Meteorology   

water that is continuously flowing day by day, and consider the amount

of the water, it is obvious that a receptacle that is to contain all

the water that flows in the year would be larger than the earth, or,

at any rate, not much smaller.

Though it is evident that many reservoirs of this kind do exist in

many parts of the earth, yet it is unreasonable for any one to

refuse to admit that air becomes water in the earth for the same

reason as it does above it. If the cold causes the vaporous air to

condense into water above the earth we must suppose the cold in the

earth to produce this same effect, and recognize that there not only

exists in it and flows out of it actually formed water, but that water

is continually forming in it too.

Again, even in the case of the water that is not being formed from

day to day but exists as such, we must not suppose as some do that

rivers have their source in definite subterranean lakes. On the

contrary, just as above the earth small drops form and these join

others, till finally the water descends in a body as rain, so too we

must suppose that in the earth the water at first trickles together

little by little, and that the sources of the rivers drip, as it were,

out of the earth and then unite. This is proved by facts. When men

construct an aqueduct they collect the water in pipes and trenches, as

if the earth in the higher ground were sweating the water out.

Hence, too, the head-waters of rivers are found to flow from

mountains, and from the greatest mountains there flow the most

numerous and greatest rivers. Again, most springs are in the

neighbourhood of mountains and of high ground, whereas if we except

rivers, water rarely appears in the plains. For mountains and high

ground, suspended over the country like a saturated sponge, make the

water ooze out and trickle together in minute quantities but in many

places. They receive a great deal of water falling as rain (for it

makes no difference whether a spongy receptacle is concave and

turned up or convex and turned down: in either case it will contain