*****
Several other meteoric epochs have been indicated; some of which, however, must yet be regarded as doubtful. In thirty years, from 1809 to 1839, 12 falls of bolides and meteoric stones occurred from the 27th to the 29th of November. Such coincidences can hardly be accidental. Unusual numbers of shooting-stars have also been seen about the 27th of July; from the 15th to the 19th of October, and about the middle of February. The radiant, for the last-mentioned epoch, is inLeo Minor. The numbers observed in October are said to be at present increasing. At least seven of the exhibitions in Quetelet's catalogue arereferable to this epoch. It is worthy of remark, moreover, that three of the dates specified by Mr. Greg asaeroliteepochs are coincident with those of shooting-stars; viz., February 15th–19th, July 26th, and December 13th. The whole number of exhibitions enumerated in Quetelet's catalogue is 315. In eighty-two instances the day of the month on which the phenomenon occurred is not specified. Nearly two-thirds of the remainder, as we have seen, belong to established epochs, and the periodicity of others will perhaps yet be discovered. But reasons are not wanting for believing that our system is traversed by numerous meteoric streams besides those which actually intersect the earth's orbit. The asteroid region between Mars and Jupiter is probably occupied by such an annulus. The number of these asteroids increases as their magnitudes diminish; and this doubtless continues to be the case far below the limit of telescopic discovery. The zodiacal light is probably a dense meteoric ring, or rather, perhaps, a number of rings. We speak of it asdensein comparison with others, which are invisible except by the ignition of their particles in passing through the atmosphere. From a discussion of the motions of the perihelia of Mercury and Mars, Leverrier has inferred the existence of two rings of minute asteroids; one within the orbit of Mercury, whose mass is nearly equal to that of Mercury himself; the other at the mean distance of the earth, whose mass cannotexceedthe tenth part of the mass of the earth.
Within the last few years a distinguished European savant, Buys-Ballot, of Utrecht, has discovered ashort period of variation in the amount of solar heat received by the earth: the time from one maximum to another exceeding the period of the sun's apparent rotation by about twelve hours. The variation cannot therefore be due to any inequality in the heating power of the different portions of the sun's surface. The discoverer has suggested that it may be produced by a meteoric ring, whose period slightly exceeds that of the sun's rotation. Such a zone might influence our temperature by partially intercepting the solar heat.
1. The average number of shooting-stars seen in a clear, moonless night by a single observer, is about 8 per hour.Oneobserver, however, sees only about one-fourth of those visible from his point of observation. About 30 per hour might therefore be seen by watching the entire hemisphere. In other words, 720 shooting-stars per day could be seen by the naked eye at any one point of the earth's surface, did the sun, moon, and clouds permit.
2. The mean altitude of shooting-stars above the earth's surface is about 60 miles.
3. The number visible over the whole earth is about 10,460 times the number to be seen at any one point. Hence the average number of those daily entering the atmosphere and having sufficient magnitude to be seen by the naked eye, is about 7,532,600.
4. The observations of Pape and Winnecke indicate that the number of meteors visible through the telescope, employed by the latter, is about 53 timesthe number visible to the naked eye, or about 400,000,000 perday.9This is two per day, or 73,000 per century, for every square mile of the earth's surface. By increasing the optical power, this number would probably be indefinitely increased. At special times, moreover, such as the epochs of the great meteoric showers, the addition of foreign matter to our atmosphere is much greater than ordinary. It becomes, therefore, an interesting question whether sensible changes may not thus be produced in the atmosphere of our planet.
5. In August, 1863, 20 shooting-stars were doubly observed in England; that is, they were seen at two different stations. The average weight of these meteors, estimated—in accordance with the mechanical theory of heat—from the quantity of light emitted, was a little more than two ounces.
6. A meteoric mass exterior to the atmosphere, and consequently non-luminous, was observed on the evening of October 4th, 1864, by Edward Heis, a distinguished European astronomer. It entered the field of view as he was observing the milky way, and he was enabled to follow it over 11 or 12 degrees of its path. It eclipsed, while in view, a number of the fixed stars.
It is now well known that much greater variety obtains in the structure of the solar system than was formerly supposed. This is true, not only in regard to the magnitudes and densities of the bodies composing it, but also in respect to the forms of their orbits. The whole number of planets, primary and secondary, known to the immortal author of theMecanique Celeste, was only 29. This number has been more than quadrupled in the last quarter of a century. In Laplace's view, moreover, all comets were strangers within the solar domain, having entered it from without. It is now believed that a large proportion originated in the system and belong properly to it.
The gradation of planetary magnitudes, omitting such bodies as differ but little from those given, is presented at one view in the following table:
The diminution doubtless continues indefinitely below the present limit of optical power. If, however, the orbits have small eccentricity, such asteroids could not become known to us unless their mean distances were nearly the same with that of the earth. But from the following table it will be seen that the variety is no less distinctly marked in the forms of the orbits:
Were the eccentricities of the nearest asteroids equal to that of Faye's comet, they would in perihelionintersect the earth's orbit. Now, in the case of both asteroids and comets, the smallest are the most numerous; and as this doubtless continues below the limit of telescopic discovery, the earth ought to encounter such bodies in its annual motion.It actually does so.The number ofcometoidsthus encountered in the form ofmeteoric stones,fire-balls, andshooting-starsin the course of a single year amounts to many millions. The extremely minute, and such as consist of matter in the gaseous form, are consumed or dissipated in the upper regions of the atmosphere. No deposit from ordinary shooting-stars has ever been known to reach the earth's surface. But there is probably great variety in the physical constitution of the bodies encountered; and though comparatively few contain a sufficient amount of matter in the solid form to reach the surface of our planet, scarcely a year passes without the fall of meteoric stones in some part of the earth, either singly or in clusters. Now, when we consider how small a proportion of the whole number are probably observed, it is obvious that the actual occurrence of the phenomenon can be by no meansrare.11
Although numerous instances of the fall of aerolites had been recorded, some of them apparently well authenticated, the occurrence long appeared too marvelous and improbable to gain credence with scientific men. Such a shower of rocky fragments occurred, however, on the 26th of April, 1803, atL'Aigle, in France, as forever to dissipate all doubt on the subject. At one o'clockP.M., the heavens being almost cloudless, a tremendous noise, like that of thunder, was heard, and at the same time an immense fire-ball was seen moving with great rapidity through the atmosphere. This was followed by a violent explosion which lasted several minutes, and which was heard not only at L'Aigle, but in every direction around it to the distance of seventy miles. Immediately after a great number of meteoric stones fell to the earth, generally penetrating to some distance beneath the surface. The largest of these fragments weighed 17½ pounds. This occurrence very naturally excited great attention. M. Biot, under the authority of the government, repaired to L'Aigle, collected the various facts in regard to the phenomenon, took the depositions of witnesses, etc., and finally embraced the results of his investigations in an elaborate memoir.
It would not comport with the design of the present treatise to give an extended list of these phenomena. The following account, however, includes the most important instances of the fall of aerolites, and also of the displays of meteoric fire-balls.
1. According to Livy a number of meteoric stones fell on the Alban Hill, near Rome, about the year 654B.C.This is the most ancient fall of aerolites on record.
2. 468B.C., about the year in which Socrates was born. A mass of rock, described as "of the size of two millstones," fell at Ægos Potamos, in Thrace. An attempt to rediscover this meteoric mass, so celebrated in antiquity, was recently made, but withoutsuccess. Notwithstanding this failure, Humboldt expressed the hope that, as such a body would be difficult to destroy, it may yet be found, "since the region in which it fell is now become so easy of access to European travelers."
3. 921A.D.An immense aerolite fell into the river (a branch of the Tiber) at Narni, in Italy. It projected three or four feet above the surface of the water.
4. 1492, November 7th. An aerolite, weighing two hundred and seventy-six pounds, fell at Ensisheim, in Alsace, penetrating the earth to the depth of three feet. This stone, or the greater portion of it, may still be seen at Ensisheim.
5. 1511, September 14th. At noon an almost total darkening of the heavens occurred at Crema. "During this midnight gloom," says a writer of that period, "unheard-of thunders, mingled with awful lightnings, resounded through the heavens. * * * On the plain of Crema, where never before was seen a stone the size of an egg, there fell pieces of rock of enormous dimensions and of immense weight. It is said that ten of these were found weighing a hundred pounds each." A monk was struck dead at Crema by one of these rocky fragments. This terrific meteoric display is said to have lasted two hours, and 1200 aerolites were subsequently found.
6. 1637, November 29th. A stone, weighing fifty-four pounds, fell on Mount Vaison, in Provence.
7. 1650, March 30th. A Franciscan monk was killed at Milan by the fall of a meteoric stone.
8. 1674. Two Swedish sailors were killed on ship-board by the fall of an aerolite.
9. 1686, July 19th. An extraordinary fire-ball was seen in England; its motion being opposite to that of the earth in its orbit. Halley pronounced this meteor a cosmical body. (See Philos. Transact., vol. xxix.)
10. 1706, June 7th. A stone weighing seventy-two pounds fell at Larissa, in Macedonia.
11. 1719, March 19th. Another great meteor was seen in England. Its explosion occurred at an elevation of 69 miles. Notwithstanding its height, however, the report was like that of a broadside, and so great was the concussion that windows and doors were violently shaken.
12. 1751, May 26th. Two meteoric masses, consisting almost wholly of iron, fell near Agram, the capital of Croatia. The larger fragment, which weighs seventy-two pounds, is now in Vienna.
13. 1756. The concussion produced by a meteoric explosion threw down chimneys at Aix, in Provence, and was mistaken for an earthquake.
14. 1771, July 17th. A large meteor exploded near Paris, at an elevation of 25 miles.
15. 1783, August 18th. A fire-ball of extraordinary magnitude was seen in Scotland, England, and France. It produced a rumbling sound like distant thunder, although its elevation above the earth's surface was 50 miles at the time of its explosion. The velocity of its motion was equal to that of the earth in its orbit, and its diameter, according to Sir Charles Blagden, was about half a mile.
16. 1790, July 24th. Between nine and ten o'clock at night a very large igneous meteor was seen near Bourdeaux, France. Over Barbotan a loud explosionwas heard, which was followed by a shower of meteoric stones of various magnitudes.
17. 1794, July. A fall of about a dozen aerolites occurred at Sienna, Tuscany.
18. 1795, December 13th. A large meteoric stone fell near Wold Cottage, in Yorkshire, England. The following account of the phenomenon is taken from Milner'sGallery of Nature, p. 134: "Several persons heard the report of an explosion in the air, followed by a hissing sound; and afterward felt a shock, as if a heavy body had fallen to the ground at a little distance from them. One of these, a plowman, saw a huge stone falling toward the earth, eight or nine yards from the place where he stood. It threw up the mould on every side; and after penetrating through the soil, lodged some inches deep in solid chalk rock. Upon being raised, the stone was found to weigh fifty-six pounds. It fell in the afternoon of a mild but hazy day, during which there was no thunder or lightning; and the noise of the explosion was heard through a considerable district."
19. 1796, February 19th. A stone of ten pounds' weight fell in Portugal.
20. 1798, March 12th. A stone weighing twenty pounds fell at Sules, near Ville Franche.
21. 1798, March 17th. An aerolite weighing about twenty pounds fell at Sale, Department of the Rhone.
22. 1798, December 19th. A shower of meteoric stones fell at Benares, in the East Indies. An interesting account of the phenomenon was given by J. Lloyd Williams, F.R.S., then a resident in Bengal. The sky had been perfectly clear for several days. At eight o'clock in the evening a large meteor appeared,which was attended with a loud rumbling noise. Immediately after the explosion a sound was heard like that of heavy bodies falling in the neighborhood. Next morning the fresh earth was found turned up in many places, and aerolites of various sizes were discovered beneath the surface.
23. 1803, April 26th. The shower at L'Aigle, previously described.
24. 1807, December 14th. A large meteor exploded over Weston, Connecticut. The height, direction, velocity, and magnitude of this body were ably discussed by Dr. Bowditch in a memoir communicated to the American Academy of Arts and Sciences in 1815. The following condensed statement of the principal facts, embodied in Dr. Bowditch's paper, is extracted from thePeople's Magazinefor January 25th, 1834:
"The meteor of 1807 was observed about a quarter-past six on Monday morning. The day had just dawned, and there was little light except from the moon, which was just setting. It seemed to be half the diameter of the full moon; and passed, like a globe of fire, across the northern margin of the sky. It passed behind some clouds, and when it came out it flashed like heat lightning. It had a train of light, and appeared like a burning fire-brand carried against the wind. It continued in sight about half a minute, and, in about an equal space after it faded, three loud and distinct reports, like those of a four-pounder near at hand, were heard. Then followed a quick succession of smaller reports, seeming like what soldiers call a running fire. The appearance of the meteor was as if it took three successive throes,or leaps, and at each explosion a rushing of stones was heard through the air, some of which struck the ground with a heavy fall.
"The first fall was in the town of Huntington, near the house of Mr. Merwin Burr. He was standing in the road, in front of his house, when the stone fell, and struck a rock of granite about fifty feet from him, with a loud noise. The rock was stained a dark-red color, and the stone was principally shivered into very small fragments, which were thrown around to a distance of twenty feet. The largest piece was about the size of a goose egg, and was still warm.
"The stones of the second explosion fell about five miles distant, near Mr. William Prince's residence, in Weston. He and his family were in bed when they heard the explosion, and also heard a heavy body fall to the earth. They afterward found a hole in the earth, about twenty-five feet from the house, like a newly dug post-hole, about one foot in diameter, and two feet deep, in which they found a meteoric stone buried, which weighed thirty-five pounds. Another mass fell half a mile distant, upon a rock, which it split in two, and was itself shivered to pieces. Another piece, weighing thirteen pounds, fell a half a mile to the northeast, into a plowed field.
"At the last explosion, a mass of stone fell in a field belonging to Mr. Elijah Seely, about thirty rods from the house. This stone falling on a ledge, was shivered to pieces. It plowed up a large portion of the ground, and scattered the earth and stones to the distance of fifty or a hundred feet. Some cattle thatwere near were very much frightened, and jumped into an inclosure. It was concluded that this last stone, before being broken, must have weighed about two hundred pounds. These stones were all of a similar nature, and different from any commonly found on this globe. When first found, they were easily reduced to powder by the fingers, but by exposure to the air they gradually hardened."
25. 1859, November 15th. Between nine and ten o'clock in the morning, an extraordinary meteor was seen in several of the New England States, New York, New Jersey, the District of Columbia, and Virginia. The apparent diameter of the head was nearly equal to that of the sun, and it had a train, notwithstanding the bright sunshine, several degrees in length. Its disappearance on the coast of the Atlantic was followed by a series of the most terrific explosions. It is believed to have descended into the water, probably into Delaware Bay. A highly interesting account of this meteor, by Prof. Loomis, may be found in theAmerican Journal of Science and Artsfor January, 1860.
26. 1860, May 1st. About twenty minutes before one o'clockP.M., a shower of meteoric stones—one of the most extraordinary on record—fell in the S. W. corner of Guernsey County, Ohio. Full accounts of the phenomena are given inSilliman's Journalfor July, 1860, and January and July, 1861, by Professors E. B. Andrews, E. W. Evans, J. L. Smith, and D. W. Johnson. From these interesting papers we learn that the course of the meteor was about 40° west of north. Its visible track was over Washington and Noble Counties, and the prolongation ofits projection, on the earth's surface, passes directly through New Concord, in the S. E. corner of Muskingum County. The height of the meteor, when seen, was about 40 miles, and its path was nearly parallel with the earth's surface. The sky, at the time, was, for the most part, covered with clouds over northwestern Ohio, so that if any portion of the meteoric mass continued on its course, it was invisible. The velocity of the meteor, in relation to the earth's surface, was from 3 to 4 miles per second; and hence its absolute velocity in the solar system was from 20 to 21 miles per second. This would indicate an orbit of considerable eccentricity.
"At NewConcord,12Muskingum County, where the meteoric stones fell, and in the immediate neighborhood, there were many distinct and loud reports heard. At New Concord there were first heard in the sky, a little southeast of the zenith, a loud detonation, which was compared to that of a cannon fired at the distance of half a mile. After an interval of ten seconds another similar report. After two or three seconds another, and so on with diminishing intervals. Twenty-three distinct detonations were heard, after which the sounds became blended together and were compared to the rattling fire of an awkward squad of soldiers, and by others to the roar of a railway train. These sounds, with their reverberations, are thought to have continued for two minutes. The last sounds seemed to come from a point in the southeast 45° below the zenith. Theresult of this cannonading was the falling of a large number of stony meteorites upon an area of about ten miles long by three wide. The sky was cloudy, but some of the stones were seen first as 'black specks,' then as 'black birds,' and finally falling to the ground. A few were picked up within twenty or thirty minutes. The warmest was no warmer than if it had lain on the ground exposed to the sun's rays. They penetrated the earth from two to three feet. The largest stone, which weighed one hundred and three pounds, struck the earth at the foot of a large oak tree, and, after cutting off two roots, one five inches in diameter, and grazing a third root, it descended two feet ten inches into hard clay. This stone was found resting under a root that was not cut off. This would seemingly imply that it entered the earth obliquely."
Over thirty of the stones which fell were discovered, while doubtless many, especially of the smaller, being deeply buried beneath the soil, entirely escaped observation. The weight of the largest ten was four hundred and eighteen pounds.
27. 1864, May 14th. Early in the evening a very large and brilliant meteor was seen in France, from Paris to the Spanish border. At Montauban, and in the vicinity, loud explosions were heard, and showers of meteoric stones fell near the villages of Orgueil and Nohic. The principal facts in regard to this meteor are the following:
or equal to that of the earth's orbital motion. "This example," says Prof. Newton, "affords the strongest proof that the detonating and stone-producing meteors are phenomena not essentially unlike."
The foregoing list contains but a small proportion even of those meteoric stones the date of whose fall is known. But besides these, other masses have been found so closely similar in structure to aerolites whose descent has been observed, as to leave no doubt in regard to their origin. One of these is a mass of iron and nickel, weighing sixteen hundred and eighty pounds, found by the traveler Pallas, in 1749, at Abakansk, in Siberia. This immense aerolite may be seen in the Imperial Museum at St. Petersburg. On the plain of Otumpa, in Buenos Ayres, is a meteoric mass 7½ feet in length, partly buried in the ground. Its estimated weight is thirty-three thousand six hundred pounds. A specimen of this stone, weighing fourteen hundred pounds, has been removed and deposited in one of the rooms of the British Museum. A similar block, of meteoric origin, weighing twelve or thirteen thousand pounds, was discovered some years since in the Province of Bahia, in Brazil.
Some of the inferences derived from the examination of meteoric stones, and the consideration of the phenomena attending their fall, are the following:
1. R. P. Greg, Esq., of Manchester, England, who has made luminous meteors a special study, has found that meteoric stone-falls occur with greater frequency than usual on or about particular days. He calls attention especially to five aerolite epochs, viz.:February 15th–19th; May 19th; July 26th; November 29th, and December 13th.
2. It is worthy of remark that no new elements have been found in meteoric stones. Humboldt, in hisCosmos, called attention to this interesting fact. "I would ask," he remarks, "why the elementary substances that compose one group of cosmical bodies, or one planetary system, may not in a great measure be identical? Why should we not adopt this view, since we may conjecture that these planetary bodies, like all the larger or smaller agglomerated masses revolving round the sun, have been thrown off from the once far more expanded solar atmosphere, and have been formed from vaporous rings describing their orbits round the central body?"13
3. But while aerolites contain no elements but such as are found in the earth's crust, the manner in which these elements are combined and arranged is so peculiar that a skillful mineralogist will readily distinguish them from terrestrial substances.
4. Of the eighteen or nineteen elements hitherto observed in meteoric stones, iron is found in the greatest abundance. The specific gravities vary from 1·94 to 7·901: the former being that of the stone of Alais, the latter, that of the meteorite of Wayne County, Ohio, described by Professor J. L. Smith inSilliman's Journalfor November, 1864, p. 385. In most cases, however, the specific gravity is about 3 or 4.
5. The contemplation of the heavenly bodies hasoften produced in thoughtful minds an intense desire to know something of their nature and physical constitution. This curiosity is gratified in the examination of aerolites. To handle, weigh, inspect, and analyze bodies that have wandered unnumbered ages through the planetary spaces—perhaps approaching in their perihelia within a comparatively short distance of the solar surface, and again receding in their aphelia to the limits of the planetary system—must naturally excite a train of pleasurable emotions.
6. It is highly probable that in pre-historic times, before the solar system had reached its present stage of maturity, those chaotic wanderers were more numerous in the vicinity of the earth's orbit than in recent epochs. Even now the interior planets, Mercury and Venus, appear to be moving through the masses of matter which constitute the zodiacal light. It would seem probable, therefore, that they are receiving from this source much greater accretions of matter than the earth.
7. As Mercury's orbit is very eccentric, he is beyond his mean distance during much more than half his period. Hence, probably, the greater increments of meteoric matter are derived from such portions of the zodiacal light as have a longer period than Mercury himself. If so, the tendency would be to diminish slowly the planet's mean motion. Such a lengthening of the period has been actuallydiscovered.14
It is highly probable that aerolites and shooting-stars are derived either from rings thrown off in the planes of the solar or planetary equators, or from streams of nebulous matter drawn into the solar system by the sun's attraction. Such annuli or streams would probably each furnish an immense number of meteor-asteroids. If any rings intersect the earth's orbit, our planet must encounter such masses as happen at the same time to be passing the point of intersection. This must be repeatedat the same epochin different years; the frequency of the encounter of course depending on the closeness and regularity with which the masses are distributed around the ring. Accordingly it has been found that not only the meteors of November 14th and of the epochs named in Chapter II. have their respective radiants, but also those of many other nights. Mr. Alexander S. Herschel, of Collingwood, England, states that fifty-six such points of divergence are now well established. We have mentioned in a previous chapter that Mr. Greg, of Manchester, has specified several epochs at which fire-balls appear, and meteoric stone-falls occur, with unusual frequency. The number of these periods will probably be increased by future observations. Perhaps the following factsmay justify the designation of July 13th–14th as such an epoch:
1. On the 13th of July, 1797, a large fire-ball was seen in Göttingen.
2. On the 14th of July, 1801, a fire-ball was seen in Montgaillard.
3. On the 14th of July, 1845, a brilliant meteor was seen in London.
4. On the 13th of July, 1846, at about 9h. and 30m.P.M., a brilliant fire-ball passed over Maryland and Pennsylvania, and was seen also in Virginia, Delaware, New Jersey, New York, and Connecticut. Its course was north, about thirty degrees east, and the projection of its path on the earth's surface passed about four miles west of Lancaster, Pennsylvania, and nearly through Mauch Chunk, in Carbon County. When west of Philadelphia its angle of elevation, as seen from that city, was forty-two degrees. Consequently its altitude, when near Lancaster, was about fifty-nine miles. The projection of its visible path, on the earth's surface, was at least two hundred and fifty miles in length. Its height, when nearest Gettysburg, was about seventy miles, and it disappeared at an elevation of about eighteen miles, near the south corner of Wayne County, Pennsylvania. Its apparent diameter, as seen from York and Lancaster, was about half that of the moon, and its estimated heliocentric velocity was between twenty and twenty-five miles.
The author was assured by persons in Harford County, Maryland, and also in York, Pennsylvania, that shortly after the disappearance of the meteor a distinct report, like that of a distant cannon, washeard. As might be expected, their estimates of the interval which elapsed were different; but Daniel M. Ettinger, Esq., of York, who was paying particular attention, in expectation of a report, stated that it was a little over six minutes. This would indicate a distance of about seventy-five miles. The sound could not therefore have resulted from an explosion at or near the termination of the meteor's observed path. The inclination of the meteoric track to the surface of the earth was such that the body could not have passed out of the atmosphere. As no aerolites, however, were found beneath any part of its path, perhaps the entire mass may have been dissipated before reaching the earth.—Silliman's Journalfor May, 1866.
5. On the 14th of July, 1847, a remarkable fall of aerolites was witnessed at Braunau, in Bohemia. Humboldt states that "the fallen masses of stone were so hot, that, after six hours, they could not be touched without causing a burn." An analysis of some of the fragments, by Fischer and Duflos, gave the following result:
6. On the 13th of July, 1848, a brilliant fire-ball was seen at Stone-Easton, Somerset, England.
7. On the 13th of July, 1852, a large bolide was seen in London.
8. On the 14th of July, 1854, a fire-ball was seen at Senftenberg.
9. On the 13th of July, 1855, a meteor, three times as large as Jupiter, was seen at Nottingham, England.
10. "One of the most celebrated falls that have occurred of late years is that which happened on the 14th of July, 1860, between two and half-past two in the afternoon, at Dhurmsala, in India. The aerolite in question fell with a most fearful noise, and terrified the inhabitants of the district not a little. Several fragments were picked up by the natives, and carried religiously away, with the impression that they had been thrown from the summit of the Himalayas by an invisible Divinity. Lord Canning forwarded some of these stones to the British Museum and to the Vienna Museum. Mr. J. R. Saunders also sent some of the stones to Europe. It appears that, soon after their fall, the stones wereintensely cold.15They are ordinary earthy aerolites, having a specific gravity of 3·151, containing fragments of iron and iron pyrites;they have an uneven texture, and a pale-gray color."
11. At a quarter-past ten o'clock on the evening of July 13th, 1864, a large fire-ball was seen in NewEngland.16The hour of its appearance, it will be observed, was nearly the same with that of the bolide of July 13th, 1846; and it is also worthy of remark that theirdirectionswere nearly the same. The meteor of 1864 had a tail three or four degrees in length, and the body, like that of 1846, exploded with a loud report.
12. On the 8th of July, 1186, an aerolite fell at Mons, in Belgium (Quetelet'sPhysique du Globe, p. 320). A forward motion of the node, somewhat less than that observed in the rings of November and August, would give a correspondence of dates between the falls of 1186, 1847, and 1860.
With the exception of the last, which is doubtful, these phenomena all occurred within a period of 67 years.
It has been stated that in different years meteoric stones have fallen about the 29th of November. One of the most recent aerolites which can be assigned to this epoch is that which fell on the 30th of November, 1850, at Shalka, in Bengal. It may be mentioned, as at least a coincidence, that the earth passes the approximate intersection of her orbit with that of Biela's comet at the date of this epoch. Doother bodies besides the two Biela comets move in the same ellipse? It is worthy of remark that two star showers have been observed at this date: one in China,A.D.930, the other in Europe, 1850 (see Quetelet's Catalogue). It is certainly important that the meteors of this epoch should be carefully studied.
Professor Charles Upham Shepard, of Amherst College, who has devoted special attention to the study of meteoric stones, has designated two districts of country, one in each continent, but both in the northern hemisphere, in which more than nine-tenths of all known aerolites have fallen. He remarks: "The fall of aerolites is confined principally to two zones; the one belonging to America is between 33° and 44° north latitude, and is about 25° in length. Its direction is more or less from northeast to southwest, following the general line of the Atlantic coast. Of all known occurrences of this phenomenon during the last fifty years, 92·8 per cent. have taken place within these limits, and mostly in the neighborhood of the sea. The zone of the Eastern continent—with the exception that it extends ten degrees more to the north—lies between the same degrees of latitude, and follows a similar northeast direction, but is more than twice the length of the American zone. Of all the observed falls of aerolites, 90·9 per cent. have taken place within this area, and were alsoconcentrated in that half of the zone which extends along the Atlantic."
The facts as stated by Professor Shepard are, of course, unquestionable. It seems, however, extremely improbable that the districts specified should receive a much larger proportion of aerolites than others of equal extent. How, then, are the facts to be accounted for? We answer, the number of aerolitesseento fall in a country depends upon the number of its inhabitants. The ocean, deserts, and uninhabited portions of the earth's surface afford no instances of such phenomena, simply for the want of observers. In sparsely settled countries the fall of aerolites would not unfrequently escape observation; and as such bodies generally penetrate the earth to some depth, the chances of discovery, when the fall is not observed, must be exceedingly rare. Now the part of the American continent designated by Professor Shepard, it will be noticed, is the oldest and most thickly settled part of the United States; while that of the Eastern continent stretches in like manner across the most densely populated countries of Europe. This fact alone, in all probability, affords a sufficient explanation of Prof. Shepard'sstatement.17
Do aerolites fall more frequently by day than by night?—Mr. Alexander S. Herschel, of Collingwood, England, has with much care and industry collected and collated the known facts in regard to bolides and aerolites. One result of his investigations is that a much greater number of meteoric stones are observedto fall by day than by night. From this he infers that, for the most part, the orbits in which they move areinteriorto that of the earth. The fact, however, is obviously susceptible of a very different explanation—an explanation quite similar to that of the frequent falls in particular districts.At night the number of observers is incomparably less; and hence many aerolites escape detection.There would seem to be no cause, reason, or antecedent probability of these falls being more frequent at one hour than another in the whole twenty-four.
The coexistence of meteorites, bolides, and the matter of shooting-stars in the same rings?—It has been stated on a previous page that several aerolite epochs are coincident with those of shooting-stars. Is the number of such cases sufficient to justify the conclusion that the correspondence of dates is not accidental? We will consider,
1. 1548, November 6th. A very large detonating meteor was seen at Mansfield, Thuringia, at two o'clock in the morning. The known rate of movement of the node brings this meteor within the November epoch.
2. 1624, November 7th. A large fire-ball was seen at Tubingen. The motion of the node brings this also within the epoch.
3. 1765, November 11th. A bright meteoric light was observed at Frankfort.
4. 1791, November 11th. A large meteor was seen at Göttingen and Lilienthal.
5. 1803, November 13th. A fire-ball, twenty-three miles high, was seen at London and Edinburgh.
6. 1803, November 13th. A splendid meteor was seen at Dover and Harts.
7. 1808, November 11th. A fire-ball was seen in England.
8. 1818, November 13th. A fire-ball was seen at Gosport.
9. 1819, November 13th. A fire-ball was seen at St. Domingo.
10. 1820, November 12th. A large detonating meteor was seen at Cholimschk, Russia.
11. 1822, November 12th. A fire-ball appeared at Potsdam.
12. 1828, November 12th. A meteor was seen in full sunshine at Sury, France.
13. 1831, November 13th. A fire-ball was seen at Bruneck.
14. 1831, November 13th. A brilliant meteor was seen in the North of Spain.
15. 1833, November 12th. A fire-ball was seen in Germany.
16. 1833, November 13th. A meteor, two-thirds the size of the moon, was seen during the great meteoric shower in the United States.
17. 1834, November 13th. A large fire-ball was seen in North America.
18. 1835, November 13th. Several aerolites fell near Belmont, Department de l'Ain, France.
19. 1836, November 11th. An aerolitic fall occurred at Macao, Brazil.
20. 1837, November 12th. A remarkable fire-ball was seen in England.
21. 1838, November 13th. A large fire-ball was seen at Cherbourg.
22. 1849, November 13th. An extraordinary meteor appeared in Italy. "Seen in the southern sky. Varied in color; a bright cloud visible one and a half hour after; according to some a detonation heard fifteen minutes after bursting. Seen also like a stream of fire between Tunis and Tripolis, where a shower of stones fell; some of them into the town of Tripolis itself."
23. 1849, November 13th. A large meteor was seen at Mecklenburg and Breslau.
24. 1856, November 12th. A meteoric stone fell at Trenzano, Italy.
25. 1866, November 14th. At Athens, Greece, a large number of bolides was seen by Mr. J. F. Julius Schmidt, during the shower of shooting-stars. One of these fire-balls was of the first class, and left a train which was visible one hour to the naked eye.
1. 1642, August 4th. A meteoric stone fell in Suffolk County, England.
2. 1650, August 6th. An aerolite fell in Holland. The observed motion of the node brings both these stone-falls within the epoch.
3. 1765, August 9th. A large bolide was seen at Greenwich.
4. 1773, August 8th. A fire-ball was seen at Northallerton.
5. 1800, August 8th. A large meteor was seen in different parts of North America.
6. 1802, August 10th. A fire-ball appeared at Quedlinburg.
7. 1807, August 9th. A bolide was seen at Nurenberg.
8. 1810, August 10th. A stone weighing seven and three-quarter pounds fell at Tipperary, Ireland.
9. 1816, August 7th. In Hungary a large fire-ball was seen to burst, with detonations.
10. 1817, August 7th. A brilliant fire-ball was seen at Augsburg.
11. 1818, August 10th. A meteoric stone, weighing seven pounds, fell at Slobodka, Russia.
12. 1822, August 7th. A meteorite fell at Kadonah, Agra.
13. 1822, August 7th. A large meteor was seen in Moravia.
14. 1822, August 11th. "A large mass of fire fell down with a great explosion" near Coblentz.
15. 1823, August 7th. Two meteoric stones fell in Nobleboro', Maine.
16. 1826, August 8th. A fire-ball was seen at Odensee.
17. 1826, August 11th. A bright meteor appeared at Halle.
18. 1833, August 10th. A fire-ball was seen at Worcestershire, England.
19. 1834, August 10th. A bolide appeared at Brussels.
20. 1838, August 9th. A fine meteor was seen in Germany.
21. 1839, August 7th. A splendid fire-ball was seen at sea.
22. 1840, August 7th. A bolide appeared at Naples.
23. 1841, August 10th. An aerolite fell at Iwan, Hungary.
24. 1842, August 9th. A greenish fire-ball was seen at Hamburg.
25. 1844, August 8th. A large meteor was seen in Brittany.
26. 1844, August 10th. A fire-ball was seen at Hamburg.
27. 1845, August 10th. A brilliant meteor was seen at London and Oxford.
28. 1847, August 9th. A large irregular meteor, "like a bright cloud of smoke," was seen at Brussels.
29. 1850, August 10th. A meteor as large as the moon was seen in Ireland.
30. 1850, August 10th. A very large bolide was observed in Paris.
31. 1850, August 11th. A fire-ball was seen in Paris.
32. 1853, August 7th. A bolide was observed at Glasgow.
33. 1853, August 7th. A meteor twice as large as Venus was seen at Paris.
34. 1853, August 9th. A large meteor was seen to separate into two parts.
35. 1855, August 10th. A bluish meteor, five times as large as Jupiter, was seen at Nottingham.
36. 1857, August 11th. A bolide was seen in Paris.
37. 1859, August 7th. A detonating meteor appeared in Germany.
38. 1859, August 11th. A meteoric stone fell near Albany, New York.
39. 1859, August 11th. A fine meteor was seen at Athens.
40. 1862, August 8th. A meteoric stone-fall occurred at Pillistfer, Russia.
41. 1863, August 11th. An aerolite fell at Shytal, India.
The following falls of meteoric stones have occurred at this epoch:
1. 1795, December 13th. At Wold Cottage, England.
2. 1798, December 13th. At Benares, India.
3. 1803, December 13th. At Mässing, Bavaria.
4. 1813, December 13th. At Luotolaks, Finland.
5. 1858, December 9th. At Ausson, France.
6. 1863, December 7th. At Tirlemont, Belgium.
7. 1863, December 10th. At Inly, nearTrebizond.18
For this epoch we have the following aerolites:
1. 1803, April 26th. At L'Aigle, France.
2. 1808, April 19th. At Casignano, Parma, Italy.
3. 1838, April 18th. At Abkurpore, India.
4. 1842, April 26th. At Milena, Croatia.
1. 1805, April 10th. At Doroninsk, Russia.
2. 1812, April 10th. At Toulouse, France.
3. 1818, April 10th. At Zaborzika, Russia.
4. 1864, April 12th. At Nerft, Russia.
The foregoing lists, which might be extended, are sufficient to establish the fact that meteoric stones are but the largest masses in the nebulous rings from which showers of shooting-stars are derived; a fact worthy of consideration whatever theory may be adopted in regard to the origin of such annuli.
It is well known that great variety has been found in the composition of aerolites. While some are extremely hard, others are of such a nature as to be easily reducible to powder. It is not impossible that when some of the latter class explode in the atmosphere they are completely pulverized, so that, reaching the earth in extremely minute particles, they are never discovered. It is very unlikely, moreover, that of the millions of shooting-stars that daily penetrate the atmosphere nothing whatever in the solid form should ever reach the earth's surface. Indeed, the celebrated Reichenbach, who devoted great attention to this subject, believed that he had actually discovered such deposits of meteoric matter. Chladni and others have detailed instances of the fall ofdust, supposed to be meteoric, from the upper regions of the atmosphere. The following may be regarded, with more or less probability, as instances of such phenomena:
1.A.D.475, November 5th or 6th. A shower of black dust fell in the vicinity of Constantinople. Immediately before or about the time of the fall, accordingto old accounts, "the heavens appeared to be on fire," which seems to indicate a meteoric display of an extraordinary character.
2. On the 3d of December, 1586, a considerable quantity of dark-colored matter fell from the atmosphere, at Verde, in Hanover. The fall was attended by intense light, as well as by a loud report resembling thunder. The substance which fell was hot when it reached the earth, as the planks on which a portion of it was found were slightly burnt, or charred. The date of this occurrence, allowance being made for the movement of the node, is included within the limits of the meteoric epoch of December 6th–13th.
3. About a century later, viz., on the 31st of January, 1686, a very extensive deposit of blackish matter, in appearance somewhat resembling charred paper, took place in Norway and other countries in the north of Europe. A portion of this substance, which had been carefully preserved, was analyzed by Grotthus, and found to contain iron, silica, and other elements frequently met with in aerolites.
4. On the 15th of November, 1755, red rain fell in Sweden and Russia, and on the same day in Switzerland. It gave a reddish color to the waters of Lake Constance, to which it also imparted an acid taste. The rain which fell on this occasion deposited a sediment whose particles were attracted by the magnet.
5. In 1791 a luminous meteor exploded over the Atlantic Ocean, and at the same time a quantity of matter resembling sand descended to the surface.
6. According to Chladni the explosion of a largebolide over Peru, on the 27th of August, 1792, was followed by a shower of cindery matter, the fall of which continued during three consecutive days.
7. On the 13th and 14th of March, 1813, a shower of red dust fell in Calabria, Tuscany, and Friuli. The deposit was sufficient to impart its color to the snow which was then upon the ground. That this dust was meteoric can scarcely be doubted, since at the same time a shower of aerolites fell at Cutro, in Calabria, attended by two loud reports resembling thunder. The shower of dust continued several hours, and was accompanied by a noise which was compared to the distant dashing of the waves of theocean.19
8. In November, 1819, black rain and snow fell in Canada.
9. On the 3d of May, 1831, red rain fell near Giessen. It deposited a dark-colored sediment which Dr. Zimmermann found to contain silica, oxide of iron, and various other substances observed in aerolites.
It is well known that quantities of sand are often conveyed, by the trade-winds, from the continent ofAfrica and deposited in the ocean. Such sand-showers have sometimes occurred several hundred miles from the coast. Volcanic matter also has been occasionally carried a considerable distance. The phenomena above described cannot, however, be referred to such causes; and there can be little doubt that most, if not all of them, were of meteoric origin.
There is, in all probability, a regular gradation from the smallest visible shooting-stars to bolides and aerolites. No doubt a great number of very small meteoric stones penetrate beneath the earth's surface and escape observation. An interesting account of the accidental discovery of suchcelestial pebbleshas recently been given by Professor Haidinger, of Vienna. The meteor from which they were derivedwas but little larger than an ordinary shooting-star. Its track was visible, however, until it terminated at the earth's surface. Professor Haidinger's account is as follows: On the 31st of July, 1859, about half-past nine o'clock in the evening, three inhabitants of the bourg of Montpreis, in Styria, saw a small luminous globe, very similar to a shooting-star, and followed by a luminous streak in the heavens, fall directly to the earth, which it attained close to the château that exists in the locality. The fall was accompanied by a whistling or hissing noise in the air, and terminated by aslightdetonation. The three observers, rushing to the spot where the meteor fell, immediately found a small cavity in the hard, sandy soil, from which they extracted three small meteoric stones about the size of nuts, and a quantity of black powder. For five to eight secondsthese stones continued in astate of incandescence, and it was necessary to allow upwards of a quarter of an hour to elapse before they could be touched without inflicting a burn. They appear to have been ordinary meteoric stones, covered with the usual black rind. The possessors would not give them up to be analyzed. The details of this remarkable occurrence of the fall of an extremely small meteor, we owe to Herr Deschann, Conservator of the Museum of Laibach, in Carniola, and member of the Austrian Chamber of Deputies.
The following is perhaps the only instance on record in which a shooting-starlower than the cloudshas been undoubtedly observed. The date is one at which meteors are said to be more than usually numerous; and the radiant point for the epoch has been recently determined, by British observers, to be aboutGamma Cygni. The meteor was seen by Mr. David Trowbridge, of Hector, Schuyler County, New York, who says: "On the evening of July 26th, 1866, about 8h. 15m.P.M., a very bright meteor flashed out in Cygnus, and moved from east to west with great rapidity. Its path was about 30° after I saw it. Height above the northern horizon about 50°. Duration of flight from one-half to one second. It left a beautiful train. The head was red and train blue. It was certainlybelowthe clouds. It passed between me and some cirro-stratus clouds, so dense as to hide ordinary stars completely. Several others that saw it said it wasbelowthe clouds."—Silliman's Journalfor Sept. 1866. It seems altogether probable that when a meteor thus descends, before its explosion or dissipation, into the lower atmosphericstrata, at least portions of its mass must reach the earth's surface.
If shooting-stars and aerolites are derived from meteoric rings revolving round the sun in orbits nearly intersecting that of the earth, then (1) these masses must sometimes transit the solar disk; (2) if any of the rings contain either individual masses of considerable magnitude, or sufficiently dense swarms of meteoric asteroids, such transits may sometimes be observed; (3) the passage of a dense meteoric cluster over the solar disk must partially intercept the sun's light and heat; and (4) should both nodes of the ring very nearly intersect the earth's orbit, meteoric falls might occur when the earth is at either; in which case the epochs would be separated by an interval of about six months. Have any such phenomena as those indicated been actually observed?
The passage of dark spots across the sun, having a much more rapid motion than the solar maculæ, has been frequently noticed. The following instances are well authenticated:
1779, June 17th. About mid-day the eminent French astronomer, Messier, saw a great number of black points crossing the sun. Rapidly moving spots were also seen by Pastorff on the following dates:
1822, October 23d,
1823, July 24th and 25th,
1836, October 18th,
and on several subsequent occasions the same astronomer witnessed similar phenomena. Anothertransit of this kind has been seen quite recently. On the 8th of May, 1865, a small black spot was seen by Coumbary to cross the solar disk. It seems difficult to account for these appearances (so frequently seen by experienced observers) unless we regard them as meteoric masses.
Numerous instances are on record of partial obscurations of the sun which could not be accounted for by any known cause. Cases of such phenomena took place, according to Humboldt, in the years 1090, 1203, and 1547. Another so-calleddark dayoccurred on the 12th of May, 1706, and several more (some of still later date) might be specified. Chladni and other physicists have regarded the transit of meteoric masses as the most probable cause of these obscurations. It is proper to remark, however, that the eminent French astronomer, Faye, who has given the subject much attention, finds little or no evidence in support of this conjecture.
An examination of meteorological records is said to have established two epochs of abnormal cold, viz., about the 12th of February and the 12th of May. The former was pointed out by Brandes about the beginning of the present century; the latter by Mädler, in 1834. The May epoch occurs when the earth is in conjunction with one of the nodes of the November meteoric ring; and that of February has a similar relation to the August meteors. M. Erman, a distinguished German scientist, soon after the discoveryof the August and November meteoric epochs, suggested that those depressions of temperature might be explained by the intervention of the meteoric zones between the earth and the sun. The period, however, of the November meteors being still somewhat doubtful, their position with respect to the earth about the 12th of May is also uncertain. But however this may be, the following dates of aerolitic falls seem to indicate May 8th–14th, or especially May 12th–13th, as a meteoric epoch:
(a) May 8th, 1829, Forsyth, Georgia, U. S. A.
(b) May 8th, 1846, Macerata, Italy.
(c) May 9th, 1827, Nashville, Tennessee, U. S. A.
(d) May 12th, 1861, Goruckpore, India.
(e) May 13th, 1831, Vouillé, France.
(f) May 13th, 1855, Oesel, Baltic Sea.
(g) May 13th, 1855, Bremevörde, Hanover.
(h) May 14th, 1861, near Villanova, in Catalonia, Spain.
(i) May 14th, 1864, Orgueil, France.
All the foregoing, except that of May 14th, 1861, may be found in Shepard's list,Silliman's Journalfor January, 1867.
It has been shown in a former chapter that more than seven millions of shooting-stars of sufficient magnitude to be seen by the naked eye daily enter the earth's atmosphere. As the small ones are the most numerous, it is not improbable that an indefinitely greater number of meteoric particles, too minute to be visible, are being constantly, in this manner, arrested in their orbital motion. Now, it would certainly be a very unwarranted conclusion that these atmospheric increments are all of a permanentlygaseous form. In view of this strong probability that meteoric dust is daily reaching the earth's surface, Baron von Reichenbach, of Vienna, conceived the idea of attempting its discovery. Ascending to the tops of some of the German mountains, he carefully collected small quantities of the soil from positions in which it had not been disturbed by man. This matter, on being analyzed, was found to contain small portions of nickel and cobalt—elements rarely found in the mineral masses scattered over the earth's surface, but very frequently met with in aerolites. In short, Reichenbach believed, and certainly not without some probability, that he had detected minute portions of meteoric matter.