Part 5

IN some Parts of the World, and especially between the Tropicks, the Winds are regular, and therefore our Philosophers seem to talk more rationally about them. But in our Northern Countries the Alterations of the Wind are so frequent, sudden, and often so little agreeable to the Season, that such general Reasonings will by no Means serve to explain them. It is however very reasonable to suppose that the same general Cause prevails here as between the Tropics, but with less Certainty, because the Power of the Sun is not so great, and the Determinations of the Winds depend on the Situation of Mountains, Rocks, and Woods, which direct the Air driving against them into certain Courses, so that it is impossible to explain, or indeed to judge of the Course of the Winds till the Country is thoroughly known, and all those Eminences that can affect the Winds are well considered.

FROM these Reflections the Value of our Shepherd's Observations will clearly appear. He was not Philosopher enough to talk in this Style, but by a long and steady Attention he came to know, experimentally, what perhaps few Philosophers, with all their Sagacity, would have been able to have found out.

XV.

S. W. WINDS. After a northerly Wind for the most Part two months or more, and then coming South, there are usually three or four fair Days at first, and then, on the fourth or fifth Day, comes Rain, or else the Wind turns North again, and continues dry.

THIS is likewise a very judicious and very useful Observation, and yet it is not a difficult matter to account for it. It is a common Observation, and a very true one, that there is usually fair Weather before a settled course of Rain. The Winds that bring the dark rainy Clouds that obscure the Sky, and cause dull cloudy Weather, often raise these Vapours to such a height, that they are attracted into the cold Region above our Sight, till being condensed there, they fall down upon us again in Snow or Rain, according to our Author's Observation.

BUT if, after a seeming Tendency to Rain, there follow several Days of fine Weather, it is a certain Indication that the Temper of the Air is altered, and that these Vapours had been driven off before they had time to condense, which is confirmed by the Change of the Wind on such Occasions.

ALL these Observations are to be understood in a proper Latitude, and not strictly and according to the very Letter. For Rain may fall the sixth or seventh Day, or the Wind may change the second or third. Besides, a Man who would make use of these Observations in the Country, must consider attentively the Situation of the Place where he lives, the bearing of the Sea, Marshes, Ponds, Lakes, Woods, Mountains, Rocks, &c. For without making proper Allowances for these, all such Observations on the Weather will be apt to fail him.

XVI.

If it return to the South within a Day or two without Rain, and turn Northward with Rain, and return to the South, in one or two Days, as before, two or three Times together after this Sort, then it is like to be in the South, or South West, two or three Months together, as it was in the North before.

The Winds will finish these Turns in a Fortnight.

THIS may appear a little perplexed to an ordinary Reader, but a little Attention will make it very clear and plain; and whoever considers what mighty Uses may be made of the Foresight of Weather for a Month or two, will not think this Labour ill bestowed. I must confess I look upon these three Rules in Relation to the Wind as the most useful in the whole Collection. Especially to Farmers and Country People, to whom they are of the greatest Consequence.

BUT it is a common Thing for such People to say, what Certainty is there that these Rules will prove true, what Probability is there that the Wind should continue so long in one Quarter, and then so long in another, how shall we be satisfied that there is any truth in this; or, if we cannot be satisfied as to the Truth of it, why should we depend upon any such like Observations?

TO this I answer, that they may have reasonable Satisfaction given them on this Head. Some of our great Naturalists, who had kept Journals of the Weather for many Years, have found that the same Wind blows every Year very near the same number of Days, and that there is a regular Continuance of different Winds annually in every Country. For Instance,

At Utrecht they blow thus,

The N. Wind 42 Days. The N. W. 33 The W. 77 The S. W. 58 The South 33 The S. E. 26 The E. 53 The N. E. 43 --- 365

IT is a Thing plain to every Capacity, that a Journal or Diary of the Winds may be kept any where, and if from such a Journal it appears that a given Wind blows for a certain Number of Days, then it follows, that if these can be determined with Certainty, the Time of their blowing may also be determined, at least with great Probability, which is as satisfactory an Answer as can be justly expected, because it shews that there is just and rational Ground for confiding in such Observations, when confirmed by long Experience.

XVII.

Fair Weather for a Week, with a Southern Wind, is like to produce a great Drought, if there has been much Rain out of the South before. The Wind usually turns from North to South, with a quiet Wind without Rain, but returns to the North, with a strong Wind and Rain; the strongest Winds are when it turns from South, to North by West.

N. B. When the North Wind first clears the Air (which is usually once a Week) be sure of a fair Day or two.

OBSERVATIONS of this Nature upon Winds have employed the ablest Heads in all Ages. Pliny the great Naturalist has left us a great deal upon this Subject, which plainly proves that it has been the Opinion of the ablest and wisest Men that Study and Experience might reduce even Things of such seeming Incertainty under stated Rules, and within the Bounds of a regular System. For Instance he tells us.

"IN Africa the South Wind is serene, the North East cloudy. All the Winds have their Turns. To judge rationally of their Changes, the fourth Day of the Moon is to be regarded.--The South Wind blows stronger than the North East, because the former rises from the Bottom, whereas the latter comes from the Surface of the Sea. It is for this Reason that those Earthquakes are most dangerous that follow after a South Wind."

IN order to understand this Notion of Pliny, we need only advert to the Account given us by the Reverend Mr. Robinson, in his natural History of Westmoreland, which is exceedingly curious, and well worthy of the Reader's perusal. This ingenious Gentleman is of Opinion that Winds have their original from the Sea, of which he gives the following very probable Account.

"IT, that is, the Wind, proceeds from vast swarms of nitrous Particles arising from the Bottom of the Sea, which being put into Motion, either by the central Fire, or by the Heat and Fermentation which abound in this great Body of the Earth; and therefore the first Commotion excited by the said Fermentation, we call a Bottom Wind, which is presently discovered by Porpusses and other Sea Fish, which delight in sporting and playing upon the Waves of the Sea, and by their playing give the Mariners the first Notice of an approaching Storm.

"WHEN these nitrous swarms are risen towards the Surface of the Sea in a dark Night, they cause such a shining light upon the Waves, as if the Sea was on fire. And being delivered from the brackish Water, and received into the open Air, those fiery and shining Meteors which fix upon the Masts and Sides of the Ships, and are only nitrous particles condensed by the circumambient Cold, and like that which the Chymists call Phosphorus, or artificial Glow-worm, shine and cast a Light but have no Heat: This gives the Mariners the second Notice that the Storm is rising, for upon the first breaking out of the Wind, the Sea begins to be rough, and the Waves swell and rise, when at the same time the Air is calm and clear.

"THIS boiling Fermentation of the Sea causes the Vapours to rise, which by the Intenseness of the circumambient Cold are condensed into thick Clouds, and fall down in Storms of Wind and Rain, first upon the Sea, from whence they rose, and then the attractive Power of the Mountain-cold, by a secret Magnetism between Vapour and Cold, attracts the waterish Vapours, intermixt with nitrous Particles, to the high Tops of Mountains and Hills, where they hang hovering in thick Fogs and waterish Mists, until the atmospherical Heat rarefies the nitrous Part of the Fog (which is always uppermost, and appears white and translucent) into brisk Gales of Wind, and the Intenseness of atmospherical Cold having attracted the Vapours into the colder Regions of the Air, where being condensed into Clouds, the Wind breaks, dissipates, and drives them before it, till they fall down in Rain, and water the Surface of the Earth. And this seems to be the Reason why, in Egypt, and those level Countries where they have no Mountains, they have little Wind and less Rain."

XVIII.

CLOUDS. In Summer or Harvest, when the Wind has been South two or three Days, and it grows very hot, and you see Clouds rise with great white Tops like Towers, as if one were upon the Top of another, and joined together with black on the nether Side, there will be Thunder and Rain suddenly.

WE may very easily account for this Observation, because in Fact the Signs here mentioned are no other than Nature's apparatus for a Storm of Thunder and Lightning, which will be perfectly understood by attending a little to the Causes of these Meteors. Lightning is a great flame, very bright, extending every way to a great distance, suddenly darting upwards, there ending, so that it is only momentaneous. The Matter which produces the Fire, is the Oil of Plants, attenuated by the heat of the Day, and raised on high. Then whatever has exhaled from the Earth that is sulphureous or Oily, which is dispersed up and down in the Atmosphere, and is not continuous, is set on Fire by Turns, and the Flame dilates itself as far as the Tract of that Exhalation reaches. Some other Substance pendant and floating in the Air meets with this also, with which it excites an effervescence, takes Fire and flashes along with it. Thunder is another bright Flame, rising on a sudden, moving with great Velocity through the Air, according to any Determination upwards from the Earth horizontally, obliquely, downwards in a right Line, or in several right Lines as it were in serpentine Tracts joined at various Angles, and commonly ending with a loud Noise or Rattling.