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Show e ALR Al immediately down towards the Center of the Earth, and remainin eternal Rett. Thus if the 4rbe full of Vapours, and the Cold fucceeds, thofe Vapours before difperfed are congregated and condenfed into Clouds, art It is known that none of thefe Clouds are above an Eng: Mile high ; and ey en the white ones, in fair Weat r, are rarely found to be more than three quarters of a Mile, and feldom abovehalf a Mile from the Surfa ce of and thus fall back again into the Form of the Earth, and on y Mountains the Water, Rain, Snowor Hail. Warmth is inconfiderable, From the Time of the Entrance of the x In effect, ourr Heat deper $ more on the Spring till Autumn, the Evaporation is con- Circumftances of the Clouds, and the Bodies ftant ; but then it begins to fail, and in the that are beneath them, than on all that is Winter ceafes, to lay up frefh Matterfor the above them, taking Sun, Moon, Stars and coming Seafon, all. And thus it is that frofty Winters, by conIt is therefore i e€ to pronounce what gealing the Waters, and by covering the the Degree of Heat wil be in any given Place Earth with a Cruft, and thus imprifoning the at any Time, even though we know everfo Exhalations, make afruitful Summer, well the Places and Pofition of the Sun and Andthis feems to be the Reafon, why in Planets, with refpec to u s, fince it depends fome Countries, where the Winteris feverer fo much .upon other variable ‘J hings, no than ordinary, the Spring is more than ordi- ways capabl e of being afcertained., tf naryfruitful: For in fuch Places the ExhalaThe Heighth or Depth of the / makes a tions being pent up a long time, are dif yet farthe r confiderable Altera:tion therein > charged in the greater Quantity, whent 3 are f xhala or th of them able to Sun makes them a Paffage ; whereas under ops of at nd 1ins ; and on a feebler Cold, the Flux would have been is Winter, ‘and continual, and confequently no great Stock rat the fame ‘Time; refervd for the next Occafion. > this Side is parched with Heat, This vapourous Matter then being at es buried in Snow: And the Inhab ts length received into the Atmofphere, is re- on one Side of a Mountain have all perifhed turn’d again in the Form of Rain, a Fore- with j the P thofe of the other runner of a cheerful Crop. Side have remain As the Sun retires, the Cold fucceeds 3; and thus the Diverfity of the Seafons of the Year depends on a Changein the Face ofthe Cruft of the Earth, the Prefence of the Air, and the Courfe of the Sun. And hence we conceive the Nature of Meteors, whichare all either Colleétions of fact Vapours, and Exhalations, or Difperfions thereof. Collections of Vapours make Clouds, which being farther and farther condenfed, turn to Snow, Rain or Hail. The fubtiler Oils are always rifing into the Air: Nowtwo Clouds, partly form’d of fuch Oils, happening to meet and mix, by the Attrition the Oil frequently takes Fire, and hence proceeds ‘I hunder, Lightenings, and other Phenomena; which may be farther promojgd by the Difpofition’ of the Clouds to favour the Excitation. And hence arife great and fudden Alterations in the Air; infomuch that it fhall now be intenfely hot, and raife the Spirits perhaps to 88 Degrees in a Thermometer ; and yet f youarrive at a Depth where the Fire goes out: Sothat Miners, who go deep, to remedy this Inconvenience, are forc’d to have Recourfe to an artificial Wind, raifed at by the Fall i of WW aters, rations by Means undergo fome Alte- of its Motion: Thus a br Wind .leffens the Preffure of the incumbent Atmotphere; by which ‘means raneous Air maybe enabled to rai of the Earth, or occafion a { And hence proceeds Mr. Zi, ; Obfervation, that the Barometer finks ver notably when the Windis raifed, or the 7 itated about the fame Time, Now confidering the Air as fach aC or Affemb of all Kinds of Bodies, and a Chaos fo amly liable to c ige, it muft ane teat Influence on vegetable _In general, the ir, as it contains di Kinds of Exhalations, has a wonderful Effect towards promoting, ftopping oraltering the again in a few Minutes no lefs than Ations ofall Bodies on 20 or 30 Degrees, ich other: pure well-fermented Wine becarried So if Ice may be, and is form’d into a even in the Place where the Air Heavens from the intenfe Cold that frequently Fumes of new Wine is re plenifh’d with the prevails ! there;3 and and the next fermenting, the Sun’s it will Sun’s Rays paffing begin to ferment duly through the Ice, have aftcth: And from the Air, their Force confi. confideér’d as before, do arife manyaftonifhing derably increafed ; as we {ee in Burning-glaffes Effects. made after a Clap of Thunder with a Showe r, it fhall fall of Ice. i é The Air is every wherein continual Motion; Ahd hence our Degree of Heat ‘ may be for in theftilleft Seafon, when greatly heightened; as accordingly we obier ve, coat when our Atmofphere is replete with oe oo they are not grofs enough oa interc cept e D the Rays, y our Heat isi then moft intenfe and fultry, no Wind i {tirring, ifa Perfon places himielf in a darken’d Room, which only receives the Light in ata little Hole, capable of admitting a fingle Rays that Ray, dividing itfelf, and illuminating the whole Length of the Room, he mayperceive every every Thing, all the external Objedts, whofe Species are brought in Motion, whichis owing to the external Air, which infinuating itfelf through the Chinks of the Edifice, moves that on the Outfide of the Chamber. And hence, The Mercuryin a verylarge accurate Barometer is found to be continually vibrating or leaping up and down, without ever remaining a Moment quiet. : ; This perpetual Motion of the 4r is owing to Fire, which acts there on the true, proper Air, by means of its native Elafticity. Others fay, the Caufe from whence the Air, which is compos’d of fo manyheteroge- neous Particles, receives its fudden and continual Motion, is properly the ZAther, or the fubtil and celeftial Matter, and from it the Yorpufcula in the Air acquire their Force and Motion ; and befides, one Part moves another by the fame Means ; and by howmuch{maller the Bodies are, by fo much is their Motion the more fudden ; andthis is done inceffantly, tho’ we cannot perce eive it, Tliefe Particles of Air are verylight, yet neverthelefs they have their Weight, according to their Proportion and Degree of Levity. “The Motion of the ir, and confequently its Force and Effect, arife wholly from Fire, by moving all the various Kinds ofParticles which are in the Air, and performs infinite Operations, ; ; In the extreameft Cold, the 4rfcarce acts atall, but is contraéted within itfelf; but when warm expands again, and agitates other Bodies ; confequently as the Degrees of Heatare infinite, fo muftthe Actions and Effects of the Air be: Add, that as the Fire aéts on all the Corpufcles that are in the Air, and thefe are infinite, ’tis evident that all the AGions thereofare indefinite. 3. Air confider’d in itfelf} or that properly call’d Air. Befides the Fire and Exhalations contain’d in the circum-ambient Atmofphere, there isa third Matter, which is what we properly mean by “To define the Nature of it would be extreamly difficult, inafmuch as its intimate Af feétions are unknown to us: All we know is, 1. That Aly is naturally an homogeneous ilar Body, That it i id. That it is heavy. That it is elaftick. thereon, and rifes, and reftores itfelf upon a Lemoval of the fame: All which Circumices fhould incline it to coalefce into a Solid, x is the contrary of the forCold, &¢. may be condenfédin= to original Water: permanent and tranfient Air fame as that between Vapour and tion ; the one, e. ¢. being dry, and moift, Hence, as Sir I/aac Newton & as the Particles of permanent /4r are g and arife from denfer Bodies than of tranfient Air or Vapour, Zrue Air is more pondrous than Vapour, and a moift Atmo{pherelighter than a dry one, But this read Air no where confifts in its Purity ; but that 4ir which concerns us, and the Properties and Effects of which are chiefly to be confider’d, is, that which has been before treated on and defecrib’d, which Mr, Boyle acknowledges to be the moft heterogeneous Bodyinthe Univerfe ; and Dr. Boerbaave fhews to be an univerfal Chaos and Colluvies of all the Kinds of created Bodies in the Univerfe, and in which may be found whatever Fire can volatili 2, That the Air is fluid, appears from the eafy Paffage it affords to Bodies through it ; asin the Propagation of Sounds, Smells, and other Effluvia: For thefe Things thewit a Bodythat gives Way to any Force impreffed; and in yielding are eafily moved among themfelves, which are the Properties of a Fluid: Sothat fearce any Body will call in Queftion, whether * be a Fluid, and thencebeing al- ways in Motion, and always moving other Bodies ; for no Surface of any Liquor that is contiguous to the 4ir, can be at reft. 3, As tothe Graa or Heavine/s of the Air, that is likewife eafily prov’d ; for that the dir is heavy, follows from its being a 3ody, Weight being an effential Property of Matter. Senfe and Experiment fufficiently prove this ; for, if a Perfon lay his Hand upon an open Veffel plac’d onan Air Pump, and the Air be exhaufted, he will fenfibly feel the Load of the incumbent Atmofphere to increafe, and prefs upon the upper Part ofhis Handas the 4/r is exhaufting. : In like manner, a hollow Sphere offive or fix Inches Diameter, divided into two Segments exactly fitting each other, after the ir is exhaufted out of them, are preffed together with a Force equal to an hundred Pounds Weight, and require the Strength of two ftrong Perfons to pull them afunder ; which as foon as ever the 4 is let into them again, will falll afunder by the meer Weight ofthe under Hemifphere. The Elements ofall Bodies are as heavy as the Elements of Gold, and Variety of Bodies, in Point of Weight, arifes only from the particular Surface which thofe Particles acquire in the Contexture: Thus, if Gold be beaten into very thin Leaves, it will {wim in Water, or be carried about by the Air ; fo that it does not appear, that the leaft Particles of Air are more porous than thofe of Gold. Again, that the ir has Gravity is demonftrable, in that it may aétually be weighed ; and a Bladderblownfull of Air, weighs more than when it was empty. Mr |