Simple and composed motion; falling flame and reflected suns
Rotation of a cylinder, burning bodies slowing as they fall, and images on a sphere
Folio 140v defines the kinds of motion: simple motion, where a body turns about its pole without shifting place (like a wheel or millstone) or shifts place without turning, and composed motion, which does both, as the wheels of a cart. Folio 139r treats the growth and shrinking of the image of the sun and of the eye seen on a sphere or a bead of quicksilver, then the physics of fire — a burning body slows as it falls because the flame consumes its matter and it grows lighter — and adds a craft note on fitting thin cut glass over gilded bone inlay. Only two text blocks are transcribed; the transmitted-light leaves carry further writing and mechanical sketches not reproduced here.
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Simple versus composed motion
Simple motion divides in two: turning about a pole without change of place, as a wheel or millstone, or changing place without turning. Composed motion does both at once, as the wheels of a cart, and a cylinder in composed motion sweeps a space equal to the surface it touches.
A falling burning body slows as it lightens
As the burning matter that feeds a flame descends through the air it slows, because during its fall the flame consumes the matter that nourishes it; losing substance it gains lightness and therefore slowness, and near the end of its fall it may turn in a contrary motion.
Images of the sun and eye on a sphere or quicksilver bead
The opening note treats how the spherical body grows and shrinks at different distances, and how the reflected image of the sun upon it, and of the eye upon a grain of quicksilver, grows and diminishes accordingly.
Mechanical sketches across the opening
Both leaves bear faint device drawings — a framed machine on posts at the left and rods, pulleys and a wheeled structure at the right — consistent with the text's examples of wheels and millstones. These are not separately transcribed in the bundle.