The quintuple staircase for a tower's defence
Five interlocking flights with separate entrances; a spring-shot arrow above
The sheet is dominated by a bold perspective study of a tower containing five separate staircases, drawn again in plan below. Leonardo explains that the five flights have five entrances and that no one can pass from one to another, so garrison troops kept apart cannot mingle, each staircase serving the tower's defence; the design can be round or square. A small device at the top shows an arrow shot by a strong spring.
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Five separate interlocking staircases in one tower
Here are five staircases with five entrances, none of which sees the others, so that anyone in one cannot enter another. It is good for garrison troops who must not mingle, all kept separate for the defence of the tower, and it can be built round or square.
Arrow driven by a strong spring
A small mechanism at the top of the sheet is labelled as an arrow shot by a strong spring.