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comet of 1680, when nearest the sun, was within 590,000, miles of its centre; and that of 1843 was within 510,000 miles. The comet of 1847, referred to above, was within four million miles.
It has long been a question whether comets shine wholly by reflected light, or partly by light emitted directly from the nuclens. It was thought that reflected light could not explain all the phenomena presented by the great comet of 1811. Some observations af Arago on the comet 1819, and on Halley's comet in 1835, by means of the polariscope, seemed to show that at least a part of their light was reflected. Since the invention of the spectroscope, however, this question has been more definitely settled. In 1864 Donati found that the spectrum of a comet visible in that year consisted of bright lines; in other words, its material was in the condition of a luminous gas. The spectrum of a comet seen in January, 1866, with a faint nucleus, was found by Mr. Huggins to to consist of two parts, a continuous spectrum and a bright point, showing that the coma shines by reflected light, but the nuclens is self-luminous, and similar in constitution to the nebular. Another observed by him in May, 1867, had a similar constitution.*
Astronomers were scarcely prepared for this result of observation. Their deductions in relation to the constitution of comets were, that the nucleus partakes of the nature of a fluid or solid, and the envelope and tail, if any part, of the nature of a nebula. The spectrescope, however, has taught us that the reverse is the truth, at least in the case of those comets which have been examined. No bright comet has recently appeared so that its light might be examined, and we must patiently wait till some such comet makes its appearance.
M. Hock, of Utrecht, has instituted a comparison of the orbits of comets in such a way as to determine whether we should not consider some of those bodies as forming families, rather than being isolated bodies. “I admit,” he says, “ that the orbits of comets are by nature parabolas or hyperbolas,
* Month. Notices, Vol. xxvii. p. 288.
and that in the cases when elliptical orbits are met with, these are occasioned by planetary attractions, or derive their character from the uncertainty of our observations. To allow the contrary would be to admit some comets as permanent members of our planetary system, to which they ought to have belonged since its origin, and so to assert the simultaneous birth of that system and of these comets. As for me I attribute to these a primitive wandering character. Travel-. ling through space they move from one star to another in order to leave it again provided they do not meet with any obstacle that may force them to remain in its vicinity. Such an obstacle was Jupiter, in the neighborhood of our sun, for the comets of Lxell and Brorsen, and probably for the greater part of periodical comets; the other part of which may be indebted for their elliptical orbits to the attractions of Saturn and the remaining planets. Generally, then, comets come to us from some star or other. The attraction of our sun modifies their orbits, as had been done already by each star through whose sphere of attraction they have passed. We can put the qnestion whether they come as single bodies or united in systems. This is the point I have undertaken to investigate. Since some time already I had felt the truth of the following thesis :There are systems of comets in space that are broken up by the attraction of our sun, and whose members attain, as isolated bodies, the vicinity of the earth during a course of several years." To prove
this thesis Hock thought it sufficient to show that some comets have once been near one another at a great distance from the sun ; and also that they composed a system and had not been brought together by chance.
By comparing together the orbits of various comets he finds the comets 1860 III., 1863 I., and 1863 VI, to fulfil the conditions required. He also finds the comets of 1689 and 1698 to answer the conditions ; also comets 1846 VII. and 1847 II.; 1857 III. and 1857 V.; 1862 II. and 1864 II.
* Monthly Notices, Vol. xxv., pp. 243-4. See also Vols. xxvi. & xxvii.
These systems which we have here enumerated, are composed of members whose motion is in the same direction. He finds several other systems some of whose members have direct, and others retrograde motion.
He calls the point where they came under the immediate control of the attraction of the sun, the aphelion point. We give his results for one system. For the aphelion positions he finds for the comets
Longitude. 1860 III.
73.2° 1863 I.
73.9° 1863 VI.
76.4° For the distance from the sun he finds, taking the comets in the above order, the following numbers for the date A.D. 756.97, 600.00, 600.42, 600.25; and for the date A.D. 1020.87, 500.00, 500.56, 500.36. He concludes that these three comets form a system not brought together by chance. He adds another proof. Since these comets were once together and formed one, they were all at the same point on the celestial sphere when broken up, and their orbits must now all intersect in that point. He finds that they do, and its position is in Long. 316° 35' 55" ; and Lat.—76° 56' 42". He further thinks that the star from which they came may be found, or its place within certain limits.
These researches of the Dutch astronomer and mathematician are very interesting. They have, it will be seen, a bearing on the origin of comets, a subject that is now attracting considerable attention. Some recent specnlations of Sig. G. V. Schiaparelli, seem to show that there is a connection between comets and meteors, and that both were derived from regions of the universe beyond the solar system. He finds that the Augnst ring of meteors and the second comet of 1862, have the same orbit, or at least within moderate limits.* According to this, then, we are to regard the comet as a large meteor, or the meteors as small comets. He also finds that the orbit of the November meteors and the orbit of the first comet of 1866, correspond, and have the same relations as in the above case. Each has a period of about thirty-three and a qnarter years.
Monthly Notices. Vol. xxvii. p. 133.
At present there seems to be a strong probability that all comets now attached to our system, have been derived ab extra.
Since Newton's discovery of the law of universal gravitation, and the possibility of comets moving in any of the conic sections, they have exercised a marked influence on the development of mathematical analysis, in the calculation of orbits and the computation of perturbations. They seem now about to reveal to us the existence of forces in the sun that otherwise might never have been discovered. The motion of one, at least, discovers the existence of some opposing force in our system, unfelt, as yet, by the planets, which may yet very much derange the existing state of things.
ART. VIII.-- A Hand Book of Politics for 1868. By EDWARD
McPherson, LL. D. Washington, 1868.
We have no intention of entering into any elaborate discussion of the respective claims of the candidates for the presidency. It would be entirely superfluons, for there never was a greater disparity between any two aspirants for that high office. Our remarks on this subject shall, therefore, be brief. We are convinced that the most thoughtless cannot compare Grant and Seymour with each other in an intelligent manner without deciding in favor of the former; no unprejudiced person endowed with common sense, and having any regard for his country, would hesitate for a moment to reject the latter. That many respectable men will vote for Seymour-men of talent and ability-we do not doubt; nor do we pretend that they should be regarded as rebels for doing 80. It is certainly wrong to vote for an inferior man merely because he belongs to one's own party, but it is a wrong of which all parties are guilty. There should be no abuse, then, on either side, on this ground. It may be freely admitted that it by no means follows that a man is a “rebel,” or that he is in any manner disloyal to his country, or its institutions, merely because he votes for Mr. Seymour; but it certainly does follow that he is a political partisan; that he is one who
has not independence enough to think and act for himself, but must think and act as his party requires him.
It is almost needless for us to say that it is not on political grounds we would choose General Grant for the presidential chair and reject Mr. Seymour; we judge each not by his party but by himself. We are in favor of the election of Grant, not because he is a Republican or a Radical, but because he has merited the gratitude of his country; and we are opposed to the election of Seymour, not because he is a Democrat, but because he has merited nothing good from his country. Indeed, we do not regard Grant as a politician at all; he is too honest and straightforward to be one ; whereas Seymour is nothing but a politician. This is no mere matter of conjecture or inference. Both the candidates are tried men in a certain sense; one commanded our armies at the hour of the nation's greatest peril; the other was the Governor of the State of New York at the same hour.
Now which performed his duties best? Which proved the most faithful public servant? Which contributed most to vindicate the prestige of the American people as capable of defending, as well as governing themselves as a nation ? In a word, did not Grant do all the good which it was possible for any one to do in his position? What more could have been done by Washington himself, could he have lived, to save the life of the Republic of which he was the founder ? Nor could the Father of his country have treated the conquered, brave enemy, with more generosity.
What, upon the other hand, did Seymour do as governor? Conld he have contributed less towards the salvation of the nation without a flagrant violation of his oath, if indeed he could have done so without rendering himself liable to be put on trial as a traitor? We do not agree with those who accuse Mr. Seymour of having sympathized with the rebels to the extent of wishing that they would succeed in dismembering the Republic. We believe that at heart he was in favor of maintaining the Union; but he had not the manliness to speak and act accordingly. The duplicity and chicanery of the politician clung to him all along. He always took into account the influence he might one day be able to exercise in