ON THE ORIGIN AND CAUSES OF SUBTERRANEAN THINGS, BOOK I

...nature hot and moist. But as soon as cold has overcome the heat, it necessarily passes into water or into some one thing that is joined to it by natural kinship. This can be observed in the upper air. For when it is refrigerated, that threefold offspring of moisture arises. For if it cools moderately, water is generated; if intensely, snow; but if the cold, having been enclosed within by exterior heat, has condensed the water it made before it flowed down from the air, hail arises. Nevertheless, when the air is most strongly refrigerated and dried, none of these are generated; because, being too cold and dry, it does not generate rains, snows, or hails, no differently than when it is very hot and dry. However, the cold that resides in the hideouts of the earth begets waters more than it begets either snows or hails. Indeed, it generates small drops from vapors, several of which gathered together make large ones; then, collected from each, they begin to flow.

Deeper wells and tunnels are proof of this, for in one part they are only damp, in another they drip water, and in another, the force of water makes an eruption. For the joints of rocks discharge themselves into the nearest veins or veinlets; veinlets into veins; narrow veins into wider ones; and these same ones into wells or tunnels. But if all of them are blocked, the wells and tunnels are dry; and as long as the air that is within them has not been refrigerated, they are not in the least moistened by water. But waters of their own accord and nature erupt from the veins into the air and open springs, from which streams are led away; and from these small beginnings, rivers having set out arrive at an immense size, especially when many streams and rivers have flowed into them.

But enough of these. Now let us see about the water that flows from the sea or from rivers. Because it is necessary for the earth to be moistened and heated by liquid before vapors are generated—and very hot regions lack rains for the whole year, except for a few months—it follows that water flows from elsewhere, from which perennial vapors arise, which, converted into water, erupt from the mountains. But inhabitants of regions where rains are rarely gathered know that the sea diffuses water through veins and veinlets into the interior of the earth. For if, because of the lack and need for water, they dig a well in maritime places, they draw from it perennial water, but salt; if in places remote from the sea, they draw water that is somehow sweet, because it has already shed its salt. The sea, moreover, diffuses water through channels as widely as reason and the nature of the orb of the earth, or rather the globe, allows it to be diffused; of which there is a certain limit of latitude, beyond which it cannot progress. For it would not diffuse if it crossed that limit, but would ascend, which cannot happen. Similarly, rivers, flooding their banks, pour water from themselves so widely through veins and veinlets that they often fill the subterranean cellars of a town situated in level and flat places. For water, by its own nature and weight, seeks the bottom more easily; but if it cannot direct its path there because of its own multitude or the difficulty of the place, it slips to some other part. Therefore, from all these...