even affect our tides. Indeed, the greater number of comets move so rapidly, that even were their attraction greater than it is, there is not time for a sufficient accumulation of impetus to produce any effect on the ocean-so that we have not a deluge to dread.

The masses are generally so small, that there is little chance of the earth or planets being deflected from their paths by a comet, neither is there any likelihood of the earth being burnt, for the great comet of 1680, which was so intensely heated by having nearly touched the sun's surface, never can come nearer to us than nine millions of miles after leaving him, and we know of no other that ever has been so close to the sun. No comet on record has ever had the smallest effect upon our climate, and M. Arago has shown that there is no connexion whatever between the number of comets that have appeared in any season and its temperature, farther than that, as most comets are telescopic objects, they can only be seen in very clear fine weather, and therefore more are discovered in a good year than in a cloudy and foggy season. Besides, as they shine by reflected light, they are probably of low temperature, and even what they have must be much reduced during the long periods in which they wander through a medium 90° below the freezing point of Fahrenheit's thermometer.

Since the proximity of comets gives no ground of alarm, the only other cause of apprehension that remains to be considered, is the chance of collision, which is by no means impossible, when we consider the multitudes of comets that are constantly traversing our system in all directions: certainly the velocity with which they move would make the concussion dreadful if the mass were of any magnitude, but the chance of collision is still less than that of appulse; and much would depend upon the direction in which the two bodies might be moving at the instant of meeting. Should the motions of both be in the same direction, each would slide off from the surface of the other without doing more than local harm. It might, indeed, cause a deflection in the path of the earth, and a change in its velocity. The most fatal effects would be produced by comets having retrograde motions, the course of which might be directly opposite to that of the earth, and the momentum might be sufficient to destroy the progressive motion of both bodies, in which case the sun's attraction would cause both to fall to his surface. Such would be the fate of the earth if it were struck by a comet, with a mass only about four times that of the moon, and moving in a contrary direction at the rate of one million seven hundred and thirty-four thousand feet in a second :both bodies would arrive at the sun in about fifty-four and a half days. If anything had destroyed the velocity of the comet of

1680, when nearest to the sun, it would have fallen to his surface in three minutes, which places the comparative distances of that comet and the earth from the sun in a strong point of view.

Were the earth to receive a violent concussion from a comet of considerable density, the position of the axis of its diurnal revolution would, in all probability, be changed. The consequence would be a sudden rush of all the waters of the ocean from their ancient bed, which would overflow the land, sweeping before them animate and inanimate beings in one undistinguishable ruin. All the countries of the globe bear testimony to the vast and destructive effects of floods of mighty waters. The debris of multitudes of plants and animals deeply buried in the ground show that, long before man became its inhabitant, the earth was tenanted by innumerable races of beings altogether different from those which share with us the present state of things, and which must have vanished from existence thousands of ages ago, because the strata under which they are found show that sometimes the waters prevailed for numberless centuries over the beds containing them, and sometimes the dry land. Enormous masses of rock torn from their native hills have been borne over extensive countries to far distant regions; and deposits of the natives of the deep on the tops of the loftiest mountain-chains declare the irresistible force and magnitude of the vast waves which, in remote times, have carried destruction over the face of nature. These effects have been attributed to the inundations produced by the shock of a comet in former ages; but the astronomer has shown that such is not the case; that the length of the day, which is the measure of the celestial motions, is immutable and exhibits no trace of change; and that if the earth had ever been struck by a comet so as to change the axis about which it performs its diurnal rotation, the effects would still be perceptible in the variations which it would have occasioned in the geographical latitudes. As nothing is known of the earth's primitive velocity, a comet may have given it a shock, and only destroyed a part of its progressive velocity, without changing the axis of rotation. In this case the effect would have been to make it go nearer the sun, and move in a smaller orbit, which, though not absolutely impossible, is very improbable. Indeed, instead of having become warmer, the tropical nature of the fossil remains in the most northern countries of Europe and America have led to the belief that the general climate of the earth is of a lower temperature now than it was in the extremely remote ages in which these plants and animals must have flourished.

The earth is in greater danger of a shock from the two small comets belonging to our system than from any others. comet, which revolves in an orbit lying nearly between

Encke's those of Mercury

Mercury and Pallas, crosses the earth's path more than sixty times in a century, and, in the immensity of time, it may meet with the earth, and, but for its extreme tenuity, might do incalculable damage; still it is not easy to say, how far velocity might compensate for want of mass in increasing the momentum.

Biela's comet also frequently comes very near the earth's orbit. In the year 1832, M. Damoiseau created very serious apprehension in France, by predicting that the comet would pass within eighteen thousand four hundred and eighty-four miles of the earth's orbit, a little before midnight, on the 29th of October, that year; and as M. Olbers had computed that the radius of the comet's head, that is, the distance from the centre of the comet's head to its surface, would be twenty-one thousand one hundred and thirtysix miles, it was clear that its nebulosity would envelope a portion of the earth's orbit; and if any cause had retarded the arrival of the earth one month, it must have passed through the comet's head. M. Arago dispelled the fears of his countrymen in a very admirable treatise on the subject, in which he assured them that the earth never would be nearer to the comet on that occasion, than twentyfour million eight hundred thousand leagues. It had been ten times as near to the earth in 1805 without creating alarm.

If the nucleus of a comet having a diameter equal only to onefourth part of that of the earth, should come nearer to the sun than the earth is, its orbit being otherwise unknown, M. Arago has computed that the probability of the earth receiving a shock from it is only one in two hundred and eighty-one millions, and that the chance of our coming in contact with its nebulosity is not more than ten or twelve times greater. Thus, though it cannot be affirmed that the earth never will come into collision with a comet, there is no reasonable cause to dread such an event. The time has now come when all such fears are at an end, and the return of a comet which formerly spread dismay over the world, is regarded as one of the greatest triumphs of science. Lo! from the dread immensity of space.

Returning with accelerated course,
The rushing comet to the sun descends;

The enlighten'd few,

Whose godlike minds philosophy exalts,

The glorious stranger hail. They feel a joy
Divinely great; they in their powers exult,

That wondrous force of thought, which mounting spurns

This dusky spot, and measures all the sky;

While, from his far excursion through the wilds

Of barren ether, faithful to his time,

They see the blazing wonder rise anew.'.

ART.

ART. VIII.-Reminiscences of an Intercourse with George Berthold Niebuhr, the Historian of Rome. By Francis Lieber. London. 12mo. 1835.

THIS

HIS is a pleasant book. We wish to love those whom we admire; and we are grateful to that Boswellism which, with friendly fidelity, but without awakening any suspicion of its veracity, shows us authors of great literary distinction under the character of high-minded and amiable men. Mr. Lieber, indeed, did not enjoy the advantage of Niebuhr's society for any considerable time; and was not perhaps qualified, particularly during the early period of his intimacy, to sound the depths of his understanding, or to draw forth all the accumulated riches of his knowledge; but he has preserved many sagacious remarks and many well-matured opinions of the Roman historian, which, if they do not invariably command our assent, severely task our intellect in investigating their truth, and always deserve our respect for their freedom and candour. Mr. Niebuhr's friends will scarcely allow this hasty though agreeable glimpse of his social and domestic character to be the only record of his fame; but, as we have not heard whether any more full and complete memoir is in preparation, we cannot pass over the work before us without some notice.

As the generous conduct of Niebuhr to his present biographer is one of the most characteristic passages in the volume, we must first introduce the author of it to our readers. His singular and rambling life is in itself sufficiently amusing. Francis Lieber, whom we have already noticed in this Journal as the author of a respectable book on America, was one of those honest and enthusiastic German youths whose imaginations were kindled with the brilliant visions of the regeneration of Greece. He was not like the more prudential of the Philhellene crew' in this country, (we too have some honourable exceptions,) whose classical ardour was contented with modest speculations in Greek loans; and whose patriotic zeal for the liberation of Athens and Sparta, some how or other, was singularly connected with the value of the said scrip. So the poet sang

'As we see in the glass that tells the weather,

The heat and the silver rise together.'

Francis Lieber, in a different spirit, devoted all he possessed-his own person, and his small fortune, a strong arm and a zealous heart-to the cause. Let him speak for himself as to his reasons for abandoning that cause:

After having suffered many hardships and bitter disappointments, and finding it impossible either to fight or to procure the means for a

bare

bare subsistence, however small, I resolved, in 1832, to return, as so many other Philhellenes were obliged to do. The small sum which I had obtained by selling nearly every article I possessed was rapidly dwindling away I should have died of hunger had I remained longer.'

Mr. Lieber soon found himself at Ancona, but poverty and passports equally precluded his ardent hope of visiting the Eternal City. A friend, to whom he wrote, a young German artist, obviated the first difficulty; his own dexterity the second. But it availed little

to have made his way into Rome, without permission and without funds to enable him to reside there. In this embarrassment he threw himself at once on the generosity of Mr. Niebuhr, then Prussian Minister of the Papal Court, frankly explaining his situation, and the arts which he had practised, excusable as he hoped they would appear to so zealous an admirer of Roman antiquities, in order to reach Rome. Nothing could exceed the kindness of Mr. Niebuhr; his favours were conferred in such a manner as not to be refused by a man of the most sensitive delicacy.

The following trait is diverting. His first personal interview with the ambassador was concluded with an invitation to return to dinner. To Niebuhr's astonishment, the young Philhellene hesitated:

66

'When I saw that my motive for declining so flattering an invitation was not understood, I said, throwing a glance at my dress, "Really, sir, I am not in a state to dine with an excellency." He stamped with his foot, and said with some animation, " Are diplomatists always believed to be so cold hearted? I am the same that I was in Berlin when I delivered my lectures: your remark was wrong." No argument could be urged against such reasons.'-p. 21.

The said dress was certainly not exactly court-attire:

My dress consisted as yet of nothing better than a pair of unblacked shoes, such as are not unfrequently worn in the Levant; a pair of socks of coarse Greek wool; the brownish pantaloons frequently worn by sea-captains in the Mediterranean; and a blue frock-coat, through which two balls had passed-a fate to which my blue cloth cap had likewise been exposed. The socks were exceedingly short, hardly covering my ankles, and so indeed were the pantaloons; so that, when I was in a sitting position, they refused me the charity of meeting, with an obstinacy which reminded me of the irreconcilable temper of the two brothers in Schiller's " Bride of Messina." There happened to dine with Mr. Niebuhr another lady besides Mrs. Niebuhr; and my embarrassment was not small when, towards the conclusion of the dinner, the children rose and played about on the ground, and I saw my poor extremities exposed to all the frank remarks of quick-sighted childhood.'-p. 24.

Mr. Niebuhr supplied the young student with books-his own history