conclusion upon this head; and it seems, therefore, demonstrated, that the amount of such parallax, even for the nearest fixed star which has hitherto been examined with the requisite attention, remains still mixed up with, and concealed among, the errors incidental to all astronomical demonstrations. Now, such is the nicety to which these have been carried, that, did the quantity in question amount to a single second (that is, did the radius of the earth's orbit subtend, at the nearest fixed star, that minute angle), it could not possibly have escaped detection and universal recognition.' Hence, by a simple mathematical process, he is led to the conclusion, that the distance of the stars cannot be so small as 4,800,000,000 radii of the earth, or 19,200,000,000,000 miles! But, for any thing we can tell, the very nearest of them may be much farther removed from us than even this inconceivable distance.

Now, with regard to the size of these bodies, remote as they are, science has invented a way of forming some comparative estimate. Dr. Wollaston, by experiments on the light of Sirius, the brightest of the fixed stars, has ascertained that his splendour, when it reaches our earth, is twenty billions of times inferior in intensity to that of the sun. That the sun, therefore, might be made to appear no brighter than Sirius, he would require to be removed from us 141,400 times his actual distance; but this is scarcely two-thirds of the distance beyond which we know the nearest fixed star to be actually placed. It follows, therefore, that the light of Sirius, and probably also his bulk, is much greater than that of our sun. Dr. Wollaston, on data that cannot easily be disputed, has assumed the distance of Sirius to be so great, that his intrinsic light must be nearly equal to fourteen suns. John Herschel, taking a more modest and cautious, but perhaps not truer, estimate of his distance, concludes that, 'upon the lowest possible computation, the light really thrown out by Sirius, cannot be so little as double that emitted by the sun; or that Sirius must, in point of intrinsic splendour, be

Sir

conclusion upon this head; and it seems, therefore, demonstrated, that the amount of such parallax, even for the nearest fixed star which has hitherto been examined with the requisite attention, remains still mixed up with, and concealed among, the errors incidental to all astronomical demonstrations. Now, such is the nicety to which these have been carried, that, did the quantity in question amount to a single second (that is, did the radius of the earth's orbit subtend, at the nearest fixed star, that minute angle), it could not possibly have escaped detection and universal recognition.' Hence, by a simple mathematical process, he is led to the conclusion, that the distance of the stars cannot be so small as 4,800,000,000 radii of the earth, or 19,200,000,000,000 miles! But, for any thing we can tell, the very nearest of them may be much farther removed from us than even this inconceivable distance.

Now, with regard to the size of these bodies, remote as they are, science has invented a way of forming some comparative estimate. Dr. Wollaston, by experiments on the light of Sirius, the brightest of the fixed stars, has ascertained that his splendour, when it reaches our earth, is twenty billions of times inferior in intensity to that of the sun. That the sun, therefore, might be made to appear no brighter than Sirius, he would require to be removed from us 141,400 times his actual distance; but this is scarcely two-thirds of the distance beyond which we know the nearest fixed star to be tually placed. It follows, therefore, that the light of Sirius, d probably also his bulk, is much greater than that of our

Sir

Dr. Wollaston, on data that cannot easily be disputed, assumed the distance of Sirius to be so great, that his sic light must be nearly equal to fourteen suns. Herschel, taking a more modest and cautious, but pert truer, estimate of his distance, concludes that, 'upon st possible computation, the light really thrown out cannot be so little as double that emitted by the Sirius must, in point of intrinsic splendour, be

at least equal to two suns, and is, in all probability, vastly greater.'

6

?

I cannot better conclude this paper, than by the judicious remarks with which the eminent philosopher, above quoted, follows up his statements on the size and distances of the fixed stars. 'For what purpose,' says he, ' are we to suppose such magnificent bodies scattered over the abyss of space Surely not to illuminate our nights, which an additional moon, of the thousandth part of the size of our own, would do much better; nor to sparkle as a pageant, void of meaning and reality, and bewilder us among vain conjectures. Useful, it is true, they are to man, as points of exact and permanent reference; but he must have studied astronomy to little purpose, who can suppose man to be the only object of his Creator's care, or who does not see, in the vast and wonderful apparatus around us, provision for other races of animated beings. The planets, as we have seen, derive their light from the sun; but that cannot be the case with the stars. These, doubtless, then, are themselves suns, and may, perhaps, each in its sphere, be the presiding centre, round which other planets, or bodies of which we can form no conception, from any analogy offered by our own system, may be circulating.'*

FIFTH WEEK-THURSDAY.

X. THE STARRY HEAVENS.-IMMENSITY OF THE UNIVERSE.

ON casting the eye across the heavens, it is arrested by a streak of faint light, which passes athwart the whole sky, in the direction, speaking loosely, of east and west. This streak is called the milky way, in allusion to a well known childish fancy of heathen mythology. When we regard the stars with reference to this permanent band, we find that, in pro portion as they recede from it on either side, they gradually become less and less numerous, till, towards the extreme

* Herschel's Astronomy, p. 380.

north and south, there is an obvious deficiency in the comparative richness of the garniture with which the mighty dome is adorned. On applying the telescope to the diffused light of this remarkable part of the heavens, the astronomer is lost in admiration to find that this appearance is occasioned by an amazing multitude of stars, too minute to be detected by the naked eye, and too numerous to be accurately calculated, scattered by millions, like glittering dust, on the black ground of the general heavens.' Sir William Herschel informs us, that, on calculating a portion of the milky way, about ten degrees long, and two and a half broad, he found it to contain 258,000 stars, a quantity so great, in so small a space, that the moon would eclipse two thousand of them at once! Now, all these are suns probably at as great a distance from each other, as our sun is from Sirius,-a distance so incomprehensible, when stated in miles, that the best way of forming some clear idea of it, is to compare it with the locity of some moving body with which we are acquainted. We know of nothing so swift as light, which moves at the rate of 12,000,000 miles in a minute; and yet light would be at least three years in passing between the sun and Sirius. Let any one, then, comprehend, if he is able, the distances implied in the conception, that the minute and thickly studded sparks of the milky way, are suns, each so far separated from each other, that it would require three years for the light of the one to reach the other! And yet this astonishing view is not a mere gratuitous imagination, but a calm philosophical deduction from observed facts and obvious analogies.

But this stretch of the mental powers is little compared with what is required for comprehending the conclusions we are led to form, from other celestial phenomena. In various parts of the heavens, and in all quarters, there are discovered either small groups of stars, or certain dusky spots, called nebulæ, which the power of the telescope has multiplied to thousands of greater or less, distinctness and magnitude.*

*'In the northern hemisphere, after making all allowances, those whose places are fixed cannot be fewer than between one and two thou