Page:The Works of John Locke - 1823 - vol 03.djvu/333

 mists call precipitation; to which it answers in all its parts.

The air may be looked on as a clear and pellucid menstruum, in which the insensible particles of dissolved matter float up and down, without being discerned, or troubling the pellucidity of the air; when on a sudden, as if it were by a precipitation, they gather into the very small but visible misty drops that make clouds.

This may be observed sometimes in a very clear sky; when, there not appearing any cloud, or any thing opake, in the whole horizon, one may see on a sudden clouds gather, and all the hemisphere overcast; which cannot be from the rising of the new aqueous vapours at that time, but from the precipitation of the moisture, that in invisible particles floated in the air, into very small but very visible drops, which by a like cause being united into greater drops, they become too heavy to be sustained in the air, and so fall down in rain.

Hail seems to be the drops of rain frozen in their falling.

Snow is the small particles of water frozen before they unite into drops.

The regular figures, which branch out in flakes of snow, seem to show that there are some particles of salt mixed with the water, which makes them unite in certain angles.

The rainbow is reckoned one of the most remarkable meteors, though really it be no meteor at all; but the reflection of the sunbeams from the smallest drops of a cloud or mist, which are placed in a certain angle made by the concurrence of two lines, one drawn from the sun, and the other from the eye to these little drops in the cloud, which reflect the sunbeams; so that two people, looking upon a rainbow at the same time, do not see exactly the same rainbow.