1014

THEORY AND PRACTICE OF ENGINEERING.

Book II.

on which it stood by means of capstans and blocks attached to the iron hoops, and theblocks hanging to the cross beams of the shears ; after it was lifted up two feet perpen-dicularly, a platform of timber was introduced beneath it, which rested on wooden rollers,9 inches in diameter, their ends being secured by iron hoops. The ropes of the blocksattached to the four lower angles of the obelisk being drawn, the platform which supported

Fig.1533.

the weight moved on the rollers, and the ropes of the blocks attached to the upper partof the obelisk being slackened, the obelisk gradually descended, and was laid horizontallyon the platform prepared to receive it: during its descent it was found necessary to supportit in the middle by two shores, made movable on an axis attached to its centre, and whichprevented any great strain on the tackle.

Fig. 1334.

hr

UHL

The inclined plane along which it was moved to its destination was formed of a moundof earth strengthened with timbers, and extended from the Circus of Caligula , afterwards