e
whirlwinds, the duller the tempests.

CHAPTER IV. OF CLOUDS, RAIN, SNOW, AND HAIL.

Anaximenes thinks that the air by being very much condensed clouds are
formed; this air being more compacted, rain is compressed through it;
when water in its falling down freezeth, then snow is generated; when it
is encompassed with a moist air, it is hail. Metrodorus, that a cloud is
composed of a watery exhalation carried into a higher place. Epicurus,
that they are made of vapors; and that hail and snow are formed in
a round figure, being in their long descent pressed upon by the
circumambient air.

CHAPTER V. OF THE RAINBOW.

Those things which affect the air in the superior places of it are of
two sorts. Some have a real subsistence, such are rain and hail; others
not. Those which enjoy not a proper subsistence are only in appearance;
of this sort is the rainbow. Thus the continent to us that sail seems to
be in motion.

Plato says, that men admiring it feigned that it took origination from
one Thaumas, which word signifies admiration. Homer sings:--

Jove paints the rainbow with a purple dye,
Alluring man to cast his wandering eye.
(Iliad, xvii. 547.)

Others therefore fabled that the bow hath a head like a bull, by which
it swallows up rivers.

But what is the cause of the rainbow? It is evident that what apparent
things we see come to our eyes in right or in crooked lines, or by
refraction: these are incorporeal and to sense obscure, but to reason
they are obvious. Those which are seen in right lines are those which we
see through the air or horn or transparent stones, for all the parts
of these things are very fine and tenuous; but those which appear in
crooked lines are in water, the thickness of the water presenting
them bended to our sight. This is the reason that oars in themselves
straight, when put into the sea, appear to us crooked. The third manner
of our seeing is by refraction, and this is perspicuous in mirrors.
After this third sort the rainbow is affected. We conceive it is a moist
exhalation converted into a cloud, and in a short space it is dissolved
into small and moist drops. The sun declining towards the west, it will
necessarily follow that the whole bow is seen opposite to the sun; for
the eye being directed to those drops receives a refraction, and by this
means the bow is formed. The eye doth not consider the figure and form,
but the color of these drops; the first of whic