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from S, and also the motion which they receive with the body, while they are with it. Thus the ray R, emitted from S towards T, would besides have a motion towards W; which it had while it was in the body, equal to the motion of the body S, and which it don't lose when emitted. Wherefore it is manifest, that the motion of R towards W, will be ten times so swift as its motion towards T: so that by the time it has got the distance from S to T, in the direction ST, it is manifest it will have got ten times as far towards W, or in that direction: so that it is most manifest, that it would never reach T. And even the ray B, that is sent out right behind the star S, moves nine times as swiftly towads W, as towards E. So that it is evident, that all the rays that can be emitted from the star S, move at least nine times so swiftly towards W, as they gain towards the Earth. It is therefore evident, that they all will fall on that side of the Earth, that is towards W. We will take one instance more. Let the emission of the ray O, be towards O, It is evident, that this ray will never gain one inch towards E, or the East, being carried at least nine times so swiftly towards W, or the West, the contrary point: Because, being carried at least nine times so swiftly towards W, by that time it is got half way of the distance in that direction, it will have got nine times as far to the West, and therefore will miss the globe of the Earth.

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55. Proposition. The Cohesion of bodies, or the parts of bodies, to one another, can be from nothing else but their tendency, or gravity, one to another. So that all cohesión in the world, arises from this. This is the only reason, why every the least part of all bodies do not move properly at liberty, without any respect one to another. For instance, the only reason of the cohesion of the bodies, or the parts of bodies a b, must be from their tending, or gravitating, c to each other: for it must be, either because they tend to each other, or because the parts of the body a, next to b, are linked and fastened in, amongst the parts of the body b. I can think of no medium. Neither is the second another, case different from the first; for the question is. Why all the corporeal parts below the plane c d, cleave to any of the parts above that plane? Let some of the corporeal parts be particles, conceived as coming out of the body a, and linked and locked into the parts of the body b, or no. It is all one, as if they are conceived as only parts of the body b. only cleaving to the body a. It is evident, therefore, that this is not the reason: therefore the other is.-N. B. When bodies are press'd together by circumambient bodies, the proposition does not regard that as cohesion.

56. The parts which constitute the Atmosphere, are two-fold. (1.) The parts of the.Ether, drawn and pressed together by gravity to the Earth: which is nothing but exceedingly minute, subtil, active particles, which parts are the most penetrating. Now it is certain if there be any Etherial Matter at all, however little, this is one part of the atmosphere. For, if there be any that which is round about the Earth, or any other celes tial body, will be very much condensed and pressed together, by its tendency to such body. So that although it be almost infinitely rare, at the distance of four or five diameters of the Earth; yet it will, according to the laws of gravity, be thick enough at the surface of the Earth, so that there are no proper bounds to this part of the Atmosphere, inasmuch as it is nothing but the Ether pressed together, according as it is nearer or farther from the centre of the Earth. It is in vain therefore to pretend to setting bounds to the Atmosphere. (2.) Another part are the vapours and exhalations which ascend from the globe-parts of liquids rarified, so as to ascend from the Earth, by means of the gravity of the rest of the Atmosghere. These vapours are wholly constituted of small bubbles, as is now

said by philosophers; these bubbles being lighter than the Atmosphere, not because the liquid of it, which makes the skin or wall of the bubble, is rarer than the air,but because the air or subtile matter, that is in the bubble is, by the sunbeams or otherwise,made more rare than the circumambient air: so that take the skin of the bubble and all together,and it is lighter than a part of the air that is round about it, of the same dimensions. When we say that the air within the bubble is rarer than that without, it must be the etherial part of the air, or at least another part of the air that is not constituted of these bubbles, for that which is in all the bubbles is not the bubbles. Now here in the first place, it is certain that these exhalations do constitute a part of the Atmosphere that is round about; and, secondly, it is certain that. they do not wholly constitute it, as has been by some thought; for it is contrary to the supposition, viz. that these bubbles are lighter than the air, and therefore ascend in it. Than what air are these bubbles lighter? It is not meant that these bubbles are lighter or rarer than these bubbles, and therefore ascend among them: so that these are not the primary parts of the air. Yea, it is certain that the matter of our Atmosphere is the very same with the Ether, the same with that which is in the spaces between the heavenly bodies; and that there is a certain subtile matter in these spaces, and that it is the same with, or at least partly constituted of, the air; only the air is the Ether much compressed. If it has been proved that the self-expanding quality of the air is so great, as has been said by the late philosophers; for if one inch square of it, when free and having nothing incumbent to press it together, will expand itself so much, it is certain that the whole Atmosphere, being free, and having nothing incumbent, will expand itself into all the Solar System. And if one inch square of air, at the distance of a semi-diameter of the Earth, will expand itself so as to fill the Solar System, then there is nothing incumbent upon the Atmosphere sufficient to hinder its free expansion: so that the matter of our air is abroad in the heavenly spaces.

2. The etherial part of the air, that is here near the Earth, is much more compressed by reason of the exhalations, or that part that is made up of bubbles floating in the air; for though they in themselves are lighter than the air, yet they have some weight, and must therefore necessarily add to the weight, that is incumbent upon that lower part of the Atmosphere, whereby the air below, in general, is denser and heavier, and so more able to bear up more such exhalations.

3. There is yet another way, whereby the rays of the Sun do doubtless cause particles to ascend off from terrestrial bodies, beside this of rarifying of liquids, and making of them lighter than the air, so as to be buoyed up thereby. For as the air or Ether is nothing but exceedingly subtile and agile particles, made so exceedingly elastic and diffusive, by their lively motion one among another; so when the rays of the Sun separate particles as subtile as they are, and like unto them, from terrestrial bodies, and give them as brisk a motion as the particles of Ether have, such particles thereby do become some of them, or in all respects whatever become particles of ether, and will move up or down, on one side or another indifferently, in the Ether, as other particles of Ether do. Now there is no doubt but that there are great plenty of particles in terrestrial bodies, that are as fine as the Ether, but only are fixed adhering to other particles by gravity, and want nothing to make them become parts of Ether, but to be disengaged and loosened, and to have a suficiently active motion given them. We have showed that all bodies are constituted of atoms, which are, it is probable, finer than any etherial particles. And it is not to be doubted, therefore, that all bodies are capable of being dissolved into parts, as fine as etherial ones.

But this is what I would, that doubtless there are great

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plenty of particles in bodies, proper for etherial matter, and wanting nothing but to be loosened and set in motion. And if it be so, I think it cannot be doubted, but that the rays of the Sun do daily disengage and loosen plenty, and set them into a motion sufficiently lively and brisk; and so that there is continually rising etherial matter from off the surface of the Earth, and that this, in considerable measure, constitutes the Atmosphere, and is not specifically different from the first constituent parts.

4. And secing these particles are so very active, and therefore diffusive, and move indifferently any way in the Ether, no doubt but those that are daily raised from ctf the Earth may disperse, many of them at immense distances, in a very short time, though not so quick as rays of light, nor in right lines as they move.

5. There are, doubtless, the like etherial particles, continually diffused from the other Planets, as from the Earth; and, ceteris paribus, the more any planet has of the Sun's influence, the more of these particles are diffused from it; and therefore, there are abundantly more from Comets, than from any of the Planets. And, seeing there is such subtile matter, diffused around, from all the heavenly bodies, into the etherial spaces, it is probable, that the Ether is chiefly composed of them.

6. We have these two reasons, to think, that the motion of these subtile particles is exceedingly rapid, (1.) Because, they receive their motion. from the rays of the Sun, which move so swiftly, as to come from the Sun in seven or eight minutes; and (2.) It can absolutely be proved, by their great elasticity-so great, that an inch square of air will, by its elasticity, if sufficiently compressed, be of sufficient force, to move a prodigious weight; which could not be, except the motion of those particles were prodigiously swift.

47. This matter, that arises from the heavenly bodies, will diffuse itself abundantly faster, at a distance from those bodies, than near them; both because they are so much less retarded, by their gravity to the bodies from whence they came, and because, they have millions of times more liberty, and their motion less resisted by circumambient particles.

8. There may be a great difference, in the kinds of particles, diffused from different planets: even as there is a great difference in the particles, that are diffused from particular bodies, upon the Earth, which causes different odours.

9. Those Effluvia, that are diffused from the bodies of the Universe, diffusing themselves so fast, and being so fine and penetrating, and of different kinds, may cause considerable and different effects in other planets. Being diffused into all parts of the etherial spaces, and mixing themselves with their atmospheres, and being so very active, they may produce considerable effects in the temperature of their air, and on their plants and animals, which have so much to do with their air. And these effects will be different, at different times, according as the bodies are nearer, or further off, and according as the rays of the Sun, which cause them, fall upon either the side that is towards them, or that that is from them. And, ceteris paribus, those bodies, which are nearest, will have much the greatest effects upon the Earth, and, therefore, the Moon has vastly greater effects of this kind, than any of the Planets. And, ceteris paribus, those bodies will have the greatest effects upon the Earth, which emit most of these effluvia; and, therefore, Comets will have much greater alterations upon the Earth, than any of the primary Planets.

10. Whether these effluvia are diffused from one star to another, in an hour, or a month, a longer or a shorter time, it alters not the case. Neither will it cause but that there shall be constant different effects, produced at certain periods, according to the different places and aspects of

the stars, provided that these effluvia are propagated to the same distance, at the same time. For, as to this, it alters not the case, whether, at the Full Moon, we have the effects of the effluvia of the Full Moon, or of the First Quarter, or of the New Moon: yet, it will not follow, but that, at every Full Moon, we shall have the same effects produced.

11. It seems to me probable, that, before the Flood, when the Earth enjoyed so temperate and undisturbed an Atmosphere, when the effects of the stars, of this nature, were constant, being not disturbed by the perturbations of the Atmosphere, as now, and the lives of men were so long, that they knew the effects of the Planets upon the Earth; that they could foretell nearly what effects such a position or aspect of the Stars would produce in the Atmosphere, and upon the plants and animals of the Earth; having so much opportunity of experience and observation, by reason of their long lives; and that the tradition of this, from Noah and his sons to their posterity, has been the cause of that general opinion, which the nations of the world have had, that the various phases and appearances of the planets had a considerable effect upon the earth; and thus gave rise to Judicial Astrology, and, in a great measure, to their Worshipping of

the Planets.

12. Corollary, from the first part. Hence it is, that the Atmosphere of the Moon is so much less, and thinner, than that of the Earth: it having so much less attraction, it cannot attract so much of the ether about it. nor will it be so much compressed, and so densc.

13. These effluvia, or subtile particles, are not only continually dissolving, and diffusing from the bodies of the Universe, but also, doubtless, are continually settling to those bodies, and so become fixed again. I do not suppose, that they precipitate, as dust in water; but, seeing that far the greatest part of the etherial matter that is in the whole Universe, is near the surface of the Stars; these particles, crowding about these bodies, doubtless often are catched, by coming so appositely to some of their fixed particles, that they adhere by their gravity, and their motion is not sufficient, to carry them clear. They may, also, so far lose their motion, that it shall not be sufficient, to keep them playing off from the Earth.

14. Here, near the surface of the Earth, where the air is so dense, particles, that are not so fine as the particles of pure ether, may easily diffuse themselves, nevertheless; the Atmosphere counterbalancing most, though not all, of their gravity, so that, their motion may cast them to a great height and distance. And of these particles, our Atmosphere is doubtless, in considerable measure, composed; and of this kind, I suppose, the effluvia, which cause odours, to be, and other effluvia, that are emitted from all bodies, upon the Earth, set in motion, not only by the rays of the Sun, but also, by the motion of circumambient aerial particles, and by intestine motion, in the bodies themselves.

57. 1. It is already determined, what Exhalations are, that they are nothing but bubbles of water, including atmospheric air, or some other etherial matter, considerably rarer than the air without. The only thing that wants to be known, is, how these bubbles come to be made. In order to determine this, we must first know, how any bubbles are made, which is, by driving a parcel of air under the surface of the water; so that, the water being so fluid, immediately closes near it, so that there is a parcel of air inclosed by the water. Now, this inclosed air immediately gathers itself into a globular form, by reason of the gravity of the parts of the air, one to another, as, likewise, the gravity of the parts of the water, which will prevent any prominences of water, inwards, amongst the air. The air, also, immediately ascends again, to emerge from the water, whereupon, most of the water that was over it, runs off on every side;

but water being a thing, whose particles are so fitted, one to another, that they adhere one to another, by their gravity, the skin, or the walls of the bubble, will not immediately break; though the particles of water run off with infinite ease, before it comes to the last skin, because they run upon other water, that attracts it as much, as these particles that they run from.

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2. What makes small bubbles break is, 1. The endeavour of the air quite to energe; for the lowest part of the air is something lower than the surface of the water, by reason of the weight of the incumbent water in the skin of the bubbles: 2. The weight of the water, whereby it endeavours to run off down to the body of water: 3. The attraction of the water, that is at the basis of the walls of the bubbles for the water, that is at A and C, attracts the water of A the skin, that is next to it, with considerable strength.

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3. We see that small bubbles live much longer than great ones, 1. be- . cause the skin is not so strongly attracted by the subjacent water, inasmuch as the margin of the bubble is not so large; and 2. the endeavour of the air to emerge is not so great, there not being so much below the surface of the water, because the weight that presses it under is not so great. 3. Because the weight of the water of the skin is not so great.

4. A very small bubble, being disjoined from the water, and suspended in the air, provided the air within remains as it was, and the bubble be not broken by something external, would live forever, or at least a very long time; for the weight of the water, whereby it tends to run from the top to the bottom of the bubble, would be very inconsiderable, the bubble being so small; and then a parcel of air, ascending out of the water, would take no more water, than just would suffice for a skin. The weight would be nothing near equal to the tendency of the particles one to another; for we see in great bubbles it is hardly equal, where the weight is so much greater; therefore the weight would not be sufficient to disjoin those particles, therefore the bubble would not be broken by the weight. 2. The attrac tion of the water, from whence it ascended, would not contribute to it, because it would be carried at a distance from it. 3. Nor the endeavour of the inclosed air to get out or emerge from the water, or in bubbles that lie on the surface, because it is supposed it would be entirely emerged and disjoined.

5. Now then all that is necessary to be done, by the Sun's rays, in order to cause bubbles to ascend from the water, is, to drive very minute particles of air under water, and to make the air inclosed so much rarer than the rest of the air, that this air, together with the watery skin, shall be lighter than a parcel of other air of the same bigness.

6. The air that is close to the surface of the water, is far more exposed to the force of the Sun's ray's, than any at a distance, because the other air has room to yield to the stroke of the rays, but this must bear all the brunt, and stand the stroke, and can go no further. A body, that is smitten upon an anvil, suffers much more by the stroke, than a thing that is floating in the free air. Therefore the air, that is next to the surface of the water, will be much more rarified by the Sun's rays than the other air.

7. If a very small parcel of air, that is next to the water, happen to be struck so to advantage, by the rays of the Sun, (by many rays striking together upon it, or otherwise,) as to be smitten just under the surface of the water, that air, being smitten more forcibly than the other air that is smitten under, will be more rarified by the Sun's rays than other air; and that parcel of the air, so smitten undér, emerging, will raise a bubble with

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