Figure projecting from a wall; weights, beams, and a float
Light through an aperture to detach a painted figure; a weight on an incline; a cork gauging current
This mixed folio opens with a method for painting a figure on a foreshortened wall so that it appears detached and projecting: a thin iron plate with a small round aperture holds a light whose middle touches the hole, casting the umbra and then the penumbra of a body onto the wall, and the viewer looks through the same aperture. Two mechanics problems follow, illustrated by a sector-divided quarter circle and by two beams on the ground: a weight is easier to raise the nearer it stands to the first 'degree of facility' on an incline, and Leonardo asks which of two beams may be pulled more easily. A cork float pierced by a reed, labeled a and n and weighted by a small tile, is proposed to reveal whether water flows faster below the surface than above it. A half-arch of brick and the headings 'Perspective' and 'On the reason of the screw' also appear on the sheet.
On this page
Making a painted figure appear to project from a wall
To paint a figure on a foreshortened wall so that it appears in its proper form and detached, one takes a thin iron plate with a small round aperture, brings a light close so it touches the hole, and sets the body against the wall. The umbra and penumbra are marked and the figure given its lights, and the viewer looks through the same aperture.
Casting umbra and penumbra with a lamp through an aperture
A lighted candle placed close to one side of the pierced iron plate, its middle touching the hole, sends rays through to illuminate a round body against the wall. The body casts its umbra and penumbra, which are indicated on the wall so the painted form appears to stand off from it.
Degrees of facility for raising a weight on an incline
A quarter circle divided into sectors, with a rectangular weight beside it, represents the angles or 'degrees of facility' at which the weight can be raised. The nearer the weight is to the first degree of facility than to the last, the easier it will be to raise.
Which of two beams is pulled more easily
Two horizontal beams rest over a ground line, one balanced on a low, narrow support that concentrates its weight onto a very small area. Leonardo asks which of the two beams will be pulled more easily.
A cork float gauging whether water flows faster below
A spherical cork floats on a watercourse with a reed stuck through it vertically, rising to a mark at a and n above and weighted by a round tile below. Making the reed extend one braccio at a n lets the inclination of the tile be read from that of a n, which proves whether the water flows faster below than above.