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sun's, or, for convenience of reckoning, say 144 times; his diameter would thus be twelve times the sun's, and his volume 1,728 times the sun's.

Have I not rightly called Sirius a 'king of suns'? From that glorious orb, nearly 2,000 such orbs as the sun, that great and mighty globe, instinct with fire and life, might be formed, each fit to be the centre of a scheme of circling worlds as important as that over which our sun bears sway! And then conceive how vast must be the scale of the planetary scheme which Sirius doubtless rules over. Indeed, it must be vast for the mere security of its inhabitants. An orb placed as far from Sirius as Mercury or Venus, or the earth or Mars from the sun, would be scorched with a heat so intense that no life would be possible upon it. The distance of Jupiter would be better, but even there the supply of heat would be six times as great as that which we receive from the sun. At Saturn's distance a world would be illuminated and warmed half as much again as our earth. Only at a distance about one-fifth greater than that of Saturn, so long regarded as the most distant member of the solar family, would an attendant on Sirius receive the same supply of light and heat as we receive from the sun. In short, a scheme of planets bearing the same relation to Sirius as respects the supply of light and heat, which the planetary system bears to the sun, would have to be constructed on a scale twelve times vaster.1

It would not even then resemble the planetary system in other repects; for the light and heat and attractive energy of Sirius are reduced at

After all, however, the most wonderful circumstance is that of which alone we are certain. We know nothing of the family over which Sirius bears sway; but we are well assured as to his own splendour and surpassing volume, and these are the features which afford the most surprising evidence of the wonders of the star depths.

In the next chapter, however, I shall have to consider yet greater wonders; I shall have to deal not with a king among suns, but with an order of kingly suns.

the square of the distance; and to make them equivalent to those in the solar system we have supposed all the distances enlarged in the same degree as his surface exceeds the sun's. But his might is more probably proportional to his volume, in which case the attraction he exerts remains still twelve times greater in the corresponding planets of the imagined system than our sun's attraction on the respective members of his family. Therefore, unless we further modify our supposition, we must set all the Sirian planets circling much more rapidly than the corresponding members of the solar family. They must, in fact, move 3 times as fast, and therefore have years correspondingly shortened. Thus the one corresponding to our earth would have a year of about 104} days, and the others in proportion.

IN

FOUR ORDERS OF SUNS.

my last chapter I described a sun-the star Sirius— so superior to our own in splendour, and doubtless in magnitude, that it must be regarded as belonging to a superior order. We might, indeed, if there were no evidence to the contrary, regard Sirius as the king of suns, not as a member of a higher order. We might suppose that he is perhaps the central sun of the star system, in which case his superiority over our own sun would not be surprising, since it would correspond precisely with the superiority of the sun over the members of his planet family. Indeed, this view was adopted before it was known how enormously Sirius exceeds the sun in magnitude. The great German philosopher Kant regarded Sirius as the central sun of the universe, because it appeared to him from other considerations that the central sun should lie towards the region occupied by the constellations Orion, the Hare, and the Two Dogs; and Sirius being the leading star of that region (as indeed of the whole stellar heavens) appeared to Kant very well suited to be the ruling orb of the universe.

But, apart from all other considerations, the enormous distance of Sirius shows conclusively that be cannot be

the orb which our sun obeys, far less the ruling orb over the stars lying far away beyond our sun towards the constellations Hercules, the Eagle, and so on, which occupy the region opposite to that in which Sirius is the leading orb. It requires no elaborate calculation to prove this. Roughly speaking, Sirius is a million times farther away than the sun; and since attraction varies as the square of the distance, his attractive influence is a million million times less than it would be if he were only at the sun's distance from us. Supposing his mass the 2,000th part of the sun's, it follows that his influence on the sun is but the 500 millionth part of the sun's influence on the earth. This would be altogether in

It may, perhaps, interest the reader to learn precisely what the influence of the sun on the earth is, and so to infer the influence of Sirius on the sun. We must of course consider equal quantities of matter, and for convenience we will take that quantity of matter which we call a ton—that is, the quantity of matter which, placed on the earth's surface, weighs a ton, or produces that amount of downward pressure. Now, a ton of the earth's matter tends sunwards with a force only equal to that which would be produced on the earth by the downward pressure of 1 lb. 3 oz. 200 gr., or roughly 8,500 grains (New Avoirdupois, which is the same as Troy measure). Accordingly, on our assumption as to the mass of Sirius, which is probably above his real mass, a ton of the sun's mass tends towards Sirius with a force corresponding to the 500 millionth part of 8,500 grains, or roughly the 59,000th part of a single grain. This is probably the greatest attrac tion which any individual star exerts on our sun, and indicates the exceeding feebleness of the forces exerted on each other by the stars, regarding these forces as moving forces. The total quantity of attraction between Sirius and the sun is of course enormous, because the sun's mass is so enormous. But this total quantity is not what we have to consider in enquiring into that star's fitness to rule our sun. For its magnitude, we see, depends on the sun's magnitude, and of course his magnitude gives him independent power. In all such cases we have only to compare the attrac

sufficient to sway the sun appreciably from his course. If, indeed, there were no other bodies in the universe than the sun and Sirius, our sun would circuit around Sirius, though the period of revolution would be enormously long. But as it is the attraction of Sirius is only one among thousands of attractions, exerted by the leading neighbouring stars; and the sun obeys the combined. influence of these attractions, not the power of any particular star. Every other star also, including Sirius, is similarly influenced by the combined influence of all

the rest.

Still Sirius, for aught that has yet been shown, might be distinguished above all other suns, and his influence, though far inferior to the combined influences of other suns, might still be paramount in the sense of being far superior to that exerted within the universe by any other sun whatever.

But we have now to consider evidence which points to Sirius as one only of a class or order of suns, and an order including a great number of stars.

I have spoken in former chapters of the teachings of the spectroscope respecting the stars; and in so doing I have mentioned specially what has been learned in this way about the colours of the stars. It has been shown

tions exerted on equal quantities of matter. Thus we may speak of Sirius's moving power on the sun as less than the moving power which our earth has on bodies near her surface (that by which she causes them to fall if unsupported), in the same proportion that the 59,000th part of a grain is less than a ton, or roughly as 925,000,000,000 to 1.

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