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SECT. XI.

OF THE LIMITATIONS OF THE WINDS; IN PURSUANCE OF THE ELEVENTH ARTICLE OF THE TABLE OF

ENQUIRY.

IT is related of Mount Athos, and Mount Olympus, that the priests who yearly sacrificed upon their tops, used to find the writing they had drawn in the ashes of the sacrifice one year, no way disordered or obliterated, when they returned the next; although these altars did not stand in a temple, but in the open air, whence it is manifest, that at such a height there fell no showers, and blew no winds*.

They relate, that on the Peak of Teneriffe; as also upon the Andes, betwixt Peru and Chili ; there lies snow along the cliffs and sides of the mountains; whilst upon the tops thereof the air is quiet; but so subtile as hardly to suffice for respiration; and so acrimonious and pungent as to inflame the eyes and give a nausea to the stomach.

Vaporous winds seem not to blow at any great height; though it is still probable that some of

+ See hereafter, Sect. xiv.

them ascend higher than most clouds†. And so much for the height; next for the breadth of winds.

It is certain, that the spaces possessed by winds are very various; being sometimes extremely wide, and sometimes small and narrow. They have been found to range a hundred miles in a few hours.

Diffusive winds, if free, are generally vehement, and durable; commonly continuing twenty-four hours; but not rainy. On the contrary, narrow, or confined winds, are either gentle or stormy; but always short-lived.

Stated winds are itinerant; and travel over vast spaces.

Stormy winds run not out far; though always beyond the limits of the storm itself.

Sea-winds blow within much narrower bounds than land-winds; insomuch, that at sea they sometimes observe a brisk gale driving the waters on one side; as appears by the ruffling and curling thereof; whilst every where else there is a calm; and the sea remains as flat as a looking-glass.

We before observed, that little sportful whirlwinds sometimes play with the dust upon the road, like the blast of a pair of bellows. And so

*Which is seldom high; or much above half, or a quarter of a mile, as has been often measured.

much for the extent of the winds: next or their duration.

Very strong winds at sea continue for a long while; as there receiving a large supply of vapour but at land, they scarce continue above a day and a half.

Very gentle winds continue not to blow constantly, for above three days, either at sea or land.

The east wind, we before observed, is more lasting than the west; and whatever wind begins to blow in the morning, usually continues longer than that which rises in the evening.

It is certain, that winds rise and increase by degrees, unless when they are perfectly stormy; but fall quicker, and sometimes all at once.

SECT. XII.

OF THE SUCCESSIONS OF THE WINDS; WITH REGARD TO THE TWELFTH ARTICLE OF THE TABLE OF ENQUIRY.

WHEN the wind changes conformably to the motion of the sun; that is, from east to south; from south to west; from west to north; and from north to east; it seldom goes back; or if it does, it is only for a short time: but if it moves in a contrary direction; viz. from east to north; from north to west; from west to south; and

from south to east; it generally returns to the former point, at least before it has gone through the whole circle.

If rain comes first, and the wind begins to blow upon it, the wind continues longer than the rain; but if the wind blow first, and is afterwards laid by the rain, the wind seldom returns; or if it does, it also rains afresh.

When winds continue to vary for a few hours, as if it were to try in which point they should settle, and afterwards begin to blow constant; they continue for many days.

If the south wind begins to blow for two or three days, the north wind will sometimes blow suddenly after it: but if the north wind blows for the same number of days; the south wind will not rise till after the east has blown a while.

When the year is upon the decline, and winter coming on; if the south wind blow at the begin ning of the winter, and afterwards the north; the winter will prove frosty: but if the north wind blow at the beginning of the winter, and afterwards the south; the winter will be mild and warm.

Pliny relates from Eudoxus, that winds return. in the same series every four years : which seems no way true; for the revolutions of the winds But the diligence of some has

are not so quick.

reached so far as to observe, that the greater and more remarkable changes, such as heats, snows, frosts, warm winters, and cold summers, generally return in a circle of thirty years.

SECT. XIII.

OF THE MOTIONS OF THE WINDS; IN PURSUANCE OF THE THIRTEENTH ARTICLE OF THE TABLE OF

ENQUIRY.

I.

TRANSITION.

MEN express themselves as if the wind were a certain body, that, of itself, impelled, and drove the air before it, by its own force; and when it changes, they speak as if the wind had removed itself to another place: and, whilst the populace talk in this manner, philosophers do not correct such notions; but, instead of stopping the error, give somewhat into the same themselves.

Having, therefore, already enquired into the local origins of winds; we are next to enquire into the excitation and direction of their motion. And for the winds which have their motion begun in their first impulse; as those have which are thrown down from above, or breathe out of the earth; the excitation of their motion is manifest: but others descend, and some ascend in their beginning; and afterwards acquire a rolling