Why bodies near the horizon look larger; sunlight through a chink
A bright body dimmed by a brighter field; stars and sun enlarged near the horizon; images through an aperture.
The note observes that a luminous body appears less bright when surrounded by a more luminous field. A large diagram of a great light and a small opaque body carries Leonardo's finding that stars nearer the horizon look larger because they see and are seen by more of the sun and so shine more, just as the sun appears larger in clear air. A second figure of the sun's rays through a chink between two walls argues that the cast image grows downward as the sun rises, and that within the forked mixed shadow no point sees the whole light.
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A bright body dimmed by a brighter field
A luminous body will appear of lesser splendor when it is surrounded by a more luminous field. Its brightness is judged only in contrast with its surroundings.
Stars and sun appear larger near the horizon
Leonardo reports finding that stars nearer the horizon appear larger than the others, because there they see and are seen by a greater portion of the solar body and so receive more light; and a more luminous body shows itself larger. He compares this to the sun, which shows itself larger in clear air and diminishes in mist.
Image through a chink grows downward as the sun rises
If the sun b c sees the whole of e f, then when it has risen to a b it will see as far as f n; from this the sun's apertures (its images cast through gaps) grow downward. Within the forked mixed derivative shadow there can be no part from which the whole luminous body is visible.