Trestle bridge on light poles, with an arc engine and gears
Framing a bridge on lance-thin timbers, ringed with sketches of engines, gears and a domed church
The mutilated caption, its line-starts continuing from the detached folio 69a r, explains how to build a bridge over water: the timbers are to be thin like lances so they can be raised from the water's surface and fixed high enough to frame the bridge in four or five places; then, in place of the lances, thick timbers are set and the deck is woven two braccia at a time. The central pen drawing shows just such a trestle bridge of crossed poles rising over hatched water, with smaller versions at the right. Around it are further untranscribed studies — a large curved arc mechanism with a wheel and cords, small gearing, and tiny architectural sketches including a domed church — which the scholarly tags associate with bombards, toothed wheels and a three-speed gear change.
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Framing a bridge on lance-thin timbers
The caption explains that the timbers should be thin, like lances, so they can easily be raised from the water's surface and fixed high enough that the bridge is framed in four or five places. Then, in place of the lances, thick timbers are put in and the deck is finished, woven two braccia by two.
Trestle bridge over water
The central drawing shows a trestle bridge of crossed poles rising over hatched water, with smaller versions repeated at the right of the sheet.
Arc mechanism with wheel and cords
A large curved arc mechanism carrying a wheel and cords is drawn at the top of the sheet; the scholarly tags note toothed wheels and a three-speed gear change.
Bombard studies (untranscribed)
Small pen studies appear among the sketches, which the scholarly tags identify as bombards.