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problem. Under this view of revolution, already expounded in a more general way as applied to meteors of every class, we obtain the only clear notion of a cause of periodicity-the law being the same which governs the planetary system at large, and even the most excentric motions depending on the great principle which maintains general order throughout the universe.
It must be admitted that this theory materially changes our manner of viewing the interplanetary spaces around us. No longer regarded as a void-or filled solely by a subtle ether, imponderable and unseen-these spaces now present themselves as occupied in various parts by matter apparently of the same nature as those of which our globe is composed-but either not yet aggregated into planetary forms, or detached from planetary bodies previously existing. If adopting this idea of meteoric zones or rings, we must necessarily admit several such; leaving open to future research the questions, whether they are of uniform composition and arrangement? whether there is any proof of a progression in the line of nodes, or of oscillation from perturbations? whether we may attribute to them the occasional obscuration of the sun for short periods, which we find on frequent record? and on what physical causes depend the luminous globes and shooting-stars which emanate from them on approaching the earth?
Other questions there are, awaiting the possible solution of the future, some of which our readers will already infer. To explain · the appearance of single meteors, always so sudden, often so brilliant as well as the more substantial phenomenon of falling stones-must we not suppose detached portions of matter, equally revolving as the zones which pour forth periodical showers, but each with an independent orbit of its own? What physical causes can have produced such separate accumulation or consolidation of these portions of matter? Both analogy and the known laws of the mechanism of the heavens furnish a certain explanation of zones or rings, but we have no similar aid to our understanding of these insulated masses moving in space. Are they residual merely upon the consolidation of larger bodies? or must we regard them as detached by some unknown force from bodies already consolidated? The fragmentary character of aerolites, as well as the materials composing them, might suggest the latter idea, and the numerous group of excentric planetoids between Mars and Jupiter give sanction to it; but we have already fol lowed out the argument derived from these sources, and seen how much is wanting to its certainty and completion.
Before closing our article we must make more particular men
tion of the valuable work composed by M. Saigey, but recording, in sequel to an Historical Introduction, those long series of observations by M. Coulvier-Gravier, in which latterly the writer himself took an important share. We prefer such separate notice, both because these researches are little known in this country; and because their purport will be better understood from the relation already given of the previous state of knowledge and opinion on the subject. We ought to begin with stating that M. Saigey acquiesces only very partially in the conclusions we have described, as adopted by the most eminent scientific men of the age. He contends that these conclusions are premature; based in many points on doubtful or insufficient observations, and pressed forward by the zeal of astronomers relying too much on analogies drawn from their own more certain science. He asserts that longer and closer research into facts is needful to all theory on the subject; and justifies this by the record of results which show at least that other and new conditions must be added to the theories of meteoric phenomena now received. Of the more remarkable of these results we shall give a short summary; such as may enable our readers to judge of their nature and bearing on the argument.
Observations on shooting-stars and other meteors were begun by M. Coulvier-Gravier at Rheims as early as 1811; under electrical and other theories of their origin, which he afterwards abandoned. It was not, however, until 1841 that, at the suggestion of Arago, he began carefully to register their number, times of appearance, and direction in the heavens. In 1845 M. Saigey associated himself to his labours, and aided greatly in generalizing and giving method to the results. In a period of 42 months, between 1841 and 1845, there were 5302 shootingstars recorded-seen during 1054 hours of observation. The number would doubtless have been much greater but for the interference of the moon, which, when full, effaces nearly three-fifths of the stars otherwise visible. An estimate made, with allowance for this cause, brings out the mean horary number of 6; the actual mean number seen per hour being 5.6. The passing obscuration by clouds makes another void in the calculation, the amount of which it is difficult to estimate.
But this general horary mean loses its interest in another more curious and unlooked-for result of these observations, viz. the variations found to exist at different hours. With rare exceptions, the number of visible meteors increases as the night advances; and this at all times of the year, and with regularity enough to furnish the basis of tables for each successive hour of the night. A few instances we give from different hours between evening
and morning. In the evening from 6 to 7 o'clock the mean number of stars falling is 3·3-from 9 to 10 o'clock 4-from 11 to 12 o'clock 5-from 2 to 3 o'clock in the morning 7 1-from 5 to 6 o'clock 8.2. And this gradation is maintained as well at the times of periodical return of such meteors as on ordinary nights.
Equally remarkable is the result as to the monthly or annual variations of these phenomena. A laborious reduction of observations has furnished a table expressing the monthly mean of the horary number at midnight. This table shows a singular disparity between the first six months of the year and the last; the mean number of shooting-stars in the former being only 3.4 in the hour—in the latter rising as high as 8—that is, a smaller number when the earth is moving from perihelion to aphelion, or receding from the sun-a much greater number in the after six months, when it is advancing towards its perihelion. The transition is rapid from one of these conditions to the other. In December the mean number in the hour is 7·2-in January only 3.6. In June it is 3.2-in July 7.0. It is well worthy of note that the two maxima in the table occur in August and November-corresponding exactly in date with the periodical showers we have described-and with the further concurrence of fact that these maxima do not present themselves every year. In 1842 the mean for August was 11.9-in 1844 only 5.4. In 1842 the mean for November was 11.3-in 1843 it was 5.4.
Another part of the researches before us regards the direction of these shooting-stars. Without entering into the details, which are also given tabularly, we may remark the general conclusion that almost exactly the same number come from the north and south conjointly, as from the east and west; but with this diversity in the two cases, that, while the number is nearly the same from north and south, the number coming from the east much more than doubles that from the west. The amount of this diversity, however, differs in different years. The copious accumulation of facts, and great exactitude in the manner of observation, afforded other curious results, as to the length of the visible trajectories, the position of the centre of the meteors, &c. The shooting-stars comprised between the N.N.E. and N.E. have the longest visible course, their mean line being upwards of 15 degrees—those between W.S.W. and S.W. are only seen through about 11 degrees. Whatever the time of year or hour of night the line is one of descent towards the horizon. Out of 5302 fifteen only were seen to describe curved lines.
The estimate of our authors as to the height of shooting-stars places their point of appearance at from 20 to 50 or 60 miles
above the earth. Their relative size, colour, and manner of apparition were carefully observed. Of Bolides (luminous globes) eight were noted during the 42 months, three only of which burst, and these without any noise of explosion. Of the proper shooting-stars 80 were registered of the first magnitude, that is, having the apparent size and lustre of Venus or Jupiter. The others were classed down to the sixth magnitude, corresponding to the fifth of the fixed stars. The colour, especially of the largest, is generally a pure white. Those of reddish tint are rarer; but they are remarkable as seeming to be slower in movement, and not leaving trains of light behind. Some occur of bluish colour, but still more rarely.
We find it necessary to abstain from further details, but we believe we have said enough to show the value of these new researches. They clearly suggest many important considerations hitherto little regarded; and some of these, as we have already remarked, at variance with the conclusions generally adopted before. We must needs admit that a revision of those conclusions is required; and their adaptation, if such be possible, to the new facts brought before us. Assuming the authenticity of the latter, we are bound to say that no theory of meteoric phenomena can be valid or complete which does not include and explain the horary and annual variations just described. They are problems of high interest, but doubtless of great difficulty. And while recording the most recent researches in this part of science, we must repeat our opinion, that a much larger basis of observation is required before we can raise the phenomena to the class of astronomical facts. Time alone is capable of affording: this. We cannot follow the fleeting meteor as we do the planet, or even the more excentric comet, night after night, on their paths. But modern science has taught us to derive certainty from averages as well as from more direct observation; and the multiplication of insulated facts, if exact and authentic in kind, is sure in the end to conduct us to the truth desired, or as near to it as human powers are permitted to approach. Happy those who can detach themselves at times from the turmoil and troubles of the busy world we inhabit, and find repose among the more silent wonders of the universe without!-a contemplation scarcely disturbed even by these flaming ministers of the sky, which now no longer come to affright mankind, but to enlighten and enlarge their intelligence and power.
ART. V.-The Cloister Life of the Emperor Charles V. By W. Stirling, M.P. 8vo. 1852.
NEVEN years have passed since the Spanish Handbook made us acquainted with Mr. Ford's visit to the convent of Yuste, where Charles V. breathed his last. Previously no Englishman of any note-Lord John Russell, we believe, excepted-had penetrated into that remote retreat, which certainly no one had described. Now that Spain is replaced in the Anglo-Saxon travelling map, a change has come over the spirit of the scene:-this secluded spot, so beautiful in itself and so rich in associations, forms a popular point to our pilgrims, and the solitude of the cell ceases when the long vacation begins. In welcoming again to our pages one of these more recent tourists the accomplished annalist of the Artists of Spain-we rejoice to see such good use made of the precious boons of leisure and fortune, and trust that the new member for Perthshire will not forswear type in disgust of bales of blue books, but continue from time to time to entertain and instruct us with tomes like this.
It is not unlikely that, in the choice of his present subject, Mr. Stirling was influenced by the feeling that it would be peculiarly becoming in a Spanish student born north of the Tweed, to make the amende honorable to history, by refuting some gross errors to which two of his countrymen had given currency nearly a century ago. We cheerfully admit the merits of the Robertson school, the first to cut down the folio Rapin phalanx into reasonable proportions. They deserve lasting gratitude as the pioneers who made history accessible; and if they sacrificed too much to style, it was the French fashion of the day, when authors, relying more on rhetoric than research, trusted to mask the shallowness of the stream by the sparkle that danced on a clear surface; and graceful writing-the secret of pleasant reading-does indeed cover a multitude of sins. History thus made easy, and speaking the language of bon ton, was sufficient for our forefathers, who, provided general outlines were drawn with a free hand, neither cared for correctness in particulars, nor were displeased with touching incidents, invented by ingenious gentlemen, either contemners of real facts or too indolent to hunt for them, and who, like contemporary geographers, placed elephants instead of towns' in the open downs of guess-work description. No Niebuhr had then arisen to separate truth from fable, to fix precision of detail, and furnish a model to modern investigation and accuracy. 'Oh! read me not history,' exclaimed Sir Robert Walpole, for that