the centre O, with OL the greater of the ditances OK and OL, decribe a circle, meeting the cord MA in D: and drawing OD, make AC parallel and DC perpendicular thereto. Now, it being indifferent whether the points K, L, D, of the cords be fixed to the plane of the wheel or not, the weights will have the ame effect whether they are upended from the points K and L, or from D and L. Let the whole force of the weight A be repreented by the line AD, and let it be reolved into the forces AC and CD; of which the force AC, drawing the radius OD directly from the centre, will have no effect to move the wheel: but the other force DC, drawing the radius DO perpendicularly, will have the ame effect as if it drew perpendicularly the radius OL equal to OD; that is, it will have the Rh