A device to break a fall: percussion cushioned by wool
On the nature of percussion, with a shock-absorbing drop apparatus
Folio 62v opens 'On the nature of percussion,' citing everyday cushioned impacts — a man landing on his toes or catching thrown bricks, a lame foot set down gently — and the paradox of stepping barefoot on a knife or an egg without breaking it. Leonardo then designs an apparatus to let a man fall from a great height unhurt: hung from irons a b, he descends between guides S h into tapering beams c n that touch at r f, so the wedging irons never bottom out and the shock is spread along oblique lines. As the beams open above at c n they close below at q p, squeezing a ball of wool like pincers, whose yielding reduces the blow to almost nothing. The tall apparatus is drawn at the right.
On this page
The nature of percussion, softened by yielding
Impacts are softened when the receiving body yields: a man landing on the tips of his feet or catching bricks thrown from above, or a lame foot set down so the body drops toward that side. By such reasoning one might set the bare foot upon the point of a knife or upon an egg without breaking it.
Drop apparatus with wool-cushioned tapering beams
The man hangs from iron a b, whose part b is as thin as a thumb and a three times thicker, falling between guides S h into beams c n. The beams are narrow at r f and wide at c n, so the irons cannot bottom out and the blow is spread along oblique lines. As the beams open above they close below at q p, gripping a ball of wool like pincers, whose yielding makes the fall harmless.
Wool packing (lana o banbagia)
A ball of wool or cotton is packed to be squeezed by the closing beams; its softness absorbs the remaining force of the descent so the man is unharmed.