Why a Sunlit Sphere Casts a Columnar, Not Conical, Shadow
A sun-and-earth shadow diagram, with a spring-and-cam mechanism below
The upper diagram, labeled sole (sun) with points a, n, o, t, b, sets out a paradox of shadows: if the sun is larger than the earth, the earth should cast a pyramidal (cone-shaped) shadow tapering behind it, and a small ball lit by the sun ought to cast only a very short shadow. Leonardo observes the opposite, noting that in place of a pyramid one sees a columnar shadow. The lower half of the sheet carries a mechanical study, drawn but not transcribed, showing V-shaped sprung arms driving a disc or cam turned by a crank and a long screw. Faint offset from the facing pages shows through the paper.
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The paradox of the sunlit sphere's shadow
If the sun is larger than the earth, the earth casts a pyramidal shadow through the air behind it. On that reasoning a small ball lit by the sun should cast a very short shadow, yet Leonardo says we see the opposite: in place of a pyramid, a columnar shadow appears. The diagram is labeled sole (sun) with points a, n, o, t, b.
A sprung cam turned by crank and screw
The lower half of the page carries an untranscribed mechanical study: a pair of V-shaped sprung arms at left and a disc or cam driven by a bent crank, with a long threaded screw running to a block at right. No accompanying text for this device is included in the transcription.