"These timbers need to be thin, like spears, so that they may easily be elevated from the level of the water and be fixed to remain up, so that the bridge is outlined at 4 or 5 places. Then, at the place where the spears are, put large timbers, and then take care of weaving the bridge, by intervals of 2 braccia."
In this design, the bridge is made up of a double row of trestles to support the framework. Leonardo gives tips on the materials to use and the steps to take to build this machine. To construct the bridge, it was necessary to set up a makeshift framework to be covered with poles of light wood that could be easily handled. The makeshift load-bearing framework was then replaced with a permanent structure of big tree trunks arranged to form trestles.
The model is based on the drawing:
- Codex Atlanticus f. 57 v. (1480-1482)
Milano, Biblioteca Ambrosiana