Book 2
10
When they were sure that from the tower they could protect all the surrounding works, they set about making out of timber two feet square a covered gallery sixty feet long, to be carried from the brick tower to the enemy’s tower and wall. And the form of the gallery was as follows. First of all two beams of equal length are laid on the ground with a distance of four feet between them, and in these posts are fixed five feet in height. These posts they con- neet by rafters of low elevation whereon to place the boarding to be laid for the roofing of the gallery. Over these rafters they lay two-foot beams and fasten them with plates and bolts. On the outside of the roof of the gallery and on the edges of these beams they fasten three-inch-square shingles to keep in place the bricks to be laid on the roof. Thus when it had all been sloped and duly constructed, after the beams had been laid on the rafters, the gallery is roofed with tiles and clay, so as to be safe from fire that might be thrown from the wall. Hides are drawn over the bricks lest water discharged at them through pipes should wash them out. The hides, too, are covered over with patchwork lest they in their turn should be spoilt by fire and stones. The whole of this work, protected by mantlets, they complete up to the tower itself, and suddenly, when the enemy were off their guard, they put rollers under it—a nautical appliance—and push it forward to the tower of the enemy, so as to join on to the structure.
