Hay-faced defensive walls to absorb artillery fire
A coloured study of tiered curved ramparts, with a note on impact and resistance
A large drawing washed in ochre and blue shows a curved, tiered defensive wall in perspective, with cutaway sections and details of its construction dimensioned in braccia. A detail describes the wall faced with hay, wetted and daubed with mud, and a note in the lower corner reasons about impact: a blow is stronger against a more resistant object and weaker against a yielding one. Leonardo concludes that it is not strong masonry but hay-clad walls that best deaden the fury of the balls hurled by powerful artillery. Faint further sketches and partly effaced writing appear at the right.
On this page
Tiered curved rampart in section
The principal coloured drawing sets out a curved, stepped defensive wall seen in perspective and cutaway, dimensioned at 15, 40 and 6 braccia. Its layered galleries and sloping faces are worked out in successive sections.
Wall faced with wetted hay
A detail specifies that the wall is to be faced with hay, wetted and daubed with mud. This soft, damp cladding is the constructional device the whole study is built around.
Impact greater on harder objects
The lower-corner note argues that a percussion is of greater force when it strikes a more resistant object, and weaker against one of lesser resistance. From this Leonardo concludes that strong walls do not resist great impacts, but hay-faced ones, in which the fury of the balls driven by powerful artillery is calmed.