Cosmos: A Sketch of the Physical Description of the Universe Part 10

A brilliant confirmation of the cosmical origin of these phenomena has been afforded by Denison Olmsted, at New Haven, Connecticut, who has shown on the concurrent authority of all eye-witnesses, that during the celebrated fall of shooting stars on the night between the 12th p 119 and 13th of November, 1833, the fire-b.a.l.l.s and shooting stars all emerged from one and the same quarter of the heavens, namely, in the vicinity of the star 'gamma' in the constellation Leo, and did not deviate from this point, although the star changed its apparent height and azimuth during the time of the observation. Such an independence of the Earth's rotation shows that the luminous body must have reached our atmosphere from 'without.'

According to Encke's computation* of the whole p 120 number of observations made in the United States of North America, between the thirty-fifth and the forty-second degrees of lat.i.tude, it would appear that all these meteors came from the same point of s.p.a.ce in the direction in which the Earth was moving at the time.

[footnote] *Encke, in Poggend., 'Annalen', bd. x.x.xiii. (1834), s. 213.

Arago, in the 'Annuaire' for 1836, p. 291. Two letters which I wrote to Benzenberg, May 19 and October 22, 1837, on the conjectural precession of the nodes in the orbit of periodical falls of shooting stars. (Benzenberg's 'Sternsch.', s. 207 and 209.) Olbers subsequently adopted this opinion of the gradual r.e.t.a.r.dation of the November phenomenon. ('Astron. Nachr.', 1838, No. 372, s. 180.) If I may venture to combine two of the falls of shooting stars mentioned by the Arabian writers with the epochs found by Boguslawski for the fourteenth century, I obtain the following more or less accordant elements of the movements of the nodes: In Oct., 902, on the night in which King Ibrahim ben Ahmed died, there fell a heavy shower of shooting stars, "like a fiery rain;" and this year was, therefore, called the year of stars. (Conde, 'Hist. de la Domin.' de los Arabes', p. 346.) On the 19th of Oct., 1202, the stars were in motion all night. "They fell like locusts." ('Comptes Rendus', 1837, t. i., p. 294; and Frhn, in the 'Bull. de l'Acad?mie de St. P?tersbourg', t. iii., p. 308.) On the 21st Oct., O.S., 1366, "'die sequente post festum XI. millia Virginum ab hora matutina usque ad horam primam vis sunt quasi stell de clo cadere continuo, et in tanta mult.i.tudine, quod nemo narrare suf ficit.'" This remarkable notice, of which we shall speak more fully in the subsequent part of this work, was found by the younger Von Boguslawski, in Benesse (de Horowic) de Weitmil or Weithm?l, 'Chronicon Ecclesi Pragensis', p. 389. This chronicle may also be found in the second part of 'Scriptores rerum Bohemicarum', by Pelzel and Dobrowsky, 1784. (Schum., 'Astr. Nachr.', Dec., 1839.) On the night between the 9th and 10th of November, 1787, many falling stars were observed at Manheim, Southern Germany, by Hemmer (K?mtz, 'Meteor.', th. iii., s. 237.) After midnight, on the 12th of November, 1799, occurred the extraordinary fall of stars at c.u.mana, which Bonpland and myself have described, and which was observed over a great part of the earth. ('Relat.

Hist.', t. i., p. 519-527.) Between the 12th and 13th of November, 1822, shooting stars, intermingled with fire-b.a.l.l.s, were seen in large numbers by Kloden, at Potsdam. (Gilbert's 'Ann.', bd. lxxii., s. 291.) On the 13th of November, 1831, at 4 o'clock in the morning, a great shower of falling stars was seen by Captain B?rard, on the Spanish coast, near Carthagena del Levante. ('Annuaire', 1836, p. 297.) In the night between the 12th and 13th of November, 1833, occurred the phenomenon so admirably described by Professor Olmsted, in North America.

In the night of the 13-14th of November, 1834, a similar fall of shooting stars was seen in North America, although the numbers were not quite so considerable. (Poggend., 'Annalen', bd. x.x.xiv., s. 129.) On the 13th of November, 1835, a barn was set on fire by the fall of a sporadic fire-ball, at Belley, in the Department de l'Ain. ('Annuaire', 1836, p. 296.) In the year 1838, the stream showed itself most decidedly on the night of the 13-14th of November. ('Astron. Nachr.', 1838, No. 372.)

On the recurrence of falls of shooting stars in North America, in the month of November of the years 1834 and 1837, and in the a.n.a.logous falls observed at Bremen in 1838, a like general parallelism of the orbits, and the same direction of the meteors from the constellation Leo, were again noticed. It has been supposed that a greater parallelism was observable in the direction of periodic falls of shooting stars than in those of sporadic occurrence; and it has further been remarked, that in the periodically-recurring falls in the month of August, as, for instance, in the year 1839, the meteors came princ.i.p.ally from one point between Perseus and Taurus, toward the latter of which constellations in the Earth was then moving. This peculiarity of the phenomenon, manifested in the retrograde direction of the orbits in November and August, should be thoroughly investigated by accurate observations, in order that it may either be fully confirmed or refuted.

The heights of shooting stars, that is to say, the heights of the points at which they begin and cease to be visible, vary exceedingly, fluctuating between 16 and 140 miles. This important result, and the enormous velocity of these problematical asteroids, were first ascertained by Benzenberg and Brandes, by simultaneous observations and determinations of parallax at the extremities of a base line of 49,020 feet in length.*

[footnote] *I am well aware that, among the 62 shooting stars simultaneously observed in Silesia, in 1823, at the suggestion of Professor Brandes some appeared to have an elevation of 183 to 240, or even 400 miles.

(Brandes, 'Unterhaltungen f?r Freunde der Astronomie und Physik', heft i., s. 48. Instructive Narratives for the Lovers of Astronomy and Physics.) But Olbers considered that all determinations for elevations beyond 120 miles must be doubtful, owing to the smallness of the parallax.

The relative velocity of motion is from 18 to 36 miles in a second, and consequently equal to planetary velocity. This planetary velocity,* as well as the direction of the orbits p 121 of fire-b.a.l.l.s and shooting stars, which has frequently been observed to be opposite to that of the Earth, may be considered as conclusive arguments against the hypothesis that a?rolites derive their origin from the so-called active 'lunar volcanoes.'

[footnote] *The planetary velocity of translation, the movement in the orbit, is in Mercury 26.4, in Venus 19.2, and in the Earth 16.4 miles in a second.

Numerical views regarding a greater or lesser volcanic force on a small cosmical body, not surrounded by any atmosphere, must, from their nature, be wholly arbitrary. We may imagine the reaction of the interior of a planet on its crust ten or even a hundred times greater than that of our present terrestrial volcanoes; the direction of ma.s.ses projected from a satellite revolving from west to east might appear retrogressive, owing to the Earth in its...o...b..t subsequently reaching that point of s.p.a.ce at which these bodies fall. If we examine the whole sphere of relations which I have touched upon in this work, in order to escape the charge of having made unproved a.s.sertions, we shall find that the hypothesis of the selenic origin of meteoric stones* depends upon a number of conditions p 122 whose accidental coincidence could alone convert a possible into an actual fact.

[footnote] *Chladni states that an Italian physicist, Paolo Maria Terzago, on the occasion of the fall of an a?rolite at Milan in 1660, by which a Franciscan monk was killed, was the first who surmised that a?rolites were of selenic origin. He says, in a memoir ent.i.tled 'Musum Septalianum, Manfredi Septal, Patricii Mediolanensis, industrioso labore constructum'

(Tortona, 1664, p. 44), "Labant philosophorum mentes sub horum lapidum ponderibus; ni dicire velimus, lunan terram alteram, sine mundum esse, ex cujus montibus divisa frustra in inferiorem nostrum hunc orben dela bantur."

Without any previous knowledge of this conjecture, Olbers was led, in the year 1795 (after the celebrated fall at Siena on the 16th of June, 1794), into an investigation of the amount of the initial tangential force that would be requisite to bring to the Earth ma.s.ses projected from the Moon.

This ballistic problem occupied, during ten or twelve years, the attention of the geometricians Laplace, Biot, Brandes, and Poisson. The opinion which was then so prevalent, but which has since been abandoned, of the existence of active volcanoes in the Moon, where air and water are absent, led to a confusion in the minds of the generality of persons between mathematical possibilities and physical probabilities. Olbers, Brandes, and Chladni thought "that the velocity of 16 to 32 miles, with which fire-b.a.l.l.s and shooting stars entered our atmosphere," furnished a refutation to the view of their selenic origin. According to Olbers, it would require to reach the Earth, setting aside the resistance of the air, an initial velocity of 8292 feet in the second; according to Laplace, 7862; to Biot, 8282; and to Poisson, 7595. Laplace states that this velocity is only five or six times as great as that of a cannon ball; but Olbers has shown "that, with such an initial velocity as 7500 or 8000 feet in a second, meteoric stones would arrive at the surface of our earth with a velocity of only 35,000 feet (or 1.53 German geographical mile). But the measured velocity of meteoric stones averages five such miles, or upward of 114,000 feet to a second; and, consequently, the original velocity of projection from the Moon must be almost 110,000 feet, and therefore fourteen times greater than Laplace a.s.serted." (Olbers, in Schum, 'Jahrb.', 1837, p. 52-58; and in Gehler, 'Neues Physik.' 'W?rterbuche', bd. vi., abth.3, s. 2199-2136.) If we could a.s.sume volcanic forces to be still active on the Moon's surface, the absence of atmospheric resistance would certainly give to their projectile force an advantage over that of our terrestrial volcanoes; but even in respect to the measure of the latter force (the projectile force of our own volcanoes), we have no observations on which any reliance can be placed, and it has probably been exceedingly overrated. Dr. Peters, who accurately observed and measured the phenomena presented by tna, found that the greatest velocity of any of the stones projected from the crater was only 1250 feet to a second. Observations on the Peak of Teneriffe, in 1798, gave 3000 feet. Although Laplace, at the end of his work ('Expos. du Syst. du Monde', ed. de 1824, p. 399), cautiously observes, regarding a?rolites, "that in all probability they come from the depths of s.p.a.ce," yet we see from another pa.s.sage (chap. vi., p. 233) 6that, being probably unacquainted with the extraordinary planetary velocity of meteoric stones, he inclines to the hypothesis of their lunar origin, always, however, a.s.suming that the stones projjected from the Moon "become satellites of our Earth, describing around it more or less eccentric orbits, and thus not reaching its atmosphere until several or even many revolutions have been accomplished."

As an Italian at Tortona had the fancy that a?rolites came from the Moon, so some of the Greek philosophers thought they came from the Sun. This was the opinion of Diogenes Laertius (ii., 9) regarding the origin of the ma.s.s that fell at "gos Potamos (see note, p. 116). Pliny, whose labors in recording the opinions and statements of preceding writers are astonis.h.i.+ng, repeats the theory, and derides it the more freely, because he, with earlier writers (Diog. Laert., 3 and 5, p. 99, H?bner), accuses Anaxagoras of having predicted the fall of a?rolites from the Sun: "Celebrant Grci Anaxagoram Clazomenium Olympiadis septuagesim octav secundo anno prdixisse clestium litterarum scientia quibus diebus saxum casurum esse e sole, idque factum interdia in Thraci parte ad gos flumen. Quod si quis prdictum credat, simul fateatur necesse est, majoris miraculi divinitatem Anaxagor fuisse, solvique rerum natur intellectum, et confundi omnia, si aut ipse Sol lapis esse aut unquam lapidem in eo fuisse credatur; decidere tamen crebro non erit dubium." The fall of a moderate-sized stone, which is preserved in the Gymnasium at Abydos, is also reported to have been foretold by Anaxagoras. The fall of a?rolites in bright suns.h.i.+ne, and when the Moon's disk was invisible, probably led to the idea of sun-stones. Moreover, according to one of the physical dogmas of Anaxagoras, which brought on him the persecution of the theologians (even as they have attacked the geologists of our own times), the Sun was regarded as "a molten fiery ma.s.s" ([Greed words]). In accordance with these views of Anaxagoras, we find Euripides, in 'Pha?ton', terming the Sun "a golden ma.s.s;" that is to say, a fire-colored, brightly-s.h.i.+ning matter, but not leading to the inference that a?rolites are golden sun-stones. (See note to page 115.) Compare Valckenaer, 'Diatribe in Eurip. perd. Dram. Reliquias', 1767, p. 30. Diog. Laert., ii., 40. Hence, among the Greek philosophers, we find four hypotheses regarding the origin of falling stars: a telluric origin from ascending exhalations; ma.s.ses of stone raised by hurricane (see Aristot., 'Meteor., lib. i., cap.

iv., 2-13, and cap. vii., 9); a solar origin; and, lastly, an origin in the regions of s.p.a.ce, as heavenly bodies which had long remained invisible.

Respecting this last opinion, which is that of Diogenes of Apollonia, and entirely accords with that of the present day, see pages 124 and 125. It is worthy of remark, that in Syria, as I have been a.s.sured by a learned Orientalist, now resident at Smyrna, Andrea de Nericat, who instructed me in Persian, there is a popular belief that a?rolites chiefly fall on clear moonlight nights. The ancients, on the contrary, especially looked for their fall during lunar eclipses. (See Pliny, x.x.xvii., 10, p. 164.

Solinus, c. 37. Salm., 'Exere.', p. 531; and the pa.s.sages collected by Ukert, in his 'Geogr. der Griechen und R?mer', th. ii., 1, s. 131, note 14.) On the improbability that meteoric ma.s.ses are formed from metal-dissolving gases, which, according to Fusinieri, may exist in the highest strata of our atmosphere, and previously diffused through an almost boundless s.p.a.ce, may suddenly a.s.sume a solid condition, and on the penetration and misceability of gases, see my '

Relat. Hist.', t. i., p. 525.

p 122 The view of the original existence of p 123 small planetary ma.s.ses in s.p.a.ce is simpler, and at the same time, more a.n.a.logous with those entertained concerning the formation of other portions of the solar system.

It is very probable that a large number of these cosmical bodies traverse s.p.a.ce undestroyed by the vicinity of our atmosphere, and revolve round the Sun without experiencing any alteration but a slight increase in the eccentricity of their orbits, occasioned by the attraction of the Earth's ma.s.s. We may, consequently, suppose the possibility of these bodied remaining invisible to us during many years and frequent revolutions. The supposed phenomenon of ascending shooting stars and fire-b.a.l.l.s, which Chladni has unsuccessfully endeavored to explain on the hypothesis of the 'reflection' of strongly compressed air, appears at first sight as the consequence of some unknown tngential force propelling bodies from the earth; but Bessel has shown by theoretical deductions, confirmed by Feldt's carefully-conducted calculations, that, owing to the absence of any proofs of the simultaneous occurrence of the observed disappearances, the a.s.sumptiopn of an ascent of shooting stars was rendered wholly improbable, and inadmissible as a result of observation.*

[footnote] *Bessel, in Schum., 'Astr. Nachr.', 1839, No 389 und 381, s. 222 und 346. At the conclusion of the Memoir there is a comparison of the Sun's longitudes with the epochs of the November phenomenon, from the period of the first observations in c.u.mana in 1799,

The opinion advanced by Olbers that the explosion of shooting stars and ignited fire-b.a.l.l.s not moving in straight lines may impel meteors upward in the manner of rockets, and influence the direction of their orbits, must be made the subject of future researches.

Shooting stars fall either seprately and in inconsiderable numbers, that is, sporadically, or in swarms of many thousands.

p 124 The latter, which are compared by Arabian authors to swarms of locusts, are periodic in their occurrence, and move in streams, generally in a parallel direction. Among periodic falls, the most celebrated are that known as the November phenomenon, occurring from about the 12th to the 14th of November, and that of the festival of St. Lawrence (the 10th of August), whose "fiery tears" were noticed in former times in a church calendar of England, no less than in old traditionary legends, as a meteorological event of constant recurrence.*

[footnote] *Dr. Thomas Forster ('The Pocket Encyclopedia of Natural Phenomena' 1827, p. 17) states that a ma.n.u.script is preserved in the library of Christ's College, Cambridge,** written in the tenth century by a monk, and ent.i.tled 'Ephemerides Rerum Naturalium', in which the natural phenomena for each day of the year are inscribed as, for instance, the first flowering of plants, the arrival of birds, etc.; the 10th of August is distinguished by the word "meteorodes." It was this indication, and the tradition of the fiery tears of St. Lawrence, that chiefly induced Dr. Forster to undertake his extremely zealous investigation of the August phenomena. (Quetelet, 'Correspond. Math?m.', S?rie III., t. i., 1837, p. 433.)

[further footnote] **[No such ma.n.u.script is at present known to exist in the library of that college. For this information I am indebted to the inquiries of Mr. Cory, of Pembroke College, the learned editor of 'Hieroglyphics of Horapollo Nilous', Greek and English, 1840.] -- Tr.

Notwithstanding the great quant.i.ty of shooting stars and fire-b.a.l.l.s of the most various dimensions, which, according to Kl?den, were seen to fall at Potsdam on the night between the 12th and 13th of November, 1822, and on the same night of the year in 1832 throughout the whole of Europe, from Portsmouth to Orenburg on the Ural River, and even in the southern hemisphere, as in the Isle of France, no attention was directed to the 'periodicity' of the phenomenon, and no idea seems to have been entertained of the connection existing between the fall of shooting stars and the recurrence of certain days, until the prodigious swarm of shooting stars which occurred in North America between the 12th and 13th of November, 1833, and was observed by Olmsted and Palmer. The stars fell on this occasion, like flakes of snow, and it was calculated that at least 240,000 had fallen during a period of nine hours. Palmer, of New Haven, Connecticut, was led, in consequence of this splendid phenomenon, to the recollection of the fall of meteoric stones in 1799, first described by Ellicot and myself,* and which, by p 125 a comparison of the facts I had adduced, showed that the phenomenon had been simultaneously seen in the New Continent, from the equator to New Herrnhut in Greenland (65 degrees 14' north lat.i.tude), and between 46 degrees and 82 degrees longitude.

[footnote] *Humb., 'Rel. Hist.', t. i., p. 519-527. Ellicot in the 'Transactions of the American Society', 1804, vol. vi., . 29. Arago makes the following observations in reference to the November phenomena: "We thus become more and more confirmed in the belief that there exists a zone composed of millions of small bodies, whose orbits cut the plane of the ecliptic at about the point which out Earth annually occupies between the 11th and 13th of November. It is a new planetary world beginning to be revealed to us." ('Annuaire', 1836, p. 296.)

The ident.i.ty of the epochs was recognized with astonishment. The stream which had been seen from Jamaica to Boston (40 degrees 21' north lat.i.tude) to traverse the whole vault of heaven on the 12th and 13th of November, 1833, was again observed in the United States in 1834, on the night between the 13th and 14th of November, although on this latter occasion it showed itself with somewhat less intensity. In Europe the periodicity of the phenomenon has since been manifested with great regularity.

Another and a like regularly recurring phenomenon is that noticed in the month of August, the meteoric stream of St. Lawrence, appearing between the 9th and 14th of August. Muschenbrock,* as early as in the middle of the last century, drew attention to the frequency of meteors in the month of August' but their certain periodic return about the time of St. Lawrence's day was first shown by Quetelet, Olbers, and Benzenberg.

[footnote] *Compare Muschenbroek, 'Introd. ad Phil. Nat.', 1762, t. ii., p.

1061; Howard, 'On the Climate of London', vol. ii., p. 23, observations of the year 1806; seven years, therefore aftr the earliest observations of Brandes (Benzenberg, '?ber Sternschnuppen', s. 240-244); the August observations of Thomas Forster, in Quetelet, op. cit., p. 438-453; those of Adolph Erman, Boguslawski, and Kreil, in Schum., 'Jahrb.', 1838, s. 317-330.

Regarding the point of origin in Perseus, on the 10th of August, 1839, see the accurate measurements of Bessel and Erman (Schum., 'Astr. Nachr.', No.

385 und 428); but on the 10th of August, 1837, the path does not apper to have been retrograde; see Arago in 'Comptes Rendus', 1837, t. ii., p. 183.

We shall, no doubt, in time, discover other periodically appearing streams,*

probably about the 22d to the p. 126 25th of April, between the 6th and 12th of December, and, to judge by the number of true falls of a?rolites enumerated by Capocci, also between the 27th and 29th of November, of about the 17th of July.

[footnote] *On the 25th of April, 1095, "innumerable eyes in France saw stars falling from heaven as thickly as hail" ('ut grando, nisi lucerent, pro densitate putaretur'; Baldr., p. 88), and this occurrence was regarded by the Council of Clermont as indicative of the great movement in Christendom. (Wilken, 'Gesch. der Kreuzz?ge', bd. i., s. 75.) On the 25th of April, 1800, a great fall of stars was observed in Virginia and Ma.s.sachusetts; it was "a fire of rockets that lasted two hours." Arago was the first to call attention to the "train?e d'astero?des," as a recurring phenomenon. ('Annuaire', 1836, p. 297.) The falls of a?rolites in the beginning of the month of December are also deserving of notice. In reference to their periodic recurrence as a meteoric stream, we may mention the early observation of Brandes on the night of the 6th and 7th of December, 1798 (when he counted 2000 falling stars), and very probably the enormous fall of a?rolites that occurred at the Rio a.s.su, near the village of Macao, in the Brazils, on the 11th of December, 1836. (Brandes, 'Unterhalt. f?r Freunde der Physik', 1825, heft i., s. 65, and 'Comptes Rendus', t. v., p. 211.) Capocci, in the interval between 1809 and 1839, a s.p.a.ce of thirty years, has discovered twelve authenticated cases of a?rolites occurring between the 27th and 29th of November, besides others on the 13th of November, the 10th of August, and the 17th of July.

('Comptes Rendus', t. xi., p. 357.) It is singular that in the portion of the Earth's path corresponding with the months of January and February, and probably also with March, no 'periodic' streams of falling stars of a?rolites have as yet been noticed; although when in the South Sea in the year 1803, I observed on the 15th of March a remarkably large number of falling stars, and they were seen to fall as in a swarm in the city of Quito, shortly before the terrible earthquake of Riobamba on the 4th of February, 1797. From the phenomena hitherto observed, the following epochs seem especially worthy of remark: 22d to the 25th of April.

17th of July (17th to the 26th of July?). (Quet., 'Corr.', 1837, p. 435.) 10th of August.

12th to the 14th of November.

27th to the 29th of November.

6th to the 12th of December.

When we consider that the regions of s.p.a.ce must be occupied by myriads of comets, we are led by a.n.a.logy, notwithstanding the differences existing between isolated comets and rings filled with asteroids, to regard the frequency of these meteoric streams with less astonishment than the first consideration of the phenomenon would be likely to excite.

Although the phenomena hitherto observed appear to have been independent of the distance from the pole, the temperature of the air, and other climatic relations, there is, however, one perhaps accidentally coincident phenomenon which must not be wholly disregarded. The Northern Light, the Aurora Borealis, was unusually brilliant on the occurrence of the Borealis, was unusually brilliant on the occurrence of the splendid fall of meteors of the 12th and 13th November, 1833, described by Olmsted. It was also observed at Bremen in 1838, where the periodic meteoric fall was, however, less remarkable than at Richmond, near London. I have mentioned in another work the singular fact observed by Admiral Wrangel, and frequently confirmed to me by himself,* that when he p 127 was on the Siberian coast of the Polar Sea, he observed, during an Aurora Borealis, certain portions of the vault of heaven which were not illuminated, light up and continue luminous whenever a shooting star pa.s.sed over them.

[footnote] *Ferd. v. Wrangle, 'Reise l?ngs der Nordk?ste von Sibirien in den Jahren', 1820-1824, th. ii., s. 259. Regarding the recurrence of the denser swarm of the November stream after an interval of thirty-three years, see Olbers, in 'Jahrb.', 1837, s. 280. I was informed in c.u.mana that shortly before the fearful earthquake of 1766, and consequently thirty-three years (the same interval) before the great fall of stars on the 11th and 12th of November, 1799, a similar fiery manifestation had been observed in the heavens. But it was on the 21st of October, 1766, and not in the beginning of November, that the earthquake occurred. Possibly some traveler in Quito may yet be able to ascertain the day on which the volcano of Cayambe, which is situated there, was for the s.p.a.ce of an hour enveloped in falling stars, so that the inhabitants endeavored to appease heaven by religious processions. ('Relat. Hist.', t. i., chap. iv., p 307; chap. x., p. 520 and 527.)

The different meteoric streams, each of which is composed of myriads of small cosmical bodies, probably intersect our Earth's...o...b..t in the same manner as Biela's comet. According to this hypothesis, we may represent to ourselves these asteroid-meteors as composing a closed ring or zone, within which they all pursue one common orbit. The s aller planets between Mars and Jupiter present us if we except Pallas with an a.n.a.logous relation in their constantly intersecting orbits. As yet, however, we have no certain knowledge as to whether changes in the periods at which the stream becomes visible, or the 'r.e.t.a.r.dations' of the phenomena of which I have already spoken, indicate a regular precession of oscillation of the nodes -- that is to say, of the points of intersection of the Earth's...o...b..t and of that of the ring; or whether this ring or zone attains so considerable a degree of breadth from the irregular grouping and distances apart of the small bodies, that it requires several days for the Earth to traverse it. The system of Saturn's satellites shows us likewise a group of immense width, composed of most intimately-connected cosmical bodies. In this system, the orbit of the outermost (the seventh) satellite has such a vast diameter, that the Earth, in her revolution round the Sun, requires three days to traverse an extent of s.p.a.ce equal to this diameter. If, therefore, in one of these rings, which we regard as the orbit of a periodical stream, the asteroids should be so irregularly distributed as to consist of but few groups sufficiently dense to give rise to these phenomena, we may easily understand why we so seldom witness such glorious spectacles as those exhibited in the November months of 1799 and 1833. The acute mind of Olbers led him almost to predict that the next appearance of the phenomenon of shooting stars and fire-b.a.l.l.s intermixed, falling like flakes of snow, would not recur until between the 12th and 14th of November, 1867.

p 128 The stream of the November asteroids has occasionally only been visible in a small section of the Earth. Thus, for instance, a very splendid 'meteoric shower' was seen in England in the year 1837, while a most attentive and skillful observer at Braunsberg, in Prussia only saw on the same night, which was there uninterruptedly clear, a few sporadic shooting stars fall between seven o'clock in the evening and sunrise the next morning. Bessel*

concluded from this "that a dense group of the bodies composing the great ring may have reached that part of the Earth in which England is situated, while the more eastern districts of the Earth might be pa.s.sing at the time through a part of the meteoric ring proportionally less densely studded with bodies."