Revolving bridge

In his presentation letter to Ludovico il Moro, Leonardo describes many revolving, joint and gantry bridges, often with a military purpose. These bridges are designed to be built with readily available and easily transportable materials. This bridge can be built using boats or barrels. It can be moved by a hoist operated on land and it can be placed in a niche created in the river embankment. The system is devised for rivers with calm waters.
Codex Atlanticus, sheet 857
1480-1490