“If you want to be able to ford the river conveniently with your army, proceed in this manner: Make a boat of willow reeds, then double the edges in such a manner that they can be opened from underneath, and fill the body of that with gravel. And when you are at the location where you want, there open the bottoms of the receptacle for the gravel, so that it falls to the bottom, and having done this, close the receptacle again, and return to the bank to reload, and this needs to be done a good number of times. But the body of the actual boat ought to be wrapped outside with cowhide, so that it will not sink to the bottom.”
The model represents a float formed of a woven wicker frame in the shape of an ellipse. The frame is partially covered with leather sheathing. The float is conceived as a circumstantial means, which can be constructed where needed, utilizing woven canes or wicker and covering these with skin. Its purpose is to transport gravel to deposit in the bed of a river to raise its bottom and allow the passage of troops. The gravel is released by opening the bottom of the device.
In order to allow proceeding along the same line of work, Leonardo draws a cord for restraining the float against the force of the water, fixed to the two banks of the river using stakes
The model is based on the drawing:
- Manuscript B f. 32 v. (1487-1492)
Paris, Institut de France