Motion of a Heavy Sphere on an Inclined Plane
A rolling sphere and a cone on a slope, with a note that uniform air reveals a body's true quality
The sheet studies the descent of a heavy spherical body down an inclined plane, arguing it takes on a swifter motion the farther its point of contact lies from the perpendicular of its central line. A large lettered diagram (a, p, n, m, b, c) works through the small retarding effect of the sphere's counterpoise, quantifying how much later the ball reaches the ground. An opening note observes that air shows bodies in their true quality when it is uniform in itself, as in purified air, and a cone on an incline is said to turn only in a circular motion about its apex. A small vessel-like sketch (untranscribed) also appears in the right margin, consistent with the sheet's catalogue tag of an alembic.
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How fast a heavy sphere rolls down a slope
Leonardo reasons that a spherical, heavy body gains a swifter motion the farther its contact with the running surface lies from the perpendicular of its central line. With m as the ball's pole and n the part resting above it, the little counterweight p slightly delays the fall: if p enters 100 times into n, the ball descends one hundredth of a time later than it otherwise would.
A cone rolls only in a circle
A heavy body in the form of a round pyramid (a cone) set on an oblique slope will move about the point of its pyramid and can take no motion other than circular. A separate small figure of a cone on an inclined plane accompanies the statement.
Uniform air reveals a body's true quality
The note opens with an observation about air itself: it makes bodies appear truly when it is uniform within, for objects set in it then display their real quality. This is offered as it appears in purified air.
Small vessel sketched in the margin
A tiny pointed-oval apparatus is drawn at the right edge, apart from the mechanical diagrams. It is not covered by the transcription; the sheet's catalogue tag identifies an alembic (distillation vessel).