1416

THEORY AND PRACTICE OF ENGINEERING.

Book II.

the position of one of the sets of principals was transferred to the other side, withoutderanging the two, which served to make the alteration in the scaflbld without danger.

The scaffold contrived by

Campanarino for the re-storation of the dome of thePantheon at Rome rivalledall others in the beauty ofits design and delicacy ofits execution : it was com-posed of two principals, anelevation of which with thebraces is shown below.At the summit, throughwhich the only light isadmitted into this mag-nificent rotunda, a stouttimber curb was fixed, inthe centre of which wasthe pivot upon which theupper part of the scaffoldrevolved: the lower endrested on the bold project-ing cornice beneath thecoffered dome, and by meansof pulleys a small powercould advance the entirescaffold; these were also at-tached to various parts forthe purpose of hoisting thematerials to their requiredsituations: iron tics andbraces were introduced toprevent any springing, ren-dering the whole perfectlysteady, and admirablyadapted for its purpose.

This noble buildingis internally 143 feet indiameter, and 148 feet 4inches in height from thepavement; the dome whichcovers it may have beenconstructed on several suchribs, supported from belowby a forest of upright tim-bers.

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Tig. 2367.

SCAFFOLDING AT THE PANTHEON.

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£■■■ 9*11111

Fig. 2368.

SECTION OF THE ArEKTLMIF. AT THE TOP OF THE DOME.