or not without Danger of Health and Life (c). But efpecially, witness the perpetual Gales which through

the Winds are however very falutiferous in fuch Cafes, in cool. ing the Air, and difperfing and driving away the moift or pettiferous Vapours.

(c) July 8, 1707, (called for fome time after the Hot Tues day,) was fo exceffively hot and fuffocating, by reafon there was no Wind ftirring, that divers Perfons died, or were in great Danger of Death, in their Harveft-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 fome Obfervations I made about the Heat of the Air under the Line, compared with the Heat of our Bodies. J. 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 fenfible ingenious Men) one to the Northern Latitude of 81; the other to the Parts under the Equinoctial: In these two different Climates, the Places were marked where the Spirits stood at the feverest Cold and greatest 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 Degree 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 Day, and indeed nearly as hot as any Day with us, and after I had heated myself 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 (although I have unfortunately forgotten them) 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 Obfer. vation it appears, that there is pretty nearly an equal Contem

throughout the whole Year do fan the Torrid Zone, and make that Climate an healthful and pleasant Habitation, which would otherwise be scarce 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; (d) and I might particularly speak of the general and coafting Trade- Winds, the Sea, and the Land-Breezes; (e) the one ferving

to

perament of the Warmth of our Bodies, to that of the hottest Part of the Atmosphere inhabited by us.

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 most ingenious Friend, the great Sir Isaac Newton, in Philof. Tranfac. No.270.

(d) In hoc Providentia ac Difpofitor ille Mundi Deus, aera ventis exercendum dedit, -non ut nos claffes partem freti occupaturas compleremus milite armato, &c. Dedit ille ventos ad cuftodiendam cœli terrarumque temperiem, ad evocandas fupprimendafque aquas, ad alendos fatorum atque arborum fructus; quos ad maturitatem cum aliis caufis adducit ipfa ja&atio, attrahens cibum in Jumma, & ne torpeat, promovens. Dedit ventos ad ulteriora nofcenda: fuiffet enim imperitum animal, fine magnâ experientia rerum Homo, fi circumfcriberetur natalis joli fine. Dedit ventos ut commoda cujufque regionis fierent communia; non ut legiones equitemque geftarent, nec ut perniciofa gentibus arma tranfveberent. Seneca, ibid.

(e) Sea Breezes commonly rife in the Morning about Nine o' Glock. They first approach the Shore gently, as if they were afraid to come near it. It comes in a fine, fmall, 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 Glass in Comparifon. In half an Hour's time after it has reached the Shore, it fans pretty briskly, and fo increaseth gradually till Twelve o' Clock; then it is commonly the ftrongest, and lafts fo till Two or Three, a very brifk Gale. After Three it begins to die away again, and gradually withdraws its Force till all is spent ; and about Five & Clock—it is lulled afleep, and comes no more till next Morning.

And

to carry the Mariner in long Voyages from Eaft to Weft; the other ferving to waft him to particular 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 all Particulars (f). Leav ing therefore the Winds, I proceed, in the next Place, to the Clouds and Rain.

And as the Sea-Breezes do blow in the Day, and rest in the Night; fo on the contrary [the Land-Breezes] blow in the Night, and reft in the Day, alternately fucceeding each other.They Spring up between Six and Twelve at Night, and laft till Six, Eighty or Ten in the Morning. Dampier's Difc. of Winds, chap. 4.

(f) 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, New-England, and some of our Parts of England. But the Obfervations being, some 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 these Places feldom agree; but when they most 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. Alfo, a ftrong Wind in one Place, is oftentimes a weak one in another Place, or moderate, according as Places have been nearer or farther diftant. Vide Phil. Tranfact. No 297, and 321. But to give a good and tolerable 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.

TH

CHA P. III.

Of the Clouds and Rain.

HE Clouds and Rain (a) we fhall find to be no less useful Meteors than the laft mentioned; as is manifeft in the refreshing pleafant Shades which the Clouds afford, and the fertile Dews and

Showers

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

Thefe Vapours are demonflratively no other than fmall Bubbles, or Veficula, detached from the Waters by the Power of the Solar, or Subterraneous Heat, or both. Of which fee Book ii. Chap. 5, Note (b). 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, Lightning, 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 manifest from those 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 copiously afcend, and foon meet the Cold, they are then condenfed into Mifling, or elfe into Showers of Small Rain, falling in numerous, thick, fmall Drops: But if thofe Vapours are not only copious, but alfo as heavy as our lower Air itself (by means their Bladders are thick and fuller of Water), in this cafe they become vifible, fwim 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,

H

Showers which they pour down on the Trees and Plants, which would languifh and die with perpetual

Height, as alfo meet not with Cold enough to condense them, nor Wind to diffipate them, they then form an heavy, thick, dark Sky, lafting oftentimes for feveral Weeks without either Sun or Rain. And in this Cafe I have scarce ever known it to Rain, till it hath been firft Fair, and then Foul. And Mr. Clarke (an ingenious Clergyman of Norfolk), who in his Life-time, long before me, took notice of it, and kept a Register of the Weather for thirty Years, which his learned Grandfon, Dr. Samuel Clarke, put into my Hands, he (I fay) faith, he scarce ever obferved the Rule to fail in all that Time; only he adds, If the Winds be in fome of the Eafterly Points. But I have obferved the fame to happen, be the Wind where it will. And from what hath been faid, the Cafe is eafily accounted for, viz. whilft the Vapours remain in the fame State, the Weather doth fo too. And fuch Weather is generally attended with moderate Warmth, and with little or no Wind to disturb the Vapours, and an heavy Atmosphere to fupport them, the Barometer being commonly high then. But when the Cold approacheth, and by condenfing drives the Vapours into Clouds or Drops, then is Way made for the Sun. beams, till the fame Vapours, being by farther Condensation formed into Rain, fall down in Drops.

The Cold's approaching the Vapours, and confequently the Alteration of fuch dark Weather, I have beforehand perceived, by fome few fmall Drops of Rain, Hail, or Snow, now and then falling, before any Alteration hath been in the Weather; which I take to be from the Cold meeting some of the ftraggling Vapours, or the uppermost of them, and condenfing them into Drops, before it arrives unto, and exerts itself upon the main Body of Vapours below.

I have more largely than ordinary infifted upon this part of the Weather, partly as being fomewhat out of the Way; but chiefly, because it gives Light to many other Phænomena of the Weather. Particularly we may hence difcover the Original of Clouds, Rain, Hail, and Snow; that they are Vapours carried aloft by the Gravity of the Air, which meeting together fo as to make a Fog above, they thereby form a Cloud. If the Cold condenfeth them into Drops, they then fall in Rain, if the Cold be not intenfe enough to freeze them: But if the Cold freezeth them in the Clouds, or in their Fall through the Air, they then become Hail or Snow.

As to Lightning, and other enkindled Vapours, I need fay little in this Place, and fhall therefore only observe, that they owe also their Rife to Vapours; but fuch Vapours as are de

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tached