( 318 )

and the bearing of the double portions of thebeams on each cross piece, C, being nearly 8inches, was more favourable to give solidity tothe whole, than could have been effected in anyother manner. The beams, D, thus formed andlaid athwart the cross-pieces C C, had theirjoints adjusted to lay exactly on those bearers,and were then firmly lashed at each end of thebridge.

Planks, (6) and (7), for flooring, E, fig. 6, wereprovided, with holes bored in the end of each,to admit of their being lashed to the beams D,and to each other.

This vast net, when completed, with its endbeams, B B, and traverses, C C, was rolled up,firmly bound together, and loaded on a pontooncarriage. The means of transport for the wholeapparatus were, two pontoon carriages, each

line of the bridge to be the ordinary catenary, and in calculat-ing the strains on this supposition.

The weight of the bridge, unloaded, may perhaps, from thematerials given above, (pp. 31 4, 315,) be estimated at18,000 lbs.; and when covered with infantry, three men infront, the load may be taken at 18,000 lbs. more. We shalltherefore have from the Rules, p. 310.

The whole length of the cord or bridge = 100,24 feet.

The weight of 1 foot of the bridge = 359 lbs.

The strain at the lowest point =410 X 359= 149344 lbs.which is to be supported by the strong rope net work.