demonstrated, that the limits of our atmosphere do not exceed an elevation of above forty-five or fifty miles, and that beyond this there is no refraction or reflection of the solar rays—that, in fact, air ceases. The finite extent of the atmosphere has been ably discussed by Dr. Wollaston,[2] his arguments being based upon the Atomic Theory of matter. We may thus condense his train of reasoning, as far as it bears more immediately upon the present subject.—If air extend throughout the universe, we shall be obliged to admit that every planet must collect an atmosphere around itself proportionate to its attractive power. In this case, as he argues, Jupiter, at whose surface the force of gravity must be much greater than that of our earth, would certainly collect a large and dense atmosphere around him. The effect of the refraction of light through this atmosphere would become visible on the approach of the satellites to the planet, when they disappear behind his disc, and would cause a sensible retardation in their rate of approach. Now, it is allowed that no such retardation, even in the minutest sensible degree, can be observed, and hence it follows that Jupiter has no such atmosphere as that of our earth, nor the means of collecting it; consequently, air, such as that composing our atmosphere, is not diffused in any degree of rarefaction through the solar system. This finite character of our atmosphere is, as Dr. Wollaston contends, more conformable to the atomic theory than to that of the infinite divisibility of matter; since, in the first case, a boundary is possible, and will exist at the point where the weight of a single atom is as great as the repulsive force of the medium; while, in the latter case, it is difficult to see the possibility of any boundary.

[2] Phil. Trans., 1822.

By way of note we would here add, that the theory of the infinite divisibility of matter, which all the laws of chemistry seem to deny, has no good grounds for our acceptance. God made matter, and, as we may humbly conceive, in the form of ultimate atoms, which, however inconceivably minute, must be definite—otherwise what is meant by creation? That which is created must have definite figure, size, etc., else it is nothing; and to talk of a creation where size of figures is absent, is absurd. We know that atheistical philosophers advocate the theory of the infinite divisibility, and infinite, essentially infinite duration of matter, for these points are steps to the theory of non-creation, or rather involve it. Infinite duration, infinite divisibility, infinite extension, and the plastic power of infinite time, together with the innate, ungiven laws of this infinite matter, form the key-stones to their unholy temple entrance. On this theory, worlds formed themselves, and harmonized with each other; living microscopic monads called themselves into being, and by voluntary exertion became developed through various phases into man. Thus, then, he owes no Creator thanks! Impious, irrational, debasing doctrine!

Supposing, then, that our atmosphere is not continued to an altitude exceeding fifty miles, forming a sort of circumambient ocean, at the bottom of which we live, and which is created for our peculiar organization, still it is not altogether improbable that some subtle ethereal fluid, altogether different from our atmosphere, may extend itself throughout space—a fluid of extreme attenuation, the nature of which is to us unknown in fact—a fluid so impalpable as to cause no sensible retardation to the rate of motion in the planets.

We do not positively assert that such a subtle fluid exists, though many astronomers are in favour of this hypothesis; and, indeed, we believe that Encke's comet appears in successive revolutions to show in some slight degree the effect of some medium resisting its motion, and that the same observation applies to the comet of Biela. But when we consider the great tenuity of the substance of these comets, through which even faint stars may be seen, we shall be justified in regarding this resisting medium as being more subtle, attenuated, and elastic, than can be well expressed in words.

To revert now to our atmosphere, there is another interesting point which requires our notice; namely, are the constituents of this atmosphere chemically united together, or only simply mixed in certain proportions? We believe that it consists of a simple mixture only of two essential gases, or elements, namely, oxygen and nitrogen, with a small and variable quantity of carbonic acid, and also with water in a state of vapour. We may consider the last two as accidental ingredients, essential as the vapour of the atmosphere may be to the necessities of animals and plants, to luxuriance of scenery, and fertility of soil. The essentials of air are united in the following proportions, namely, one part of oxygen and two of nitrogen, or one atom of oxygen and two atoms of nitrogen; but as the atomic weights of oxygen are as 8 to 14, the proportion of the weights of the two in any given quantity of air will be that of 8 to 28, or two to seven; in other words, nine grains by weight of air will contain two grains of oxygen, and seven of nitrogen, supposing the air to be pure.

But, as we have said, a portion of carbonic acid gas is usually contained in air; this gas is exhaled from the earth, and collects in certain localities, rendering the air more impure than it otherwise would be; as a rule, however, the quantity of this gas in intermixture with the air we breathe—its lower strata—varies from three to eight parts out of a thousand in weight; in its pure state, it is immediately destructive to animal life; but thus diluted is in this respect innoxious, while to the vegetable kingdom it is necessary. With respect to water in a state of viewless vapour, the quantum in any given weight of air seldom exceeds 1½ per cent.

Now if, as most philosophers of the present day seem to consider, there is no chemical union of the gases constituting the atmosphere, it may be supposed that, according to their respective weights, a partial separation and subsidence of the heavier will take place, while the lighter will chiefly compose the upper portion—thus, for example, a stratum of nitrogen will surmount a stratum of mixed nitrogen and oxygen, and this a stratum of mixed nitrogen, oxygen, and carbonic acid. The following passage from the Penny Magazine will illustrate this theory: "A law is found to prevail in the mixture of gases and vapours, as universal as is that relative to their expansion arising from temperature, namely, that two gases in a state of mixture exercise no influence one upon the other, except communication of temperature, but that each is disposed in exactly the same way as it would be if the other were not present. Thus it is found, entirely contrary to all previous notions, that no pressure of dry air upon water exerts the least influence in preventing the formation of steam, which goes on exactly as if the space above were a vacuum, and continues until further evaporation is stopped by the pressure of the steam already created. It is found that no pressure of one gas can confine another in water; but that, supposing a bottle partly full of water, the gas confined in the water will escape to the surface, and distribute itself in precisely the same way as if the other gas were not