Chap. XII.

MACHINES, TOOLS, ETC.

999

Fig.1497.

A modification of the above capstan consistsin applying two cylinders in a vertical position,around the larger of which the rope coils, as thehandspikes applied to the smaller made to workin a frame turn it. When two cylinders of dif-ferent sizes revolve on the same axis, and theweight is wound round the larger, its operationis very powerful, as we have previously shown.

The capstan made use of on wharf walls or indocks is usually of iron, with a shaft of consider-able length, turning on a pivot at the bottom ofa brick or stone chamber constructed to receiveit t at the top of the chamber is a capping, whichguides the motion of the capstan as it is turned round bya handspike or lever applied at the top.

The manner of applying the pulley to two cylindersof different diameters on the same axis is very simple; therope is made to pass from the smaller one, over a pulleyconnected with the weight, and returns again, to be woundup by the larger one; a considerable length of rope isrequired for a small extent of motion, but the action isone of considerable power.

One of the most curious applications of the capstan wasmade by the Count deCarbury, when he moveda mass of granite to St.

Petersburgh for the pe-destal of the celebratedstatue of Peter the Great ,which was estimated toweigh upwards of 1500tons; its dimensions being42 feet 6 inches long,

26 feet wide, and 23 feethigh. Thisimmenseblockwas supported upon atimber platform of greatstrength, beneath which were placed a series of axles with grooved ends that worked orran upon balls of copper 6 inches in diameter. The axles of the carriage were moved

Fig. 1498.

Fig. 1499.

■ Lii^. - rn^ .r r \ rx u.

Fig. 1500.

PLAN OF CARBURY’S MACHINE.

by the revolution of the balls, on a bed prepared to receive them, which was movable to thefore part of the frame as the carriage progressed, forming a sort of continued railway ; oneof these pieces of timber is shown under the side elevation.

The end or front of the stone mass was cut into steps, on the top of which the directorof the operation took his station; from whence he could make the various signals necessaryfor the progress of the machine.

The capstans, firmly fixed, were worked by levers and pulleys ; and as one set of workmenbecame fatigued with turning them, they retired to mats attached by other ropes to theflanks of the carriage and were drawn along, steadying the block at the same time, whilstothers who had previously rested took their places. This operation rivals that describedby Herodotus of the transport of the enormous rock, 240 feet in circumference, which wasbrought from the quarry in the Isle of Philoe near the cataracts, for the shrine of the goddessLatona, thousands of labourers being employed three years in taking it to its place of

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