Mud sledge, ditch-emptying crane and rivellino plan
A sledge that won't sink in mud, a twin crane for emptying ditches, and a solid rivellino with a hidden stair
Three engineering ideas share the sheet. At the top a loaded sledge has its ground-facing part made continuous so it will not sink into mud. The centre is filled by a large twin crane set within a ditch and lifting crates, labelled for emptying ditches. Below, a plan of a rivellino keeps its forward defences solid except for a central spiral stair that reaches the battlements and is entered through underground tunnels.
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Sledge that will not sink in mud
A loaded sledge is designed for muddy ground. The part that touches the earth is made continuous and solid so that it does not stick into the mud.
Twin crane for emptying ditches
A double crane stands inside a ditch, hoisting crates on its two arms. The note gives its purpose plainly: for emptying ditches.
Solid rivellino with a hidden spiral stair
A plan of a rivellino marks its forward works 'solid, solid'. Only a central spiral stair is left open, to reach the battlements above, and it is entered through underground tunnels.