On percussion: hammer, nail and the coining die
Simple versus composite percussion, illustrated by the coin-stamping die
Leonardo opens a study 'On percussion,' which he ranks as the greatest of the accidental powers of nature, exceeding every force made by movers of heavy bodies in equal time, motion, weight and force. He divides percussion into simple, where the striking mover ends its motion at the point struck, and composite, where it does not, as with the hammer that strikes a coining die. He argues composite percussion is much weaker, reasoning that a coin would take a cleaner impression from a simple blow than from the composite one that rebounds off the die back against the hammer. The drawings show a large horizontal wheel with oblique teeth, a nail b being driven into wood, and further hammers and nails.
On this page
Percussion ranked greatest of the accidental powers; simple vs composite
Percussion exceeds by a great excess every other force made by movers of heavy bodies in equal time, motion, weight and force. It divides into simple, where the mover ends at the point struck, and composite, where it does not, as in the hammer that strikes the coining die; the composite kind is much weaker and yields a less clean impression.
Hammer driving a nail upward into wood
Beside the nail marked b, Leonardo notes that here the hammer moves upward against the nail, which is to be driven into the wood.
Horizontal wheel with oblique teeth
A large horizontal wheel fitted with oblique teeth is drawn at the head of the page as an illustration accompanying the study of percussion; the transcription records only its caption.