Page images
PDF
EPUB

matter, the lasting motions of nature are. maintained, and its stores unexhausted; and so general is this reciprocation, that it might be pursued through more instances than we shall have occasion to consider.

At the poles of the earth, and at the equatorial parts, the matter of the heavens must necessarily be in two very different conditions; and this never happens without a perpetual effort to restore the equilibrium by an interchanging of the matter, so as to reduce the whole to one uniform condition. To

say that the matter of the heavens is rarefied in one part, and condensed in another, is only to say, in other words, that there is a reciprocal attempt in each to qualify the other, because this is the necessary consequence according to the established laws of nature; and if this continual attempt can never succeed so far as to restore the balance, the result is a perpetual motion *. The matter of the heavens being in a more fluid state at the equator, and accumulated by the daily effect

of

* On this principle of restoring an equilibrium, which is interrupted before it is restored, a perpetual motion is exhi bited in a barometer of a most ingenious and elegant construction, which the workman who made it was so obliging as to explain to me at Mr. Cox's Museum.

of the sun on that part of the world, will necessarily fly off sideway toward the denser matter at the poles; and the matter there condensed will, at the same time, flow in toward the equator; so that there will always be a double motion of the etherial matter in and about the direction of the meridian : and indeed the great effect of polarity, upon the surface of the earth, and underneath it, seems to be a natural consequence of this doctrine: it is probably the effect of two different conditions of the etherial medium, always flowing in two contrary directions. It may seem difficult to conceive how two fluid mediums, or even two conditions of the same medium, can move in opposite directions*; but nothing can be more certain than the fact. Light is a fluid medium, and air is a fluid medium; yet the rays of the rising sun will move without interruption to the west, while the wind blows strongly toward the east; and neither of these will seem in the least to hinder or disturb one another's motions;

How two ethers, says Sir Isaac Newton, can be diffused through ali space, one of which acts upon the other, and by consequence is reacted upon, without retarding, shattering, dispersing, and confounding one another's motions, is inconceivable." Opt. Quer. 28.

motions; though they must be some millions of times more intimately mixed in their progress, than the cross threads of a weaver's loom. The same thing happens at every common culinary fire, where the matter of fire is flowing outwards, so as to be capable of inflaming bodies at a considerable distance; and the matter of air as constantly rushing inwards, the effect of which is so sensible, that light bodies will be carried by it into the face of the fire. Indeed to suppose one of these motions is to suppose the other, because fire will subsist only so long as it has pure air to support it; and air cannot flow into any space already full, unless somewhat be going out of that space at the same time: su that a contrary motion in fluid mediums ist not only possible and consistent, but even necessary by the common laws of nature.

And here I think we may go on to observe, that there must necessarily be different conditions in the element of air, in order to keep up a proper circulation, even as the element of water is found circulating through the world under the several forms of vapour, mist, drops, and a fluid mass, or even a solid and frozen one. Whoever shall consider the immense consumption of common air by

culinary

culinary fires, (which I have elsewhere endeavoured to calculate and demonstrate,) must needs conclude, either that this element is daily decaying, or that, according to the analogy of other cases, nature has a method of bringing it round again, through a certain course of transformation and regeneration, into its primitive condition of common air; then all will be easy and natural, and this case will agree with others of the kind. This rule may be extended even to the sun itself. How have philosophers perplexed themselves to account for the constant emission of light from the sun! A subject in which we cannot greatly err; if we suffer ourselves to be influenced by the best of all arguments, the general analogy of nature: for this will soon teach us, that whatever the particular mode may be, some there must be, of bringing his own matter back to him in circulation; without which, his source must inevitably have been exhausted some thousands of years ago. Some have argued that the matter of his light is so exceedingly rare, as to put him to little or no expence in furnishing it at the rate of above ten millions of miles in a minute, for several thousands years together; though it is certain there

of

is not a point of space in the solar system capable of holding a particle of light, but what hath such a particle in it. Nothing in nature can give without receiving; and therefore the incredibility of this plan hath inclined others to deny that the matter of light is progressive; instead of which, they have supposed that the rays of light are not emitted, but directed and determined by a vibratory motion impressed upon them by the sun, or by any other centre of irradiation, as the flame of a candle, &c. Some moderns, who deny the progression of light, are still aware that the constant flame at the orb of the sun must occasion a vast consumption of fuel; for the supplying of which, they provide a circulation of phlogiston *; supposing, that as fast as the phlogiston is consumed in some parts of the sun, it is regenerated in others, where it had been burned away and wasted some time before: and thus, with an alternate wasting and reviving of the phlogiston, the flame of the sun is perpetuated,

Phlogiston is a term used by the chemists to denote the inflammable principle in any kind of fuel, whether it be oil, sulphur, animal fat, bitumen, spirit of fermented liquors, volatile vapour of smoke, resinous juice of trees, or any other that may be referred to the same class.

« PreviousContinue »