But the perpetual Commotions it receives from the Gales, and Storms, keep it pure and healthful (2). Neither are thofe Ventilations beneficial only to the Health, but to the Pleasure alfo of the Inhabi tants of the Terraqueous Globe witness the Gales which fan us in the Heat of Summer, without which, even in this our temperate Zone, Men are fcarce able to perform the Labours of their Calling,

Kor

that the Morning was Warm, and what Wind ftirred was WeftSouth-west, but the Clouds were Thick and Black (as generally they are when Snow enfues): A little before Noon the Wind vered about to North by Weft, and fometimes to other Points, the Cloud at the fame time flying fome North by Weft, fome SouthWeft: About One of the Clock it rained apace, the Clouds flying fometimes North-Eaft, then North, and at laft both Wind and Clouds fettled North by Weft: At which time Sleet fell plentifully, and it grew very Cold. From all which I obferve, i. That although our Region below was warm, the Region of the Clouds was Cold, as the black fnowy Clouds fhewed. 2. That the struggle between the warmth of ours, and the cold of the cloudy Region, ftopped the airy currents of both Regions. 3. That the falling of the Snow through our warmer Air melted into Rain at first but that it became Sleet after the fuperiour Cold had conquered the inferiour Warmth. 4. That, as that Cold prevailed by Degrees, fo by Degrees it wheeled about both the Winds and Clouds from the Northwards towards the South.

"Hippocrates, 1. 2. De Fict. orat. omnes Ventos vel à nive, glacie, vehementi gelu, fluminibus, &c. fpirare neceffe judicat. Bartholin. de ufu Nivis, c. I.

(2) It is well obferved in my Lord Howard's Voyage to Conftantinople, that at Vienna they have frequent Winds, which if they cease long in Summer, the Plague often enfues: So that it is now grown into a Proverb, that if Austria be not windy, it is fubject to Conta gion. Bohun of Wind, p. 213.

From fome fuch Commotions of the Air, I imagine it is, that at Grand Cairo the Plague immediately ceafes, as foon as the Nile begins to overflow; although Mr. Boyl attributes it to nitrous Corpufcles. Determ. Nat. of Efflur. Chap. 4.

Nulla enim propemodum regio eft, qua non habeat aliquem flatum ex fe nafcentem, & circa fe cadentem

Inter cætera itaq; Providentia opera,hoc quoq; aliquis,ut dignum admiratione fufpexerit. Non enim ex unâ causâ Ventos aut invenit, aut per diverfa difpofuit: fed primum ut aera non finerent pigrefcere, fed affidua vexatione utilem redderent, vitalemq; tracturis. Sen. Nat. Quæft. 1. 5. c. 17, 18.

or not without Danger of Health and Life (3). But efpecially, witness the perpetual Gales which throughout the whole Year do fan the Torrid Zone, and make that Climate an healthful and ati ( QU plea

All this is more evident, from the Caufe affigned to malignant epidemical Difeafes, particularly the Plague, by my ingenious learned Friend, Dr. Mead, and that is, an hot and moift Tem perament of the Air, which is obferved by Hippocrates, Galen, and the general Hiftories of epidemical Diseases, to attend thofe Diftempers. Vid. Mead of Poifons, Essay 5. p. 161. But indeed, whether the Caufe be this, or poisonous, malignant Exhalations, as others think, the Winds are however very falutiferous in fuch Cafes, in cooling the Air, and difperfing and driving away the moift or peftiferous Vapours.

(3) July 8. 1707, (called for fome time after the Hot-Tuesday,) was fo exceffively hot and fuffocating, by reason there was no Wind firring, that divers Perfons died, or were in great Danger of Death, in their Harvest-work. Particularly one who had formerly been my Servant, a healthy, lufty, young Man, was killed by the Heat And feveral Horfes on the Road dropped down and died the fame Day.

In the foregoing Notes, having taken Notice of fome things relating to Heat, although it be fomewhat out of the way, I hope the Reader will excufe me, if I entertain him with some Obfervations I made about the Heat of the Air under the Line, compared with the Heat of our Bodies. 7. Patrick, who, as he is very accurate in making Barometrical and Thermometrical Inftruments, had the Curiofity for the nicer adjusting his Thermometers, to fend Two abroad under the Care of Two very sensible ingenious Men, one to the Northern Lat. of 81; the other to The Parts under the Equinoctial! In thefe two different Climates, the Places were marked where the Spirits flood at the fevereft Cold and greatet Heat. And according to thefe Obfervations he graduates his Thermometers. With his Standard I compared my Standard Thermometer, from all the Degrees of Cold, I could make with Sal Armoniack, &c. to the greatest Degrees of Heat, our Thermometers would reach to. And with the fame Thermometer (of mine) I experimented the greatest Heat of my Body, in July 1709. First in an hot Day without Exercise, by putting the Ball of my Thermometer under my Armpits, and other hotteft Parts of my Body. By which means the Spirits were raised 284 Tenths of an Inch above the Ball. After that, in a much hotter

C

Day,

pleasant Habitation, which would otherwife be fcarce habitable.

To thefe I might add many other great Conveniencies of the Winds in various Engines, and various Bufineffes. I might particularly infift upon its great Use to tranfport Men. to the fartheft diftant Regions of the World (†) and I might particularly fpeak of the general and coafting, Trade-Winds, the Sea, and the Land-Breezes; (4) the one ferving to carry the Mariner in long Voyages from Eaft to Weft, the other ferving to waft him to particular on Places;

231

Day, and indeed nearly as hot as any Day with us, and after I had heated my felf with ftrong Exercife too, as much as I could well bear, I again tried the fame Experiment, but could not get the Spirits above 288 Tenths; which I thought an inconfiderable Difference, for fo feemingly a very different Heat of my Body. But from fome Experiments I have made (altho' I have unfortunately forgotten it) in very cold Weather, I imagine the Heat of an healthy Body to be always much the fame in the warmest Parts thereof, both in Summer and Winter. Now between those very Degrees of 284 and 288, the Point of the equatorial Heat falleth. From which Obfervation it appears, that there is pretty nearly an equal Contemperament of the Warmth of our Bodies, to that of the hottest Part of the Atmosphere inhabited by us...

3

If the Proportion of the Degrees of Heat be defired from the Freezing-point, to the Winter, Spring, and Summer Air, the Heat of Man's Body, of heated Water, melted Metals, and fo to actual Fire; an Account may be met with of it, by my moft ingenious Friend, the great Sir Ifaac Newton, in Phil Tranfalt. No. 270,

(†) In hoc Providentia, ar Difpofitor ille Mundi Deus, aera vextis exercendum dedit,- non ut nos claffes partem freti occupaturas compleremus milite armato, &c. Dedit ille ventos ad cuftodiendam cœli terrarumq; temperiem, ad evocandas fupprimendafq; aguas, ad alendos fatorum atq; arborum fructus; quos ad maturitatem cum aliis caufis adducit ipfa jaltatio, attrahens cibum in fumma, & ne torpeat, promovens. Dedit ventos ad ulteriora nofcenda fuiffet enim imperitum animal, & fine magnâ experientia rerum Homo, fi circumfcriberetur natalis foli fine. Dedit ventos ut commoda cujufq; regionis fierent communia non ut legiones equitemq; geftarent, nec ut perniciofa gentibus armatranfveherent. Seneca, ibid. O

(4) Sea-Breezes commonly rife in the Morning about Nine a Clock. They first approach the Shore gently, as if they were afraid to

come

Places; the one ferving to carry him into his Harbour, the other to bring him out. But I fhould go too far to take notice of aftParticulars (5). Leaving therefore the Winds, I proceed in the next Place to the Clouds and Rain holda 40

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come near it. It comes in a fine, small, black Curle upon the Water, whereas all the Sea between it, and the Shore (not yet reached by it) is as smooth and even as Glafs in Comparison. In half an Hours time after it has reached the Shore, it fans pretty briskly, and Jo entreafeth gradually till Twelve a Clock; then it is commonly ftrongeft, and lafts fo till Two or Three, a very brisk Gale.-After Three it begins to die away again, and gradually withdraws its force till all is spent and about five a Clock it is lulled afleep, and comes no more till next Morning 1 gr (2

And as the, Sea, Breezes do blow in the Day, and ref in the Night; So on the contrary [The Land Breezes] blow in the Night, and rest in the Day, alternately fucceeding each other. They spring up be tween six and Twelve at Night, and last till Six, Light, or Ten in the Morning Dampier's Difc. of Winds, ch. 4.

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(5) One thing more I believe fome of my Friends will expect from me is, that I fhew the Refult of comparing my own Obfervations of the Winds, with others they know I have from Ireland, Switzerland, Italy, France, and fome of our Parts of England. But the Obfervations being fome of them but of one Year, and most of the rest of but a few Years, I have not been able to determine any great Matters. The chief of what I have obferved is, that the Winds in all thefe places feldom agree, but when they moft certainly do fo, it is commonly when the Winds are ftrong, and of long continuance in the fame Quarter: And more I think in the Northerly and Eafterly, than other Points, Also a strong Wind in one Place, is oftentimes a weak one in another Place, or moderate, according as Places have been nearer, or farther, diftant. Vid. Phil. Tranf No. 297, & 321. But to give a good and tole. rable Account of this or any other of the Weather, it is neceffary to have good Hiftories thereof from all Parts; which, as yet we have but few of, and they imperfect, for want of longer and fufficient Obfervations.

CHA P. III.

Of the Clouds and Rain.

TH HE Clouds and Rain (1) we shall find to be no less useful Meteors than the last mentioned; as is manifeft in the refreshing pleasant Shades which the Clouds afford, and the fertile Dews and Showers which they pour down on the Trees and Plants,

(1) Clouds and Rain are made of Vapours raised from Water, or Moisture only. So that I utterly exclude the Notion of Dry, Terrene Exhalations, or Fumes, talked much of by moft Philofophers; Fumes being really no other than the humid Parts of Bodies refpectively Dry.

Thefe Vapours are demonftratively no other than small Bubbles, or Veficulæ detatched from the Waters by the Power of the Solar, or Subterraneous Heat, or both. Of which fee Book 2. Chap. 5. Note 2. And being lighter than the Atmosphere, are buoyed up thereby, until they become of an equal Weight therewith, in fome of its Regions aloft in the Air, or nearer the Earth; in which thofe Vapours are formed into Clouds, Rain, Snow, Hail, Light ning, Dew, Mifts, and other Meteors.

In this Formation of Meteors the grand Agent is Cold, which commonly, if not always, occupies the fuperior Regions of the Air; as is manifeft from thofe Mountains which exalt their lofty Tops into the upper and middle Regions, and are always covered with Snow and Ice.

This Cold, if it approaches near the Earth, prefently precipitates the Vapours, either in Dews; or if the Vapours more copioufly ascend, and foon meet the Cold, they are then condensed into Mifling, or elfe into Showers of small Rain, falling in numerous, thick, finall Drops: But if thofe Vapours are not only copious, but alfo as heavy as our lower Air it self, (by means their Blad ders are thick and fuller of Water,) in this Cafe they become visible, swim but a little Height above the Earth, and make what we call a Mift or Fog. But if they are a Degree lighter, fo as to mount higher, but not any great Height, as alfo meet not with Cold enough to condenfe them, nor Wind to diffipate them, they then form an heavy, thick, dark Sky, lafting oftentimes for several Weeks without either Sun or Rain. And in this Cafe, I have

fcarce