Leverage in a Mast Pulled by a Cord
Lever r m against counter-lever c m, with a weight of 400
Leonardo works out the leverage in a mast held and pulled by a cord. He finds that when the cord f pulls point m, the member r bears on c and breaks a through the force acting as a lever, so that one can reckon what weight resists at the middle of the mast a by weighing the lever r m against the counter-lever c m. Beside the pen diagram of the pulled mast, a red-chalk rectangle is marked with the number 400.
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Lever and counter-lever on a pulled mast
When the cord f pulls point m, the member r presses on c and breaks a by leverage. Leonardo says the resistance at the middle of the mast a can then be found by comparing the lever r m with the counter-lever c m.
Rectangle marked 400
A red-chalk rectangle carries the number 400, apparently a weight or load entering the leverage calculation. It sits beside the pen study of the mast.