Message #168432

[Bathos]

Most salt rivers and springs must once have been hot. Then the original
fire in them was extinguished but the earth through which they percolate
preserves the character of lye or ashes. Springs and rivers with all
kinds of flavours are found in many places. These flavours must in
every case be due to the fire that is or was in them, for if you expose
earth to different degrees of heat it assumes various kinds and shades
of flavour. It becomes full of alum and lye and other things of the
kind, and the fresh water percolates through these and changes its
character. Sometimes it becomes acid as in Sicania, a part of Sicily.
There they get a salt and acid water which they use as vinegar to
season some of their dishes. In the neighbourhood of Lyncus, too,
there is a spring of acid water, and in Scythia a bitter spring. The
water from this makes the whole of the river into which it flows bitter.
These differences are explained by a knowledge of the particular mixtures
that determine different savours. But these have been explained in
another treatise.

We have now given an account of waters and the sea, why they persist,
how they change, what their nature is, and have explained most of
their natural operations and affections.

Part 4

Let us proceed to the theory of winds. Its basis is a distinction
we have already made. We recognize two kinds of evaporation, one moist,
the other dry. The former is called vapour: for the other there is
no general name but we must call it a sort of smoke, applying to the
whole of it a word that is proper to one of its forms. The moist cannot
exist without the dry nor the dry without the moist: whenever we speak
of either we mean that it predominates. Now when the sun in its circular
course approaches, it draws up by its heat the moist evaporation:
when it recedes the cold makes the vapour that had been raised condense
back into water which falls and is distributed through the earth.
(This explains why there is more rain in winter and more by night
than by day: though the fact is not recognized because rain by night
is more apt to escape observation than by day.) But there is a great
quantity of fire and heat in the earth, and the sun not only draws
up the moisture that lies on the surface of it, but warms and dries
the earth itself. Consequently, since there are two kinds of evaporation,
as we have said, one like vapour, the other like smoke, both of them
are necessarily generated. That in which moisture predominates is
the source of rain, as we explained before, while the dry evaporation
is the source and substance of all winds. That things must necessarily
take this course is clear from the resulting phenomena themselves,
for the evaporation that is to produce them must necessarily differ;
and the sun and the warmth in the earth not only can but must produce
these evaporations.