13 66

THEORY AND PRACTICE OF ENGINEERING.

Book II.

protected by horizontal pieces, one under the braces, and the other immediately above thelevel of the river, through which passed iron bolts that tied and secured the whole piertogether : the 13 double posts, which formed the pier, were capped, and on them were laidas many longitudinal timbers, which formed the supports to the floor of the bridge, andan additional piece or two was bolted to them, in the middle of their span, with strutsand pendant braces.

3JLL1I!

Fig. 2218.

Lj CjfhJ VfTll

Fig. 2217

Palladio’s Bridge over the Cismone.

—This was executed over a river at —Jthe foot of the Alps, between Trentand Bassano ; its length is about 108 HTjfeet; it is divided into six equalopenings. The river being rapid and --J fT*^ |!IT*^jsubject to floods, bringing down trees 't.r S!! *»qnp“^and stones, it was not thought advi- ri g 2 2l9.sable to fix any piles in the current:the timbers mutually support each other, and the whole system is strongly framedtogether.

LYONS, BY NEANGREZ.

Palladio's biudgb at bassano.

Five girders, 12 or 13 inches square, disposed at equal distances, are laid at rightangles to the length of the bridge, or about 18 feet from centre to centre: these appearto have no support; the girders being a little longer than the width of the bridge, carrythe principal timbers or joists which cross the river, on which the planks are laid whichform the floor. The five girders do not lie level; the three in the middle are elevateda little above theother two, so that thesill which lies uponthem, and into whichthe king- and queen-posts are framed,is also out of a level;the part at which the ‘two outer sills abutagainst that in themiddle being ele-vated, the whole takesthe form of a seg-ment ; the uprightposts or colonelli,which are framedinto them, are alsobolted through andsecured on the underside : all the struts, p»g. 222 :

Fig. 2221.

Palladio’s bridgb.