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dimensions of this will, therefore, begin, and continue to increase by the precipitation immediately above it of fresh nebula ; just as we see fogs in cold still nights forming on the surface of the earth, and gradually extending upwards as the heat near the surface is dissipated. The comet would thus appear to enlarge rapidly in its visible dimensions at the moment that its real volume is in fact slowly shrinking by the general abstraction of heat from the mass.
• This process,' says Sir John Herschel, might go on in the entire absence of any solid or fluid nucleus ; but supposing such a nucleus to exist, and to have acquired a considerable increase of temperature in the vicinity of the sun, evaporation from its surface would afford a constant and copious supply of vapour, which, rising into its atmosphere, and condensing at its exterior parts, would tend get more to dilate the visible limits of the nebula. Some such process would naturally enough account for the appearances which have been noticed in the head of certain comets, where a stratum void of nebula has been observed, interposed, as it were, between the denser portion of the head, or nucleus, and the coma. It is analogous to the meteorological phenomenon of a definite rapour plane, so commonly observed ; and in certain cases, may admit of two or more alternations of nebula and clear atmosphere.'
Sir John offers a third supposition to account for the effects, by attributing them to the ethereal medium surrounding the sun.
* Fourier,' says he, ' has rendered it not improbable that the region in which the earth circulates has a temperature of its own greatly superior to what may be presumed to be the absolute zero, and even to some artificial degrees of cold. I have shown, I think satisfactorily, that if this be the case, such temperature cannot be due simply to the radiation of the stars, but must arise from some other cause, such as the contact of an ether, possessing itself a determinate temperature, and tending, like all known fluids, to communicate this temperature to bodies immersed in it. Now, if we suppose the temperature of the ether to increase as we approach the sun, which seems a natural, and indeed a necessary consequence, of regarding it as endued with the ordinary relations of Auids to beat
, we are furnished with an obvious explanation of the phenomenon in question. A body of such extreme tenuity as a comet, may be presumed to take very readily the temperature of the ether in which it is plunged; and the vicissitude of warmth and cold thus experienced, may alternately convert into transparent vapour, and reprecipitate the nebulous substance, just as we see an increase of atmospheric temperature dissipate a fog, not by abstracting or annihilating its aqueous particles, but by causing them to assume the elastic and transparent state which they lose, and again appear in fog when the temperature sinks.'
We cannot conclude without noticing some of the imaginary influences imputed to comets; the more so, because, notwithstanding the general intelligence of these times, such erroneous impressions do still to a certain extent prevail.
One of the most common effects attributed to these bodies, is an influence over the temperature of our seasons. It would be easy to expose such an error, by showing upon general physical principles, that there is no reason whatever, why a comet should produce such an influence; but it will perhaps be more satisfactory to refute it by showing, that it is not in conformity with observed facts. M. Arago has given a table, in which he has exhibited in one column the temperatures of the weather at Paris for every year, from 1735 to 1831 inclusive ; and in juxtaposition with these he has stated the number of comets which appeared, with their magnitude and general appearance. The result is, that no coincidence whatever is observable between the temperatures and the number or appearance of comets. For example, in 1737, although two comets appeared, the mean temperature was inferior to that of the preceding years, during which no comet appeared. The year 1765, in which no comet appeared, was hotter than the year 1766, when two comets appeared; the year 1775, when no comet appeared, was hotter than the year 1780, which was marked by the appearance of two comets; and the temperature was still lower in the year 1785, in which two comets appeared; while on the other hand the temperature of the year 1781 was greater, which was likewise marked by the appearance of two comets.
This question, of the supposed connexion between the temperature and the appearance of comets, has been completely sifted by M. Arago. He has given not only the general temperatures, but also a table of the years of greatest cold-of the years in which the Seine has been frozen over, and also of the years of the greatest heat—and he has shown that the corresponding appearances of comets have been varied without any connexion whatever with these vicissitudes of temperature.
We should have hoped that the absurd influences attributed to comets would, at least in our times, have been confined to physical effects, in which the excuse of ignorance might be pleaded with a less sense of humiliation. But will it be believed that within a few years persons could be found among the better classes of society, and holding some literary and professional station—and in our own country too,—who could attribute to the influence of comets every prevalent disease, local or general, by which, since the commencement of the Christian era, not the human race only was afflicted, but even the lower species of animals?
The splendid comet of 1811 was, on the continent, considered as the immediate cause of the fine vintage of that year, and the produce was distinguished as the wine of the comet. But with us still more extraordinary effects were ascribed to that comet. In the Gentleman's Magazine' for 1818, we were told that its influence produced a mild winter, a moist spring, and a cold summer ; that there was not sufficient sunshine to ripen the fruits of the earth; that, nevertheless (such was the cometic influence), the harvest was abundant, and some species of fruits, such as melons and figs, were not only plentiful, but of a delicious flavour ; that wasps rarely appeared, and flies became blind, and died early in the season ; that, in the neighbourhood of London, numerous instances occurred of women bearing twins, and it even happened, in one instance, that the wife of a shoemaker in Whitechapel had four children at a birth!
So recently as the year 1829, a work appeared upon epidemic diseases, by Mr Forster, an English practitioner, in which it is asserted that, since the Christian era, the most unhealthy periods have been precisely those in which some great comet appeared ; that such appearances were accompanied by earthquakes, volcanic eruptions, and atmospheric commotions, while no comet has been observed during healthy periods. Not contented however, with the influences formerly attributed to comets, Mr Forster, says M. Arago, has so extended, in his learned catalogue, the circle of imputed cometary influences, that there is scarcely any phenomenon which he does not lay to their charge. Hot seasons and cold, tempests, earthquakes, volcanic erruptions, hail, rain and snow, floods and droughts, famines, clouds of midges and locusts, the plague, dysentery, the influenza,+ are all duly registered by Mr Forster; and each affliction is assigned to its eomet, whatever kingdom, city, or village the famine, pestilence or other visitation may have ravaged. In making thus, from year to year, a complete inventory of the misfortunes of this lower world, who would not have foreseen the impossibility of any comet approaching the earth, without finding some por
Illustrations of the atmospherical origin of epidemic diseases, by T. Forster, Chelmsford, 1829.
† We quote M. Arago, not having seen the publication to which he alludes. The celebrated traveller Rüppel wrote from Cairo (8th October, 1835). «The Egyptians think, that the comet now visible is the cause of the great earthquake which we felt here on the 21st of August, and that it also exercises its malign influence over the horses and asses which perish. The truth is, the animals are dying from starvation, their usual forage baving failed in consequence of the insufficent inundation of the Nile.' Were I not restrained by personal considerations, says M. Arago, I could easily convince the reader that, in respect to astronomical knowledge, Egyptians are not confined to the banks of the Nile.
tion of its inhabitants suffering under some affliction; and who would not have granted at once, what Lubienietski has written a large work to prove, that there never was a disaster without a comet, nor a comet without a disaster!
Nevertheless, even the credulity and ingenuity of Mr Forster were in one or two cases at fault, to discover corresponding afflictions for some of the most remarkable comets ;—that of the year 1680, for example, which was not only one of the most brilliant of modern times, but the one which of all others approached nearest to the earth. The utmost delinquency with which he can charge this comet, was that of producing a cold winter, follow• ed by a dry and warm summer, and of causing meteors in Ger* many. To the comet of 1665, he ascribes the great plague of London ; but he does not favour us with any reason why Edinburgh, Dublin, and Paris, not to mention various English towns and villages, were spared from its malign influence. The crowning absurdity, however, is the effect imputed to the comet of 1668. It appears, according to Mr Forster, that the presence of this body made all the cats in Westphalia sick!'
Though our countryman probably stands alone in the degree of his absurdity on this subject, still, society in general, including even the classes reputed most enlightened, cannot be altogether acquitted of ignorance in regard to it. I would have
wished,' says M. Arago, . for the honour of modern philosophy, 6 to be freed from the necessity of taking serious notice of such * absurdities; but I have acquired personal knowledge that some • refutation of them is not useless, and that the advocates of these influences have no inconsiderable number of followers. Listen,
when you are present at one of those brilliant assemblies, where ' you meet what is called good society ;-listen to the talk of • which the approaching comet furnishes the subject, and then • decide if we ought to boast of that diffusion of knowledge, which so many declare to be the characteristic feature of our times.'
Art. VIII.-Specimens of the Table Talk of Samuel Taylor
Coleridge. 2 vols. 8vo. London: 1835.
early period of their lives, to have abandoned for a time the career into which their genius had led them; and that a long interval of silence has frequently elapsed between their youthful efforts and the production of the great performances on which their fame chiefly rests. If the friends of Virgil, according to received tradition, had obeyed his dying injunctions, and destroyed the unfinished Æneid, the greatest of Latin poets would have been known to us only through a few juvenile essays in bucolic and descriptive poetry, differing very widely in character from the epic labour of his later days. If Milton had been surprised by death before the publication of his Paradise Lost, his name would only survive in the annals of English literature as that of an author of great early promise, who had deserted the paths of the Muses for political and religious controversy. Probably the truth is, that a strong poetical temperament, after giving way at first to its own irresistible impulses, subsides often into languor and inactivity, when the judgment, more tardy in its developement, whispers how far all that has been already done falls short of that ideal model of excellence which early aspirations had framed. True genius is ever distinguished by this peculiar craving and seeking after something more elevated than it has been able to attain, or than has been attained by others. It is also too easily discouraged by such disappointment; and either falls into inactivity, or turns its energies into a new direction. There is a precise point in the life of most writers of this higher class, at which the actual effort of composition ceases to be a pleasure, and becomes a toil; and this period generally coincides with that in which the mind becomes conscious of the imperfection of its own powers. With them, consequently, the poetical faculty appears after a time to become stationary; and whether it receives in after-life a fresh impulse or no, depends in great measure upon the course of external discipline into which the mind is thrown, and also upon its own powers of steadiness and concentration. If ever the second crop comes to maturity, it may realize far more than the first had promised. But with many it never comes to maturity at all. In some the engrossing occupations of a busy age, or an increased devotion to other and exclusive pursuits—in others, as was pre-eminently the case with the author from whose Conversations the work before us is com
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