Machine for beating gold and drawing lead wire
A wheel-and-lever press, with notes on 'equal versus unequal power', tongs, and a measure of 23 braccia
A clean drawing of a mechanism built around a large wheel, a weighted lever arm and a vertically guided hammer or press, with a smaller detail of the same fitting at the lower right. Leonardo's notes describe using it 'to beat gold in the manner that lead is drawn into wire', and to draw the lead for glass-window leading, aided by tongs. A marginal aside on whether the power is 'unequal' or 'equal', and a figure of 23 braccia, accompany the sketch.
On this page
Beating gold as lead is drawn into wire
The heading caption states the machine's purpose: 'to beat gold in the manner that lead is drawn into wire'. The device combines a large driving wheel with a weighted lever arm and a guided vertical hammer or press, so that the same drawing action used for lead can flatten gold leaf.
Drawing lead for glass windows; the tongs
A lower caption identifies the mechanism as being for drawing lead for glass windows (the leading cames), noting the tongs (tanaglia) that grip the metal. It is annotated as 'unequal power', with a column of small numbers and a measure of 23 braccia.
Equal versus unequal power
In the margin Leonardo corrects himself on the mechanical advantage of the device: 'Unequal power — rather, I meant to say equal. To draw wire.' The note weighs whether the force delivered along the lever and wheel is uniform or varies through the stroke.