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if the ear be applied, various sounds and murmurs are heard under the earth.

An indirect phenomenon.

Acosta observes, that the towns of Plata and Potosi in Peru, lie not far asunder, and both of them situate in a rising or.mountainous ground; so as not to differ in this respect; and yet that Potosi has a cold and wintery temperature of air; but Plata a mild and vernal one: which appears imputable to the silver mines near Potosi. And this seems to shew, that there are vents of heat and cold in the earth.

If the earth be the primum frigidum, as Parmenides would have it, on a supposition that cold is close linked in with density; it is no less probable that warm exhalations should arise from the central cold of the earth; than that the like should be thrown down by the cold of the upper region.

There are certain pits in Dalmatia, and the country of Cyrene, into which, as some of the ancients relate, if a stone be thrown, a storm will soon after be raised; as if the stone had broke some covering in the place where winds are imprisoned.

An indirect phenomenon.

Etna, and many other mountains, cast up flames in like manner, it is probable, that air

may break out; especially when expanded, and put into motion by subterraneal heat.

Certain noxious and foreign winds are observed to blow, both before and after earthquakes; in the same manner as a certain light and rarified smoke rises before and after great conflagrations.


1. Air, pent up in the earth is compelled to break out, for several reasons, as, 1. because sometimes the earth hangs loose together, and falls into a hollow; 2. sometimes the waters make a breach or ingulph themselves under the earth; 3. sometimes the air is expanded by subterraneal fires, so as to endeavour at more room; and 4. sometimes the earth, which before was solid, is burnt hollow, and reduced to ashes by fire; and thus being unable to support itself, falls in; with many other causes of the like kind. And so much for the first local origin of winds; viz. from subterraneal causes. We come next to their second origin, or that from above; viz. the middle region of the air, as it is called,

2. Let it not be supposed we any way deny that the other winds may likewise proceed from vapours of the earth and sea; but what we have spoke to, is the first kind, which come out of the earth, as winds already formed.

Woods are observed to murmur, before any winds are manifestly perceived; whence it is conjectured that the wind descends from on high. This is also observed in mountains; though the cause be here more doubtful, by reason of their caverns.

Winds follow upon the shooting of the stars, as it is vulgarly called, and come from that quarter where the star shot: whence it appears, that the air is in commotion above, before we feel the effects of it below.

The opening of the firmament and the scattering of the clouds, foreshew winds, before they blow upon the earth: which, again, is a proof that winds begin above.

The smaller stars are not perceived before the wind rises, though the night be clear: whence the air seems to be condensed, and rendered less transparent, by the matter which is afterwards resolved into wind.

Halos about the body of the moon; the sun setting blood-red; the moon rising red, on the fourth day after the change; with many other prognostics of winds derived from above, shew the matter of them to be there begun and prepared.

From these phenomena we may observe the difference already mentioned, as to the two ways wherein winds are generated above; viz. before

and after the collection of vapours into clouds: for the prognostics from halos, and the colour of the sun and moon depend, in some measure, upon cloudiness; but the shooting and appearance of the lesser stars, are observed in a clear sky.

When wind issues from a formed cloud, either the cloud is totally dissipated, and converted into wind; or separated, part into 'rain, and part into wind; or rent asunder, when the wind bursts out as in a storm.

There are every where many indirect phænomena in nature with regard to the reflection by cold; and therefore as the cold is very intense in the middle region of the air, vapours cannot, generally, break through that region; but must either be coagulated, or darted out again; according to the opinion of the ancients, which, in this particular, is just.

There is a third local origin of winds, here in the lower air; which we call by the name of swells or overcharges of the air: the thing itself is familiar and obvious; but hitherto passed over in silence.


The generation of these winds in the lower air, proceeds after this plain manner. The air newly made of attenuated and rarified water and


vapour, being added to the former mass of the

air, the whole can now
no longer be con-
tained in the same bounds; but increases, and
rolls onwards, still possessing a greater space.
Though this depends upon two suppositions;
viz. 1. that a drop of water, converted into air,
requires at least a hundred times more space
than before; and 2. that a little new air in mo-
tion, being superadded to the old mass, disturbs
and puts the whole in motion; like a small blast
coming from a pair of bellows, or a crack in
the window; which give a motion to all the air
of a room, so as to disturb the flames of the

As dews and mists are generated, here in the lower air, without being formed into clouds, or reaching to the middle region; the case is the same with many winds.

A continual breeze arises from the sea and waters; and this breeze is nothing more than a faint wind, newly generated.

The rainbow, which seems the lowest of all the meteors, and generated near the earth, is resolved into winds as much as into rain, if not more, when it appears not entire, but shortened at the ends, or broken.

Some winds have been observed, in countries separated by the interposition of mountains, to blow familiar on one side of those mountains,

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