556 



NATURE 



[Oct. 4, 



NOTES ON METEORITES. 1 



IV. 



Meteorites are Bodies which, like the Earth itself, revolve round 

 the Sun. 



"\X/"E have seen that the phenomena which accompany meteorites 

 entering our air, whether they are soon burnt up and give 

 rise only to the appearance of a shooting or falling star, or 

 whether they are bulky enough to withstand the melting process 

 till they reach the earth's surface, are similar. We are now in 

 a position to discuss the origin of all these phenomena on the 

 assumption that they have a common cause. 



It is not so many years ago since the planetary spaces were 

 supposed to be untenanted by anything more tangible than that 

 mysterious fluid called ether. This notion is exactly represented 

 by the French equivalent for those spaces, le vide planetaire. 

 Hence, not to mention imagined supernatural causes — such as 

 that, for instance, embodied in the tradition that Saint Lawrence, 

 on the anniversary of his martyrdom (August 10), shed burning 

 tears — the cause of the phenomenon was ascribed to atmospheric 

 perturbations, exhalations of sulphur, ignes fatui, and so forth. An 

 account of the August shower of 1857, even, published in the 

 Bulletin de F Academie Royale de Belgique, is accompanied by a 

 minute record of rain, temperature, atmospheric electricity, &c. 

 Leaving out of consideration the opinions of the ancients, 

 among whom Anaxagoras and Seneca may be especially men- 

 tioned, as being in favour of a cosmical origin, it may be pointed 

 out that Kepler 2 regarded meteorites and shooting-stars as akin, 

 and derived both from the ethereal regions. 



Halley was the next to express an opinion that shooting-stars 

 were of cosmical origin, but to Chladni belongs the credit of 

 having broached the theory which modern observations have so 

 abundantly justified. This theory was that space was full of the 

 matter which, attracted by the earth, entered its atmosphere, 

 accompanied by luminous effects only in some cases, and by 

 actual falls of the matter in others. 3 The general acceptance of 

 this view was retarded by Laplace and others, who saw a more 

 probable origin for the phenomena by suppo-ing meteorites to 

 be masses shot out of lunar volcanoes. The first step in the 

 demonstration of such an origin, which is now universally 

 accepted, was made when Chladni, 4 in 1794, showed that 

 no known terrestrial agency was capable of producing masses 

 like the meteorites which had been seen to fall. At his and 

 Lichtenbergh's suggestion, Brandes and Benzenberg in 1798 

 showed that, whatever they appear to do, shooting-stars never 

 shoot upwards, but always downwards towards the earth. At 

 the same time he showed the similarity of phenomena presented 

 by fire-balls, shooting-stars, and the fall of meteorites, to which 

 we have already called attention. He subsequently returned 

 to and strengthened this view. 5 



" Should it be asked how such masses originated, or by what 

 means they were brought into such an insulated position, this 

 question would be the same as if it were asked how the planets 

 originated. Whatever hypothesis we may form, we must either 

 admit that the planets, if we except the many revolutions which 

 they may have undergone, either on or near their surface, have 

 always been since their first formation, and ever will be, the 

 same ; or that Nature, acting on created matter, possesses the 

 power to produce worlds and whole systems, to destroy them, and 

 from their materials to form new ones. For the latter opinion 

 there are, indeed, more grounds than the former, as alternations 

 of destruction and creation are exhibited by all organized and un- 

 organized bodies on our earth ; which gives us reason to suspect 

 that Nature, to which greatness and smallness, considered in 

 general, are merely relative terms, can produce more effects of 

 the same kind on a larger scale. 



"But many variations have been observed on distant bodies, 

 which, in some measure, render the last opinion probable ; for 

 example, the appearing and total disappearing of certain stars, 

 when they do not depend upon periodical changes. If we now 

 admit that planetary bodies have started into existence, we can- 

 not suppose that such an event can have otherwise taken place, 

 than by conjecturing that either particles of matter, which were 

 before dispersed throughout infinite space, in a more soft and 



1 Continued fro-ri p. 533. 2 "Opera," ed. Fritsch, vol. vi. p. 157. 



3 " Ueber den Ursprang der von Pallas gefundenen Eisenmassen," p. 24. 



4 His paper on the Pallas iron is abstracted in Phil. Mag., Tiliock's Series, 

 vol. ii., 1798. 



5 See Phil. ■fl/a£".,Srillock, vol. ii. p. 225, et seq. 



chaotic condition, have united together in large masses, by the 

 power of attraction ; or that new planetary bodies have been 

 formed from the fragments of much larger ones that have been 

 broken to pieces, either perhaps by some external shock, or by 

 an internal explosion. Let whichever of these hypotheses be the 

 truest, it is not improbable, or at least contrary to nature, if we 

 suppose that a large quantity of such material particles, either on 

 account of their too great distance, or because prevented by a 

 stronger movement in another direction, may not have united 

 themselves to the larger accumulating mass of a new world ; but 

 have remained insulated, and, impelled by some shock, have con- 

 tinued their course through infinite space, until they approach so 

 near to some planet as to be within the sphere of its attraction, 

 and then by falling down to occasion the phenomena before 

 mentioned. ■ ■ ...... 



" It is worthy of remark that iron is the principal component - 

 part of all the masses of this kind hitherto discovered ; that it 

 is found almost everywhere on the surface of the earth as a com- 

 ponent part of many substances in the vegetable and animal 

 kingdom ; and that the effects of magnetism give us reason to 

 conclude that there is a large provision of it in the interior parts 

 of the earth. We may therefore conjecture that iron in general 

 is the principal matter employed in the formation of new planetary 

 bodies ; and is still farther probable by this circumstance, that 

 it is exclusively connected with the magnetic power, and also on 

 account of their polarity may be necessary to these bodies. It is 

 also probable, if the above theory be just, that other substances 

 contained in such fallen masses, such as sulphur, siliceous earth, 

 manganese, &c, may be peculiar, not to our globe alone, but 

 may belong to the common materials employed in the formation 

 of all planetary worlds " 



This paper of Chladni's, it will be seen, dates from just 

 before the beginning of the present century. 



The subject was invested with a new interest in 1799, when 

 the great Humboldt, who was then travelling in South America, 

 saw an enormous quantity of shooting-stars covering the sky. 

 In his long account of the shower in his " Personal Narra- 

 tive," he states that, from the beginning of the phenomenon, 

 there was not a space in the firmament equal in extent to three 

 diameters of the moon that was not filled at every instant with 

 bolides and falling stars ; while he was locally informed that j 

 during a previous display in 1766 the inhabitants of Cumanal 

 had beheld the neighbouring volcano, Cayamba, veiled for an 

 hour by a similar display. 



In the next display, observed in the year 1833, 240,000 meteors 

 were computed by Arago to have been visible above the horizon 

 of Boston on the morning of November 13 ; while Mr. 

 Baxendell, who observed the shower from the west coast of 

 Mexico, states that "the number of meteors seen at once often 

 equalled the apparent number of the fixed stars seen at a glance." j 

 Olmsted, when he had witnessed the shower of 1833 (a shower 

 heralded and followed by less brilliant displays in 1831-32 and 

 1834-35-36), and when, moreover, he had compared the 

 phenomena with those recorded by Humboldt and Bonpland in: 

 1799, announced the view which has since been so brilliantly 

 confirmed — that the appearances are due to the passage of the 

 earth through a storm, so to speak, of planetary bodies. 



This was the first blow given to le vide planetaire. Space, 

 instead of being empty, was full of bodies, some of them 

 being congregated into rings, each body composing the rinr. 

 revolving like a planet round the sun. In fact, these rings may 

 be compared to tangible orbits ; indeed, they almost realize tht 

 schoolboy's idea of an orbit, as a considerable part of the path V 

 occupied by a string of little planets, while in the case of 

 earth's orbit, for instance, each point of the path is occupie 

 succession only. 



Still Olmsted did not accept the view that the falling s 

 were of the same nature as meteorites. 



Olmsted also noted that, however numerous the falling 

 might be, or in whatever direction they appeared, or w! 

 ever the apparent lengths of their paths, the lines of m 

 of these paths, retraced along the sky, nearly all found a com 

 focus of emanation or visual crater of projection among the fi 

 stars. This has since been called the radiant point. 



The most salient fact, noticed even by those who did not 

 its significance, during the subsequent display in 1866, was 

 all the meteors seemed to come from the same region of the 

 Among all those seen by myself from 11 p.m. on Tuesday ti 

 a.m. on Wednesday morning, two only were exceptions to tn 

 general direction. In fact, there was a region in which tli 



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