Cities in Thick Air; the Tower Divided into Four Degrees
Smoke and mist dim low buildings, and a marginal diagram divides a tower's air into four grades of thickness.
The page opens with the reason a bright part sends a stronger ray to the eye than a dark part, illustrated by a woman dressed in black with a white headcloth who appeared twice as broad as her black-clad shoulders. A new chapter on cities in thick air states that buildings seen from above, in mist or smoke, grow less distinct the lower they stand and sharper the higher. A small marginal diagram supports this: the tower a e, viewed from the eye n, is set in thick air divided into four degrees, thicker toward the bottom. The closing lines state that the more air a thing is seen through, the more its colour takes on the colour of that air.
On this page
A woman in black with a white headcloth looks broader than she is
The brighter part of a thing sends its image to the eye with a more vigorous ray than its dark part. Leonardo reports seeing a woman dressed in black with a white cloth on her head who appeared twice as broad as the thickness of her black-clad shoulders.
City buildings dimmed by their own smoke and mist
Buildings of cities seen from above in mist, or in air thickened by the smoke of fires and other vapours, are less distinct the lower they stand and sharper the higher they are seen. This follows from the rule that air is thicker the lower it lies and thinner the higher.
The tower a e set in four degrees of thickening air
A marginal figure shows the tower a e seen from the eye n through thick air a e, divided into four degrees that grow thicker toward the foot. The more air interposed between eye and object, the more the object's colour partakes of the air's colour.