Metal-Drawing Mill Against a Curved Wall
The great apparatus with wall, rope and roller; a balanced rod and oblique weight
The verso is dominated by a large drawing of the metal-drawing mill built against a curved brick wall (the walled centering): the sheet is pulled by a single rope across the middle of its front, wound onto a roller (subbio) in one whole turn, while a stout walnut frame clamps the start and end of the drawn sheet. Leonardo notes that the wall and the pulling should be done lying flat for the operator's convenience, that the drawn sheet would otherwise bow downward, and that the plates must be well burnished. A balanced rod (h f g / a b c d e) illustrates that oblique motion of a heavy body through air splits its weight into two aspects, one toward where it moves and one toward what impedes it, while marginal notes mention 'Venus in crescent' and making lime without firewood.
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The drawing mill built against a curved brick wall
The wall should lie flat for the operator's convenience, or the drawn sheet would arch downward. A powerful walnut frame is fitted to the square of the walled centering; the start and end of the drawn sheet are nailed to it, then the frame is separated from the wall carrying all the sheets fixed upon it, and kept with the burnished sheets.
Pulling the sheet evenly onto the roller (subbio a)
Let the sheet be pulled by a single cord through the middle of its front, so that it is drawn evenly. The roller a must gather its whole pull in one entire turn.
Oblique motion splits a body's weight in two (h f g / a b c d e)
Every oblique motion made by a heavy body through the air divides the gravity of the moving body into two different aspects: one attends to the place where it moves, and the other attends to the cause that impedes it. A balanced rod at the upper right illustrates the equilibrium.
Burnished plates, a crescent note, and lime without wood
The plates should be well burnished. A cryptic marginal note reads 'Of Venus in crescent (allunato).' A separate note adds that the method will make lime without firewood.