. An encyclopaedia of architecture, historical, theoretical, & practical. New ed., rev., portions rewritten, and with additions by Wyatt Papworth. ork, wherein the teeth of onecircumference work in therounds or pinions of another toturn the wheel. In case, here,of an equilibrium, the power isto the weight as the continualj)roduct of the radii of all theaxles to that of all the if the power P (Jig. 554.)turn the wheel Q, and this turnthe small wheel or axle R, andthis turn the wheel S, and thisturn the axle T, and this turnthe wheel V, and this turn theaxle X, which raises the weightW
. An encyclopaedia of architecture, historical, theoretical, & practical. New ed., rev., portions rewritten, and with additions by Wyatt Papworth. ork, wherein the teeth of onecircumference work in therounds or pinions of another toturn the wheel. In case, here,of an equilibrium, the power isto the weight as the continualj)roduct of the radii of all theaxles to that of all the if the power P (Jig. 554.)turn the wheel Q, and this turnthe small wheel or axle R, andthis turn the wheel S, and thisturn the axle T, and this turnthe wheel V, and this turn theaxle X, which raises the weightW; then P : W::CB. DE .EG : AC . BD . EF. And in «•• the same proportion is the velocity of W slower than that of P. Thus, if each wheeli)e to its axle as 10 to 1, then P : W;;! : 10-, or as 1 to 1000. Hence a power of onepound will balance a weight of 1000 pounds; but when j)ut in motion, the power willmove 1000 times faster than the weight. 1314. We do not think it necessary to give examples of the different machines for raisingweights used in the construction of buildings : they are not many, and will be hereafternamed and OF THE rULLEY. 1315. A ])ulley ia a small wheel, usually made of wood or brass, turning about a metalaxis, and enclosed in a frame, or case, called its block, which admits of a rope to pass freelvover the circumference of the pvdley, wherein there is usually a concave groove to preventthe rope slipping out of its place. The pulley is said to be fixed or moveable as its blockis fixed or rises and falls with the weight. An assemblage of several })ulleys is called asystem of pulleys, of which some are in a fixed block and the rest in a moveable one. 1316. If a power sustain a weight by means of a fixed pulley, the power and weight are 350 THEORY OF AIlCIIITECTUllE. Book TI. etjual. For if through the centre C (fg- 555.) of the pulley we draw the horizontaldiameter A15; then will A15 represent a lever of the first kind, itsprop heing tlie fixed
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