earthly abode; I conceive the following considerations sufficient to meet the objection.

1. The absolute distances of fixed stars and groups from each other, may be such as to require respective intervals of years and even centuries for the light of the more remote objects to reach us; that light arriving successively from each according to the distance.

2. Our case refers to objects which, though self-luminous, are not visible to the naked eye. They may "blush out," even frequently; but men are not capable of being their observers. Only a few of mankind can enjoy, and be qualified to use, such telescopes as those of Sir William Herschel, and his still more accomplished son.

3. Granting the possession of those advantages, the opportunities for observation are too scanty for the construction of a negative argument. Sir William Herschel, in the same paper, says that the number of night-hours, suited to this kind of celestial observation, is averaged favourably in our climate at one hundred in a year; and that to "sweep,"-to examine as rapidly as is consistent with astronomical attention,-every zone of the heavens, for the two hemispheres, would require eight hundred and eleven of such favourable years. The number of the objects to be observed is great almost beyond conception. Sir W. H. by counting the stars in a definite portion of the field of view, which he observed in one hour, and estimating the rest, concluded that fifty thousand passed under his review in that hour. It is therefore within the scope of probability that new masses of light are achieving their first arrival in parts of our telescopic sphere, frequently, without its being possible for men to be aware of it: and, when any of them come to be discovered, the date of their arrival is unknown.

I draw no argument from the fact that, within the short period of the last two or three centuries, stars have been discovered which earlier catalogues or descriptions had not noticed. The attention, requisite to give certainty in this matter, we cannot assume to have been exercised; and to look for evidence from this quarter would be forgetting that it can exist in the domain of only the greatest telescopic powers.

These views of the antiquity of that vast portion of the Creator's works which Astronomy discloses, may well abate our reluctance to admit the deductions of Geology, concerning the past ages of our planet's existence.

Fourth ed. The argument of this Note may be usefully represented by comparison. The velocity of light is 192,000 miles in a second of time. I borrow the following Table and observations from an interesting paper intitled "Astronomical Transcendentalism," in the Scottish Congregational Magazine, Jan. 1847.

"From the Moon, light comes to the earth in 14 second.

66

Now, as we see objects by the rays of light passing from those objects to our eye, it follows that we do not perceive the heavenly bodies as they are at the moment of our seeing them, but as they were at the time the rays of light by which we see them left those bodies. Thus, when we look at the moon, we see her, not as she is at the moment of our beholding her disc, but as she was a second and a quarter before; for instance, we see her, not at the moment of her rising above the horizon, but 1 second after she has risen. The sun, also, when he appears to us to have just passed the horizon, has already passed it by 8 minutes. So, in like manner, of the planets and the fixed stars. We see Jupiter, not as he is at the moment of our catching a sight of him, but as he was 52 minutes before. Uranus appears to us, not as he is at the moment of our discovering him, but as he was 2 hours previously. And a star of the 12th magnitude presents itself to our eye, as it was 4000 years ago: so that, suppose such a star to have been annihilated 3000 years back, it would still be visible on the earth's surface for 1000 years to come: or, suppose a star of the same magnitude had been created at the time the Israelites left Egypt, it will not be perceptible on the earth for nearly 700 years from this date" [i.e. till A.D. 2547].

After some striking applications of these truths, the able and ingenious author proceeds :-" Of what use are such speculations? We reply that, besides seeking to awaken-impressive views of the grandeur of creation, and reverential feelings towards HIM who made and who sustains all this wondrous scheme,they may help us to apprehend, in some degree, what may be the grand conditions of knowledge, in that higher state which, for ransomed man, is to succeed the resurrection."-The whole Essay will richly reward perusal.

May I intreat my young readers to brace themselves up to the acquiring of astronomical knowledge? Let them combine with the facts, above stated, just ideas of the number, magnitudes, distances, and motions of the heavenly bodies. Let them reflect upon such truths as these. Of our earth the circumference is 25,000 miles. The moon, at the distance of 240,000 miles, is less than a fiftieth of

:

the earth's bulk. If the sun were laid upon the earth, the centres corresponding, it would cover the orbit of the moon around the earth, and its circle extend 200,000 miles beyond. Our distance from the sun is 95 millions of miles that of the planet Herschel [-I abhor and lament the change, to which we have no choice but to submit :— Christians owe no honour to the Grecian idolatry :-] is from the sun twenty times our distance: that of Le Verrier's planet, which we are condemned to call Neptune (three thousand two hundred millions of miles,) about thirty-five times our distance. To travel from the earth to the Herschel, at the rate of 20 miles an hour, would require ten thousand years; but, at a thousand miles an hour, it would take only 200 years. Our solar system is itself moving, at the rate of 35,000 miles an hour, among the fixed stars; and were our system to be annihilated, it would not be missed by an intellect like ours surveying no more than what we know of the astral universe. Of that astral universe, the number of stars, within the range of good telescopes, is computed at 100 millions: but, to examine every part of the celestial hemisphere, with due observance, supposing 100 favourable hours each year (a good average for the climate of Britain,) would require 800 years. If, from the most distant part of the heavens, the light has taken two millions of years to come to us,-could we be transported thither, perhaps we should have advanced to the threshold only of the material creation.

It will interest the ingenuous reader to see two paragraphs from subsequent papers of Sir William Herschel, which, being in the Philosophical Transactions of the Royal Society, are accessible to those only who have the opportunity of consulting that voluminous repository of science.

.....

"Hence it follows, that, when we see an object of the calculated distance at which one of these very remote nebula may still be perceived, . . the rays of the light which convey its image to the eye, must have been more than nineteen hundred and ten thousand, that is almost two millions of years on their way; and that consequently so many years ago, this object must already have had an existence in the sidereal heavens, in order to send out those rays by which we now perceive it." Philos. Trans. for 1802; p. 498.

66

When our gages will no longer resolve the Milky Way into stars, it is not because its nature is ambiguous, but because it is fathomless." Philos. Trans. 1818; p. 463. The last contribution,. I believe, to Astronomy, from that distinguished man. He died, Aug. 23, 1822, aged 83.

Alexander von Humboldt, in his Cosmos, transl. by Mrs. Colonel Sabine, (vol. i. pp. 145, 496; Lond. 1846,) cites the former of the two of these memorable passages, and adds the observation :-"Such

events or occurrences-reach us as voices of the past.-We penetrate at once into space and time.--Much [of the phenomena in past periods] may have disappeared even before it became visible to our eyes, and in much the arrangement and order may have varied. ——It is more than probable that the light of the most distant cosmical bodies offers us the oldest sensible evidence of the existence of matter."

I subjoin a recent contribution to this branch of astronomical science, extracted from the " Etudes d'Astronomie Stellaire," a Report upon the State of Astral Observation, made to Count Ouvaroff, Min. of Publ. Instr. and Presid. of the Imperial Acad. of Sciences, by Prof F. G. W. Struve; May 19, 1847. Petersburgh.

Table of the Time required by the different Magnitudes of Stars, for the passage of their respective Emissions of Light to our Sun. The Earth may be safely taken to be the same, as the difference is only a very minute fraction.

"And these are SUNS! Vast, central, living fires,

Lords of dependent systems, kings of worlds

That wait as satellites upon their power

And flourish in their smile. Awake, my soul,

And meditate the wonder. Countless suns

Blaze round thee, leading forth their countless worlds!

Worlds, in whose bosoms living things rejoice,

And drink the bliss of being from the fount
Of all-pervading love. What mind can know,
What tongue can utter, all their multitudes?
Thus numberless in numberless abodes!

Known but to THEE, Blest Father! Thine they are,

Thy children and thy care; and none o'erlooked
Of thee. No, not the humblest soul that dwells
Upon the humblest globe that wheels its course
Amid the giant glories of the sky;

Like the mean mote that dances in the beam
Amongst the thousand mirror'd lamps, which fling
Their wasteful splendour from the palace-wall.
None can escape the kindness of thy care;
All compass'd underneath thy spacious wing;
Each fed and guided by тHY рowerful hand.”

Prof. Henry Ware, jun., Cambridge Univ. Massachusetts. For the citation
I am indebted to Dr. W. B. Carpenter's Popular Cyclop. vol. iv. 1843.

[B b.]

Referred to at page 34.

ON THE THICKNESS OF THE SOLID CRUST OF THE EARTH.

"As for the internal heat of the earth, I am of opinion that it ought not to be considered as an hypothesis, but as a fact well grounded on numerous phenomena." Prof. Gustav Bischoff, of Bonn, in Jameson's Journal, Jan. 1841, p. 14.

"All the calculations,—if they can be at all trusted, tend to prove that the earth's crust is not much more, and perhaps less, than twenty miles in thickness: and if this be so, the crust may indeed be well compared with a thin sheet of ice over a frozen pool.”—Mr. Darwin, in Memoir on the Connexion of certain Volcanic Phenomena in South America, Geol. Trans. second ser. vol. v. p. 608, 1840. This able philosopher uses the language of deferential caution from respect to Mr. Parrot, (known for his observations on the Caspian Sea, &c.) but with little or no doubt in his own richly-informed mind. In this interesting Memoir, Mr. Darwin brings much evidence to establish the position, that the crust of the earth rests upon a mass of melted mineral matter, whose undulations, with other modifying causes, produce elevations, earthquakes, and volcanos. He has eminently the talent of simple but graphic description, and luminous deduction. Considering the extent of the field of action, a space, in the instance considered, of little less than 7000 miles,-" and likewise the symmetry of the whole, we shall be deeply impressed with the grandeur of the one motive power which, causing the elevation of the continent, has produced, as secondary effects, mountain-chains and volcanos. The same reasons, which led me to the conviction that the train of connected volcanos in Chile and the recently uplifted coast, together