SECT. XXIX. To Die therefore in an Air divefted of its Elafticity, is the Refult only of the Will of GOD.

CAN it therefore be denyed, that fince all Creatures are not equally affected with the Elafticity. and Gravity of the Air, what had been faid before must not be admitted to be a general Law of Nature, which taking place between the Air and all Creatures, produces fuch Effects without Understanding? And muft not that Man be al lowed to argue much more rationally, that does acknowledge herein the Hand and Work of a wife Artificer, who, that we may not afcribe that which happens to moft of the living Creatures with refpect to the Air, to neceffary and unavoidable Confequences of ignorant Corporeal Motions, has been pleafed by fuch an Exception as this, and perhaps by many others, to fhew that all must be refolved into his good Liking and Wisdom; and that he hasthought fit that the Air amongst its other Properties, fhould always preferve a certain degree of Force in its Expanfion; without which the whole Globe of the Earth would be in a manner deprived of all Living Creatures? And likewise, that when he thought fit to order it otherwife, he could -preserve some of 'em alive without Air.

SE CT. XXX. The Elaftick Faculty of the Air is not alone fufficient for the Prefervation of Life.

For the proof of this laft Propofition, it may likewife be particularly ferviceable to fhew, that this Elaftick Faculty of the Air is indeed neceffary to Life, but that it is not fufficient alone. Thus we find in times of Peftilence, that the Air is fufficiently Elaftick, but nevertheless Contagious and

Fatal.

Fatal. And the great Naturalist, de Stair, resates, that not only many other Creatures, but likewife a Frog that can live in Air, in Water, and without Air, yet died in a little fpace of time with an › Air or Steam that proceeded from Dough. And Experience does abundantly teach us, that a Living Creature fhut up in the fame Air, without any Circulation or Change therein, cannot long fubfift fo, altho' the Elafticity or Spring of the Air were not so much weaken'd, as that we fhould afcribe the Cause thereto; forafmcuh as it appears by the Barometers, that the Air by which we are furrounded, can undergo great Alterations in its Elaftick Faculty, without any Prejudice to breathing Creatures. But of this Property of the Air, which, befides its Gravity and Elafticity, is neceffary for the fupport of Creatures, we have already faid something in our Difcourfe upon Refpiration.

SECT. XXXI. The Elaftick Power of the Air does likewife caufe Fish to live and fubfift under Water.

BUT before we take our Leave of Living Creatures, can any one obferve without Aftonishment, that even the Fifh in the Water do receive their Life and Well-being from the Preffure and Elasticity of the Air? which being removed or taken away, fcarce any of 'em can contain themselves under the Water, but in fpight of all the Resistance, muft emerge and rife up to the top of it.

They that would fee the Experiment of it, may put fome Water and a Gudgeon, or any other little Fish, into the Recipient of the Air-Pump; and removing the Preffure of the Air, will find that a Fish immediately rifes up to the Top, but upon letting in the Air, it will fink down again, The Reafon thereof, and how the Bladders within their Body being dilated by the diminution of the Air's Pref fure

A a 3

A

fure, and becoming larger, do render the Fifh fo much lighter than Water, as to make them afcend' fhall be more fully treated of hereafter, when we come to confider the Nature of Beafts, &c.

Now fince moft Fishes are of fo wonderful a Structure, that they can and must make ufe of the Preffure of the Air, in order to remain under the Water, and in fuch Places as are moft convenient for them, without being forced to Ascend or Defcend against their Wills; and that all of 'em, without fuch a Preffure of the Air, being forced to the Top of the Water, would foon be deftroyed; let us draw this Conclufion only here, That he must be a very strange Perfon that fhall maintain, that the Air and its Preffure, fo very neceffary in this cafe, is produced upon the Earth by meer Accident, and without any view towards fo ufeful an Operation; and that the Fishes are likewife formed cafually, juft after fuch a manner, as to be provided with Inftruments by which they can encrease or leffen the quantity of Air, for the aforemention'd Purposes.

SECT. XXXII. Plants do alfo live by Air.

THE Air is not only of fuch great Ufe to Men, Beafts and Fishes, but even to Plants themselves, which vegetate thereby in fuch a manner, that a great Part of the Sap with which they are noutifh'd, is composed of it. Wherefore, in cafe Men could have lived even without Air, yet they could not have enjoyed fufficient Food from the Earth without it, because it contributes fo much to the Fertility thereof, which is well known to the Husbandmen, who for that reafon Break up and Plough their Lands fo frequently, in order to expofe them to the influence of the Air.

However, if what we have here faid, be not clear nor intelligible enough to any one, namely,

that

that Air infinuates itself into Plants, and that they cannot grow without it, they may confult thofe accurate Enquirers into the Nature of Plants, Malpighi and Grew, concerning the Air-Veffel's which they have difcover'd therein by the help of Microscopes; and Boyle and de Stair, concerning their Obfervations with the Air-Pump; thefe Gentlemen having fhewn, that Air can be drawn out of Plants placed in Vacho. But he that would have ocular Demonftration thereof, let him take a little piece of a Twig from a growing Tree, or Green Leaves, cut afunder, and other Parts of Plants, and tie them to a Nail, or any other heavy Matter, and put them into a Glafs in which there is Lye, made of Salt of Tartar, or Pot-afhes, in order to make them fink down into it; then putting them all together under the Receiver of an Air-Pump, and exhaufting the Air out of the Receiver, he will prefently fee the Air coming out of the Ends that were cut off from the Plants, in numberlefs Bubbles, and rifing up to the top of the Lye; at leaft it happen'd fo in all the Experiments which I have had occafion to make in this Matter; and from fome of them particularly, as from the Twig of an Elm tree, I obferv'd a much greater Stream of Air than can easily be believed by thofe that had never feen the fame.

The reafon why we rather prefcribe the ufe of Lye than of Water in thefe Experiments, is, be caufe no Air will mix itfelf with the former, tho it be never fo long expofed in an open Veffel. You may ufe Water alfo, after you have boiled it fo long, till all the Ait be evaporated, and let it stand till it be cold again.

Can any one fancy that this is likewife accidental, and without defign, or believe that he owes no Thanks for this noble benefit of the Air, ·A· ·a 45 1

to

to the bountiful Giver of it? Who has been graciously pleased to provide thereby not only for the Life of Man, but alfo for his Suftenance and Food, which springs out of the Earth.

SECT. XXXIII. Fire is maintained by Air.

ADD to what has been faid, that Air has this Property likewife befides all the reft, that Fire (which, without all Contradiction, is one of the moft ufeful things that is known to Man) cannot burn without Air; at least, that kind of Fire that we commonly make ufe of: So that for want of Air, almost all Fire will be extinguifhed in Vacuo, or in any Veffels into which one puts live Coals and clofes them therein. Now how many Inconveniences would befall the whole World, if we had not the use of this glorious Creature, but fhould be bereaved of its Warmth in Cold Weather, of its Light in Darkness, and of many other Advantages it brings along with it! But we Thall fay no more of it here, because we defign to treat of it more exprefly in our Difcourfe upon that Element.

SECT. XXXIV. Air caufes Smoak, and the Parti cles thereof to afcend.

THIS is certainly true, that if the Preffure of the Air did not caufe the Smoak of all things that are burnt with Fire, of all putrified and rotten Matters, and other difagreeable Vapours perfpiring from folid or fluid Bodies, to mount up like Oyl in Water, the fame would render the furrounding Air foul and unhealthy to us: And how would Mankind be refreshed with that vaft number of fweet-fcented Flowers and Plants with lovely Perfumes and Spices, if the Creator had not endowed

the