R"EESE LIBRARY 
 
 UNIVERSITY OF CALIFORNIA 
 
 Received : 
 
 Accessions No. 
 
 Shelf No. . _ 
 
The Solar System. 
 
METEORIC ASTRONOMY: 
 
 A TREATISE 
 
 SHOOTING-STARS, FIRE-BALLS, 
 
 AEROLITES. 
 
 BY 
 
 DANIEL KIRKWOOD, LL.D. 
 
 PROFESSOR OF MATHEMATICS IN WASHINGTON AND JEFFERSON COLLEGE. 
 
 PHILADELPHIA: 
 
 J. B. LIPPINOOTT & CO. 
 
 1867. 
 
Entered, according to Act of Congress, in the year 1867, by 
 
 DANIEL KIRKWOOI), LL.D., 
 
 Ti> the Clerk s Office of the District Court of the United States for the 
 Western District of Pennsylvania. 
 
K5" 
 
 PREFACE. 
 
 ARISTOTLE and other ancient writers regarded comets as 
 meteors generated in the atmosphere. This opinion was 
 generally accepted, even by the learned, until the observa 
 tions of Tycho, near the close of the sixteenth century, 
 showed those mysterious objects to be more distant than 
 the moon, thus raising them to the dignity of celestial 
 bodies. An achievement somewhat similar, and certainly 
 no less interesting, was reserved for the astronomers of the 
 nineteenth century. This was the great discovery that 
 shooting- stars, fire-balls, and meteoric stones, are, like 
 comets, cosmical bodies moving in conic sections about the 
 sun. DR. HALLEY was the first to foretell the return of a 
 comet, and the year It 59 will ever be known in history as 
 that which witnessed the fulfillment of his prophecy. But 
 in the department of meteoric astronomy, a similar honor 
 must now be awarded to the late DR. OLBERS. Soon after 
 the great star-shower of 1833 he inferred from a comparison 
 of recorded facts that the November display attains a max 
 imum at intervals of thirty three or thirty-four years. He 
 accordingly designated 1866 or 1861 as the time of its 
 probable return ; and the night of November 13th of the 
 former year must always be memorable as affording the 
 first verification of his prediction. On that night several 
 thousand meteors were observed in one hour from a single 
 station. This remarkable display, together with the fact 
 that another still more brilliant is looked for in November, 
 1861, has given meteoric astronomy a more than ordinary 
 degree of interest in the public mind. To gratify, in some 
 
IV PREFACE. 
 
 measure, the curiosity which has been awakened, by pre 
 senting in a popular form the principal results of observa 
 tion and study in this new field of research, is the main 
 design of the following work. 
 
 The first two chapters contain a popular view of what is 
 known in regard to the star- showers of August and Novem 
 ber, and also of some other epochs. The third is a descrip 
 tion, in chronological order, of the most important falls of 
 meteoric stones, together with the phenomena attending 
 their descent. The fourth and following chapters to the 
 eleventh inclusive, discuss various questions in the theory 
 of meteors: such, for instance, as the relative number of 
 aerolitic falls during different parts of the day, and also of 
 the year; the coexistence of the different forms of meteoric 
 matter in the same rings ; meteoric dust ; the stability of 
 the solar system ; the doctrine of a resisting medium ; the 
 extent of the atmosphere as indicated by meteors ; the me 
 teoric theory of solar heat ; and the phenomena of variable 
 and temporary stars. The twelfth chapter regards the 
 rings of Saturn as dense meteoric swarms, and accounts for 
 the principal interval between them. The thirteenth pre 
 sents various facts, not previously noticed, respecting the 
 asteroid zone between Mars and Jupiter, with suggestions 
 concerning their cause or explanation 
 
 As the nebular hypothesis furnishes a plausible account 
 of the origin of meteoric streams, it seemed desirable to pre 
 sent an intelligible view of that celebrated theory. This 
 accordingly forms the subject of the closing chapter. 
 
 The greater part of the following treatise, it is proper to 
 remark, was written before the publication (in England) of 
 Dr. Phipson s volume on " Meteors, Aerolites, and Falling- 
 stars." The author has had that work before him, however, 
 while completing his manuscript, and has availed himself 
 of some of the accounts there given of recent phenomena. 
 
 ( ANONSBI KU, I .\ , Nay, 18(57. 
 
CONTENTS. 
 
 PAGE 
 IN TRODUCTION 7 
 
 CHAPTER I. 
 The Meteors of November 12th-14th 18 
 
 CHAPTER II. 
 Other Meteoric Rings 26 
 
 CHAPTER III. 
 Aerolites 35 
 
 CHAPTER IV. 
 Conjectures in Regard to Meteoric Epochs 50 
 
 CHAPTER V. 
 
 Geographical Distribution of Meteoric Stones Do Aerolitic Falls 
 occur more frequently by Day than by Night? Do Meteorites, 
 Bolides, and the matter of ordinary Shooting-stars, coexist in 
 the same Rings? 50 
 
 CHAPTER VI. 
 
 Phenomena supposed to be Meteoric Meteoric Dust Dark 
 Days 65 
 
 CHAPTER VII. 
 
 Researches of Reichenbach Theory of Meteors Stability of 
 
 the Solar System Doctrine of a Resisting Medium 74 
 
 1* (v) 
 
VI CONTENTS. 
 
 CHAPTER VIII. 
 
 PAOE 
 
 Does the Number of Aerolitic Falls vary with the Earth s Distance 
 from the Sun? Relative Numbers observed in the Forenoon 
 and Afternoon Extent of the Atmosphere as indicated by 
 Meteors 70 
 
 CHAPTER IX. 
 The Meteoric Theory of Solar Heat 84 
 
 CHAPTER X. 
 
 Will the Meteoric Theory account for the Phenomena of Vari 
 able and Temporary Stars? 92 
 
 CHAPTER XL 
 The Lunar and Solar Theories of the Origin of Aerolites 9G 
 
 CHAPTER XII. 
 The Rings of Saturn 102 
 
 CHAPTER XIII. 
 The Asteroid Ring between Mars and Jupiter 105 
 
 CHAPTER XIV. 
 Origin of Meteors The Nebular Hypothesis 112 
 
 APPKNDIX . 123 
 
INTRODUCTION. 
 
 A GENERAL VIEW OF THE SOLAR SYSTEM. 
 
 THE SOLAR SYSTEM consists of the sun, together with 
 the planets and comets which revolve around him as the 
 center of their motions. The sun is the great controlling 
 orb of this system, and the source of light and heat to its 
 various members. Its magnitude is one million four hun 
 dred thousand times greater than that of the earth, and it 
 contains more than seven hundred times as much matter 
 as all the planets put together. 
 
 MERCURY is the nearest planet to the sun ; its mean dis 
 tance being about thirty-seven millions of miles. Its diam 
 eter is about three thousand miles, and it completes its 
 orbital revolution in 88 days. 
 
 YENUS, the next member of the system, is sometimes our 
 morning and sometimes our evening star. Its magnitude 
 is almost exactly the same as that of the earth. It revolves 
 round the sun in 225 days. 
 
 THE EARTH is the third planet from the sun in the order 
 of distance; the radius of its orbit being about ninety-five 
 millions of miles. It is attended by one satellite the moon 
 the diameter of which is 2160 miles. 
 
 MARS is the first planet exterior to the earth s orbit. It 
 is considerably smaller than the earth, and has no satellite. 
 It revolves round the sun in 687 days. 
 
 ( vii ) 
 
Vlil INTRODUCTION. 
 
 THE ASTEROIDS. Since the commencement of the 
 present century a remarkable zone of telescopic planets has 
 been discovered immediately exterior to the orbit of Mars. 
 These bodies are extremely small ; some of them probably 
 containing less matter than the largest mountains on the 
 earth s surface. More than ninety members of the group 
 are known at present, and the number is annually in 
 creasing. 
 
 JUPITER, the first planet exterior to the asteroids, is 
 nearly five hundred millions of miles from the sun, and re 
 volves round him in a little less than twelve years. This 
 planet is ninety thousand miles in diameter and contains 
 more than twice as much matter as all the other planets, 
 primary and secondary, put together. Jupiter is attended 
 by four moons or satellites. 
 
 SATURN is the seventh planet in the order of distance- 
 counting the asteroids as one. Its orbit is about four hun 
 dred millions of miles beyond that of Jupiter. This planet 
 is attended by eight satellites, and is surrounded by three 
 broad, flat rings. Saturn is seventy-six thousand miles in 
 diameter, and its mass or quantity of matter is more than 
 twice that of all the other planets except Jupiter. 
 
 URANUS is at double the distance of Saturn, or nineteen 
 times that of the earth. Its diameter is about thirty-five 
 thousand miles, and its period of revolution, eighty-four 
 years. It is attended by four satellites. 
 
 NEPTUNE is the most remote known member of the sys 
 tem; its distance being nearly three thousand millions of 
 miles. It is somewhat larger than Uranus ; has certainly 
 one satellite, and probably several more. Its period is 
 about one hundred and sixty-five years. A cannon-ball 
 flying at the rate of five hundred miles per hour would not 
 reach the orbit of Neptune from the sun in less than six 
 hundred and eighty years. 
 
 These planets all move round the sun in the same direr- 
 
INTRODUCTION. IX 
 
 tion from west to east. Their motions are nearly circular, 
 and also nearly in the same plane. Their orbits, except 
 that of Neptune, are represented in the frontispiece. It is 
 proper to remark, however, that all representations of the 
 solar system by maps and planetariums must give an ex 
 ceedingly erroneous view either of the magnitudes or dis 
 tances of its various members. If the earth, for instance, 
 be denoted by a ball half an inch in diameter, the diameter 
 of the sun, according to the same scale (sixteen thousand 
 miles to the inch), will be between four and five feet; that 
 of the earth s orbit, about one thousand feet; while that of 
 Neptune s orbit will be nearly six miles. To give an accu 
 rate representation of the solar system at a single view is 
 therefore plainly impracticable. 
 
 COMETS. The number of comets belonging to our system 
 is unknown. The appearance of more than seven hundred 
 has been recorded, and of this number, the elements of 
 about two hundred have been computed. They move in 
 very eccentric orbits some, perhaps, in parabolas or hyper 
 bolas. 
 
 THE ZODIACAL LIGHT is a term first applied by Dominic 
 Cassini, in 1683, to a faint nebulous aurora, somewhat re 
 sembling the milky- way, apparently of a conical or lenticu 
 lar form, having its base toward the sun, and its axis nearly 
 in the direction of the ecliptic. The most favorable time 
 for observing it is when its axis is most nearly perpendicu 
 lar to the horizon. This, in our latitudes, occurs in March 
 for the evening, and in October for the morning. The angu 
 lar distance of its vertex from the sun is frequently seventy 
 or eighty degrees, while sometimes, though rarely (except 
 within the tropics), it exceeds even one hundred degrees. 
 
 The zodiacal light is probably identical with the meteor 
 called trabes by Pliny and Seneca. It was noticed in the 
 latter part of the sixteenth century by Tycho Brahe, who 
 considered it to be an abnormal spring-evening twilight." 
 
X INTRODUCTION. 
 
 It was described by Descartes about the year 1630, and 
 again by Childrey in 1661. The first accurate description 
 of the phenomenon was given, however, by Cassini. This 
 astronomer supposed the appearance to be produced by the 
 blended light of an innumerable multitude of extremely 
 small planetary bodies revolving in a ring about the sun. 
 The appearance of the phenomenon as seen in this country 
 is represented in Fig. 2. 
 
 For general readers it may not be improper to premise 
 the following explanations : 
 
 Meteors are of two kinds, cosmical and terrestrial: the 
 former traverse the interplanetary spaces ; the latter orig 
 inate in the earth s atmosphere. 
 
 Bolides is a general name for meteoric fire-balls of 
 greater magnitude than shooting-stars. 
 
 The period of a planet, comet, or meteor is the time 
 which it occupies in completing one orbital revolution. 
 
INTRODUCTION. 
 
 XI 
 
 The motion of a heavenly body is said to be direct when 
 it is from west to east; and retrograde when it is from 
 east to west. 
 
 Encke s Hypothesis of a Resisting Medium. The time 
 occupied by Encke s comet in completing its revolution 
 about the sun. is becoming less and less at each successive 
 return. Professor Encke explains this fact by supposing 
 the interplanetary spaces to be filled with an extremely 
 rare fluid, the resistance of which to the cometary motion 
 produces the observed contraction of the orbit. 
 
METEORIC ASTRONOMY. 
 
 CHAPTER I. 
 
 SHOOTING-STARS. 
 
 I. The Meteors of November 12th-14th. 
 
 ALTHOUGH shooting- stars have doubtless been 
 observed in all ages of the world, they have never, 
 until recently, attracted the special attention of 
 scientific men. The first exact observations of the 
 phenomena were undertaken, about the close of the 
 last century, by Messrs. Brandes and Benzenberg. 
 The importance, however, of this new department 
 of research was not generally recognized till after 
 the brilliant meteoric display of November 13th, 1833. 
 This shower of fire can never be forgotten by those 
 who witnessed it.* The display was observed from 
 the "West Indies to British America, and from 60 
 to 100 west longitude from Greenwich. Captain 
 Hammond, of the ship Restitution, had just arrived 
 at Salem, Massachusetts, where he observed the 
 phenomenon from midnight till daylight. He 
 
 * For a full description, see Silliman s Journal for January and 
 April, 1834 (Prof. Olmsted s article). Also a valuable paper, in 
 ^the July No. of the same year, by Prof. Twining. 
 
 2 (13) 
 
14 METEORIC ASTRONOMY. 
 
 noticed with astonishment that precisely one year 
 before, viz., on the 13th of November, 1832, he had 
 observed a similar appearance (although the meteors 
 were less numerous) at Mocha, in Arabia. It was 
 soon found, moreover, as a further and most remark 
 able coincidence, that an extraordinary fall of meteors 
 had been witnessed on the 12th of November, 1799. 
 This was seen and described by Andrew Ellicott, 
 Esq., who was then at sea near Cape Florida. It 
 was also observed in Cumana, South America, by 
 Humboldt, who states that it was "simultaneously 
 seen in the new continent, from the equator to New 
 Herrnhut, in Greenland (lat. 64 14 ), and between 
 46 and 82 longitude." 
 
 This wonderful correspondence of dates excited a 
 very lively interest throughout the scientific world. 
 It was inferred that a recurrence of the phenomenon 
 might be expected, and accordingly arrangements 
 were made for systematic observations on the 12th, 
 13th, and 14th of November. The periodicity of 
 the shower was thus, in a very short time, placed 
 wholly beyond question. The examination of old 
 historical records led to the discovery of at least 12 
 appearances of the November shower previous to 
 the great fall of 1833. The descriptions of these 
 phenomena will be found collected in an interesting 
 article by Prof. H. A. Newton, in the American Jour 
 nal of Science and Arts, for May, 1864. They occurred 
 in the years 902, 931, 934, 1002, 1101, 1202, 1366, 
 1533, 1602, 1698, 1799, and 1832. Besides these 12 
 enumerated by Professor Newton as "the predeces 
 sors of the great exhibition on the morning of No 
 vember 13th, 1833," we find 6 others, less distinctly 
 
SHOOTING-STARS. 15 
 
 marked, in the catalogue of M. Quetelet.* These 
 were in the years 1787, 1818, 1822, 1823, 1828, and 
 1831. From 1833 to 1849, inclusive, Quetelet s 
 catalogue indicates 11 partial returns of the Novem 
 ber shower; making in all, up to the latter date, 29. 
 In 1835, November 13th, a straw roof was set on lire 
 by a meteoric fire-ball, in the department de 1 Aine, 
 France. On the 12th of November, 1837, "at 8 
 o clock in the evening, the attention of observers in 
 various parts of Great Britain was directed to a 
 bright luminous body, apparently proceeding from 
 the North, which, after making a rapid descent, in 
 the manner of a rocket, suddenly burst, and scatter 
 ing its particles into various beautiful forms, vanished 
 in the atmosphere. This was succeeded by others 
 all similar to the first, both in shape and the manner 
 of its ultimate disappearance. The whole display 
 terminated at ten o clock, when dark clouds, which 
 continued up till a late hour, overspread the earth, 
 preventing any further observations." Milner s Gal 
 lery of Nature, p. 142. 
 
 In 1838, November 12th-13th, meteors were 
 observed in unusual numbers at Vienna. One of 
 extraordinary brilliancy, having an apparent magni 
 tude equal to that of the full moon, was seen near 
 Cherburg. 
 
 On several other returns of the November epoch 
 the number of meteors observed has been greater 
 than on ordinary nights; the distinctly marked 
 exhibitions, however, up to 1866, have all been 
 enumerated. 
 
 * Physique du Globe, Chap. IV. 
 
16 METEORIC ASTRONOMY. 
 
 THE SHOWER OF NOVEMBER 14, 1866. 
 
 The fact that all great displays of the November 
 meteors have taken place at intervals of thirty- three 
 or thirty-four years, or some multiple of that period, 
 had led to a general expectation of a brilliant shower 
 in 1866. In this country, however, the public curi 
 osity was much disappointed. The numbers seen 
 were greater than on ordinary nights, but not such 
 as would have attracted any special attention. The 
 greatest number recorded at any one station was seen 
 at New Haven, by Prof. Newton. On the night of 
 the 12th, 694 were counted in five hours and twenty 
 minutes, and on the following night, 881 in five 
 hours. This was about six times the ordinaiy num 
 ber. A more brilliant display was, however, wit 
 nessed in Europe. Meteors began to appear in 
 unusual frequency about eleven o clock on the night 
 of the 13th, and continued to increase with great 
 rapidity for more than two hours; the maximum 
 being reached a little after one o clock. The Edin 
 burgh Scotsman, of November 14th, contains a highly 
 interesting description of the phenomenon as ob 
 served at that city. "Standing on the Calton Hill, 
 and looking westward," the editor remarks, "with 
 the Observatory shutting out the lights of Prince s 
 Street it was easy for the eye to delude the imagin 
 ation into fancying some distant enemy bombarding 
 Edinburgh Castle from long range; and the occa 
 sional cessation of the shower for a few seconds, only 
 to break out again with more numerous and more 
 brilliant drops of fire, served to countenance this 
 fancy. Again, turning eastward, it was possible now 
 
SHOOTING-STARS. 
 
 and then to catch broken glimpses of the train of 
 one of the meteors through the grim dark pillars of 
 that ruin of most successful manufacture, the Na 
 tional Monument; and in fact from no point in or 
 out of the city was it possible to watch the strange 
 rain of stars, pervading as it did all points of the 
 heavens, without pleased interest, and a kindling of 
 the imagination, and often a touch of deeper feeling 
 that bordered on awe. The spectacle, of which the 
 loftiest and most elaborate description could but be 
 at the best imperfect which truly should have been 
 seen to be imagined will not soon pass from the 
 memories of those to whose minds were last night 
 presented the mysterious activities and boundless 
 fecundities of that universe of the heavens, the very 
 unchangeableness of whose beauty has to many made 
 it monotonous and of no interest." 
 
 The appearance of the phenomenon, as witnessed 
 at London, is minutely described in the Times of 
 November 15th. The shower occurred chiefly be 
 tween the hours of twelve and two. About one 
 o clock a single observer counted 200 in two min 
 utes. The whole number seen at Greenwich was 
 8485. The shower was also observed in different 
 countries on the continent. 
 
 The Meteors of 1866 compared with those of former 
 Displays. 
 
 The star shower of 1866 was much inferior to those 
 of 1799 and 1833.* With these exceptions, however, 
 
 * Professor Olmstcd estimated the number of meteors, visible at 
 New Haven, during the night of November 12ih-13th, 18^3, at 
 240,000. 
 
 2* 
 
18 METEORIC ASTRONOMY. 
 
 it has, perhaps, been scarcely surpassed during the 
 last 500 years. Historians represent the meteors of 
 902 as innumerable, and as moving like rain in all 
 possible directions.* The exhibition of 1202 was 
 no less magnificent. The stars, it is said, were seen 
 to dash against each other like swarms of locusts; 
 the phenomenon lasting till daybreak. f The shower 
 of 1366 is thus described in a Portuguese chronicle, 
 quoted by Humboldt: "In the year 1366, twenty- 
 two days of the month of October being past, three 
 months before the death of the king, Dom Pedro 
 (of Portugal), there was in the heavens a movement 
 of stars, such as men never before saw or heard of. 
 At midnight, and for some time after, all the stars 
 moved from the east to the west; and after being 
 collected together, they began to move, some in one 
 direction, and others in another. And afterward 
 they fell from the sky in such numbers, and so thickly 
 together, that as they descended low in the air, they 
 seemed large and fiery, and the sky and the air 
 seemed to be in flames, and even the earth appeared 
 as if ready to take fire. That portion of the sky 
 where there were no stars, seemed to be divided 
 into many parts, and this lasted for a long time." 
 The following is Humboldt s description of the 
 
 * Conde says, "there were seen, as it were lances, an infinite 
 number of stars, which scattered themselves like rain to the right 
 and left, and that year was called the year of stars. : 
 
 f In 1202, "on the last day of Muharrem, stars shot hither and 
 thither in the heavens, eastward and westward, and flew against one 
 another like a scattering swarm of locusts, to the right and left; this 
 phenomenon lasted until daybreak; people were thrown into con 
 sternation, and cried to God the Most High with confused clamor." 
 Quoted by Prof. Newton, in Silliman s Journal, May, 1864. 
 
SHOOTING-STARS. 19 
 
 shower of 1799, as witnessed by himself and Bon- 
 pland, in Cumana, South America: "From half 
 after two, the most extraordinary luminous meteors 
 
 were seen toward the east Thousands of bolides 
 
 and falling stars succeeded each other during four 
 hours. They filled a space in the sky extending from 
 the true east 30 toward the north and south. In an 
 amplitude of 60 the meteors were seen to rise above 
 the horizon at E. N. E. and at E., describe arcs more 
 or less extended, and fall toward the south, after 
 having followed the direction of the meridian. Some 
 of them attained a height of 40, and all exceeded 
 
 25 or 30 Mr. Bonpland relates, 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 The Guaiqueries in 
 
 the Indian suburb came out and asserted that the 
 firework had begun at one o clock The phe 
 nomenon ceased by degrees after four o clock, and 
 the bolides and falling-stars became less frequent; 
 but we still distinguished some toward the northeast 
 
 CD 
 
 a quarter of an hour after sunrise." 
 
 DISCUSSION OF THE PHENOMENA. 
 
 Since the memorable display of November 13th, 
 1833, the phenomena of shooting-stars have been 
 observed and discussed by B ramies, Benzenberg, 
 Gibers, Saigey, Heis, Glmsted, Herrick, Twining, 
 Newton, Greg, and many others. In the elaborate 
 paper of Professor Glmsted, it was shown that the 
 meteors had their origin at a distance of more than 
 
20 METEORIC ASTRONOMY. 
 
 2000 miles from the earth s surface; that their paths 
 diverged from a common point near the star Gamma 
 Leonis ; that in a number of instances they became 
 visible about 80 miles from the earth s surface ; that 
 their velocity was comparable to that of the earth in 
 its orbit; and that in some cases their extinction 
 occurred at an elevation of 30 miles. It was in 
 ferred, moreover, that they consisted of combustible 
 matter which took fire and was consumed in passing 
 through the atmosphere; that this matter was de 
 rived from a nebulous body revolving round the sun 
 in an elliptical orbit, but little inclined to the plane 
 of the ecliptic; that its aphelion was near that point 
 of the earth s orbit through w T hich we annually pass 
 about the 13th of November the perihelion being 
 a little within the orbit of Mercury; and finally that 
 its period was about one-half that of the earth. Dr. 
 Olmsted subsequently modified his theory, having 
 been led by further observations to regard the zodi 
 acal light as the nebulous body from which the 
 shooting-stars are derived. The latter hypothesis 
 was also adopted by the celebrated Biot. 
 
 The fact that the position of the radiant point does 
 not change with the earth s rotation, places the cos- 
 mica! origin of the meteors wholly beyond question. 
 The theory of a closed ring of nebulous matter re 
 volving round the sun in an elliptical orbit which 
 intersects that of the earth, affords a simple and 
 satisfactory explanation of the phenomena. This 
 theory was adopted by Humboldt, Arago, and others, 
 shortly after the occurrence of the meteoric shower 
 of 1833. That the body which furnishes the mate 
 rial of these meteors moves in a closed or elliptical 
 
SHOOTING-STARS. 21 
 
 orbit is evident from the periodicity of the shower. It 
 is also manifest from the partial recurrence of the phe 
 nomenon from year to year, that the matter is dif 
 fused around the orbit; while the extraordinary falls 
 of 1833, 1799, 1366, and 1202, prove the diffusion to 
 be far from uniform. 
 
 ELEMENTS OF THE ORBIT. 
 
 Future observations, it may be hoped, will ulti 
 mately lead to an accurate determination of the 
 elements of this ring: many years, however, will 
 probably elapse before all the circumstances of its 
 motion can be satisfactorily known. Professor New 
 ton, of Yale College, has led the way in an able dis 
 cussion of the observations.* He has shown that 
 the different parts of the ring are, in all probability, 
 of very unequal density; that the motion is retro 
 grade; and that the time, during which the meteors 
 complete a revolution about the sun, must be limited 
 to one of five accurately determined periods, viz. : 
 180-05 days, 185-54 days, 354-62 days, 376 5 days, or 
 33-25 years. He makes the inclination of the ring to 
 the ecliptic about 17. The five periods specified, he 
 remarks, u are not all equally probable. Some of the 
 members of the group which visited us last November 
 [1863] gave us the means of locating approximately 
 the central point of the region from which the paths 
 diverge. Mr. G. A. Nolen has, by graphical processes 
 specially devised for the purpose, found its longitude 
 to be 142, and its latitude 8 30 . This longitude 
 
 * Am. Journ. of Sci. and Arts, May and July, 1864. 
 
22 METEORIC ASTRONOMY. 
 
 is very nearly that of the point in the ecliptic toward 
 which the earth is moving. Hence the point from 
 which the ahsolute motion of the bodies is directed 
 (being in a great circle through the other two points) 
 has the same longitude. The absolute motion of 
 each meteor, then, is directed very nearly at right 
 angles to a line from it to the sun, the deviation be 
 ing probably not more than two or three degrees. 
 
 "Now, if in one year the group make 2 33 1 23 revo 
 lutions, there is only a small portion of the orbit near 
 the aphelion which fulfills the above condition. In 
 like manner, if the periodic time is 33-25 years, only 
 a small portion of the orbit near the perihelion ful 
 fills it. On the other hand, if the annual motion is 
 1 3 -^ revolutions, the required condition is answered 
 through a large part of the orbit. Inasmuch as no 
 reason appears why the earth should meet a group 
 near its apsides rather than elsew r here, we must regard 
 it as more probable that the group makes in one 
 year either l+g-^, or 1 ~ revolutions." 
 
 Professor Newton concludes that the third of the 
 above-mentioned periods, viz., 354 62 days, combines 
 the greatest amount of probability of being the true 
 one. We grant the force of the reasons assigned for 
 its adoption. At least one consideration, however, 
 in favor of the long period of 33-25 years is by no 
 means destitute of weight: of nearly 100 known 
 bodies which revolve about the sun in orbits of small 
 eccentricity, not one has a retrograde motion. Now 
 if this striking fact has resulted from a general cause, 
 how shall we account for the backward motion of a 
 meteoric ring, in an orbit almost circular, and but 
 little inclined to the plane of the ecliptic? In such 
 
SHOOTING-STARS. 23 
 
 a case, is not the preponderance of probability in 
 favor of the longer period? 
 
 A revolution in 33-25 years corresponds to an 
 ellipse whose major axis is 20-6. Consequently the 
 aphelion distance would be somewhat greater than 
 the mean distance of Uranus. It may also be worthy 
 of note, that five periods of the ring would be very 
 nearly equal to two of Uranus. 
 
 The Monthly Notices of the Eoyal Astronomical 
 Society for December, 1866, and January, 1867, con 
 tain numerous articles on the star shower of Novem 
 ber 13th-14th, 1866. Sir John Herschel carefully 
 observed the phenomena, and his conclusions in 
 regard to the orbit are confirmatory of those of Pro 
 fessor Newton. "We are constrained to conclude," 
 he remarks, " that the true line of direction, in space 
 of each meteor s flight, lay in a plane at right angles 
 to the earth s radius vector at the moment; and that 
 therefore, except in the improbable assumption that 
 the meteor was at that moment in perihelia or in ap- 
 helio, its orbit would not deviate greatly from the 
 circular form." The question is one to be decided 
 by observation, and the only meteor whose track 
 and time of flight seem to have been well observed, 
 is that described by Professor Newton in Silliman s 
 Journal for January, 1867, p. 86. The velocity in 
 this case, if the estimated time of flight was nearly 
 correct, was inconsistent with the theory of a circular 
 orbit. 
 
 It is also worthy of notice that Dr. Oppolzer s 
 ^elements of the first cornet of 1866 resemble, in a 
 remarkable manner, those of the meteoric ring, sup 
 posing the latter to have a period of about 33 J years. 
 
24 METEORIC ASTRONOMY. 
 
 Schiaparelli s elements of the November ring, and 
 Oppolzer s elements of the comet of 1866, are as 
 follows: 
 
 November Comet of 
 
 Meteors. 1866. 
 
 Longitude of perihelion 56 25 60 28 
 
 Longitude of ascending node 231 28 231 26 
 
 Inclination 17 44 17 18 
 
 Perihelion distance 0-9873 0-9765 
 
 Eccentricity 0-9046 0-9054 
 
 Semi-axis major 10-3400 10-3240 
 
 Period, in years 33-2500 33-1760 
 
 Motion Retrograde. Retrograde. 
 
 It seems very improbable that these coincidences 
 should be accidental. Leverrier and other astrono 
 mers have found elements of the meteoric orbit agree 
 ing closely with those given by Schiaparelli. Should 
 the identity of the orbits be fully confirmed, it will 
 follow that the comet of 1866 is a very large meteor of 
 the November stream. 
 
 The researches of Professor C. Bruhns, of Leipzig, 
 in regard to this group of meteors afford a probable 
 explanation of the division of Biela s comet a phe 
 nomenon which has greatly perplexed astronomers 
 for the last twenty years. Adopting the period of 
 331 years, Professor Bruhns finds that the comet 
 passed extremely near, and probably through the me 
 teoric ring near the last of December, 1845. It is 
 easy to perceive that such a collision might produce 
 the separation soon afterward observed. 
 
 As the comet of Biela makes three revolutions in 
 twenty years, it was again at this intersection, or 
 approximate intersection of orbits about the end of 
 1865. But although the comet s position, with re- 
 
Hg. 3. 
 
SHOOTING-STARS. 25 
 
 spect to the earth, was the same as in 1845-6, and 
 although astronomers watched eagerly for its ap 
 pearance, their search was unsuccessful. In short, 
 the comet is lost. The denser portion of the meteoric 
 stream was then approaching its perihelion. A por 
 tion of the arc had even passed that point, as a 
 meteoric shower was observed at Greenwich on the 
 13th of November, 1865.* The motion of the me 
 teoric stream is retrograde; that of the comet, direct. 
 Did the latter plunge into the former, and was its 
 non appearance the result of such collision and en 
 tanglement? 
 
 * The stream or arc of meteors is several years in passing its node. 
 The first indication of the approach of the display of 1866 was the 
 appearance of meteors in unusual numbers at Malta, on the 13th of 
 November, 1864. The great length of the arc is indicated, more 
 over, by the showers of 931 and 934. 
 
CHAPTER II. 
 
 OTHER METEOEIC KINGS. 
 
 II. The Meteors of August Gth-llth. 
 
 MUSCIIENBROEK, in his Introduction to Natural Philos 
 ophy, published in 1762, called attention to the fact 
 that shooting-stars are more abundant in August 
 than in any other part of the year. The annual 
 periodicity of the maximum on the 9th or 10th of 
 the month was first shown, however, by Quetelet, 
 shortly after the discovery of the yearly return of 
 the November phenomenon. Since that time an ex 
 traordinary number of meteors has been regularly 
 observed, both in Europe and America, from the 
 7th to the llth of the month; the greatest number 
 being generally seen on the 10th. In 1839, Edward 
 Heis, of Aix-la-Chapelle, saw 160 meteors in one 
 hour on the night of the 10th. In 1842, he saw 34 
 in ten minutes at the time of the maximum. In 
 1861, on the night of the 10th, four observers, watch 
 ing together at New Haven, saw in three hours 
 from ten to one o clock 289 meteors. On the same 
 night, at Natick, Massachusetts, two observers saw 
 397 in about seven hours. At London, Mercer 
 County, Pennsylvania, on the night of August 9th, 
 1866, Samuel S. Gilson, Esq., watching alone, saw 
 72 meteors in forty minutes, and, with an assistant, 
 (26) 
 
OTHER METEORIC RINGS. 27 
 
 117 in one hour and fifteen minutes. Generally, the 
 number observed per hour, at the time of the Au 
 gust maximum, is about nine times as great as on 
 ordinary nights. Like the November meteors, they 
 have a common "radiant;" that is, their tracks, 
 when produced backward, meet, or nearly meet, in 
 a particular point in the constellation Perseus. 
 
 Of the 315 meteoric displays given in Quetelet s 
 "Catalogue des principales apparitions <Te*toiles fi- 
 lantes," 63 seem to have been derived from the Au 
 gust ring. The first 11 of these, with one exception, 
 were observed in China during the last days of July, 
 as follows: 
 
 1 A.D. 811, July 25th. 
 
 o 820, " 25th-30th. 
 
 3 824, " 26th-28th. 
 
 4 830, " 26th. 
 
 5 -. 833, " 27th. 
 
 6 835, " 20th. 
 
 7 841, " 25th-30th. 
 
 8 924, 27th-30th. 
 
 9 925, " 27th-30th. 
 
 10 926, " 27th-30th. 
 
 11 933, " 25tk-30th. 
 
 The next dates are 1243, August 2d, and 1451, 
 August 7th. A comparison of these dates indicates 
 a forward motion of the node of the ring along the 
 ecliptic. This was pointed out several years since 
 by Boguslawski. A similar motion of the node has 
 also been found in the case of the November ring. 
 That these points should be stationary is, indeed, al 
 together improbable. The nodes of all the planetary 
 orbits, it .is well known, have a secular variation. 
 On the evening of August 10th, 1861, at about 
 
METEORIC ASTRONOMY. 
 
 llh. 30m., a meteor was seen by Mr. E. C. Herrick 
 and Prof. A. C. Twining, at New Haven, Connecticut, 
 which " was much more splendid than Venus, and left 
 a train of sparks which remained luminous for twenty 
 seconds after the meteor disappeared." The same 
 meteor was also accurately observed at Burlington, 
 New Jersey, by Mr. Benjamin Y. Marsh. It was 
 "conformable," that is, its track produced back 
 ward passed through the common radiant and it 
 was undoubtedly a member of the August group. 
 The observations were discussed by Professor H. A. 
 Newton, of Yale College, who deduced from them 
 the following approximate elements of the ring:* 
 
 Semi-axis major 84 
 
 Eccentricity 0-28 
 
 Perihelion distance 0-60 
 
 Inclination g4 
 
 Period 281 days. 
 
 Motion, retrograde. 
 
 The earth moving at the rate of 68,000 miles per 
 hour, is at least five days in passing entirely through 
 the ring. This gives a thickness of more than 
 8,000,000 miles. 
 
 The result of Professor Newton s researches on 
 the oribit of this ring, though undertaken with in 
 adequate data, and hence, in some respects, probably 
 far from correct, is nevertheless highly interesting 
 as being the first attempt to determine the orbit 
 of shooting-stars. More recent investigations have 
 shown a remarkable resemblance between the ele 
 ments of these meteors and those of the third comet 
 
 * Silliman s Journ. for Sept. and Nov., 1861. 
 
OTHER METEORIC RINGS. 29 
 
 of 1862. The former, by Schiaparelli, and the latter, 
 by Oppolzer, are as follows: 
 
 Meteors of August 10th. Comet III., 1862. 
 
 Longitude of perihelion 343 38 344 41 
 
 Ascending node 138 16 137 27 
 
 Inclination 03 3 66 25 
 
 Perihelion distance 0-9643 0-9626 
 
 Period 105 years (?). 123 years (?). 
 
 Motion Retrograde. Retrograde. 
 
 This similarity is too great to be accidental. The 
 August meteors- and the third comet of 1862 probably be 
 long to the same ring. 
 
 III. The Meteors of April 18th-26th. 
 
 The following dates of the April meteoric showers 
 are extracted from Quetelet s table previously re 
 ferred to : 
 
 1 
 
 A D 401 April 9th. 
 
 [8 AD 
 
 1096 April 10th 
 
 o 
 
 538 " 7th 
 
 9 
 
 1122 " llth 
 
 3 
 
 839 " 17th 
 
 10 
 
 1193 a nth 
 
 4 
 
 997 it i7 t h 
 
 11 
 
 1803, " 20th 
 
 5 
 
 934 " 18th 
 
 12 
 
 1838 " 20th 
 
 6 
 
 1009, " 16th. 
 
 13... 
 
 1841. " 19th. 
 
 1094, 10th. 14... 1850, llth-17th. 
 
 The display of 401 was. witnessed in China, and 
 is described as "very remarkable." That of 1803 
 was best observed in Virginia, and was at its maxi 
 mum between one and three o clock. The alarm of 
 fire had called many of the inhabitants of Richmond 
 from their houses, so that the phenomenon was gen 
 erally witnessed. The meteors "seemed to fall from 
 every point in the heavens, in such numbers as to 
 
 3* 
 
30 METEORIC ASTRONOMY. 
 
 resemble a shower of sky-rockets." Some were of 
 extraordinary magnitude. "One in particular, ap 
 peared to fall from the zenith, of the apparent size of 
 a ball 18 inches in diameter, that lighted the whole 
 hemisphere for several seconds." 
 
 The probability that the meteoric falls about the 
 20th of April are derived from a ring which inter 
 sects the earth s orbit, was first suggested by Arago, 
 in 1836. The preceding list indicates a forward 
 motion of the node. The radiant, according to Mr. 
 
 o 
 
 G-reg, is about Corona. The number of meteors 
 observed in 1838, 1841, and 1850, was not very ex 
 traordinary. Recent observations indicate April 
 9th-12th as another epoch. The radiant is in Virgo. 
 
 IV. The Meteors of December 6th-13th. 
 
 On the 13th of December, 1795, a large meteoric 
 stone fell in England. On the night, between the 
 6th and 7th of December, 1798, Professor Brandes, 
 then a student in Gottingen, saw 2000 shooting-stars. 
 On the llth of the month, 1836, a fall of meteoric 
 stones, described by Humboldt as "enormous," oc 
 curred near the village of Macao, in Brazil. During 
 the last few years unusual numbers of shooting-stars, 
 have been noticed by different observers from the 
 10th to the 13th; the maximum occurring about the 
 llth. From A.D. 848, December 2d, to 1847, De 
 cember 8th-10th, we find 14 star showers in Quete- 
 let s catalogue, derived, probably, from this meteoric 
 stream. As in other cases, the dates seem to show 
 a progressive motion of the node. The position of 
 the radiant, as determined by Benjamin V. Marsh, 
 
OTHER METEORIC RINGS. 31 
 
 Esq., of Philadelphia, from observations in 1861 and 
 1862, and also by R. P. Greg, Esq., of Manchester, 
 England, is at a point midway between Castor and 
 Pollux. 
 
 V. The Meteors of January 2d-3d. 
 
 About the middle of the present century, Mr. 
 Julius Schmidt, of Bonn, a distinguished and accu 
 rate observer, designated the 2d of January as a 
 meteoric epoch ; characterizing it, however, as "prob 
 ably somewhat doubtful." Recent observations, espe 
 cially those of R. P. Greg, Esq., have fully confirmed 
 it. The meteors for several hours are said to be as 
 numerous as at the August maximum. The radiant 
 is near the star Beta of the constellation Bootes. 
 
 Quetelet s list contains at least five exhibitions 
 which belong to this epoch. Two or three others 
 may also be referred to it with more or less proba 
 bility. 
 
 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 in Leo Minor. The numbers observed in 
 October are said to be at present increasing. At least 
 seven of the exhibitions in Quetelet s catalogue are 
 
32 METEORIC ASTRONOMY. 
 
 referable to this epoch. It is worthy of remark, 
 moreover, that three of the dates specified by Mr. 
 Greg as aerolite epochs are coincident with those of 
 shooting-stars; viz., February 15th-19th, July 26th, 
 and December 13th. The whole number of exhi 
 bitions 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 num 
 ber 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 
 as dense in comparison with others, which are invisi 
 ble 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, Le- 
 verrier 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 him 
 self; the other at the mean distance of the earth, 
 whose mass cannot exceed the tenth part of the mass 
 of the earth. 
 
 Within the last.few years a distinguished European 
 savant, Buys-Ballot, of Utrecht, has discovered a 
 
OTHER METEORIC RINGS. 33 
 
 short period of variation in the amount of s olar 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 pro 
 duced by a meteoric ring, whose period slightly ex 
 ceeds that of the sun s rotation. Such a zone might 
 influence our temperature by partially intercepting 
 the solar heat. 
 
 GENERAL REMARKS. 
 
 1. The average number of shooting-stars seen in 
 a clear, moonless night by a single observer, is about 
 8 per hour. One observer, however, sees only about 
 one-fourth of those visible from his point of observa 
 tion. 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 indi 
 cate that the number of meteors visible through the 
 telescope, employed by the latter, is about 53 times 
 
34 METEORIC ASTRONOMY. 
 
 the number visible to the naked eye, or about 
 400,000,000 per day.* This is two per day, or 73,000 
 per century, for every square mile of the earth s sur 
 face. 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, the} 7 were seen at two 
 different stations. The average weight of these me 
 teors, 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 decrees of 
 
 o 
 
 its path. It eclipsed, while in view, a number of the 
 fixed stars. 
 
 * The numerical results here given are those found by Professor 
 Newton. See Silliinan s Journ. for March, 1805. 
 
CHAPTER III. 
 
 AEROLITES. 
 
 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 com 
 posing 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 the 
 Mecanique 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 en 
 tered 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: 
 
 / Name. Diameter in miles. 
 
 Jupiter 90,000 
 
 Uranus 35,000 
 
 The Earth 7,926 
 
 Mercury 3,000 
 
 The Moon 2,160 
 
 Rhea, Saturn s 5th satellite 1,200 
 
 Dione " 4th " 500 
 
 (35) 
 
6b METEORIC ASTRONOMY. 
 
 Name. Diameter \u miles. 
 
 Vesta* 260 
 
 Juno 104 
 
 Melpomene 52 
 
 Polyhymnia 35 
 
 Isis 25 
 
 Atalanta 20 
 
 Hestia 15 
 
 The diminution doubtless continues indefinitely be 
 low the present limit of optical power. If, however, 
 the orbits have small eccentricity, such asteroids 
 could not become known to us unless their mean dis 
 tances 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: 
 
 Name. Eccentricity. 
 
 Venus 0-00683 
 
 The Earth 0-01677 
 
 Jupiter 0-04824 
 
 Metis 0-12410 
 
 Mercury 0-20562 
 
 Pallas 0-24000 
 
 Polyhymnia 0-33820 
 
 Faye s comet 0-55660 
 
 D Arrest s " 0-66090 
 
 Biela s " 0-75580 
 
 Encke s " 0-84670 
 
 Halley s " 0-96740 
 
 Fourth comet of 1857 /. 0-98140 
 
 Fifth comet of 1858 (Donati s) 0-99620 
 
 Third comet of 1827 0-99927 
 
 Were the eccentricities of the nearest asteroids equal 
 to that of Faye s comet, they would in perihelion 
 
 * The diameters of the asteroids are derived from a table by Prof. 
 Lespiault, in the Rep. of the Smithsonian Inst. for 1861, p. 216. 
 
AEROLITES. 37 
 
 intersect 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 of cometpids thus en 
 countered in the form of meteoric stones, fire-balls, and 
 shooting-stars in the course of a single year amounts 
 to many millions. The extremely minute, and such 
 as consist of matter in the gaseous form, are con 
 sumed or dissipated in the upper regions of the at 
 mosphere. ~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 proba 
 bly observed, it is obvious that the actual occurrence 
 of the phenomenon can be by no means rare.* 
 
 Although numerous instances of the fall of aero 
 lites 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, at 
 
 * "It appears probable, from the researches of Schreibevs, that 
 700 fall annually." Cosmos, vol. i. p. 119 (Bohn s Ed.). Reichen- 
 bach makes the number much greater. 
 
 4 
 
38 METEORIC ASTRONOMY. 
 
 L Aigle, in France, as forever to dissipate all doubt 
 on the subject. At one o clock P.M., the heavens 
 being almost cloudless, a tremendous noise, like that 
 of thunder, was heard, and at the same time an im 
 mense 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 dis 
 tance beneath the surface. The largest of these 
 fragments weighed 17J 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 pres 
 ent treatise to give an extended list of these phe 
 nomena. 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 
 654 B.C. This is the most ancient fall of aerolites 
 on record. 
 
 2. 468 B.C., about the year in which Socrates was 
 born. A mass of rock, described as " of the size of 
 two millstones," fell at ^Egos Potamos, in Thrace. 
 An attempt to rediscover this meteoric mass, so 
 celebrated in antiquity, was recently made, but with- 
 
AEROLITES. 39 
 
 out success. Notwithstanding this failure, Humboldt 
 expressed the hope that, as such a body would be dif 
 ficult 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. 921 A.D. An immense aerolite fell into the 
 river (a branch of the Tiber) at Kami, 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 Ensis- 
 heim, 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. "Dur 
 ing 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 hun 
 dred pounds each." A monk was struck dead at 
 Crema by one of these rocky fragments. This ter 
 rific 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 Yaison, 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. 
 
40 METEORIC ASTRONOMY. 
 
 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 ele 
 vation 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, con 
 sisting 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 w r as 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 lire-ball of extraordi 
 nary 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 explosion 
 
AEROLITES. 41 
 
 was heard, which was followed by a shower of mete 
 oric 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 s Gallery 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 plow 
 man, 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 thun 
 der 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 Yille 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 inter 
 esting account of the phenomenon was given by J. 
 Lloyd Williams, F.K.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 ap- 
 
 4* 
 
42 METEORIC ASTRONOMY. 
 
 peared, which was attended with a loud rumbling 
 noise. Immediately after the explosion a sound was 
 heard like that of heavy bodies falling in the neigh 
 borhood. 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 ex 
 ploded 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 the People s 
 Magazine for January 25th, 1834: 
 
 " The meteor of 1 807 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, 
 
AEROLITES. 43 
 
 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 h rst fall was in the town of Huntington, 
 near the house of Mr. Merwin Burr. He was stand 
 ing 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 shiv 
 ered 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 resi 
 dence, 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 shiv 
 ered 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 that 
 
44 METEORIC ASTRONOMY. 
 
 were 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 ex 
 posure 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 Jerse} r , 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 the American Journal of Science and 
 Arts for January, 1860. 
 
 26. 1860, May 1st. About twenty minutes before 
 one o clock P.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 in Sillimaris Journal 
 for July, 1860, and January and July, 1861, by Pro 
 fessors 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 Wash 
 ington and Noble Counties, and the prolongation of 
 
AEROLITES. 45 
 
 its projection, on the earth s surface, passes directly 
 through New Concord, in the S. E. corner of Musk- 
 ingum 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 invisi 
 ble. 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 New Concord,* Muskingum County, where 
 the meteoric stones fell, and in the immediate neigh 
 borhood, 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 deto 
 nation, 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 to 
 gether 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. The 
 
 * New Concord is close to the Guernsey County line. Nearly all 
 the stones fell in Guernsey. 
 
46 METEORIC ASTRONOMY. 
 
 result 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 it 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 ob 
 servation. 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: 
 
 Elevation when first seen, over 55 miles. 
 
 " at the time of its explosion 20 " 
 
 Inclination of its path to the horizon 20 or 25 
 
 Velocity per second, about 20 miles, 
 
AEROLITES. 47 
 
 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 me 
 teors 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 aero 
 lite may be seen in the Imperial Museum at St. 
 Petersburg. On the plain of Otumpa, in Buenos 
 Ayres, is a meteoric mass 7J- 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 examin 
 ation of meteoric stones, and the consideration of 
 the phenomena attending their fall, are the follow 
 ing : 
 
 1. K. 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.: 
 
48 METEORIC ASTRONOMY. 
 
 February 15th-19th; May 19th; July 26th; Novem 
 ber 29th, and December 13th. 
 
 2. It is worthy of remark that no new elements 
 have been found in meteoric stones. Humboldt, in 
 his Cosmos, 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 plan 
 etary bodies, like all the larger or smaller agglomer 
 ated 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?"* 
 
 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 in 
 Sillimarts Journal for November, 1864, p. 385. In 
 most cases, however, the specific gravity is about 3 
 or 4. 
 
 5. The contemplation of the heavenly bodies has 
 
 * Cosmos, vol. i. p. 120. 
 
AEROLITES. 49 
 
 often produced in thoughtful minds an intense desire 
 to know something of their nature and physical con 
 stitution. This curiosity is gratified in the examin 
 ation of aerolites. To handle, weigh, inspect, and 
 analyze bodies that have \vandered unnumbered 
 ages through the planetary spaces perhaps ap 
 proaching in their perihelia within a comparatively 
 short distance of the solar surface, and again reced 
 ing 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 stags 
 of maturity, those chaotic wanderers were more nu 
 merous in the vicinity of the earth s orbit than in re 
 cent 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 re 
 ceiving from this source much greater accretions of 
 matter than the earth. 
 
 7. As Mercury s orbit is very eccentric, he is be 
 yond 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 Mer 
 cury himself. If so, the tendency would be to di 
 minish slowly the planet s mean motion. Such a 
 lengthening of the period has been actually dis 
 covered.* 
 
 * Leverrier s Annals of the Observ 
 
CHAPTER IV. 
 
 CONJECTURES IN REGARD TO METEORIC EPOCHS. 
 
 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 repeated at the 
 same epoch in 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 Collins-wood, England, 
 
 O O 
 
 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 num 
 ber of hese periods will probably be increased by 
 future observations. Perhaps the following facts 
 (50) 
 
CONJECTURES IN REGARD TO METEORIC EPOCHS. 51 
 
 may 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 Gb ttingen. 
 
 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. Conse 
 quently 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 Get 
 tysburg, 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, was 
 
52 METEORIC ASTRONOMY. 
 
 heard. 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 aero 
 lites, however, were found beneath any part of its 
 path, perhaps the entire mass may have been dissi 
 pated before reaching the earth. SUlimaris Journal 
 for 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: 
 
 Iron 91-862 
 
 Nickel 5-517 
 
 Cobalt 0-529 
 
 Copper, manganese, arsenic, calcium, magne 
 sium, silicium, carbon, chlorine and sulphur. 2-072 
 
 100-000 
 
 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. 
 
CONJECTURES IN REGARD TO METEORIC EPOCHS. 53 
 
 8. On the 14th of July, 1854, a fire-ball was seen 
 at Senftenberg. 
 
 9. On the 13th of July, 1855, ti 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, arid terri 
 fied 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 Vi 
 enna Museum. Mr. J. R. Saunders also sent some of 
 the stones to Europe. It appears that, soon after 
 their fall, the stones were intensely cold.* They are 
 ordinary earthy aerolites, having a specific gravity 
 of 3-151, containing fragments of iron and iron py- 
 
 * " This is a remarkable example of a stone arriving on the earth 
 with a temperature approaching that of the interplanetary spaces. 
 Aerolites containing much iron, a substance which conducts heat 
 well, get thoroughly heated by their passage through the atmos 
 phere. But the stony aerolites, containing less iron, conducting 
 heat badly, preserve in their interior the temperature of the locality 
 from which they fall; their surface only is heated, and generally 
 fused. When the stones are large, the excessive cold of their interior 
 portion, which must be nearly that of interplanetary space, is re 
 marked; but when small, they remain hot for some time." Dr. 
 P hips on. 
 
 5* 
 
54 METEORIC ASTRONOMY. 
 
 rites; 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 New 
 England.* The hour of its appearance, it will be 
 observed, was nearly the same with that of the bo 
 lide of July 13th, 1846; and it is also worthy of 
 remark that their directions were 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 s Physique 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 be 
 tween 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. 
 
 THE EPOCH OF NOVEMBER 29. 
 
 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 No 
 vember, 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. Do 
 
 * Silliman s Journal, September, 1804. 
 
CONJECTURES IN REGARD TO METEORIC EPOCHS. 55 
 
 other 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. 
 
CHAPTER Y. 
 
 GEOGRAPHICAL DISTRIBUTION OF METEORIC STONES 
 DO AEROLITIC FALLS OCCUR MORE FREQUENTLY BY 
 DAY THAN BY NIGHT? DO METEORITES, BOLIDES, 
 AND THE MATTER OF ORDINARY SHOOTING-STARS, 
 COEXIST IN THE SAME RINGS ? 
 
 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 south 
 west, following the general line of the Atlantic coast. 
 Of all known occurrences of this phenomenon dur 
 ing the last fifty years, 92-8 per cent, have taken 
 place within these limits, and mostly in the neigh 
 borhood 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 also 
 (56) 
 
DISTRIBUTION OF METEORIC STONES. 57 
 
 concentrated 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 ac 
 counted for? We answer, the number of aerolites 
 seen to 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 Eu 
 rope. This fact alone, in all probability, affords a 
 sufficient explanation of Prof. Shepard s statement.* 
 
 Do aerolites fall more frequently by day than by night? 
 Mr. Alexander S. Herschel, of Collingwood, Eng 
 land, 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 ob- 
 
 * The same explanation is given by T. M. Hall, F.G.S., in the 
 Popular Science Review for Oct. 1866. 
 
58 METEORIC ASTRONOMY. 
 
 served to fall by day than by night. From this he 
 infers that, for the most part, the orbits in which 
 they move are interior to 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 con 
 clusion that the correspondence of dates is not acci 
 dental? We will consider, 
 
 I. The Epoch of November llth-14th. 
 
 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 move 
 ment of the node brings this meteor within the No 
 vember 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 llth. A bright meteoric light 
 was observed at Frankfort. 
 
 4. 1791, November llth. A large meteor was 
 seen at Gottingen and Lilienthal. 
 
DISTRIBUTION OF METEORIC STONES. 59 
 
 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 llth. 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 Cholirnschk, Russia. 
 
 11. 1822, November 12th. A fire-ball appeared 
 at Potsdam. 
 
 12. 1828, November 12th. A meteor \vas seen in 
 full sunshine at Sury, Erance. 
 
 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 me 
 teoric shower in the United States. 
 
 17. 1834, November 13th. A large fire-bail was 
 seen in North America. 
 
 18. 1835, November 13th. Several aerolites fell 
 near Belmont, Department de 1 Ain, France. 
 
 19. 1836, November llth. An aerolitic fall oc 
 curred at Macao, Brazil. 
 
 20. 1837, November 12th. A remarkable fire-ball 
 was seen in England. 
 
60 METEORIC ASTRONOMY. 
 
 21. 1838, November 13th. A large fire-ball was 
 seen at Cherbourg. 
 
 22. 1849, November 13th. An extraordinary me 
 teor 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. 
 
 II. The Epoch of August 7th-llth. 
 
 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. 
 
DISTRIBUTION OF METEORIC STONES. 61 
 
 6. 1802, August 10th. A fire-ball appeared at 
 Quedlinburg. 
 
 7. 1807, August -9th. A bolide was seen at Nu- 
 renberg. 
 
 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, weigh 
 ing seven pounds, fell at Slobodka, Russia. 
 
 12. 1822, August 7th. A meteorite fell at Ka- 
 donah, Agra. 
 
 13. 1822, August 7th. A large meteor was seen 
 in Moravia. 
 
 14. 1822, August llth. "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 llth. 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. 
 
 6 
 
62 METEORIC ASTRONOMY. 
 
 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 llth. 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 llth. A bolide was seen in 
 Paris. 
 
 37. 1859, August 7th. A detonating meteor ap 
 peared in Germany. 
 
DISTRIBUTION OF METEORIC STONES. 63 
 
 38. 1859, August llth. A meteoric stone fell near 
 Albany, New York. 
 
 39. 1859, August llth. A fine meteor was seen 
 at Athens. 
 
 40. 1862, August 8th. A meteoric stone-fall oc 
 curred at Pillistfer, Russia. 
 
 41. 1863, August llth. An aerolite fell at Shytal, 
 India. 
 
 III. The Epoch of December 6th-13th. 
 
 The following falls of meteoric stones have occured 
 at this epoch : 
 
 1. 1795, December 13th. At Wold Cottage, Eng 
 land. 
 
 2. 1798, December 13th. At Benares, India. 
 
 3. 1803, December 13th. At Massing, 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, near Trebizond.* 
 
 * This list contains nothing but aerolites. In the Edinburgh Re 
 view for January, 1867, we find the following statements: "Out of 
 the large number of authentic aerolites preserved in mineralogical 
 collections, two only one on the 10th of August, and one on the 
 13th of November are recorded to have fallen on star-shower dates. 
 On the other hand, five or six meteorites, on the epoch of the 13th- 
 14th of October, belong to a date when star-showers, so far as is at 
 present known, do not make their appearance." The inaccuracy of 
 the former statement is sufficiently apparent. In regard to the latter 
 we remark that Quetelet s Catalogue gives one star-shower on the 
 14th of October, and another on the 12th. 
 
64 METEORIC ASTRONOMY. 
 
 IV. The Epoch of April 18th-26th. 
 
 For this epoch we have the following aerolites: 
 
 1. 1803, April 26th. At L Aigle, France. 
 
 2. 1808, April 19th. At Casignano, Parma, Italy. 
 8. 1838, April 18th. At Abkurpore, India, 
 
 4. 1842, April 26th. At Milena, Croatia. 
 
 V. The Epoch of April 9th-12th. 
 
 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 ISTerft, 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. 
 
UNIVERSITY 
 
 CHAPTER VI. 
 
 PHENOMENA SUPPOSED TO BE METEORIC METEORIC 
 DUST DARK DAYS. 
 
 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 atmos 
 phere they are completely pulverized, so that, reach 
 ing the earth in extremely minute particles, they are 
 never discovered. It is very unlikely, moreover, 
 that of the millions of shooting-stars that daily pene 
 trate the atmosphere nothing whatever in the solid 
 form should ever reach the earth s surface. Indeed, 
 the celebrated Reiehenbach, who devoted great at 
 tention to this subject, believed that he had actually 
 discovered such deposits of meteoric matter. Chladni 
 and others have detailed instances of the fall of dust, 
 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, ac- 
 
 6* ( 65 ) 
 
66 METEORIC ASTRONOMY. 
 
 cording to old accounts, "the heavens appeared to 
 be on fire," which seems to indicate a. meteoric dis 
 play of an extraordinary character. 
 
 2. On the 3d of December, 1586, a considerable 
 quantity of dark-colored matter fell from the atmos 
 phere, at Yerde, in Hanover. The fall was attended 
 by intense light, as well as by a loud report resem 
 bling 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 Jan 
 uary, 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 Switzer 
 land. 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 large 
 
PHENOMENA SUPPOSED TO BE METEORIC. 67 
 
 bolide 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 the 
 ocean.* 
 
 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 aero 
 lites. 
 
 It is well known that quantities of sand are often 
 conveyed, by the trade-winds, from the continent of 
 
 * The date of this remarkable occurrence is worthy of note as a 
 probable aerolite epoch. From the 12th to the 15th of March we 
 have the following falls of meteoric stones: 
 
 1. 1731, March 12th. At Halstead, Essex, England. 
 
 2. 1798, March 12th. At Sale s, France. 
 
 3. 1806, March 15th. At Alais, France. 
 
 4. 1807, March 13th. At Timochin, Russia. 
 
 5. 1811, March 13th. At Kuleschofka, Russia. 
 
 6. 1813, March 13th-14th. The phenomena above described. 
 
 7. 1841, March 12th. At Gruneberg, Silesia. 
 Numerous fire-balls have appeared at the same epoch. 
 
68 METEORIC ASTRONOMY. 
 
 Africa 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 mete 
 oric 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 ac 
 count of the accidental discovery of such celestial 
 pebbles has recently been given by Professor Haidin- 
 ger, of Vienna. The meteor from which they were 
 derived ivas but little larger than an ordinary shooting- 
 star. Its track was visible, however, until it termin 
 ated 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 chateau that exists in the locality. The 
 fall was accompanied by a whistling or hissing noise 
 in the air, and terminated by a slight detonation. 
 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 seconds 
 
PHENOMENA SUPPOSED TO BE METEORIC. 69 
 
 these stones continued in a state 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 ordi 
 nary 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 Lai- 
 bach, in Carniola, and member of the Austrian 
 Chamber of Deputies. 
 
 The following is perhaps the only instance on re 
 cord in which a shooting-star lower than the clouds has 
 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 about Gamma 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 certainly below the 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 was below the clouds." Sillimaris 
 Journal for Sept, 1866. It seems altogether proba 
 ble that when a meteor thus descends, before its ex 
 plosion or dissipation, into the lower atmospheric 
 
70 METEORIC ASTRONOMY. 
 
 strata, at least portions of its mass must reach the 
 earth s surface. 
 
 METEORIC TRANSITS DARK DAYS. 
 
 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 maculse, 
 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 PastorfFon the following dates: 
 
 1822, October 23d, 
 
 1823, July 24th and 25th, 
 1836, October 18th, 
 
 and 011 several subsequent occasions the same as 
 tronomer witnessed similar phenomena. Another 
 
PHENOMENA SUPPOSED TO BE METEORIC. 71 
 
 transit 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 dif 
 ficult to account for these appearances (so frequently 
 seen by experienced observers) unless we regard 
 them as meteoric masses. 
 
 PARTIAL INTERCEPTION OF THE SUN S LIGHT AND 
 HEAT. 
 
 Numerous instances are on record of partial ob 
 scurations 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-called dark day occurred 
 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 obscura 
 tions. It is proper to remark, however, that the 
 eminent French astronomer, Faye, who has given 
 the subject much attention, finds little or no evi 
 dence 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 
 Madler, 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 dis- 
 
72 METEORIC ASTRONOMY. 
 
 covery of 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 some 
 what 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, Macerate, Italy. 
 
 (c) May 9th, 1827, Nashville, Tennessee, U. S. A. 
 
 (d) May 12th, 1861, Goruckpore, India. 
 
 (e) May 13th, 1831, Youilld, France. 
 (/) May 13th, 1855, Oesel, Baltic Sea. 
 
 (g) May 13th, 1855, Brernevorde, Hanover. 
 
 (h) May 14th, 1861, near Villanova, in Catalonia, 
 Spain. 
 
 ({) May 14th, 1864, Orgueil, France. 
 All the foregoing, except that of May 14th, 1861, 
 may be found in Shepard s list, Sillimaris Journal for 
 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 indef 
 initely 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 per- 
 
PHENOMENA SUPPOSED TO BE METEORIC. 73 
 
 manently gaseous 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. As 
 cending 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 con 
 tain 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, Eeichenbach believed, and cer 
 tainly not without some probability, that he had 
 detected minute portions of meteoric matter. 
 
CHAPTER VII. 
 
 FURTHER RESEARCHES OF REICHENBACH THEORY OF 
 METEORS STABILITY OF THE SOLAR SYSTEM DOC 
 TRINE OF A RESISTING MEDIUM. 
 
 THE able and original researches of the celebrated 
 Reichenbach, who has made meteoric phenomena 
 the subject of long-continued and enthusiastic in 
 vestigation, have attracted the general attention of 
 scientific men. It is proposed to present, in the fol 
 lowing chapter, a brief resume of his views and con 
 clusions. 
 
 1. The Constitution of Comets. It is a remarkable 
 fact that cometary matter has no refractive power, 
 as is manifest from the observations of stars seen 
 through their substance.* These bodies, therefore, 
 are not gaseous; and the most probable theory in 
 regard to their nature is that they consist of an in 
 finite number of discrete, solid molecules, at great 
 distances from each other, with very little attraction 
 among themselves, or toward the nucleus, and hav 
 ing, therefore, great mobility. Now Baron Reichen 
 bach, having carefully examined a great number of 
 meteoric stones, has found them for the most part 
 
 * The innermost or semi-transparent ring of Saturn appears to 
 be similarly constituted, as the body of the planet is seen through it 
 without any distortion whatever. 
 
 (t4) 
 
FURTHER RESEARCHES OF REICHENBACH. 75 
 
 composed of extremely minute globules, apparently 
 cemented together. He "hence infers that they have 
 been comets perhaps very small ones whose com 
 ponent molecules have by degrees collected into 
 single masses. 
 
 2. The Number of Aerolites. The average number 
 of aerolitic falls in a year was estimated by Schreibers, 
 as previously stated, at 700. Reichenbach, however, 
 after a thorough discussion of the data at hand, makes 
 the number much larger. He regards the probable 
 annual average, for the entire surface of the earth, 
 as not less than 4500. This would give about twelve 
 daily falls. They are of every variety as to magni 
 tude, from a weight of less than a single ounce to 
 over 30,000 pounds. The Baron even suspects the 
 meteoric origin of large masses of dolerite which all 
 former geologists had considered native to our planet. 
 In view of the fact that from the largest members of 
 our planetary system down to the particles of mete 
 oric dust there is an approximately regular gradation, 
 and that the larger, at least in some instances, appear 
 to have been formed by the aggregation of the 
 smaller, he asks may not the earth itself have been 
 formed by an agglomeration of meteorites? The 
 learned author, from the general scope of his specu 
 lations, would thus seem to have adopted a form 
 of the nebular hypothesis somewhat different from 
 that proposed by Laplace. 
 
 3. Composition and mean Density of Aerolites. A 
 large proportion of meteoric stones are similar in 
 structure to the volcanic or plutonic rocks of the 
 earth; and all consist of elements identical with 
 those in our planet s crust. Their mean density, 
 
76 METEORIC ASTRONOMY. 
 
 moreover, is very nearly the same with that of the 
 earth. These facts are regarded by Reichenbach as 
 indicating that those meteoric masses which are 
 daily becoming incorporated with our planet, have 
 had a common origin with the earth itself. Baron 
 Reichenbach s views, as presented by himself, will 
 be found at length in Poggmdorfs Annalen for De 
 cember, 1858. 
 
 Stability of the Solar System. The well-known dem 
 onstrations of the stability of the solar system, 
 given by Lagrange and Laplace, are not to be ac 
 cepted in an unlimited sense. They make no provi 
 sion against the destructive agency of a resisting 
 medium, or the entrance of matter into the solar 
 domain from the interstellar spaces. In short, the 
 conservative influence ascribed to these celebrated 
 theorems extends only to the major planets; and 
 even in their case it is to be understood as applying 
 only to their mutual perturbations. The phenomena 
 of shooting-stars and aerolites have demonstrated 
 the existence of considerable quantities of matter 
 moving in unstable orbits. The amount of such mat 
 ter within the solar system cannot now be determ 
 ined; but the term probably includes the zodiacal 
 light, man} 7 , if not all, of the meteoric rings, and a 
 large number of comets. These unstable parts of the 
 system are being gradually incorporated with the 
 sun, the earth, and doubtless also with the other 
 large planets. It is highly probable that at former 
 epochs the quantity of such matter was much greater 
 than at present, and that, unless new supplies be re 
 ceived ab extra, it must, by slow degrees, disappear 
 from the system. 
 
DOCTRINES OF A RESISTING MEDIUM. 77 
 
 The fact, now well established, of the extensive 
 diffusion of meteoric matter through the interplan 
 etary spaces has an obvious bearing on Encke s theory 
 of a resisting medium. If we grant the existence of 
 such an ether, it would seem unphilosophical to as 
 cribe to it one of the properties of a material fluid 
 the power of resisting the motion of all bodies mov 
 ing through it and to deny it such properties in 
 other respects. Its condensation, therefore, about 
 the sun and other large bodies must be a necessary 
 consequence. This condensation existed in the 
 primitive solar spheroid, before the formation of the 
 planets: the rotation of the spheroid would be com 
 municated to the coexisting ether; and hence, during 
 the entire history of the planetary system, the ether has 
 revolved around the sun in the same direction with the 
 planets. This condensed ether, it is also obvious, 
 must participate in the progressive motion of the 
 solar system. 
 
 But again; even if we reject the doctrine of the 
 development of the planetary bodies from a rotating 
 nebula, we must still regard the density of the ether 
 as increasing to the center of the system. The sun s 
 rotation, therefore, would communicate motion to 
 the first and denser portions; this motion would be 
 transmitted outward through successive strata, with 
 a constantly diminishing angular velocity. The 
 motion of the planets themselves through the me 
 dium in nearly circular orbits would concur in im 
 parting to it a revolution in the same direction. 
 Whether, therefore, we receive or reject the nebular 
 hypothesis, the resistance of the ethereal medium to 
 bodies moving in orbits of small eccentricity and 
 
 7* 
 
78 METEORIC ASTRONOMY. 
 
 in the direction of the sun s rotation, becomes an 
 infinitesimal quantity. 
 
 The hypothesis of Encke, it is well known, was 
 based solely on the observed acceleration of the 
 comet which bears his name. More recently, how 
 ever, a still greater acceleration has been found in 
 the case of Faye s comet. Now as the meteoric 
 matter of the solar system is a known cause for such 
 phenomena, sufficient, in all probability, both in 
 mode and measure, the doctrine of a resisting ethe 
 real medium would seem to be a wholly unnecessary 
 assumption. 
 
CHAPTER VIII. 
 
 DOES THE NUMBER OF AEROLITIC FALLS VARY WITH THE 
 EARTH S DISTANCE FROM THE SUN? RELATIVE NUM 
 BERS OBSERVED IN THE FORENOON AND AFTERNOON 
 
 EXTENT OF THE ATMOSPHERE AS INDICATED BY ME 
 TEORS. 
 
 AN analysis of any extensive table of meteorites 
 and fire-balls proves that a greater number of aero- 
 litic falls have been observed during the months of 
 June and July, when the earth is near its aphelion, 
 than in December and January, when near its peri 
 helion. It is found, however, that the reverse is true 
 in regard to bolides, or fire-balls. Now the theory 
 has been held by more than one physicist, that aero 
 lites are the outriders of the asteroid ring between 
 Mars and Jupiter; their orbits having become so 
 eccentric that in perihelion they approach very near 
 that of the earth. If this theory be the true one, the 
 earth would probably encounter the greatest number 
 of those meteor-asteroids when near its aphelion. 
 The hypothesis therefore, it has been claimed, ap 
 pears to be supported by well-known facts. The 
 variation, however, in the observed number of aero 
 lites may be readily accounted for independently of 
 
 (79) 
 
80 METEORIC ASTRONOMY. 
 
 any theory as to their origin. The fall of meteoric 
 stones would evidently be more likely to escape ob 
 servation by night than by day, by reason of the 
 relatively small number of observers. But the days 
 are shortest when the earth is in perihelion, and 
 longest when in aphelion : the ratio of their lengths 
 being nearly equal to that of the corresponding num 
 bers of aerolitic falls. 
 
 On the other hand, it is obvious that fire-balls, un 
 less of very extraordinary magnitude, would not be 
 visible during the day. The observed number will 
 therefore be greatest when the nights are longest; 
 that is, when the earth is near its perihelion. This, 
 it will be found, is precisely in accordance with ob 
 servation. 
 
 It has been found, moreover, that a greater num 
 ber of meteoric stones fall during the first half of the 
 day, that is, from midnight to noon, than in the lat 
 ter half, from noon to midnight. This would seem 
 to indicate that a large proportion of the aerolites 
 encountered by the earth have direct motion. 
 
 Height of the Atmosphere. The weight of a given 
 volume of mercury is 10,517 times that of an equal 
 volume of air at the earth s surface; and since the 
 mean height of the mercurial column in the ba 
 rometer is about thirty inches, if the atmosphere 
 were of uniform density its altitude would be about 
 26,300 feet, or nearly five miles. The density rap 
 idly diminishes, however, as we ascend above the 
 earth s surface. Calling it unity at the sea level, the 
 rate of variation is approximately expressed as fol 
 lows: 
 
HEIGHT OF THE ATMOSPHERE. 81 
 
 Altitude in Miles. Density. 
 
 ....... 1 
 
 7 ....... i 
 
 14 . . . . . ... . T V 
 
 21 ..... . 
 
 28 ........ ^ 
 
 35 ....... 
 
 etc. etc. 
 
 From this table it will be seen that at the height of 
 35 miles the air is one thousand times rarer than at 
 the surface of the earth; and that, supposing the 
 same rate of decrease to continue, at the height of 
 140 miles the rarity would be one trillion times greater. 
 The atmosphere, however, is not unlimited. When it 
 becomes so rare that the force of repulsion between 
 its particles is counterbalanced by the earth s attrac 
 tion, no further expansion is possible. To determine 
 the altitude of its superior surface is a problem at 
 once difficult and interesting. ~Not many years since 
 about 45 or 50 miles were generally regarded as a 
 probable limit. Considerable light, however, has 
 been thrown upon the question by recent observa 
 tions in meteoric astronomy. Several hundred det 
 onating meteors have been observed, and their 
 average height at the instant of their first appear 
 ance has been found to exceed 90 miles. The great 
 meteor of February 3d, 1856, seen at Brussels, Gen 
 eva, Paris, and elsewhere, was 150 miles high when 
 first seen, and a few apparently well-authenticated 
 instances are known of a still greater elevation. We 
 conclude, therefore, from the evidence afforded by 
 
82 .METEORIC ASTRONOMY. 
 
 meteoric phenomena, that the height of the atmos 
 phere is certainly not less than 200 miles. 
 
 It might be supposed, however, that the resistance 
 of the air at such altitudes would not develop a 
 sufficient amount of heat to give meteorites their 
 brilliant appearance. This question has been dis 
 cussed by Joule, Thomson, Haidinger, and Reichen- 
 bach, and may now be regarded as definitively settled. 
 When the velocity of a meteorite is known the 
 quantity of heat produced by its motion through air 
 of a given density is readily determined. The tem 
 perature acquired is the equivalent of the force with 
 which the atmospheric molecules are met by the 
 moving body. This is about one degree (Fahren 
 heit) for a velocity of 100 feet per second, and it 
 varies directly as the square of the velocity. A 
 velocity, therefore, of 30 miles in a second would 
 produce a temperature of 2,500,000. The weight 
 of 5280 cubic feet of air at the earth s surface is 
 about 2,830,000 grains. This, consequently, is the 
 weight of a column 1 mile in length, and whose 
 base or cross section is one square foot. The weight 
 of a column of the same dimensions at a height of 
 140 miles would be about - 3 smooth of a grain. Hence 
 the heat acquired by a meteoric mass whose cross 
 section is one square foot, in moving 1 mile would 
 be one grain raised 7 4 degrees, or one-fifth of a grain 
 2500 in 70 miles. This temperature would un 
 doubtedly be sufficient to render meteoric bodies 
 brilliantly luminous. 
 
 But there have been indications of an atmosphere 
 at an elevation of more than 500 miles. A discus 
 sion of the best observations of the great aurora seen 
 
ATMOSPHERE S EXTENT AS INDICATED BY METEORS. 83 
 
 throughout the United States on the 28th of August, 
 1859, gave 534 miles as the height of the upper limit 
 above the earth s surface. The aurora of September 
 2d, of the same year, had an elevation but little in 
 ferior, viz., 495 miles. Now, according to the ob 
 served rate of variation of density, at the height of 
 525 miles, the atmosphere would be so rare that a 
 sphere of it filling the orbit of Neptune would con 
 tain less matter than aVth of a cubic inch of air at 
 the earth s surface. In other words, it would weigh 
 less than ^Vth of a grain. We are thus forced to the 
 conclusion either that the law of variation is not the 
 same at great heights as near the surface; or, that 
 beyond the limits of the atmosphere of air, there is 
 another of electricity, or of some other fluid. 
 
CHAPTER IX. 
 
 THE METEORIC THEORY OF SOLAR HEAT. 
 
 OF the various theories proposed by astronomers 
 to account for the origin of the sun s light and heat, 
 only two have at present any considerable number 
 of advocates. These are 
 
 1. The Chemical Theory ; according to which the 
 light and heat of the sun are produced by the chemi 
 cal combination of its elements; in other words, by 
 an intense combustion. 
 
 2. The Meteoric Theory, which ascribes the heat of 
 our centra] luminary to the fall of meteors upon its 
 surface. The former is advocated with great inge 
 nuity by Professor Ennis in a recent work on " The 
 Origin of the Stars, and the Causes of their Motions and 
 their Light" It has, on the other hand, been ably 
 opposed by Dr. Mayer, Professor William Thomson, 
 and other eminent physicists. A brief examination 
 of its claims may not be destitute of interest. 
 
 If the sun s heat is produced by chemical action, 
 whence comes the necessary supply of fuel to support 
 the combustion ? The quantity of solar heat radiated 
 into space has been determined with at least an ap 
 proximation to mathematical precision. We know 
 also the amount produced by the combustion of a 
 given quantity of coal. Now it has been found by 
 (84) 
 
THE METEORIC THEORY OF SOLAR HEAT. 85 
 
 calculation that if the sun were a solid globe of coal, 
 and a sufficient supply of oxygen were furnished to 
 support its combustion, the amount of heat resulting 
 from its consumption would be less than that actually 
 emitted during the last 6000 years. In short, no 
 known elements would meet the demands of the 
 case. But it is highly probable that the different 
 bodies of the solar system are composed of the same 
 elements. This view is sustained by the well-known 
 fact that meteoric stones, which have reached us 
 from different and distant regions of space, have 
 brought us no new elementary substances. The 
 chemical theory of solar heat seems thus encumbered 
 with difficulties well-nigh insuperable. 
 
 Professor Ennis mode of obviating this objection, 
 though highly ingenious, is by no means conclusive. 
 The latest analyses of the solar spectrum indicate, 
 he affirms, the presence of numerous elements be 
 sides those with which we are acquainted. Some of 
 these may yield by their combustion a much greater 
 amount of heat than the same quantity of any known 
 elements in the earth s crust. "Every star," he re 
 marks, " as far as yet known, has a different set of 
 fixed lines, although there are certain resemblances 
 between tliem. They lead to the conclusion that 
 each star has, in part at least, its peculiar modifica 
 tions of matter, called simple elements; but the 
 number of stars is infinite, and therefore the num 
 ber of elements must be infinite."* He argues, 
 moreover, that in a globe so vast as the sun there 
 may be forces in operation with whose nature we 
 
 * Origin of the Stars, p. 173. 
 
 8 
 
86 METEORIC ASTRONOMY. 
 
 are wholly unacquainted. This leaving of the blown 
 elements as well as the known laws of nature for un 
 known possibilities will hardly be satisfactory to un 
 biased minds. 
 
 Again: that the different bodies of the universe 
 are composed of different elements is inferred by our 
 author from the following among other considera 
 tions : " In our solar system Mercury is sixty or eighty 
 times more dense than one of the satellites of Jupiter, 
 and probably in a much greater proportion denser 
 than the satellites of Saturn. This indicates a wide 
 difference between the nature of their elements." 
 This statement is again repeated in a subsequent 
 page.* " The densities of the planets and their 
 satellites prove that they are composed of very dif 
 ferent elements. Mercury is more than sixty times, 
 and our earth about fifty times, more dense than the 
 inner moon of Jupiter. Saturn is only about one- 
 ninth as dense as the earth ; it would float buoyantly 
 on water. There is a high probability that the satel 
 lites of Saturn and Uranus are far lighter than those 
 of Jupiter. Between the two extremes of the attend 
 ants of the sun, there is probably a greater difference 
 in density than one hundred to one; and from one 
 extreme to the other there are regular gradations of 
 small amount. 
 
 " The difference in constitution between the earth 
 and the moon is seen in their densities: that of the 
 moon being about half that of the earth. The 
 nitrogen of our globe is found only in the atmos 
 phere, and such substances as derive it from the 
 
 * Origin of the Stars, p. 184. 
 
THE METEORIC THEORY OF 
 
 atmosphere. The moon has no 
 
 phere, and therefore, in a high pfols^mrf^^jvm 
 
 nitrogen." fy? t * 
 
 The statements here quoted were desigtieB/^to 
 show that the physical constitution of the sun and 
 planets is widely different from that of the earth, 
 and that the combustion of some of the elements in 
 this indefinite variety may account for the origin of 
 solar heat. Let us examine the facts. 
 
 According to Laplace the mass of Jupiter s first 
 satellite is 0-000017328, that of Jupiter being 1. The 
 diameter is 2436 miles. Hence the corresponding 
 density is a little more than one-fifth of the mean 
 density of the earth. In other words, it is somewhat 
 greater than the density of water, and very nearly 
 equal to that of Jupiter himself. Professor Ennis 
 value is therefore erroneous.* In regard to the 
 densities of the Saturnian and Uranian satellites 
 nothing is known, and conjecture is useless. In 
 short, Saturn has the least mean density of all the 
 planets, primary or secondary, so far as known. 
 This may be owing to the great extent of his atmos 
 pheric envelope. The density of the moon is but 
 three-fifths that of the earth: it is to be borne in 
 mind, however, that the mass and pressure are also 
 much less. 
 
 With respect to meteorites the same author re 
 marks that " like the moon, they are probably satel 
 lites of the earth; but being very small, they are 
 
 * Since the above was written Prof. Ennis has informed the author 
 that, without making any estimate of his own, he adopted the 
 density of Jupiter s first satellite as given in Lardnev s Handbook <>f 
 Astronomy, 
 
88 METEORIC ASTRONOMY. 
 
 liable to extraordinary perturbations, and hence 
 strike the earth in many directions." Here, again, his 
 facts are at fault; for (1) the observed velocities of 
 these bodies are inconsistent with the supposition of 
 their being satellites of the earth; and (2) the 
 amount of perturbation of such bodies does not vary 
 with their masses : a small meteorite would fall 
 toward the earth or any other planet with no greater 
 velocity than a large one. 
 
 THE METEORIC THEORY. 
 
 It has been shown in a previous chapter that im 
 mense numbers of meteoric asteroids are constantly 
 traversing the planetary spaces that many millions, 
 in fact, daily enter the earth s atmosphere. Reasons 
 are not wanting for supposing the numbers of these 
 bodies to increase with great rapidity as we approach 
 the center oi the system. Moreover, on account of 
 the greater force of gravity at the sun s surface the 
 heat produced by their fall must be much greater 
 than at the surface of the earth. It has been calcu 
 lated that if one of these asteroids be arrested in 
 perihelion by the solar atmosphere, the quantity of 
 heat thus developed will be 9000 times greater than 
 that produced by the combustion of an equal mass 
 of coal. There can, therefore, be no reasonable 
 doubt that a portion of the sun s heat is produced by 
 the impact of meteoric matter. In considering the 
 probability that it is chiefly so generated, the follow 
 ing questions naturally present themselves : 
 
 1. What amount of matter precipitated upon the sun 
 would develop the quantity of heat actually emitted? 
 
THE METEORIC THEORY. 89 
 
 This question has been satisfactorily discussed by 
 eminent physicists, and it will be sufficient for our 
 purpose to give the result. According to Professor 
 William Thomson, of Glasgow, the present rate of 
 emission would be kept up by a meteoric deposit 
 which would form an annual stratum 60 feet in 
 thickness over the sun s surface. 
 
 2. Could such an increase of the sun s magnitude be 
 detected by micrometrical measurement? This inquiry 
 is readily answered in the negative. The apparent 
 diameter would be augmented only one second in 
 17,600 years. 
 
 3. Is there any known or visible source from which 
 this amount of meteoric, matter may be supplied? Thom 
 son, Mayer, and other distinguished writers regard 
 the zodiacal light as the source of such meteorites. 
 The inner portions of this immense "tornado" must 
 be resisted in their motions by the solar atmosphere, 
 and hence precipitated upon the sun s surface. 
 
 4. Would this increase of the sun s mass derange the 
 motions of the solar system? To this question Prof. 
 Ennis gives an affirmative answer; his first objection 
 to the theory under consideration being stated as 
 follows: "The constant accumulation of such ma 
 terials, during hundreds of millions of years, would 
 increase the body of the sun and its consequent 
 gravity so greatly as to derange the entire solar sys 
 tem, by destroying the balance between the cen 
 tripetal and centrifugal forces now acting on the 
 planets."* This, it must be confessed, would be a 
 valid objection, if the meteoric matter were sup- 
 
 * Origin of the Stars, p. 77. 
 
MKTEOHIC ASTRONOMY. 
 
 posed to be derived from the extra-planetary spaces. 
 As their source, however, the zodiacal light is 
 interior to the earth s orbit, it can have no applica 
 tion to any planet exterior to Venus. Most probably 
 the greater portion of the meteoric mass is even 
 within the orbit of Mercury, so that the effect of its 
 convergence could scarcely be noticed even in the 
 motion of the interior planets. In pre-historic time 
 the zodiacal light may have extended far beyond the 
 earth s orbit. If so, its convergence to its present 
 dimensions was undoubtedly attended by an accel 
 eration of the earth s mean motion. We can of 
 course have no evidence that such a shortening of 
 the year has never occurred. 
 
 The second objection urged against the meteoric 
 theory by the author of "The Origin of the Stars" 
 is thus expressed: "As we must believe that all stars 
 were lighted up by the same means, so we must be 
 lieve, according to this theory, that the present inte 
 rior heat of the earth and its former melted condition 
 in both exterior and interior, was caused by the fall 
 of meteorites. But if so, they must have gradually 
 ceased to fall, as space became cleared of their pres 
 ence, and we would now find a thick covering of 
 meteorites on the earth s cooled surface. Instead of 
 this, we find them very rarely, and in accordance 
 with their present very rare falls." 
 
 To this it may be replied that the primitive igneous 
 fluidity of the earth and planets was a necessary con 
 sequence of their condensation a fact which has no 
 inconsistency with the theory in question. 
 
 A different mechanical theory of the origin of solar 
 heat is advocated by Professor Helmholtz in his in- 
 
THE METEORIC THEORY. 91 
 
 teresting work On, the Interaction of Natural Forces. 
 In regard to the sun he says: "If we adopt the very 
 probable view, that the remarkably small density of 
 so large a body is caused by its high temperature, 
 and may become greater in time, it may be calcu 
 lated that if the diameter of the sun were diminished 
 only the ten-thousandth part of its present length, by 
 this act a sufficient quantity of heat would be gen 
 erated to cover the total emission for 2100 years. 
 Such a small change besides it would be difficult to 
 detect by the finest astronomical observations."* 
 The same view is adopted by Dr. Joel E. Hendricks, 
 of Des Moines, lowa.f 
 
 * Youman s Correlation and Conservation of Forces, p. 244. 
 
 f Iowa Instructor and School Journal for November, 1866, p. 49. 
 
CHAPTER X. 
 
 WILL THE METEORIC THEORY ACCOUNT FOR THE PHE 
 NOMENA OF VARIABLE AND TEMPORARY STARS? 
 
 HAVING shown that meteor-asteroids are diffused 
 in vast quantities throughout the universe; that ac 
 cording to eminent physicists the solar heat is pro 
 duced by the precipitation of such matter on the 
 sun s surface; and that Leverrier has found it neces 
 sary to introduce the disturbing effect of meteoric 
 rings in order fully to account for the motion of 
 Mercury s perihelion; we now propose extending 
 the meteoric theory to a number of phenomena that 
 have hitherto received no satisfactory explanation. 
 
 VARIABLE AND TEMPORARY STARS. 
 
 No theory as to the origin of the sun s light and 
 heat would seem to be admissible unless applicable 
 also to the sidereal systems. Will the meteoric 
 theory explain the phenomena of variable and tem 
 porary stars? 
 
 "It has been remarked respecting variable stars, 
 
 that in passing through their successive phases, they 
 
 are subject to sensible irregularities, which have not 
 
 hitherto been reduced to fixed laws In general 
 
 (92) 
 
VARIABLE AND TEMPORARY STARS. 93 
 
 they do not always attain the same maximum bright 
 ness, their fluctuations being in some cases very 
 considerable. Thus, according to Argelander, the 
 variable star in Corona Borealis, which Pigott dis 
 covered in 1795, exhibits on some occasions such 
 feeble changes of brightness, that it is almost im 
 possible to distinguish the maxima from the minima 
 by the naked eye; but after it has completed several 
 of its cycles in this manner, its fluctuations all at 
 once become so considerable, that in some instances 
 it totally disappears. It has been found, moreover, 
 that the light of variable stars does not increase and 
 diminish symmetrically on each side of the maximum, 
 nor are the successive intervals between the maxima 
 exactly equal to each other." Grant s History of Phys 
 ical Astronomy, p 541. 
 
 Of the numerous hypotheses hitherto proposed to 
 account for these phenomena we believe none can be 
 found to include and harmonize all the facts of ob 
 servation. The theories of Herschel and Maupertius 
 fail to explain the irregularity in some of the periods; 
 while those of Newton and Dunn afford no explana 
 tion of the periodicity itself.* But let us suppose 
 that among the fixed stars some have atmospheres 
 of great extent, as was probably the case with the 
 sun at a remote epoch in its history. Let us also 
 suppose the existence of nebulous rings, like those 
 of our own system, moving in orbits so elliptical 
 
 * A recent hypothesis in regard to the temporary star of 1572 has 
 been proposed by Alexander Wilcocks, M.D., of Philadelphia. See 
 Journ. Acad. Nat. Sci. of Phila. for 1859. 
 
94 METEORIC ASTRONOMY. 
 
 that in their perihelia they pass through the atmos 
 pheric envelopes of the central stars. Such meteoric 
 rings of varying density, like those revolving about 
 the sun, would evidently produce the phenomena of 
 variable stars. The resisting medium through which 
 they pass in perihelion must gradually contract their 
 orbits, or, in other words, diminish the intervals be 
 tween consecutive maxima. Such a shortening of 
 the period is now well established in the case of 
 Algol. Again, if a ring be influenced by perturba 
 tion the period will be variable, like that of Mira 
 Ceil. A change, moreover, in the perihelion distance 
 will account for the occasional increase or diminution 
 of the apparent magnitude at the different maxima 
 of the same star. But how are we to account for the 
 variations of brightness observed in a number of 
 stars where no order or periodicity in the variation 
 has as yet been discovered ? It is easy to perceive 
 that either a single nebulous ring with more than 
 one hiatus, or several rings about the same star, may 
 produce phenomena of the character described. 
 Finally, if the matter of an elliptic ring should ac 
 cumulate in a single mass, so as to occupy a com 
 paratively small arc, its passage through perihelion 
 might produce the phenomenon of a so-called tem 
 porary star. 
 
 Recent researches relating to nebulae seem in some 
 measure confirmatory of the view here presented. 
 These observations have shown (1) a change of posi 
 tion in some of these objects, rendering it probable 
 that in certain cases they are not more distant than 
 fixed stars visible to the naked eye; and (2) a varia- 
 
VARIABLE AND TEMPORARY STARS. 95 
 
 tion in the brilliancy of many small stars situated in 
 the great nebula of Orion, and also the existence of 
 numerous masses of nebulous matter in the form of 
 tufts apparently attached to stars, facts regarded as 
 indicative of a physical connection between the stars 
 and nebulae.* 
 
 * Gautier s Notice of Recent Researches relating to Nebulae. 
 Silliman s Journal for Jan. 1863, and March, 1864. 
 
CHAPTER XI. 
 
 THE LUNAR AND SOLAR THEORIES OF THE ORIGIN OF 
 AEROLITES. 
 
 BESIDES the cosmical theory of aerolites which has 
 been adopted in this work, and which is now accepted 
 by a great majority of scientific men, at least four 
 others have been proposed: (1) the atmospheric, ac 
 cording to which they are formed, like hail, in the 
 earth s atmosphere; (2) the volcanic, which regards 
 them as matter ejected with great force from ter 
 restrial volcanoes ; (3) the lunar, which supposes 
 them to have been thrown from craters in the moon; 
 and (4) the solar hypothesis, according to which they 
 are projected by some tremendous explosive force 
 from the great central orb of our system. The first 
 and second have been universally abandoned as un 
 tenable. The third and fourth, however, are entitled 
 to consideration. 
 
 THE LUNAR THEORY. 
 
 The theory which regards meteoric stones as pro 
 ducts of eruption in lunar volcanoes was received 
 with favor by the celebrated Laplace: "As the 
 gravity at the surface of the moon," he remarks, "is 
 much less than at the surface of the earth, and as 
 this body has no atmosphere which can oppose a 
 (96) 
 
THE LUNAR THEORY. 97 
 
 sensible resistance to the motion of projectiles, we 
 may conceive that a body projected with a great 
 force, by the explosion of a lunar volcano, may 
 attain and pass the limit, where the attraction of the 
 earth commences to predominate over that of the 
 moon. For this purpose it is sufficient that its ini 
 tial velocity in the direction of the vertical may be 
 2500 meters in a second; then in place of falling 
 back on the moon, it becomes a satellite of the earth, 
 and describes about it an orbit more or less elon 
 gated. The direction of its primitive impulsion may 
 be such as to make it move directly toward the 
 atmosphere of the earth; or it may not attain it, till 
 after several and even a great number of revolu 
 tions; for it is evident that the action of the sun, 
 which changes in a sensible manner the distances of 
 the moon from the earth, ought to produce in the 
 radius vector of a satellite which moves in a very 
 eccentric orbit, much more considerable variations, 
 and thus at length so diminish the perigean distance 
 of the satellite, as to make it penetrate our atmos 
 phere. This body traversing it with a very great 
 velocity, and experiencing a very sensible resistance, 
 might at length precipitate itself on the earth; the 
 friction of the air against its surface would be suffi 
 cient to inflame it, and make it detonate, provided 
 that it contained ingredients proper to produce these 
 effects, and then it would present to us all those 
 phenomena which meteoric stones exhibit. If it was 
 satisfactorily proved that they are not produced by 
 volcanoes, or generated in our atmosphere, and that 
 their cause must be sought beyond it, in the regions 
 of the heavens, the preceding hypothesis, which 
 
 9 
 
98 METEORIC ASTRONOMY. 
 
 likewise explains the identity of composition ob 
 served in meteoric stones, by an identity of origin, 
 will not be devoid of probability." Systeme dn 
 Monde, t. ii. cap. v. 
 
 Knowing the masses and volumes of the earth and 
 moon, it is easy to estimate the force of gravity at 
 their surfaces, the distance from each to the point of 
 equal attraction, and the force with which a projectile 
 must be thrown from the lunar surface to pass within 
 the sphere of the earth s influence. It has been cal 
 culated that an initial velocity of about a mile and a 
 half in a second would be sufficient for this purpose 
 a force not greater than that known to have been 
 exerted by terrestrial volcanoes. The possibility, 
 therefore, that volcanic matter from our satellite 
 may reach the earth s surface seems fairly admis 
 sible. 
 
 Since the time of Laplace, several distinguished 
 European astronomers have regarded the lunar hy 
 pothesis as more or less probable. It was advocated 
 as recently as 1851 by the late Prof. J. P. Mchol, of 
 Glasgow. This popular and interesting writer, after 
 describing Tycho, a large and well-known lunar 
 crater, from which luminous rays or stripes radiate 
 over a considerable part of the moon s surface, ex 
 presses the opinion that that immense cavity was 
 formed by a single tremendous explosion. " Reflect 
 ing," he remarks, " on the probable suddenness and 
 magnitude of that force, or rather of that explosive 
 energy one of whose acts we have traced, as well as 
 on the immense mass of matter which seems to have 
 been thus violently dispersed, is not the inquiry a 
 natural one, where is that matter now ? It is a mass 
 
THE LUNAR THEORY. 99 
 
 indeed which cannot well have wholly disappeared. 
 It filled a cavern 55 miles in breadth, and 17,000 
 feet deep a cavern into which even now one might 
 cast Chimborazo and Mont Blanc, and room be left 
 for Teneriffe behind! Like rocks flung aloft by our 
 volcanoes, did this immense mass fall back in frag 
 ments to the surface of the moon, or was the expul 
 sive force strong enough to give it an outward ve 
 locity sufficient to resist the attractive power of its 
 parent globe? The moon, be it recollected, is very 
 small in mass compared with the earth, and her at 
 tractive energy greatly inferior accordingly. Laplace 
 has even calculated that the force urging a cannon- 
 ball, increased to a degree quite within the limits of 
 what is conceivable, could effect a final separation 
 between our satellite and any of its component 
 parts. It is possible then, and, although not demon 
 strable, very far from a chimera, that the disrupted 
 and expelled masses were, in the case of which we 
 are speaking, driven conclusively into space; but if 
 so, where are they now? where their new residence, 
 and what their functions? In the emergency to 
 which I refer, such fragments would necessarily 
 wander among the inter-planetary spaces in most 
 irregular orbits, and chiefly in the neighborhood of 
 the moon and the earth. Now, while the planetary 
 orbits are so nicely adjusted that neither confusion 
 nor interference can ever occur, it is not at all likely 
 that the same order could be established here ; nay, 
 it is next to certain, that in the course of its orbital 
 revolution our globe would ever and anon come in 
 contact with these lunar fragments; in other words, 
 STONES would fall occasionally to its surface, and ap- 
 
100 METEORIC ASTRONONY. 
 
 parently from its atmosphere." Planetary System, pp. 
 301, 302. 
 
 We have preferred to give the views of these 
 eminent scientists in their own language. Olbers, 
 Biot, and Poisson, who adopted the same theory, 
 estimated the initial velocity which would be neces 
 sary in order that lunar fragments might pass the 
 point of equal attraction, and also the final, or ac 
 quired velocity on reaching the earth s surface . The 
 several determinations of the former were as fol 
 lows: 
 
 According to Olbers 1-570 miles a second. 
 
 Biot 1-569 " " 
 
 Laplace 1-483 
 
 " Poisson 1-437 " 
 
 The mean being almost exactly a mile and a half. 
 The velocity on reaching our planet, according to 
 Olbers, would be about six and a half miles. At the 
 date of these calculations, however, the true velocity 
 of aerolites had not been in any case satisfactorily 
 determined. Since that time it has been found in 
 numerous instances to exceed twenty miles a second 
 a velocity greater than that of the earth s orbital 
 motion. This fact of itself would seem fatal to the 
 theory of a lunar origin. 
 
 At the meeting of the American Association for 
 the Advancement of Science, in 1859, Dr. B. A. 
 Gould read a paper on the supposed lunar origin of 
 aerolites, in which the hypothesis was subjected to 
 the test of a rigid mathematical analysis. We will 
 not attempt even an abstract of this interesting 
 memoir. It amounts, however, to a virtual disproof 
 of the lunar hypothesis. 
 
THE SOLAE THEORY. 101 
 
 THE SOLAR THEORY. 
 
 The theory which ascribes a solar origin to me 
 teorites is not of recent date, having been held by 
 Diogenes Laertius and other ancient Greeks. Among 
 the moderns its advocates have been much less nu 
 merous than those of the lunar hypothesis. The late 
 Professor Charles W. Hackley, of New York, re 
 garded shooting-stars, aerolites, and even comets, as 
 matter projected with enormous force from the solar 
 surface. The corona seen during total eclipses of 
 the sun he supposed to be the emanations of this 
 matter through the intervals of the luculi. (See the 
 Proceedings of the American Association for the Ad 
 vancement of Science, Fourteenth Meeting, 1860.) 
 An ingenious theory, differing in its details from 
 that of Professor Hackley, though somewhat similar 
 in its general features, has lately been advocated 
 by Alexander Wilcocks, M.D., of Philadelphia, in a 
 memoir read before the American Philosophical 
 Society, May 20th, 1864, and published in their Pro 
 ceedings. In regard to this hypothesis it seems suf 
 ficient to remark that it fails to give a satisfactory 
 account of the annual periodicity of meteoric phe 
 nomena. 
 
 9* 
 
CHAPTEE XII. 
 
 THE RINGS OF SATURN. 
 
 UNTIL about the middle of the present century the 
 rings of Saturn were universally regarded as solid 
 and continuous. The labors, however, of Professors 
 Bond and Pierce, of Cambridge, Massachusetts, as 
 well as the more recent investigations of Prof. Max 
 well, of England, have shown this hypothesis to be 
 wholly untenable. The most probable opinion, based 
 on the researches of these astronomers, is, that they 
 consist of streams or clouds of meteoric asteroids. 
 The zodiacal light and the zone of small planets be 
 tween Mars and Jupiter appear to constitute analo 
 gous primary rings. In the latter, however, a large 
 proportion of the primitive matter seems to have 
 collected in distinct, segregated masses. These 
 meteoric zones have probably presented what are 
 not elsewhere found in the solar system cases of 
 commensurability in the planetary periods. The 
 interior satellites of Saturn are so near the ring as 
 doubtless to exert great perturbative influence. Un 
 fortunately, the elements of the Saturnian system as 
 determined by different astronomers are somewhat 
 discordant. This, however, is by no means sur 
 prising when we consider the great distance of the 
 (102) 
 
THE RINGS OF SATURN. 
 
 ioa 
 
 planet and the small magnitude of some of the satel 
 lites. For convenience of reference the mean ap 
 parent distances of the satellites, together with their 
 periodic times, are given in the following table. The 
 former are taken from Hind s Solar System; the latter 
 from Herschel s Outlines of Astronomy. 
 
 TABLE I, THE SATELLITES OF SATURN. 
 
 NAME. 
 
 SIDEREAL REVOLUTION. 
 
 MEAN APPARENT 
 DISTANCE. 
 
 Mimas 
 
 d. h. m. s. 
 22 37 22-9 
 
 it 
 
 26-78 
 
 Enceladus 
 
 1 8 53 6-7 
 
 34-38 
 
 Tethys 
 
 1 21 18 95.7 
 
 42-57 
 
 Dione 
 
 2 17 41 8-9 
 
 54-54 
 
 Rhea 
 
 4 12 25 10-8 
 
 76-16 
 
 Titan 
 
 15 22 41 25-2 
 
 176-55 
 
 Hyperion 
 
 22 12 
 
 213-3? 
 
 Japetus 
 
 79 7 53 40-4 
 
 514-52 
 
 
 
 
 The late Professor Bessel devoted much attention 
 to the theory of Titan, whose mean distance he found 
 to be 20*706 equatorial radii of the primary. Struve ? s 
 measurements of the ring .are given in the second 
 column of the following table. Sir John Herschel, 
 however, regards the Russian astronomer s interval 
 between the rings as "somewhat too small."* This 
 remark is confirmed by the measurements of Encke, 
 whose results are given in column third. The fourth 
 contains the mean of Struve s and Encke s measure 
 ments; and the fifth, the same, expressed in equa 
 torial radii of Saturn. 
 
 Outlines of Astronomy, Art. 442. 
 
104 
 
 METEORIC ASTRONOMY. 
 
 TABLE II, THE RINGS OF SATURN. 
 
 
 STKUVE. 
 
 ENCKE. 
 
 MEAN. 
 
 IN SEMI-DIAM. 
 OP SATURN. 
 
 Equatorial radius of 
 the planet 
 
 // 
 
 8-9955 
 
 // 
 
 // 
 
 
 Ext. semi-diameter of 
 exterior ring 
 
 20-047 
 
 20-2225 
 
 20-13475 
 
 2-23830 
 
 Int. semi-diameter of 
 exterior ring 
 
 17-644 
 
 18-0190 
 
 17-83150 
 
 1-98230 
 
 Ext. semi-diameter of 
 interior ring 
 
 17-237 
 
 17-3745 
 
 17-30575 
 
 1-9380 
 
 Int. semi diameter of 
 interior rin " 
 
 13-334 
 
 13-3780 
 
 13-35600 
 
 1-48470 
 
 Breadth of interval... 
 
 00-407 
 
 00-6445 
 
 00-52575 
 
 0-05844 
 
 The period of a satellite revolving at 
 the distance, 1-9238, the interior limit 
 of the interval .... =10h. 50m. 
 One-sixth of the period of Dione . =10 56 
 One-third " Enceladus. =10 59 
 
 One-half " Mimas . =11 18 
 
 One-fourth " Tethys . =11 19 
 
 And the period of a satellite at the dis 
 tance, 1-9823, the exterior limit of 
 the interval . . =11 
 
 16s. 
 
 53 
 
 22 
 
 32 
 
 36 
 
 28 3 
 
 The interval, therefore, occupies precisely the space 
 in which the periods would be commensurable with 
 those of the four members of the system immediately 
 exterior. Particles occupying this portion of the 
 primitive ring would always come into conjunction 
 with one of these satellites in the same parts of their 
 orbits. Such orbits would become more and more 
 eccentric until the matter moving in them would 
 unite near one of the apsides with other portions 
 of the ring. We have thus a physical came for the ex 
 istence of thi* remarkable interval. 
 
CHAPTER XIII. 
 
 THE ASTEROID RING BETWEEN MARS AND JUPITER. 
 
 THE mean distances of the minor planets between 
 Mars and Jupiter vary from 2-20 to 349. The 
 breadth of the zone is therefore 20,000,000 miles 
 greater than the distance of the earth from the sun ; 
 greater even than the entire interval between the 
 orbits of Mercury and Mars. Moreover, the perihe 
 lion distance of some members of the group exceeds 
 the aphelion distance of others by a quantity equal to 
 the whole interval between the orbits of Mars and 
 the earth. The Olbersian hypothesis of the origin of 
 these bodies seems thus to have lost all claim to 
 probability.* Professor Alexander s theory of the 
 disruption of a primitive discoidal planet of great 
 equatorial diameter, is less objectionable; still, how 
 ever, it requires confirmation. But whatever may 
 have been the original constitution of the ring,f its 
 existence in its present form for an indefinite period 
 
 * A learned and highly interesting examination of this hypothesis 
 will be found in a memoir "On the Secular Variations and Mutual 
 Relations of the Orbits of the Asteroids," communicated to the Am. 
 Acad. of Arts and Sciences, April 24th, 1860, by Simon Newcomb, 
 Esq. 
 
 | For an explanation of the origin of the asteroids according to 
 the nebular hypothesis, see an article by David Trowbridge, A.M., 
 in Silliman s Journal for Nov. 1864, and Jan. 1865. 
 
 (105) 
 
106 METEORIC ASTRONOMY. 
 
 is unquestioned. Let us then consider some of the 
 effects of its secular perturbation by the powerful 
 mass of Jupiter. 
 
 Portions of the ring in which the periods of asteroids 
 
 would be commensurable with that of Jupiter. The 
 
 breadth of this zone is such as to contain several 
 portions in which the periods of asteroids would be 
 commensurable with that of Jupiter. As in the case 
 of the perturbation of Saturn s ring by the interior 
 satellites, the tendency of Jupiter s influence would 
 be to form gaps or chasms in the primitive ring. 
 
 The mean distance of an asteroid whose period 
 
 is that of Jupiter =3-2776 
 
 That of one whose period is $ of Jupiter s . =2-5012 
 I " . =2-8245 
 
 f " . =2-2569 
 
 f " . =2-9574 
 
 | " . =3-0299 
 
 For the purpose of facilitating the comparison of these 
 numbers with the mean distances of the asteroids 
 and of observing whether any order obtains in the 
 distribution of these mean distances in space, we 
 have arranged the minor planets, in the following 
 table, in the consecutive order of their periods: 
 
ASTEROID RING BETWEEN MARS AND JUPITER. 107 
 
 Periods and Distances of the Asteroids. 
 
 ORDER OP 
 DISCOVERY. 
 
 NAME. 
 
 8 Flora 22014 
 
 43 Ariadne 22034 
 
 72 Feronia 2-2654 
 
 40 Harmonia 2-2677 
 
 18 Melpomene 2-2956 
 
 80 Sappho 2-2971 
 
 12 Victoria 2-3342 
 
 27 Euterpe 2-3468 
 
 4 Vesta 2-3613 
 
 84 Clio 2-3618 
 
 30 Urania 2-3655 
 
 51 Nemausa 2-8657 
 
 9 Metis 2-3858 
 
 7 Iris 23863 
 
 60 Echo 2-3931 
 
 63 Ausonia 2-3949 
 
 25 Phocea 2-4008 
 
 20 Massilia 2-4144 
 
 67 Asia 2-4217 
 
 44 Nysa 2-4234 
 
 6 Hebe 2-4244 | 
 
 83 Beatrice 2-4287 
 
 42 Isis 24400 
 
 21 Lutetia 2-4411 
 
 19 Fortuna 2-4416 
 
 79 Eurynome 2-4437 
 
 11 Parthenope 2-4519 
 
 17 Thetis 2-4737 
 
 46 Hestia 2-5262 
 
 89 2-5498 
 
 29 Amphitrite 2-5544 
 
 5 Astrsea 2-5772 
 
 13 Egeria 2-5775 
 
 14 Irene 2-5860 
 
 32 Pomona 2-5868 
 
 91 2-5958 
 
 56 Melete 2-5959 
 
 70 Panopea 2-6129 
 
 53 Calypso 2-6188 
 
 78 Diana 2-6236 
 
 23 Thalia 2-6280 
 
 37 Fides 2-6414 
 
 15 Eunomia 26436 
 
 85 lo 2-6466 
 
 50 Virginia 2-6491 
 
 DISTANCE. 
 
 PERIOD. 
 
 1193d 
 1194-6 
 1245-4 
 1247-3 
 1270-4 
 1271-6 
 1302-6 
 1313-2 
 1325-3 
 1325-8 
 1328-9 
 1329-0 
 13460 
 1346-5 
 1352-2 
 1353-8 
 1358-8 
 1365-5 
 1376-5 
 1378-0 
 1379-0 
 1382-5 
 1392-2 
 1393-0 
 1393-5 
 1395-3 
 1402-4 
 1421-1 
 1466-5 
 1487-2 
 1491-2 
 1511-2 
 1511-4 
 1519-0 
 1519-6 
 1527-5 
 1527-7 
 1543-0 
 1548-0 
 1555-3 
 1568-0 
 1570-0 
 1572-6 
 1573-0 
 1575-0 
 
108 
 
 METEORIC ASTRONOMY. 
 
 Periods and Distances of the Asteroids Continued. 
 
 ORDER OF 
 DISCOVERT. 
 
 NAME. 
 
 DISTANCE. 
 
 PERIOD. 
 
 88 
 
 Thisbe 
 
 2-6553 
 
 1580-0 
 
 26 
 
 Proserpina 
 
 2-6561 
 
 1581-1 
 
 66 
 
 Maia 
 
 2-6635 
 
 1587-8 
 
 73 
 
 Clytie 
 
 2-6666 
 
 1590-5 
 
 3 
 
 Juno 
 
 2-6707 
 
 1594-2 
 
 75 
 
 Eurydice . 
 
 2-6707 
 
 1594-2 
 
 77 
 
 f rio-o-a . .. 
 
 2-6719 
 
 1595-3 
 
 64 
 
 Angelina 
 
 2-6805 
 
 1603-0 
 
 34 
 
 Circe 
 
 2-6865 
 
 1608-3 
 
 58 
 
 Concordia 
 
 2 7014 
 
 1622-0 
 
 54 
 
 Alexandra 
 
 2-7123 
 
 1631-6 
 
 59 
 
 Elpis 
 
 2-7131 
 
 1632-3 
 
 45 
 
 Eugenia 
 
 2-7218 
 
 1640-1 
 
 38 
 
 Leda . . 
 
 2-7401 
 
 1656-8 
 
 36 
 
 Atalanta. . 
 
 2-7458 
 
 1662-0 
 
 71 
 
 Niobe 
 
 2 7501 
 
 1665-8 
 
 82 
 
 Alcniene 
 
 2-7547 
 
 1670-0 
 
 55 
 
 Pandora 
 
 2-7591 
 
 1674-0 
 
 41 
 
 Daphne 
 
 2-7657 
 
 1679-9 
 
 1 
 
 Ceres 
 
 2-7663 
 
 1681-0 
 
 2 
 
 Pallas 
 
 2-7696 
 
 1683-5 
 
 39 
 
 Laetitia 
 
 2-7740 
 
 1687-6 
 
 74 
 
 Galatea 
 
 2-7777 
 
 1690-9 
 
 28 
 
 Bellona 
 
 2-7785 
 
 1691-6 
 
 68 
 
 Leto 
 
 2-7836 
 
 1696-3 
 
 81 
 
 Terpsichore 
 
 2-8591 
 
 1765-7 
 
 33 
 
 Polyhymnia 
 
 2-8653 
 
 1770-6 
 
 47 
 
 Aglaia ... 
 
 2-8812 
 
 1786-4 
 
 22 
 
 Calliope 
 
 2-9092 
 
 1812-4 
 
 16 
 
 Psyche 
 
 2 9233 
 
 1826-0 
 
 69 
 
 Hesperia 
 
 2-9707 
 
 1871-1 
 
 61 
 
 D<inae 
 
 2-9837 
 
 1882-4 
 
 35 
 
 Leucothea 
 
 3-0040 
 
 1904-2 
 
 49 
 
 Pales 
 
 3-0825 
 
 1976-6 
 
 86 
 
 Semele 
 
 3-0909 
 
 1984-7 
 
 52 
 
 Europa 
 
 3-1000 
 
 1993-6 
 
 48 
 
 Doris 
 
 3-1094 
 
 2002-7 
 
 62 
 
 Erato 
 
 3-1297 
 
 2022-3 
 
 24 
 
 Themis 
 
 3-1431 
 
 2035-3 
 
 10 
 
 Hvoieia 
 
 3-1512 
 
 2043-2 
 
 31 
 
 Euphrosyne 
 
 3-1513 
 
 20446 
 
 57 
 
 Mnemosyne 
 
 3-1565 
 
 2048-4 
 
 90 
 
 
 3-1576 
 
 2049-4 
 
 76 
 
 Freia 
 
 3-3864 
 
 2276-2 
 
 65 
 
 Cybele 
 
 3-4205 
 
 2310-6 
 
 87 
 
 Sylvia 
 
 3-4927 
 
 2384-2 
 
 
 
 
 
ASTEROID RING BETWEEN MARS AND JUPITER. 109 
 
 REMARKS ON THE FOREGOING TABLE. 
 
 1. The first two members of the group, Flora and 
 Ariadne, have very nearly the same mean distance. 
 Immediately exterior to these, however, occurs a 
 wide interval, including the distance at which seven 
 periods of an asteroid would be equal to two of 
 Jupiter. 
 
 2. On the outer limit of the ring Freia, Cybele, and 
 Sylvia have also nearly equal distances, and are sep 
 arated from the next interior member by a wide 
 space including the distance at which two periods 
 would be equal to one of Jupiter, and also that at 
 which five would be equal to one of Saturn. 
 
 3. Besides these extreme members of the group, 
 our table contains eighty-six minor planets, all of 
 which are included between the distances 2-26 and 
 3-16; the mean interval between them being 0-0105. 
 The distances are distributed as follows: 
 
 2-26 to 2-36 6 minimum. 
 
 2-36 to 2 46 19 maximum. 
 
 2-46 to 2-56 4 minimum. 
 
 2-56 to 2-66 16 lmaximum. 
 
 2-66 to 2 76 16J 
 
 2-76 to 2 86 8 
 
 2-86 to 2-96 4 lminimum. 
 
 2-96 to 3-06 3 J 
 
 3-06 to 3-16 10 maximum. 
 
 The clustering tendency is here quite apparent. 
 
 4. The three widest intervals between these bodies 
 are 
 
 (a) between Leucothea and Pales 0-0785, 
 
 (b) " Leto and Terpsichore 0-0755, 
 
 (c) " Thetis and Hestia 0-0525; 
 
 10 
 
110 METEORIC ASTRONOMY. 
 
 and these, it will be observed, are the three remain 
 ing distances, indicated on a previous page, at which 
 the periods of the primitive meteoric asteroids would 
 be commensurable with that of Jupiter. Now, if 
 the original ring consisted of an indefinite number 
 of separate particles moving with different velocities, 
 according to their respective distances, those revolv 
 ing at the distance 2-4935 in the interval between 
 Thetis and Hestia would make precisely three rev 
 olutions while Jupiter completes one. A planetary 
 particle at this distance would therefore always come 
 in conjunction with Jupiter in the same parts of its 
 path: consequently its orbit would become more 
 and more eccentric until the particle itself would 
 unite with others, either exterior or interior, thus 
 forming an asteroidal nucleus, while the primitive 
 orbit of the particle would be left destitute of matter, 
 like the interval in Saturn s ring. 
 
 5. If the distribution of matter in the zone was 
 originally nearly continuous, as in the case of Saturn s 
 rings, it would probably break up into a number of 
 concentric annuli. On account, however, of the 
 great perturbations to which they were subject, these 
 narrow rings would frequently come in collision. 
 After their rupture, and while the fragments were 
 collecting in the form of asteroids, numerous inter 
 sections of orbits and new combinations of matter 
 would occur, so as to leave, in the present orbits, 
 but few traces of the rings from which the existing 
 asteroids were derived. A comparison, however, of 
 the elements of Clytie and Frigga shows a striking 
 similarity; and Professor Lespiault has pointed out 
 a corresponding likeness between the orbits of Fides 
 

 ASTEROID RING BETWEEN MARS AND JUPITER. Ill 
 
 and Maia. For these four asteroids the nodal lines and 
 also the inclinations are nearly the same; while the 
 periods differ by only a few days. It is probable, 
 therefore, that they are all fragments of the same 
 narrow ring. Finally, as they all move nearly in the 
 same plane, they must at some future time approach 
 extremely near each other, and perhaps become 
 united in one large asteroid. 
 
CHAPTER XIV. 
 
 ORIGIN OF METEORS THE NEBULAR HYPOTHESIS. 
 
 IN regard to the physical history of those meteoric 
 masses which, in such infinite numbers, traverse the 
 interplanetary spaces, our knowledge is exceedingly 
 limited. Such as have reached the earth s surface 
 consist of various elements in a state of combination. 
 It has been remarked, however, by a distinguished 
 scientist* that "the character of the constituent 
 particles of meteorites, and their general microscop 
 ical structure, differ so much from what is seen in 
 terrestrial volcanic rocks, that it appears extremely 
 improbable that they were ever portions of the moon, 
 or of a planet, which differed from a large meteorite 
 in having been the seat of a more or less modified 
 volcanic action." As the celebrated nebular hypoth 
 esis seems to afford a very probable explanation of 
 the origin of those bodies, whether in the form of 
 rings or sporadic masses, its brief consideration may 
 not be destitute of interest. We will merely pre 
 mise that the existence of true nebulae in the heavens 
 that is, of matter consisting of luminous gas has 
 been placed beyond doubt by the revelations of the 
 spectroscope. 
 
 * H. C. Sorby, F.R.S. 
 (112) 
 
ORIGIN OF METEORS. 113 
 
 As a group, our solar system is comparatively 
 isolated in space; the distance of the nearest fixed 
 star being at least seven thousand times that of 
 Neptune, the most remote known planet. Besides 
 the central or controlling orb, it contains, so far as 
 known at present, ninety-nine primary planets, 
 eighteen satellites, three planetary rings, and nearly 
 eight hundred comets. In taking the most cursory 
 view of this system we cannot fail to notice the fol 
 lowing interesting facts in regard to the motions of 
 its various members: 
 
 1. The sun rotates on his axis from west to east. 
 
 2. The primary planets all move nearly in the 
 plane of the sun s equator. 
 
 3. The orbital motions of all the planets, primary 
 and secondary, except the satellites of Uranus and 
 Neptune, are in the same direction with the sun s 
 rotation. 
 
 4. The direction of the rotary motions of all the 
 planets, primary and secondary, in so far as has been 
 observed, is identical with that of their orbital rev 
 olutions; viz., from west to east. 
 
 5. The rings of Saturn revolve about the planet 
 in the same direction. 
 
 6. The planetary orbits are all nearly circular. 
 
 7. The cometary is distinguished from the planetary 
 portion of the system by several striking character 
 istics: the orbits of comets are very eccentric and 
 inclined to each other, and to the ecliptic at all pos 
 sible angles. The motions of a large proportion of 
 comets are/rom east to west. The physical constitu 
 tion of the latter class of bodies is also very different 
 from that of the former; the matter of which comets 
 
 10* 
 
114 METEORIC ASTRONOMY. 
 
 are composed being so exceedingly attenuated, at 
 least in some instances, that fixed stars have been 
 distinctly visible through what appeared to be the 
 densest portion of their substance. 
 
 None of these facts are accounted for by the law 
 of gravitation. The sun s attraction can have no in 
 fluence whatever in determining either the direction 
 of a planet s motion, or the eccentricity of its orbit. 
 In other words, this power would sustain a planetary 
 body moving from east to west, as well as from west 
 to east; in an orbit having any possible degree of 
 inclination to the plane of the sun s equator, no less 
 than in one coincident with it; or, in a very eccen 
 tric ellipse, as well as in one differing but little from 
 a circle. The consideration of the coincidences 
 which we have enumerated led Laplace to conclude 
 that their explanation must be referred to the mode 
 of our system s formation a conclusion which he 
 regarded as strongly confirmed by the contemporary 
 researches of Sir William Herschel. Of the numer 
 ous nebulae discovered and described by that emi 
 nent observer, a large proportion could not, even by 
 his powerful telescope, be resolved into stars. In 
 regard to many of these, it was not doubted that 
 glasses of superior power would show them to be 
 extremely remote sidereal clusters. On the other 
 hand, a considerable number were examined which 
 gave no indications of resolvability. These were 
 supposed to consist of self-luminous, nebulous mat 
 ter the chaotic elements of future stars. The great 
 number of these irresolvable nebulae scattered over 
 the heavens and apparently indicating the various 
 stages of central condensation, very naturally sug- 
 
ORIGIN OF METEORS. 115 
 
 gested the idea that the solar system, and perhaps 
 every other system in the universe, originally existed 
 in a similar state. The sun was supposed by Laplace 
 to have been an exceedingly diffused, rotating neb 
 ula, of spherical or spheroidal form, extending be 
 yond the orbit of the most distant planet; the planets 
 as yet having no separate existence. This immense 
 sphere of vapor, in consequence of the radiation of 
 heat and the continual action of gravity, became 
 gradually more dense, which condensation was ne 
 cessarily attended by an increased angular velocity 
 of rotation. At length a point was thus reached 
 where the centrifugal force of the equatorial parts 
 was equal to the central attraction. The condensa 
 tion of the interior meanwhile continuing, the equa 
 torial zone was detached, but necessarily continued 
 to revolve around the central mass with the same 
 velocity that it had at the epoch of its separation. If 
 perfectly uniform throughout its entire circumfer 
 ence, which would be highly improbable, it would 
 continue its motion in an unbroken ring, like 
 that of Saturn; if not, it would probably collect 
 into several masses, having orbits nearly identical. 
 "These masses should assume a spheroidal form, 
 with a rotary motion in the direction of that of their 
 revolution, because their inferior articles have a less 
 real velocity than the superior; they have therefore 
 constituted so many planets in a state of vapor. But 
 if one of them was sufficiently powerful to unite 
 successively by its attraction all the others about its 
 center, the ring of vapors would be changed into 
 one spheroidal mass, circulating about the sun, with 
 a motion of rotation in the same direction with that 
 
116 METEORIC ASTRONOMY. 
 
 of revolution."* Such, according to the theory of 
 Laplace, is the history of the formation of the most 
 remote planet of our system. That of every other, 
 both primary and secondary, would be precisely 
 similar. 
 
 In support of the nebular hypothesis, of which the 
 foregoing is a brief general statement, we remark 
 that it furnishes a very simple explanation of the motions 
 and arrangements of the planetary system. In the first 
 place, it is evident that the separation of a ring would 
 take place at the equator of the revolving mass, where 
 of course the centrifugal force would be greatest. 
 These concentric rings and consequently the result 
 ing planets would all revolve in nearly the same plane. 
 It is evident also that the central body must have a 
 revolution on its axis in the same direction with the pro 
 gressive motion of the planets. Again : at the breaking 
 up of a ring, the particles of nebulous matter more 
 distant from the sun would have a greater absolute 
 velocity than those nearer to it, which would pro 
 duce the observed unity of direction in the rotary and 
 orbital revolutions. The motions of the satellites are 
 explained in like manner. The hypothesis, more 
 over, accounts satisfactorily for the fact that the orbits 
 of the planets are all nearly circular. And finally, 
 it presents an obvious explanation of the rings of 
 Saturn. It would almost seem, indeed, as if these 
 wonderful annul! had been left by the Architect of 
 Nature, as an index to the creative process. 
 
 The argument derived from the motions of the 
 various members of the solar system is not new, 
 
 * Harte s Trans, of Laplace s Syst. of the World, vol. ii., note vii. 
 
ORIGIN OF METEORS. 117 
 
 having been forcibly stated by Laplace, Pontdcou- 
 lant, Nichol, and other astronomers. Its full weight 
 and importance, however, have not, we think, been 
 duly appreciated. That a common physical cause 
 has determined these motions, must be admitted by 
 every philosophic mind. But apart from the nebu 
 lar hypothesis, no such cause, adequate both in 
 mode and measure, has ever been suggested; in 
 deed none, it seems to us, is conceivable. The phe 
 nomena which we have enumerated demand an ex 
 planation, and this demand is met by the nebular 
 hypothesis. It will be found, therefore, when closely 
 examined, that the evidence afforded by the celestial 
 motions is sufficient to give the theory of Laplace a 
 very high degree of probability. 
 
 A comparison of the facts known in regard to 
 comets, falling-stars, and meteoric stones, seems to 
 warrant the inference that they are bodies of the 
 same nature, and perhaps of similar origin; differ 
 ing from each other mainly in the accidents of mag 
 nitude and density. The hypothesis of Laplace very 
 obviously accounts for the formation of planets and 
 satellites, moving in the same direction, and in orbits 
 nearly circular; but how, it may be asked, can the 
 same theory explain the extremely eccentric, and in 
 some cases retrograde, motions of comets and aero 
 lites? This is the question to which we now direct 
 our attention. 
 
 After the nuclei of the solar and sidereal systems 
 had been established in the primitive nebula, and 
 when, in consequence, immense gaseous spheroids 
 had collected around such nuclei, we may suppose 
 that about the points of equal attraction between 
 
118 METEORIC ASTRONOMY. 
 
 the sun and neighboring systems, portions of nebu 
 lous matter would be left in equilibrio. Such out 
 standing nebulosities would gradually contract 
 through the operation of gravity; and if, as would 
 sometimes be the case, the solar attraction should 
 preponderate, they would commence falling toward 
 our system. Unless disturbed by the planets they 
 would probably move round the sun in parabolas. 
 Should they pass, however, near any of the large 
 bodies of the system, their orbits might be changed 
 into ellipses by planetary perturbation. Such was 
 the view of Laplace in regard to the origin of 
 comets. 
 
 It seems probable, however, that many of these 
 bodies originated within the solar system, and belong 
 properly to it. The outer rings thrown off by the 
 planets may have been at too great distances from 
 the primaries to form stable satellites. Such masses 
 would be separated by perturbation from their 
 respective primaries, and would revolve round the 
 sun "in independent orbits. Again: small portions 
 of nebulous matter may have been abandoned as 
 primary rings, at various intervals between the 
 planetary orbits. At particular distances such rings 
 would be liable to extraordinary perturbations, in 
 consequence of which their orbits would ultimately 
 assume an extremely elliptical form, like those of 
 comets, and perhaps also those of meteors. It was 
 shown in Chapter XIII. that several such regions 
 occur in the asteroid zone between Mars and Ju 
 piter. We may add, in confirmation of this view, 
 that there are twelve known comets whose periods 
 are included between those of Flora and Jupiter. 
 
ORIGIN OF METEORS. 119 
 
 Their motions are all direct; their orbits are less 
 eccentric than those of other comets; and the mean 
 of their inclinations is about the same as that of the 
 asteroids. These facts certainly appear to indicate 
 some original connection between these bodies and 
 the zone of minor planets. 
 
 The nebular hypothesis, it is thus seen, accounts 
 satisfactorily for the origin of comets, aerolites, 
 fire-balls, shooting-stars, and meteoric rings ; regard 
 ing them all as bodies of the same nature, moving 
 in cometary orbits about the sun. In this theory, 
 the zodiacal light is an immense swarm of meteor- 
 asteroids; so that the meteoric theory of solar heat, 
 explained in a previous chapter, finds its place as a 
 part of the same hypothesis. 
 
CONCLUSION. 
 
 SOME of the prominent results of observation and 
 research in meteoric astronomy may be summed up 
 as follows : 
 
 1. The shooting-stars of November, August, and 
 other less noted epochs, are derived from elliptic 
 rings of meteoric matter which intersect the earth s 
 orbit. 
 
 2. Meteoric stones and the matter of shooting-stars 
 coexist in the same rings; the former being merely 
 collections or aggregations of the latter. 
 
 3. The most probable period of the November 
 meteors is thirty-three years and three months. 
 Leverrier s elements of this ring agree so closely 
 with Oppolzer s elements of the comet of 1866 as 
 to render it probable that the latter is merely a large 
 meteor belonging to the same annulus. 
 
 4. The spectroscopic examination of this comet 
 (of 1866) by "William Huggins, F.K.S., indicated 
 that the nucleus was self-luminous, that the coma 
 was rendered visible by reflecting solar light, and 
 that "the material of the comet was similar to the 
 matter of which the gaseous nebulae consist." 
 
 5. The time of revolution of the August meteors 
 is believed to be about 105 years. M. Schiaparelli 
 has found a striking similarity between the elements 
 of this ring and those of the third comet of 1862. 
 The same distinguished astronomer has shown, 
 
 (120) 
 
CONCLUSION. 121 
 
 moreover, that a nebulous mass of considerable ex 
 tent, drawn into the solar system ab extra, would 
 form a ring or stream. 
 
 6. The aerolitic epochs, established with more or 
 less certainty, are the following: 
 
 1. February 15th-19th. 
 
 2. March 12th-15th. 
 
 3. April 10th-12th. 
 
 4. April 18th-26th. 
 
 5. May 8th-14th; or especially, 12th-13th. 
 
 6. May 19th. 
 
 7. July 13th-14th. 
 
 8. July 26th. 
 
 9. August 7th-llth. 
 
 10. October 13th-14th. 
 
 11. November llth-14th. 
 
 12. November 27th-30th. 
 
 13. December 7th-13th. 
 
 About one-half of this number are also known as 
 shooting-star epochs. 
 
 7. The epoch of November 27th-30th corresponds 
 with that of the earth s crossing the orbit of Biela s 
 two comets. The aerolites of this epoch may there 
 fore have been moving in nearly the same path. 
 
 8. A greater number of aerolitic falls are ob 
 served 
 
 1. By day than by night. 
 
 2. In the afternoon than in the forenoon. 
 
 3. When the earth is in aphelion than when in perihelion. 
 
 The first fact is accounted for by the difference in 
 the number of observers; the second indicates that a 
 majority of aerolites have direct motion; and the 
 third is dependent on the relative lengths of the 
 
 11 
 
122 METEORIC ASTRONOMY. 
 
 day and night in the aphelic and perihelic portions 
 of the orbit. 
 
 9. The observed velocities of meteorites are in 
 compatible with the theory of their lunar origin. 
 
 10. If the meteoric swarm of November 14th has 
 a period of thirty-three years, Biela s comet passed 
 very near, if not actually through it toward the close 
 of 1845, about the time of the comet s separation. 
 Was the division of the cometary mass produced by 
 the encounter? 
 
 11. The rings of Saturn may be regarded as dense 
 meteoric masses, and the principal or permanent 
 division accounted for by the disturbing influence 
 of the interior satellites. 
 
 12. The asteroidal space between Mars and Jupiter 
 is probably a wide meteoric ring in which the largest 
 aggregations are visible as minor planets. In the 
 distribution of the mean distances of the known 
 members of the group a clustering tendency is quite 
 obvious. 
 
 13. The meteoric masses encountered by Encke s 
 comet may account for the shortening of the period 
 of the latter without the hypothesis of an ethereal 
 medium. 
 
APPENDIX. 
 
 A. 
 
 The Meteors of November 14th. 
 
 The American Journal of Science and Arts for May, 
 186T (received by the author after the first chapters of this 
 work had gone to press), contains an interesting article by 
 Professor Newton "On certain recent contributions to Astro- 
 Meteorology." Of the five possible periods of the Novem 
 ber ring, first designated by Professor N , it is now granted 
 that the longest, viz., 33^ years, is most probably the true 
 one. The results of Leverrier s researches in regard to the 
 epoch at which this meteoric mass was introduced into the 
 solar system, are given in the same article. This distin 
 guished astronomer supposes the group of meteors to have 
 been thrown into an elliptic orbit by the disturbing influ 
 ence of Uranus. The meteoric stream, according to the 
 most trustworthy elements of its orbit, passed extremely 
 near that planet about the year 126 of our era ; which date 
 is therefore assigned by Leverrier as the probable time of 
 its entrance into the planetary system. This result, how 
 ever, requires confirmation. 
 
 Although the earliest display of the November meteors, 
 so far as certainly known, was that of the year 902, several 
 more ancient exhibitions may, with some probability, be 
 referred to the same epoch. The?e are the phenomena of 
 532, 599, and COO, A.D., and 17G8, B.C. (See Quetelet s 
 
 (123) 
 
124 APPENDIX. 
 
 Catalogue.) The time of the year at which these showers 
 occurred is not given. The years, however, correspond 
 very well with the epochs of the maximum display of the 
 November meteors. The intervals arranged in consecutive 
 order, are as follows : 
 
 From B.C. 1768 to A.D. 532, 69 periods of 33-319 years each. 
 
 " A.D. 532 (o " 5995, 2 33-750 
 
 " " 599-5 to " 902, 9 " 33-614 
 
 " 902 to " 934, 1 " 32-000 
 
 934 to " 1002, 2 t " 34-000 
 
 " 1002 to " 1101, 3 " 33-000 
 
 " " 1101 to " 1202, 3 33667 
 
 " 1202 to " 1366, 5 " 32-800 " 
 
 " " 1366 lo " 1533, 5 33-400 
 
 " 1533 to " 1698, 5 " 33000 " 
 
 " " 1698 to " 1799, 3 " 33 667 
 
 " 1799 to " 1833, 1 " 34000 
 
 " 1833 to " 1866, 1 " 33-000 
 
 The first three dates are alone doubtful. The whole num 
 ber of intervals from B.C. 1768 to A.D. 1866 is 109, and the 
 mean length is 33*33 years. 
 
 The perturbations of the ring by Jupiter, Saturn, and 
 Uranus, are doubtless considerable. It is worthy of note 
 that 
 
 14 periods of Jupiter are nearly equal to 5 of the ring. 
 
 9 " Siturn " " 8 
 
 23 " Uranus " " 58 
 
 This group or stream has its perihelion at the orbit of 
 the earth; its aphelion, at that of Uranus. (See diagram, 
 p. 24.) It must therefore produce star-showers at the latter 
 as well as at the former. Our planet, moreover, at each 
 encounter appropriates a portion of the meteoric matter; 
 while at the remote apsis of the stream Uranus in all prob 
 ability does the same. The matter of the ring will thus by 
 slow degrees be gathered up by the two planets. 
 
APPENDIX. 125 
 
 B. 
 
 Comets and Meteors. 
 
 The recent researches and speculations of European as 
 tronomers in regard to the origin of comets and of meteoric 
 streams, have suggested to the author the propriety of re 
 producing the following extracts from an article written by 
 himself, in July, 1861, and published in the Danville Quar 
 terly Review for December of that year: 
 
 " Different views are entertained by astronomers in regard 
 to the origin of comets ; some believing them to enter the 
 solar system ab extra; others supposing them to have 
 originated within its limits. The former is the hypothesis 
 of Laplace, and is regarded with favor by many eminent 
 astronomers. It seems to afford a plausible explanation of 
 the paucity of large comets during certain long intervals of 
 time. In one hundred and fifty years, from 1600 to H50, 
 sixteen comets were visible to the naked eye; of which 
 eight appeared in the twenty-five years from 1664 to 1689. 
 Again, during sixty years from 1750 to 1810, only five 
 comets were visible to the naked eye, while in the next fifty 
 years there were double that number. Now, according to 
 Laplace s hypothesis, patches of nebulous matter have been 
 left nearly in equilibrium in the interstellar spaces. As the 
 sun, in his progressive motion, approaches such clusters, 
 they must, by virtue of his attraction, move toward the 
 center of our system; the nearer portions with greater 
 velocity than the more remote. The nebulous fragments 
 thus introduced into our system would constitute comets ; 
 those of the same cluster would enter the solar domain at 
 periods not very distant from each other ; the forms of their 
 
 11* 
 
12t) APPENDIX. 
 
 orbits depending upon their original relative positions with 
 reference to the sun s course, and also on planetary perturb 
 ations. On the other hand, the passage of the system 
 through a region of space destitute of this chaotic vapor 
 would be followed by a corresponding paucity of comets. 
 
 " Before the invention of the telescope, the appearance of 
 a comet was a comparatively rare occurrence. The whole 
 number visible to the naked eye during the last three hun 
 dred and sixty years has been fifty-five ; or a mean of fifteen 
 per century. The recent rate of telescopic discovery, how 
 ever, has been about four or five annually. As many of 
 these are extremely faint, it seems probable that an indef 
 inite number, too small for detection, may be constantly 
 traversing the solar domain. If we adopt Laplace s hy 
 pothesis of the origin of comets, we may suppose an almost 
 continuous fall of primitive nebular matter toward the cen 
 ter of the system the drops of which, penetrating the 
 earth s atmosphere, produce sporadic meteors ; the larger 
 aggregations forming comets. The disturbing influence of 
 the planets may have transformed the original orbits of 
 many of the former, as well as of the latter, into ellipses. 
 It is an interesting fact that the motions of some luminous 
 meteors or cometoids, as perhaps they might be called 
 have been decidedly indicative of an origin beyond the 
 limits of the planetary system. 
 
 " But how are the phenomena of periodic meteors to be 
 accounted for, in accordance with this theory ? 
 
 " The division of Biela s comet into two distinct parts 
 suggests several interesting questions in cometary physics. 
 The nature of the separating force remains to be discovered ; 
 but it is impossible to doubt that it arose from the divellent 
 action of the sun, whatever may have been the mode of 
 operation. 
 
 " A signal manifestation of the influence of the sun, says 
 a distinguished writer, Ms sometimes afforded by the break- 
 
APPENDIX. 127 
 
 ing up of a comet into two or more separate parts, on the 
 occasion of its approach to the perihelion. Seneca relates 
 that Ephoras, an ancient Greek author, makes mention- of a 
 comet which before vanishing was seen to divide itself into 
 two distinct bodies. The Roman philosopher appears to 
 doubt the possibility of such a fact; but Keppler, with 
 characteristic sagacity, has remarked that its actual occur 
 rence was exceedingly probable. The latter astronomer 
 further remarked that there were some grounds for suppos 
 ing that two comets, which appeared in the same region of 
 the heavens in the year 1618, were the fragments of a comet 
 that had experienced a similar dissolution. Hevelius states 
 that Cysatus perceived in the head of the great comet of 
 1G18 unequivocal symptoms of a breaking up of the body 
 into distinct fragments. The comet when first seen in the 
 month of November, appeared like a round mass of con 
 centrated light. On the 8th of December it seemed to be 
 divided into several parts. On the 20th of the same month 
 it resembled a multitude of small stars. Hevelius states 
 that he himself witnessed a similar appearance in the head 
 of the comet of 1661. * Edward Biot, moreover, in his 
 researches among the Chinese records, found an account of 
 three dome-formed comets that were visible simultane 
 ously in 896, and pursued very nearly the same apparent 
 path. 
 
 "Another instance of a similar phenomenon is recorded 
 by Dion Cassius, who states that a comet which appeared 
 eleven years before our era, separated itself into several 
 small comets. 
 
 " These various examples are presented at one view, as 
 follows : 
 
 " I. Ancient bipartition of a comet. Seneca, Qusest. Nat., 
 lib. VII. cap. XVI. 
 
 * Grant s Hist, of Phys. Astr., p. 302. 
 
128 APPENDIX. 
 
 " II. Separation of a comet into a number of fragments, 
 11 B.C. Dion Cassius. 
 
 " III. Three comets seen simultaneously pursuing the 
 same orbit, A.D. 896 Chinese records Comptes 
 JRendus, torn. xx. 1845, p. 334. 
 
 "IV. Probable separation of a comet into parts, A.D. 
 1618. Hevelius, Cometographia, p. 341. Kep- 
 pler, De Cometis, p. 50. 
 
 "V. Indications of separation, 1661. Hevelius Cometo 
 graphia, p. 41 1. 
 
 "VI. Bipartition of Biela s comet, 1845-6. 
 
 " In view of these facts it seems highly probable, if not 
 absolutely certain, that the process of division has taken 
 place in several instances besides that of Biela s comet. 
 May not the force, whatever it is, that has produced one 
 separation, again divide the parts? And may not this 
 action continue until the fragments become invisible? Ac 
 cording to the theory now generally received, the periodic 
 phenomena of shooting-stars are produced by the intersec 
 tions of the orbits of such nebulous bodies with the earth s 
 annual path. Now there is reason to believe that these 
 meteoric rings are very elliptical, and in this respect wholly 
 dissimilar to the rings of primitive vapor which, according 
 to the nebular hypothesis, were successively abandoned at 
 the solar equator ; in other words, that the matter of which 
 they are composed moves in cometary rather th&u planetary 
 orbits. May not our periodic meteors be the debris of an 
 cient but now disintegrated comets, whose matter has 
 become distributed around their orbits?" 
 
APPENDIX. 129 
 
 C. 
 
 Biela s Comet and the Meteors of November 27th-30th. 
 
 At the close of Chapter IY. it was suggested that the 
 meteors of November 2Tth-30th might possibly be derived 
 from a ring of meteoric matter moving in the orbit of Biela s 
 comet. Since that chapter was written similar conjectures 
 have been started in the Astronomixche Nachricliten* by 
 Dr. Edmund Weiss and Prof. d Arrest. The latter attempts 
 to show that the December meteors may be derived from 
 the same ring. The question will doubtless bo decided at 
 no distant day. 
 
 IX 
 
 The First Comet of 1861 and the Meteors of April 20th. 
 
 Recent investigations render it probable that the orbit of 
 the first comet of 18G1 is identical with that of the meteors 
 of April 20th. The orbit is nearly perpendicular to the 
 ecliptic. 
 
 * Nos. 1632 and 1033. 
 
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