. An encyclopaedia of architecture, historical, theoretical, & practical. New ed., rev., portions rewritten, and with additions by Wyatt Papworth. dy, the quotientwill express the distance of two other planes BKL,DHI\I, parallel to those first named. Their inter-section will give a line IP, or an axis of equilibriiun, upon which the centre of gravity of the solid will 11«. oifi. be found. To determine the point G, imagine a third plane NOP perpendicular to the pre-ceding ones, that is, horizontal; u])on which let the solid be supposed to stand. In respectof this plane let the momenta of the py
. An encyclopaedia of architecture, historical, theoretical, & practical. New ed., rev., portions rewritten, and with additions by Wyatt Papworth. dy, the quotientwill express the distance of two other planes BKL,DHI\I, parallel to those first named. Their inter-section will give a line IP, or an axis of equilibriiun, upon which the centre of gravity of the solid will 11«. oifi. be found. To determine the point G, imagine a third plane NOP perpendicular to the pre-ceding ones, that is, horizontal; u])on which let the solid be supposed to stand. In respectof this plane let the momenta of the pyramids befound by also multiplying their solidity by the dis-tance of their centres of gravity. Lastly, dividingthe sum of these products by the solidity of the en-tire body, the quotient gives on the axis the dis-tance PG of this third plane from the centre ofgravity of the irregular solid. Mechanically, where two of the surfaces of a bodyare parallel, the mode of finding the centre of gravityis simple. Thus, if the body be hung up by anypoint A (^figs. 54 7, 548.), and a plumb line AB besuspended from the same point, it will pass through. Fig. lAI. Klg 44H. Chap. 1. MECHANICS AND STATICS. 347 tlie centre of gravity, because that centre is not in the lowest point till it fall in the plumbline. Mark the line AB upon it; then hang the body up by any other point D, with aplumb line DE, which will also pass through the centre of gravity, for the same reason asbefore. Therefore the centre of gravity will be at C, where the lines cross each other. ] 292. We have, perhaps, pursued this subject a little further than its practical utility inarchitecture renders necessary ; but cases may occur in which the student will find our ex-tended observations of service. OF THE INCLINED 1293. That a solid may remain in a perfect state of rest, the plane on which it standsmust be perpendicular to the direction of its gravity ; that is, level or horizontal, and the ver-tical let fall from
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