Rod-and-spring mechanism for doubling a motion
An unlatched rod that a spring lowers so its travel doubles, then returns it aloft
The top of the leaf carries a drawn mechanism: a long rod or shaft mounted on a central pivoted fitting with linkages spreading to either side. The accompanying note works out how the linked points move so that lowering the rod produces a doubled motion, and argues that a good spring could drive the return stroke without the cord shown above. The rest of the sheet bears faint, partly effaced writing.
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Linkage that doubles the motion (m, r, c, a, o, g, n, f)
As the unlatched rod is lowered and point c meets a, point m descends to n; when r drops to o at the same time, n descends to f, so the motion is doubled. Leonardo adds that with a good spring the device could work without the cord above, since the spring alone would carry m back up to where it started.