Cold reflected from a mirror, and the height of a rebound (f. 85r)
A concave-mirror ray study joined to notes on percussion and action-reaction
A transmitted-light view of folio 85r combining optics and mechanics. Leonardo notes that cold gathered from a mirror's surface and thrown back to the point of its 'pyramid' multiplies no less effectively than the sun's rays do, alongside a large circular diagram in which ruled lines converge like reflected rays. Further notes state that the height of a struck body's rebound matches the power of the percussion, while a longer but lower rebound comes from the mover's power rather than the blow, and that every body flees in the direction opposite to the blow, with action equal to reaction and every motion tending to be circular. A small branching, organic sketch appears at the lower right.
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Cold reflected from a mirror like the sun's rays
The cold taken from the surface of a mirror and thrown back to the point of its pyramid multiplies with no less effect than do the rays of the sun. The claim accompanies a large circular ray-convergence diagram on the sheet.
The rebound's height matches the blow's power
The elevation of a heavy body's rebound from the site where it was struck equals the power of the percussion. A rebound that is long but not high comes from a weaker blow, owing not to the percussion's power but to the power of its mover.
Every body flees opposite the blow; motion seeks the circular
Every body flees toward the side opposite the place that drives it, that which strikes it. The body's striking of the object equals the object's striking back on the body. Every motion seeks to be circular, but ...