Chap. CCCII.—Why the Colour and Shape of Objects are lost in some Situations apparently dark, though not so in Reality.
There are some situations which, though light, appear dark, and in which objects are deprived both of form and colour. This is caused by the great light which pervades the intervening air; as is observable by looking in through a window at some distance from the eye, when nothing is seen but an uniform darkish shade; but if we enter the house, we shall find that room to be full of light, and soon distinguish every small object contained within that window. This difference of effect is produced by the great brightness of the air, which contracts considerably the pupil of the eye, and by so doing diminishes its power. But in dark places the pupil is enlarged, and acquires as much in strength, as it increases in size. This is proved in my second proposition of perspective[1].
- ↑ This book on perspective was never drawn up.