Page:A Treatise on Painting.djvu/339

 Those objects which are near a river, or a lake, in the distant part of a landscape, are less apparent and distinct than those that are remote from them.

Of bodies of equal density, those that are nearest to the eye will appear thinnest, and the most remote thickest.

A large eye-ball will see objects larger than a small one. The experiment may be made by looking at any of the celestial bodies, through a pin-hole, which being capable of admitting but a portion of its light, it seems to diminish and lose of its size in the same proportion as the pin-hole is smaller than the usual apparent size of the object.

A thick air interposed between the eye and any object, will render the outlines of such object undetermined and confused, and make it appear of a larger size than it is in reality; because the linear perspective does not diminish the angle which conveys the object to the eye. The aerial perspective carries it farther off, so that the one removes it from the eye, while the other preserves its magnitude.

When the sun is in the West the vapours of the earth fall down again and thicken the air, so that objects not enlightened by the sun remain dark and confused, but those which receive its light will be tinged yellow and red, according to the sun’s appearance on the horizon. Again, those that receive its light are very distinct, particularly public build- Rh