Tackle-blocks and forming metal plates over a mould
Compound pulley blocks with 24 wheels, and shaping curved laminae on a worked stone form.
Leonardo studies compound tackle-blocks ('taglie') and their ropes, comparing a square block and a cylindrical one, the latter carrying 24 pulleys on eight axles and praised as more compact and easier to thread. Notes on mechanical advantage observe that a weight hung on the lower block divides equally among its ropes, and that blocks with larger wheels and thinner axles lift more easily. A second cluster of notes and drawings describes forming quarter-thick metal plates by hammering them over a polishable stone 'wall' (p q S t) shaped by a moving centering, then soldering them with tin or burnt copper.
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A cylindrical tackle-block of 24 pulleys
The round block, built in the form of a cylinder, carries 24 wheels driven by eight motors placed at a b c d e f g h. Leonardo judges the cylindrical or columnar form more praiseworthy than the square block above it: it is reduced to a smaller volume and its pulleys are easier to thread onto the circular axle, like rosary beads.
How a hung weight divides among the ropes
The weight attached to the lower block divides in equal parts among the ropes that join to that block. Blocks lift their load more easily when their pulley-wheels have a larger diameter and thinner axles, provided the axles keep their due strength.
Shaping metal plates over a worked stone form
The plates are made a quarter thick, stamped with a hammer over the male form, and soldered with tin or burnt copper. The 'wall' p q S t is built of marble or other polishable stone, each piece fitted and worked to the motion of a centering that travels from b to d, its guides converging to the point r.