Impetus, and Parts of a Metal-Drawing Machine
Impetus as an impressed, self-persisting force; the block, die and rollers of the trafila
The recto opens with a definition of impetus as an impression of motion transmitted from the mover to the moved, a power that seeks to persist, illustrated by the sun's image lingering in the beholder's eye and a bell that keeps ringing after the hammer strikes. The rest of the page turns to a metal-drawing mill (trafila): notes on a block that fits into its 'mother' by a joint, on truing the lips of the die with emery once it is tempered, on the framing, and on the roller (subbio) that winds up the drawn sheet. Isometric drawings of the machine blocks accompany the notes.
On this page
Impetus as an impressed, self-persisting force
Leonardo defines impetus as the impression of motion transmitted from the mover to the moved, a power impressed by the mover in the moving body. Every impression tends toward permanence, or rather desires it. He proves this by the sun's image imprinted on the beholder's eye and by the sound the hammer leaves ringing in the struck bell.
The drawing die: block, mother-socket and truing its lips
A block marked a is to enter its 'mother' (socket) by a mortise joint. The greatest diligence lies in adjusting the lips of the die into perfect straightness with emery, once the die has been perfectly tempered.
Framing and the winding roller (subbio)
The roller a of the wheel, with a revolving motion, gathers the drawn sheet to itself. The sheet, thick and round at the front as the drawing shows, is fed into the roller that projects outside its wheel through a sluice-like channel; the iron roller is an inch thick. Leonardo advises using two rollers so the sheet need not be unwound each time.
Isometric drawings of the machine blocks
Three solid blocks are drawn in isometric projection down the right side of the sheet, showing the die-block and its housing in section. The hatched shading models their depth and internal cavities.