Bridge with parabolic profile
Where: Codex Atlanticus, folio 855 r.

In the drawing, dateable to Leonardo's early days in Milan, reference is made to those "ponti leggerissimi e forti atti a portare facilissimamente, e con quelli seguire e alcune volte fuggire li nemici, e altri securi e inoffensibili da foco di battaglie, facili e comodi da levare e ponere" (very light yet rugged bridges suitable for being moved, and for pursuing and sometimes escaping from the enemy, and others still, which are safe and cannot be burnt by the fire of battles and are easily removed and laid down).