Distant mountains: whitening air and darkened tree-covered crests
Air gains whiteness with distance so f to b reads twice as clear as f to a; overlapping trees darken summits
Two short chapters 'Of the mountains' with two pen diagrams of jagged mountain profiles. The first explains that distant summits are more discernible than anything on them because the air whitens and loses definition with distance, so that from f to b it reads twice as clear as from f to a. The second explains why the crests appear darker: many trees overlap and hide the clearer flat intervals between them, the same reason that darkens the middle of fields. The two profile drawings, labelled a, b and f, illustrate the graded distances.
On this page
Air gains whiteness with distance; f to b twice as clear as f to a
In distant hills and mountains the summits are discerned more than anything on them, because at every degree of distance from the eye toward the east the air gains degrees of loss of definition and of clarity, or whiteness; and from f to b it is twice as clear as from f to a. A jagged mountain profile carries the labels a, b and f.
Why the crests of mountains and hills appear darker
The summits of mountains and hills appear darker because a greater number of trees meet one another and the clearer flat interval between them is not seen, as it is on open slopes; and it is the same reason that darkens fields in their middle.
Rendering ranges of hills receding into distance
Two pen profiles of jagged mountain ranges accompany the text, showing how successive distances of hills and their summits are to be graded in a painted landscape as the air whitens toward the horizon.