may be seen from the original text of section* 294.
The question as to the composition of the atmosphere, which is inseparable from a discussion on Aerial Perspective, forms a separate theory which is treated at considerable length. Indeed the author enters into it so fully that we cannot escape the conviction that he must have dwelt with particular pleasure on this part of his subject, and that he attached great importance to giving it a character of general applicability.
General rules (289—291).
289.
The variety of colour in objects cannot be discerned at a great distance, excepting in those parts which are directly lighted up by the solar rays.
290.
As to the colours of objects: at long distances no difference is perceptible in the parts in shadow.
291.
OF THE VISIBILITY OF COLOURS.
Which colour strikes most? An object at a distance is most conspicuous,