\\ 
 
THE COMETS. 
 
THE COMETS 
 
 A DESCRIPTIVE TREATISE UPON THOSE BODIES 
 
 WITH 
 
 A CONDENSED ACCOUNT 
 
 OF 
 
 THE NUMEKOUS MODERN DISCOVERIES 
 
 RESPECTING THEM; 
 ~AND 
 
 A TABLE OF ALL THE CALCULATED COMETS, 
 
 From the Earliest Ages to the Present Time. 
 
 BY 
 
 J. RUSSELL HIND, 
 
 FOREIGN SECRETARY OF THE ROYAL ASTRONOMICAL SOCIETY OF LONDON; 
 
 CORRESPONDING MEMBER OF THE NATIONAL INSTITUTE OF FRANCE, ETC. ETC. 
 
 AND FORMERLY OF THE ROYAL OBSERVATORY, GREENWICH. 
 
 LONDON: 
 
 JOHN W. PARKER AND SON, WEST STRAND. 
 
 MDCCCLII. 
 
LONDON : 
 
 SAVILL AND EDWABD8, PKINTEBS, 
 CHAND08 STBEET. 
 
PREFACE. 
 
 THERE is perhaps no branch of astronomy in 
 which our knowledge has progressed more 
 rapidly of late years than that relating to the 
 Comets, but I believe there is not at present 
 any special descriptive work upon the subject. 
 In treatises on the science of astronomy 
 generally, the space allotted to the Comets is 
 usually very limited, and many interesting 
 points connected with their history are neces- 
 sarily passed over unnoticed. I have endea- 
 voured, in the following pages, to supply the 
 want of an elementary treatise upon these 
 bodies, and to place before the reader a popular 
 account of the discoveries which have been 
 made in the cometary department of astronomy 
 in modern times, and a brief description of the 
 most remarkable comets recorded in history. 
 
 263255 
 
vi PREFACE. 
 
 The facts which are here collected together 
 are, for the most part, scattered through many 
 works of a purely scientific character, usually 
 in foreign languages, and not known or easily 
 accessible to the general reader. The Cata- 
 logue of the elements of the Orbits of Comets, 
 with the accompanying Notes, will, it is hoped, 
 be acceptable to the young student, as pre- 
 senting in a small compass the results of a vast 
 amount of time and labour which various 
 astronomers have expended upon them. 
 
 J. KUSSELL HIND. 
 
 Grove-road, St. John's Wood, London, 
 November, 1852. 
 
CONTENTS. 
 
 CHAPTER I. 
 
 PAGE 
 
 Of Comets in general Their number Duration of 
 visibility Length of their apparent tracks in the 
 heavens Their nuclei and tails Apparent di- 
 mensions . . . . . ... .1 
 
 CHAPTER II. 
 
 Of the real dimensions of comets Phases observed 
 in some of them Their physical constitution 
 Chances of collision with the earth . . .17 
 
 CHAPTER III. 
 
 Of the paths of comets in space Elements of their 
 orbits Uses of a table of elements Effects of 
 planetary attraction upon their movements . 27 
 
 CHAPTER IV. 
 The comet of HaUey . . . . .35 
 
 CHAPTER V. 
 Comets of short period The comet of Encke . . 58 
 
viii CONTENTS. 
 
 CHAPTER VI. 
 
 PAGE. 
 
 Comets of short period (continued) The comet of 
 Biela .... . 71 
 
 CHAPTER VII. 
 
 Other comets of short period Faye's, De Vico's, 
 Brorsen's, D' Arrest's 80 
 
 CHAPTER VIII. 
 
 Periodical comets (continued) Of six comets, pro- 
 bably with short periods Lexell's comet in 1770 
 Comets which appear to revolve round the sun 
 in about seventy-five years Others to which 
 longer periods have been assigned . . .87 
 
 CHAPTER IX. 
 
 A brief notice of some of the most remarkable comets 
 that have been observed from the earliest times 
 to the present day ...... 102 
 
 CHAPTER X. 
 On the expected Great Comet . . . . .116 
 
 A Catalogue of the Orbits of all the Comets hitherto 
 computed, B.C. 370 to A.D. 1852 . . .125 
 
 Hotes to the Catalogue of Cometary Orbits . .139 
 
THE COMETS. 
 
 CHAPTER I 
 
 OF COMETS IN GENERAL THEIR NUMBER DURA- 
 TION OF VISIBILITY LENGTH OF THEIR APPARENT 
 TRACKS IN THE HEAVENS THEIR NUCLEI AND 
 TAILS APPARENT DIMENSIONS. 
 
 COMETS are nebulous -looking bodies, moving in 
 orbits of great eccentricity, and visible to us only about 
 the time of their nearest approach to the sun, or, as it is 
 termed by astronomers, the time of perihelion passage. 
 Unlike the planets, they move in every possible di- 
 rection, and are seen as well near the poles as about 
 the equatorial or zodiacal regions of the heavens. 
 
 In the dark ages of superstition and ignorance, these 
 bodies were regarded as omens of evil to men in 
 general, and the sudden appearance of a great comet 
 excited the utmost consternation, and on more than 
 one occasion influenced the progress of sublunary 
 affairs. One which became visible in the spring of 
 837 in the southern parts of the heavens, so alarmed 
 Louis I. of France, that he ordered the building of 
 churches and monasteries, in the hope of appeasing the 
 
2 THE COMETS. 
 
 wrath of heaven, which was considered to be manifested 
 by its appearance. Again, in June, 1456, when the 
 successes of the Turks under Mahomet II. excited the 
 utmost fear at Rome for the safety of Christendom, a 
 great comet (known at the present day as Halley's) was 
 observed, and the Pope, Calixtus III., regarding it as 
 a sign of approaching evils, caused prayers to be said 
 in the churches, and the bells to be rung every day at 
 noon, as a warning to the inhabitants to supplicate 
 the divine aid and forgiveness. Those who neglected 
 this call were subject to severe punishment. Hence 
 arose the custom, still prevalent in Raman Catholic 
 countries, of ringing the cathedral bells at noon. A cen- 
 tury later, or in 1556, the appearance of a fine comet 
 is said to have induced Charles V. of Austria to cede 
 the imperial crown to his son Ferdinand. The his- 
 torians of these ages, in speaking of comets, fre- 
 quently describe them as of ' horrible aspect/ or as 
 celestial monsters of prodigious magnitude, fearful 
 and terrible stars. While they were beheld with 
 such feelings of dread and superstition, it will hardly 
 be expected that many useful accounts of their move- 
 ments amongst the stars would be transmitted to 
 us, and it accordingly happens that but very little 
 information available to astronomers at the present 
 day, is to be found in European chronicles. The 
 Chinese astronomers, though they looked upon comets 
 without any fears of their malignant agencies, had a 
 very fanciful opinion respecting them, which never- 
 "theless led to the frequent observation of the position 
 of these bodies in the heavens, the results of which 
 have been found most valuable in modern times. 
 
THEIK NUMBER. 3 
 
 The number of comets from the Christian era to 
 the middle of the present century, of which there is 
 any trustworthy record, is rather over 600, including, 
 besides the comets mentioned by European historians, 
 all those observed in China, according to the annals 
 of the various dynasties reigning in that country. 
 But as the telescope was not much employed in 
 searching out these objects before the middle of the 
 eighteenth century, the real number of comets which 
 have visited these parts of space must be very much 
 larger, probably amounting to not less than 3000, 
 since it would appear, from the experience of the past 
 century, that only one in every five becomes sufficiently 
 conspicuous to the naked eye to attract general atten- 
 tion. The Chinese, it is true, were very diligent in 
 their celestial observations, yet many comets must 
 have escaped their notice, since they had no telescopes 
 to assist them. A considerable number of comets 
 have doubtless appeared in past times in the southern 
 heavens only, so as to be invisible in Europe, and 
 allowing for this, we shall probably be within reason- 
 able limits when we assume that upwards of 4000 
 have approached the sun within the orbit of Mars 
 since the commencement of the Christian era. 
 
 The following table exhibits the number of suffi- 
 ciently authenticated comets in each century : 
 
 Century. 
 I 
 
 Comets observed in 
 Europe and China. 
 
 Century. 
 
 VI 
 
 Comets observed in 
 Europe and China. 
 
 II 
 
 23 
 
 VII 
 
 22 
 
 III 
 
 . . . 44 
 
 VIII 
 
 16 
 
 IV. . 
 
 27 
 
 IX. . 
 
 . . . . 42 
 
 V. 
 
 16 
 
 X. 
 
 26 
 
 B 2 
 
THE COMETS. 
 
 Comets observed in 
 Century. Europe and China. 
 
 XI 36 
 
 XII 26 
 
 XIII 26 
 
 Comets observed in 
 Century. Europe and China. 
 
 XVI. ..... 31 
 
 XVII 25 
 
 XVIII 64 
 
 XIX. (first half ) . 80 
 
 XIV 29 
 
 XV 27 
 
 Giving a total of 607. 
 
 The duration of a cornet's visibility varies from a 
 few days to more than a year, but it most usually 
 happens that it does not exceed two or three months. 
 Much depends on the apparent position of a comet in 
 reference to the sun's place, on its distance from the 
 earth, and particularly on its intrinsic brightness, or 
 rather, we should say, on its capability of reflecting 
 the sun's rays. Some of these bodies have been 
 observed at a far greater distance from the earth and 
 sun than others. The remarkable comet of 1729 
 never approached nearer to the sun than four times 
 the earth's mean distance from that luminary, yet it 
 was seen without any great optical aid for nearly six 
 months. That discovered by Colla, in May, 1847, 
 was also followed till its distance from the earth was 
 three-and-a-quarter times the distance of our globe 
 from the sun, and another found in the same year by 
 Mauvais was visible in the large telescopes at several 
 observatories in this country, till it had receded to 
 nearly three times that distance. In both these in- 
 . stances the comet's distance from the sun was equally 
 great. Many of these bodies, on the contrary, fade 
 away even in the most powerful instruments we 
 possess, before they have attained anything like a 
 distance equal to the diameter of the earth's orbit. 
 
DURATION OF VISIBILITY. 5 
 
 Amongst those comets which have continued longest 
 in sight, we may mention the following : 
 
 A.D. 
 
 60 (in China) . . . .135 days. 
 
 64 (according to Seneca) 180 days or more. 
 
 247 (in China) . . . .156 days. 
 
 1729 171 
 
 1773 184 
 
 1807 188 
 
 1811 510 
 
 1815 172 
 
 1825 . . . ' . . . 358 
 
 1835 286 
 
 1844 (Mauvais' comet) . . . 246 
 
 1847 (Colla's comet) . . .240 
 
 1847 (Mauvais' comet) . . . 285 
 
 The first three comets in the above list were of 
 course observed without the assistance of a telescope, 
 the others have all been followed with optical aid. 
 That of 1835 was predicted, and therefore discovered 
 much sooner than it is probable it otherwise would 
 have been. In several cases the comets have not 
 remained visible throughout the whole period, but 
 after disappearing for some days or weeks in the sun's 
 rays, have become conspicuous again on the other side : 
 in these instances we have given the interval between 
 the earliest and latest observations as sufficient for our 
 present purpose. It would appear that out of the 
 many hundred comets recorded in history, only six 
 have been observed so long as eight months, and 
 these six instances have all occurred during the 
 piesent century. There are some few comets which 
 .have only been seen oncej unfavourable weather 
 
6 THE COMETS. 
 
 preventing further observation. In these cases we 
 cannot ascertain any particulars respecting their 
 distances, or real paths in space. 
 
 The lengths of the apparent tracks of comets in the 
 heavens, during the time of visibility, varies greatly, 
 being dependent on the distance of the body from the 
 earth, and on the direction of its real movement, in 
 reference to that of our globe. The comet of 1729 
 which, as already remarked, was always very remote 
 from us, traversed an arc of only 15 during the six 
 months it continued in view, while that of 1769 
 passed through an arc of 240 in longitude ; and 
 another in 1825, which moved extremely slow at first, 
 (the change of right ascension and declination in ten 
 days being little over two degrees), subsequently 
 quickened its rate of progress, and traversed an arc 
 of 225. 
 
 It is possible that a comet may be so situated in 
 reference to the earth, as to appear to pass through 
 no less than 140 in the space of an hour, or 178 in 
 a day ; but the combination of circumstances neces- 
 sary to produce this enormous change in the apparent 
 positions, has never yet taken place : the real motion 
 of the comet must be retrograde or contrary to that 
 of the earth in its orbit, it must be in opposition to 
 the sun, and in perihelion, moving in the plane of the 
 ecliptic, and at a distance from us not exceeding that 
 of the moon. If a comet be moving in the same di- 
 rection as the earth, the" distance of the two bodies 
 being small, its apparent position may scarcely change 
 in the course of the day, and if it be advancing 
 towards the earth, the same, or nearly the same place 
 
THEIR FIGURES. 7 
 
 in the heavens, may be preserved for many weeks, as 
 in the case of the comet of 1825, to which we have 
 just alluded. 
 
 When a comet is conspicuous to the naked eye, it 
 consists, in nearly every case, of a roundish and more 
 or less condensed mass of nebulous matter, termed the 
 head, from which issues, in a direction opposite to that 
 nf the sun, a train of a lighter kind of nebulosity, 
 called the tail. Sometimes the centre of the head is 
 occupied by a starlike point or nucleus ; at others by 
 a well-defined planetary disk, while in by far the 
 greater number of instances, it exhibits nothing more 
 than a higher degree of condensation of the nebulous 
 matter, which always has a confused appearance in the 
 telescope. Occasionally a low magnifying power will 
 afford evidence of the existence of a stellar nucleus, 
 but, on applying higher magnifiers, this appearance 
 vanishes, the light towards the centre being merely 
 of greater intensity than at the borders, without 
 coming up suddenly to a point, so as to resemble a 
 star. Telescopic comets are generally destitute of a 
 tail, and appear most commonly as roundish nebu- 
 losities, strongly condensed towards the centre, but 
 without any decided nucleus. There are exceptions, 
 however, to this rule, as we shall presently find. The 
 same comet may put on at different times of its visi- 
 bility, every variety of figure and general appearance 
 from the dim nebulous spot hardly discernible in the 
 telescope to the ' cometa terribilis/ c horrendse mag- 
 nitudinis/ the tailed and hairy stars which spread so 
 much alarm amongst our forefathers, before science 
 showed the groundlessness of such fears. These 
 
8 * THE COMETS. 
 
 changes in the aspect of the same comet, are caused 
 by variation in its distance from the earth and sun, 
 by its position in respect to the former, and possibly 
 also in some degree by actual change in the form of 
 the comet itself. 
 
 The envelope, mentioned by astronomers in their 
 observations of large comets, consists of a border of 
 light surrounding the head on the side near the sun, 
 and passing round in each direction, so as to form the 
 commencement of the tail. 
 
 The Coma is the nebulosity which surrounds a 
 highly condensed or planetary nucleus. 
 
 Some comets have attained such an extraordinary 
 degree of splendour, as to be distinctly visible at noon- 
 day, or to render the stars dim by contrast, and cast 
 sensible shadows at night. A comet mentioned by 
 Diodorus Siculus, was so brilliant as to cast shadows 
 during the night, as strongly marked as those formed 
 by the moon. Another, which appeared, according to 
 Seneca, shortly before the war of Achaia, B.C. 146, 
 was as large as the sun, and dissipated the darkness 
 of the nights : its disk was red and fiery. The comets 
 recorded by Justin, at the time of the birth and 
 accession of Mithridates, rivalled the sun in splendour. 
 One observed in February, 1106, was seen close to 
 the sun all over Europe. That of March, 1402, was 
 visible day and night in the circumpolar regions of 
 the heavens, in Germany and Italy ; and another 
 grand comet in the summer of the same year, was 
 bright enough to be discerned before sun-set. The 
 second comet of 1618, was distinctly seen in full 
 daylight by Marsilius, in Bohemia. The comet of 
 
USUAL COLOUE. 9 
 
 March, 1843, by far the most imposing of the present 
 century, was discovered in various parts of the world, 
 two or three degrees only from the sun's limb : it 
 must have far exceeded the planet Venus in bril- 
 liancy. Instances are on record where comets have 
 become visible during an eclipse of the sun, a circum 
 stance indicative of great intrinsic splendour, since 
 stars of the second magnitude are not very readily dis- 
 cerned on such occasions. Philostorgius says, that on 
 the 19th of July, 418, when the sun was eclipsed, and 
 stars were visible, a great comet, in the form of a 
 cone, was discovered near that luminary, and was 
 afterwards observed during the nights. The comet 
 of 1744 was observed with the telescope at noon-day, 
 and some persons were able to follow it without 
 optical aid for a considerable time after sunrise. The 
 first comet of 1847, discovered by the author, was 
 seen for some hours about two degrees from the sun's 
 limb, with a powerful telescope, and is the last instance 
 of the kind on record. 
 
 In most comets the head is white, or has a pale 
 watery appearance. Occasionally, however, the more 
 condensed part has a dull reddish or yellowish tinge, 
 or more rarely inclines to green. Out of forty-nine 
 instances, in which the colours of comets were re- 
 corded by the Chinese, we find twenty-three were 
 white, twenty bluish, four red or reddish-yellow, and 
 two greenish. 
 
 Planetary nuclei in comets, are of rare occurrence, 
 
 and it is pretty certain that they consist of nothing 
 
 more than nebulous matter in a very high degree of 
 
 condensation, and are not to be regarded as solid 
 
 B 3 
 
10 THE COMETS. 
 
 bodies. It is questionable whether any comet has yet 
 exhibited during the whole of its visibility, a well 
 denned disk of the same magnitude and appearance : 
 changes of form and apparent diameter are observed, 
 which clearly indicate a gaseous nature, or at any 
 rate are conclusive against the idea of solidity. 
 
 The nucleus of the great and celebrated comet of 
 1680 is described by some observers as resembling 
 ' a burning coal red and glowing ;' and the same 
 simile is used by Struve, in reference to the appear- 
 ance of Halley's comet during the autumn of 1835. 
 Some comets are pale and livid, as that of 1652, 
 stated by Comiers and Hevelius to be equal to the 
 moon in apparent size. Others, like that of 1744, are 
 bright and dazzling. The head of the fine comet of 
 December 1618, is said to have been composed of 
 several bright points or nuclei : Cysat observed three 
 or four on the 8th of that month, and on the 20th the 
 head seemed to be a cluster of small stars. Hevelius 
 mentions something analogous in the appearance of 
 the comet of 1661 and 1665 ; such phenomena are to 
 be attributed to -changes in the gaseous envelope of 
 the nucleus. We are not aware that they have been 
 remarked in any of the larger comets of recent 
 times. 
 
 Though, as we have seen, the nuclei of comets have 
 occasionally attained so great a degree of brightness 
 as to be discernible in full daylight, or to cast shadows 
 at night, it is their tails or trains which give them so 
 imposing an appearance in the heavens, and which 
 have excited so much astonishment in all ages. But 
 very few of the brighter comets have been observed 
 
THE TAILS OF COMETS. 11 
 
 without an appendage of this kind, though the 
 telescopic class rarely appear otherwise than as 
 roundish nebulosities. In some comets the tail has 
 been observed as a long narrow ray of light, somewhat 
 brighter near the head, and gradually fading away 
 into darkness. In others a dark line has divided it 
 into two branches, and instances are on record where 
 two tails, evidently distinct from each other, have 
 been remarked. Other comets have bushy, fan-shaped 
 tails, compared by the ancient observers to the train 
 of a peacock. Not unfrequently the appearance of 
 the tail will vary greatly on successive evenings, or 
 even during the same night. 
 
 As a general rule, the tail of a comet is turned from 
 the sun, forming a prolongation of the radius vector, 
 or of the line joining the sun and comet. This 
 remarkable fact was first noticed by Peter Apian of 
 Ingoldstadt, who found it the case with the trains of 
 five conspicuous comets which he observed between 
 the years 1531 and 1539. Exceptions do, however, 
 occur. The tail of the comet of 1577 deviated 21 
 from the line joining the sun and comet, and that of 
 the comet of 1 680, nearly 5. In some few instances 
 where more than one tail has been observed, the 
 second has extended towards the sun, as was the case 
 with a comet discovered in October, 1851. That 
 which appeared in January, 1824, exhibited two tails, 
 both distinctly visible to the naked eye, forming with 
 each other an angle varying from 138 to 170 : one 
 tail was in the usual direction, and appeared shorter 
 but brighter than the second, which streamed off from 
 the nucleus towards the sun. A fine comet, visible in 
 
12 THE COMETS. 
 
 the southern hemisphere early in 1845, had, in 
 tion to a lengthy tail turned from the sun, a second 
 narrow ray of light, forming an angle of about 1 40 
 with the other. 
 
 A comet mentioned by Diodorus SicUus, and ob- 
 served by Aristotle in the year 371 B.C., exhibited a 
 train 60 long. Another, in the year 133 after the 
 Christian era, was attended by a tail 50 long and 2 
 broad, according to the Chinese observations. The 
 comet of 178 had an appendage of equal length. 
 That of 390, observed in Europe and China, is said to 
 have had a train of the enormous length of 100. 
 The grand comet of 837, mentioned by nearly all the 
 historians of the time, was remarkable for the length 
 of its tail : on April 10th it extended 50 from the 
 head, and was divided near the extremity into two 
 branches ; next day its length was 60, but only one 
 ray was visible, and on the 14th it had increased to 
 80. Another great comet in 1264 was accompanied 
 by a train fully 100 long, agreeably to the Chinese 
 description, while European contemporaries tell us, 
 when the head was just clear of the eastern horizon, 
 the tail stretched past the mid-heaven westward, 
 which seems to indicate an extent of more than 90. 
 The comet of 1362 is said to have had a train 100 
 long, as observed in China : in Europe it was de- 
 scribed as a 'very great and brilliant star/ The 
 comet of 1456, known as Halley's, which created so 
 much alarm amongst the Turks, was accompanied by 
 a tail 60 in length. The great one, which appeared 
 in the winter of 1618, exhibited a tail no less than 
 104 long, according to Longomontanus, the Danish 
 
THE TAILS OF COMETS. 13 
 
 astronomer. Kepler had observed it fully 70 in 
 length a day or two previous. The famous comet of 
 1680, which was attentively watched by Newton and 
 Halley, was attended by a train 90 long. That ob- 
 served in the southern hemisphere in 1689, had a 
 tail more than 60 in length, and was two hours 
 and a half in rising ; and in another which appeared 
 six years afterwards, the tail was nearly of equal mag- 
 nitude. The comet of 1769 was attended by a long 
 and conspicuous tail, but observers differ considerably 
 in their estimations of its apparent length, even on 
 the same day, which can only be attributed to the 
 state of our atmosphere at the various stations. This 
 circumstance had been previously noticed in reference 
 to the comet of 1 680, but it was more marked in the 
 present case. Thus on the 9th of September, 1769, 
 Maskelyne at Greenwich considered the length of the 
 tail 43 ; at Paris it was judged to be 55; at the Isle 
 of Bourbon, it was traced 60 and more by La Nux, 
 while Pingre saw it fully 75 long, being at sea at the 
 time, between Teneriffe and Cadiz. Two days after- 
 wards, this astronomer found it 90 long, while La 
 Nux traced it 97 from the nucleus. The only comet 
 of the present century which has been accompanied 
 by a tail of very great length, is that of 1843, its 
 average extent was about 45, but on one occasion a 
 narrow ray of light attained the enormous distance of 
 65 from the head. 
 
 It would lead us far beyond the limits of the pre- 
 sent work, were we to particularize all the varied 
 phenomena which have been observed in the tails of 
 comets, but there is one singular appearance in the 
 
14. THE COMETS. 
 
 trains of great comets which we must not pass over 
 in silence. It consists of apparent vibrations or co- 
 ruscations, similar to the pulsations peculiar to the 
 Aurora Borealis. These vibrations commence at the 
 head, and appear to traverse the whole length of the 
 tail in a few seconds of time. The cause was long 
 supposed to be connected with the nature of the 
 comet itself, but Olbers pointed out that such appear- 
 ances could only be attributed to the effects of our 
 own atmosphere. The reason is this : the various 
 portions of the tail of a large comet must often be 
 situated at widely different distances from the earth, 
 so that it will frequently happen that light would re- 
 quire several minutes longer to reach us from the 
 extremity of the tail than from the end near the 
 nucleus. Hence, if the coruscation were caused by 
 some electrical emanation from the head of the comet, 
 travelling along the tail, even if it occupied only one 
 second in passing over the whole distance, several 
 minutes must necessarily elapse before we could see 
 it reach the end of the tail. This is contrary to ob- 
 servation, the pulsations being almost instantaneous. 
 
 Gregory of Tours mentions a comet in January 582, 
 the train of which resembled the smoke of a distant 
 conflagration, a description which may perhaps have 
 some relation to these vibrations or coruscations. The 
 first distinct mention of the phenomenon is to be found, 
 we believe, in the Chinese Annals in reference to the 
 comet of 615, the tail of which was between 50 and 
 60 long, and during the night had a kind of libration 
 to and fro. Kepler says the tail of the comet of 1607 
 was short one moment, but extended itself in the 
 
CURVATURE OF THE TAIL. 15 
 
 twinkling of an eye. Longomontanus, in describing 
 the immense tail of the comet of 1618, states that it 
 had ' an enormous vibration/ and Father Cysat says 
 it appeared as though it had been agitated by the 
 wind ; the same phenomenon was remarked by Kepler, 
 Wendelin, and other observers of this splendid comet. 
 Hevelius noticed similar undulations in the tails of 
 the comets of 1652 and 1661, and Pingre' says he had 
 observed them in the train of that which was visible 
 in 1769. The pulsations were very distinctly seen in 
 the tail of the grand comet of March 1843, and they 
 have been remarked in a greater or less degree in other 
 cases. 
 
 Another curious phenomenon occasionally observed 
 in the tails of comets is a curvature of the extremity, 
 or of a greater or less portion, so as to give the whole 
 train the form of a sabre. The ancient historians fre- 
 quently make use of this simile in describing the 
 aspect of these bodies. The comet which appeared 
 about the time of the Battle of Salamina, A.D. 479, 
 was of this form, as also those observed at Constan- 
 tinople in 912, 1340, 1402, 1456, and many others. 
 The Chinese compare the tail of the comet of 1232 to 
 the tusk of an elephant. The grand comets of 1264, 
 1618, and 1689, exhibited curved tails 80 or 100 in 
 length, the latter being particularly described by an 
 observer in the southern hemisphere as having a strik- 
 ing resemblance to ( a great sabre/ Pingre noticed 
 a curvature in the tail of the comet of 1769, the 
 convexity towards the north, and at times a second 
 small arc was formed near the extremity, turned in 
 the opposite direction ; the same appearances were 
 
16 THE COMETS. 
 
 remarked by La Nux at the Isle of Bourbon. The 
 train of the last great comet in 1843 was very sensibly 
 bent downwards towards the horizon at the end of 
 March, when it became conspicuous in this country, 
 and the smaller comet of December and January 
 1844-5 exhibited the same phenomenon, 
 
THE COMETS. 17 
 
 CHAPTER II. 
 
 OF THE REAL DIMENSIONS OF COMETS PHASES OB- 
 SERVED IN SOME OF THEM THEIR PHYSICAL CON- 
 STITUTION CHANCES OF COLLISION WITH THE 
 EARTH. 
 
 HAVING described the apparent dimensions of various 
 comets we must now say a few words relative to their 
 real magnitude. When the distance of one of these 
 bodies is known, and we have observed the angular 
 diameter subtended by the nucleus or head, it becomes 
 a very easy matter to ascertain the true diameter in 
 the same way that we find the dimensions of the sun, 
 moon, and planets. But as it never happens that the 
 borders of the nebulosity are sharply defined, and but 
 rarely so as regards the nucleus, our determinations 
 of their real dimensions are necessarily open to a good 
 deal of uncertainty. One thing, however, is quite 
 certain, that the cometic atmosphere surrounding the 
 nucleus varies greatly in extent in different comets, 
 and even in the same body at different epochs during 
 its visibility. The actual length of the tail of a comet 
 may be computed by trigonometry, when we know 
 the distance of the nucleus from the earth and its 
 position in respect to the sun, always assuming that 
 
18 THE COMETS. 
 
 the tail is projected from the sun in the line joining 
 that luminary and the head of the comet. 
 
 The following were the real diameters in English 
 miles of the nuclei of some of the more remarkable 
 comets, which have been satisfactorily measured within 
 the last century : 
 
 Mil os. 
 
 The comet of 1815, discovered by Gibers . . . 5300 
 The great comet of 1825 . . . , . 5100 
 The great comet of March, 1843 . , .... 5000 
 The first comet of 1780 , , : , , , ., 4270 
 The first comet of 1847, discovered by the author . . 3500 
 The fine comet of July, 1819 . .... 3280 
 
 Second comet of 181 1, measured by Herschel . . 2640 
 
 The great comet of 1 807, measured by Herschel ... 538 
 The celebrated comet of 181 1, measured by Herschel . 423 
 The second, of 1798, according to Schroter and Harding 125 
 The comet of 1805, known as Biela's . . . 70 to 112 
 
 The comet which was visible to the naked eye in 
 June 1845 had a bright planetary-looking nucleus, 
 which must have been nearly 8000 miles in diameter, 
 or about equal to that of the earth. On the 24-th of 
 January, 1836, Mr. Maclear, at the Cape of Good 
 Hope, saw a well-defined disk within the head of the 
 comet of Halley, which, from the apparent diameter 
 assigned, could not have been less than 97,000 miles 
 in breadth, but in the previous autumn the very same 
 comet had exhibited a brilliant ' kernel/ or nucleus, 
 varying on different dates from 250 to 1000 miles in 
 diameter. A more striking proof of the variable 
 dimensions of a comet could hardly be adduced. 
 
 The coma, or atmosphere enveloping the nucleus, 
 
REAL DIMENSIONS. 19 
 
 or more condensed part of a comet, is subject to the 
 same variation, as the subjoined results will show : 
 
 Diameter of Head. 
 
 The grand comet of 1811 . . 1,125,000 miles. 
 
 Comet of Halley, 1836 . . . 357,000 
 
 Comet of Encke, 1828 . . . 312,000 
 
 The first, of 1780 269,000 
 
 The first, of 1846 248,000 
 
 The comet of Lexell, 1770 . . 204,000 
 
 The third, of 1846 ... . 130,000 
 
 The second, of 1849 .... 51,000 
 
 The first comet of 1847 . . . 25,500 
 
 The fifth of the same year . . 18,000 
 
 During the autumn of 1811, or while the splendid 
 comet of that year was visible to the naked eye, the 
 real diameter of the head appears to have differed but 
 little from 1,000,000 miles, or more than four times 
 the distance which separates the moon from the earth. 
 No other on record has surpassed this. In most in- 
 stances the visible atmosphere of a comet is less than 
 100,000 miles in diameter, and but very rarely exceeds 
 200,000. It must be remembered, however, that the 
 nebulosity may extend much further than we can 
 trace it from the earth, and consequently that our 
 estimates of the true magnitudes are very likely to be 
 under-rated. 
 
 It has been remarked above, that the real dimen- 
 sions of comets are found to vary greatly at different 
 dates during their visibility. Contrary to what we 
 might have expected, there is no doubt that many of 
 these bodies contract as they approach the sun, and 
 dilate on receding from that luminar^. We have the 
 
20 THE COMETS. 
 
 r 
 
 strongest proofs of this in the case of Encke's comet, 
 which is one of short period, and has been repeatedly 
 observed, as we shall notice more at length presently. 
 This comet arrived at its least distance from the sun 
 on the 10th of January, 1829, and the following were 
 its actual dimensions on the various dates of observa- 
 tion during its descent towards the sun : 
 
 1828. Diameter in Miles. Distance from Sun. 
 
 October 28 . . 312,000 . . 1-46 
 
 November 7 . . 257,000 . . 1-32 
 
 November 30 . . 119,000 . . 0'97 
 
 December 7 . . 79,000 . . 0-85 
 
 December 14 .. 46,000 . . 072 
 
 December 24 . . 14,000 . . 0'54 
 
 The observations of the same comet ten years later 
 furnish another instance. It was at its least distance 
 from the sun on the 19th of December, 1838, and 
 found to have had the following diameters on different 
 days preceding the arrival at perihelion. 
 
 1838. Diameter in Miles. Distance from Sun. 
 
 October 9 . . 281,000 . . 1-42 
 
 October 25 . . 120,500 . . M9 
 
 November 6 . . 79,000 . . 1-00 
 
 November 13 .. 74,000 . . 0-88 
 
 November 16 .. 63,000 . . 0'83 
 
 November 20 . . 55,500 . . 0-76 
 
 November 23 . . 38,500 . . 071 
 
 November 24 . . 30,000 . . 0'69 
 
 December 12 . . 6,600 . . 0*39 
 
 December 14 . . 5,400 . . 036 
 
 December 16 .. 4,250 . . 0'35 
 
 December 17 .. 3,000 . . 0-34 
 
 The nebulosity surrounding the nucleus of the great 
 comet of 1807 expanded as the distance from the sun 
 
REAL DIMENSIONS. 21 
 
 Increased. The measures of Schroter give the fol- 
 lowing diameters, expressed as before in English miles. 
 The comet was nearest to the sun on September 
 19th : 
 
 1807. Diameter in Miles. Distance from Sun. 
 
 October 20 . . 117,900 . . 0'92 
 
 October 21 .. 
 
 125,800 . 
 
 . 0-93 
 
 October 22 . . 
 
 133,500 . 
 
 . 0-94 
 
 October 23 . . 
 
 138,400 . 
 
 . 0-96 
 
 October 25 . . 
 
 156,200 . 
 
 . 0-99 
 
 October 31 .. 
 
 159,000 . 
 
 . 1-08 
 
 November 3 . . 
 
 198,400 . 
 
 . 1-12 
 
 Kepler first remarked this singular contraction and 
 expansion of the nebulosity surrounding the nucleus 
 of a comet as it approaches and recedes from the sun 
 respectively, in the case of the fine comet which ap- 
 peared in the year 1618. 
 
 The tails of comets in some cases extend only a 
 few hundred thousand miles from the nucleus, while 
 in others they are projected to the astonishing distance 
 of one hundred or one hundred and fifty millions of 
 miles, or even more. The train of the first comet of 
 1847 was 5,000,000 miles in length ; of the beautiful 
 comet of 17^4, 19,000,000 ; of the comet of 1769, 
 about 40,000,000. The third of 1618 had a tail more 
 than 50,000,000 miles in length, when it crossed the 
 plane of the earth's orbit about the 25th of November, 
 and it was subsequently of greater extent. The great 
 comets of 1680 and 1811. had trains considerably 
 more than 100,000,000 miles long; and the second of 
 the latter year was accompanied by a tail 130,000,000 
 miles in length. Even these comets, however, were 
 surpassed by the grand one which attracted so much 
 
22 THE COMETS. 
 
 attention in 1843, and which exhibited a brilliant 
 train that on different dates was found to attain the 
 enormous distances of 150, 180, and 200 millions of 
 miles from the head ! If such a comet had been in 
 the plane of the ecliptic, and close to the sun, the 
 train would have extended far beyond the orbits of 
 the Earth and Mars, terminating amongst those of the 
 minor planets. Yet this wonderful appendage was 
 formed in less than three weeks. 
 
 It has frequently been remarked, that, if comets 
 shine by reflected light, and there be anything like 
 solidity in the nucleus, we ought at certain times to 
 observe phases similar to those presented by the 
 moon in the course of her revolution round the earth. 
 There are some few instances on record where such 
 appearances have been noticed. We cannot place 
 much reliance on the cometary nature of the object 
 mentioned in the Chinese Annals as having been 
 observed in the northern heavens in October 684, 
 which resembled a half moon, or of that recorded by 
 the historians of the ninth century, at the beginning 
 of the reign of Leo the Armenian in 813, said to have 
 been like two moons joined together. Something 
 very closely analogous to a phase was, however, ob- 
 served in the head of the fine comet of 1744, and in 
 another large one of the same century (1769), an 
 observer expressly states that he had seen the nucleus 
 first as a thin crescent, and subsequently as a half- 
 moon, in the course of the comet's descent towards 
 the sun. The nucleus of the comet of 1819 pre- 
 sented a very distinct crescent, according to Nicholas 
 Cacciatore, of Palermo. 
 
PHYSICAL CONSTITUTION. 23 
 
 Concerning the physical constitution of comets we 
 have but a very imperfect knowledge at present. Sir 
 John Herschel regards them as masses of thin vapour, 
 capable of reflecting the solar rays from their internal 
 as well as external parts an inference which is ren- 
 dered necessary, in order to account for all the pheno- 
 mena revealed by telescopes. It is certain that stars 
 of a very faint class have been repeatedly seen through 
 comets of from fifty thousand to one hundred thou- 
 sand miles in diameter, and, in the majority of cases, 
 not the least perceptible diminution of the star's 
 brightness took place. There are one or two instances 
 on record, where astronomers have been convinced of 
 a sensible increase of brilliancy when a star has been 
 viewed through the cometic vapour. In addition to 
 a remarkable observation of this kind by Piazzi, at 
 Palermo, during the appearance of the grand comet 
 of 1811, we may mention a more recent one by Pro- 
 fessor Reslhuber of Kremsmunster, in reference to a 
 star seen through the denser part of a comet disco- 
 vered by M. Brorsen in March 1846, and which, under 
 ordinary circumstances, belonged to the eighth class, 
 or was just beyond unassisted vision. When the star 
 was centrally covered by the comet, it became very 
 considerably brighter, and was judged to be equivalent 
 to a star of the sixth magnitude, in which case it 
 would have been distinctly visible without a telescope. 
 Professor Struve made some interesting observations 
 during the transit of the comet of Biela over a small 
 star, on November 6th, 1832. The brightness of the 
 star was not in the least diminished by the interven- 
 tion of the comet, and its light suffered no perceptible 
 
24 THE COMETS. 
 
 refraction, a point established by a continuous series 
 of measures with the micrometer. 
 
 That comets shine by a reflected light is a conclu- 
 sion which few astronomers will dispute. It is evi- 
 dent from telescopic observation of the degree of 
 brilliancy at different distances, and in various posi- 
 tions of a comet, with respect to the sun and earl . 
 and M. Arago has established the fact from experi- 
 ments with a polariscope, during the visibility of the 
 famous comet of Halley in the autumn of 1835 
 Still the variation in the intensity of light is not un> 
 versally such, as should follow if the comet mere, 
 reflected the sun's rays, under certain permanent 
 conditions, and we are under the necessity of looking 
 . to physical causes inherent in the body itself for an 
 explanation of some few observations which appeal 
 irreconcilable with the theory of reflected solar light. 
 The first comet of 1780 was closely examined by Dr 
 Olbers, the eminent astronomer of Bremen. He 
 found it attained its greatest brightness on the 8th of 
 November, thirteen days subsequent to its discovery 
 whereas, according to the law of reflected light, it 
 should have become gradually fainter since the first 
 observation ; and, supposing the comet self-luminous, 
 the intensity of light should have increased each day 
 until November 26, when the maximum would take 
 place : yet, in the interval between the 8th and 26th 
 of that month, it grew rapidly less. The comet dis- 
 covered by Dr. Galle, of Berlin, on the 25th of Janu- 
 ary, 1840, presented similar anomalies. Assuming 
 that it had no light of its own, it should have appeared 
 twice as bright on the 23rd of February as on the 21 si 
 
\ 
 
 PHYSICAL CONSTITUTION. 25 
 
 of March, yet at the latter date Professor Plantamour 
 found the intensity of light had increased in the pro- 
 portion of more than two to one. Such variations 
 are probably to be attributed to changes in the physi- 
 jil constitution of the comet, due to the action of the 
 sun. 
 
 j. With our present imperfect knowledge of the nature 
 of the matter of which these bodies are composed, it 
 is not to be expected that we can gain a clear insight 
 into the laws of the forces exercised upon it, through 
 ' .vhich the envelope and tail are formed. The nucleus, 
 or more condensed part of the head, appears to pos- 
 ;;ess the power of throwing off towards the sun a 
 portion of the cometic atmosphere, which, before it 
 can attain any great distance from the nucleus, is 
 driven backward in two streams passing on either side 
 of the head, and ultimately blending into one to form 
 the tail. This repulsive energy must very far exceed 
 the force of gravitation. Generally speaking, the axis 
 of the tail preserves a rectilinear form throughout 
 the greater part of its length, a curvature of the 
 extremity being only occasionally seen, and probably 
 attributable to the failure of the repulsive force, and 
 the gradual effect of a resisting medium upon these 
 distant and extremely rare portions of the train. 
 The disappearance of the tail as the comet recedes 
 from the sun, may be owing either to its being attracted 
 into the nucleus as that luminary loses its power upon 
 it, or it may be partly dispersed in the surrounding 
 space. 
 
 In the case of bodies like comets, moving through 
 the planetary spaces in every direction, it cannot 
 
 C 
 
26 THE COMETS. 
 
 be denied that there is a, possibility of the Earth's 
 coming in collision with one of them in the lapse 
 of time ; but we are able to show from legitimate 
 reasoning that the chance of such a catastrophe is 
 very small indeed. M. Arago has calculated that the 
 probability against it is greater than 250,000,000 to 
 one. We know that the earth has had one or two 
 narrow escapes within the last two centuries, as in 
 1680 and 1832, when comets crossed the plane of the 
 ecliptic almost on the path of our globe, though at 
 these times we were, perhaps fortunately, removed 
 many millions of miles from the dangerous part of 
 the orbit. The comet of 1*770 has approached nearer 
 to us than any other of these bodies whose elements 
 have been sufficiently well determined. On the 1st 
 of July it was distant from the Earth only 363 ter- 
 restrial semidiameters or 1,438,000 miles. The great 
 comets of 837, 1402, and 1472, must have come within 
 a very short distance from our globe, and another 
 small one, which was observed by Flaugergues ill 
 1826, seems to have made a close appulse. Olbers 
 mentions several which have crossed the ecliptic at 
 points not far removed from the annual track of the 
 earth. 
 
 The comet of 1684 approached it within 216 terrestl.semidiamtrs. 
 That of 1805 261 
 
 That of 1742 331 
 
 That of 1779 347 
 
THE COMETS. 27 
 
 CHAPTER III. 
 
 OF THE PATHS OF COMETS IN SPACE ELEMENTS OF 
 THEIR ORBITS USES OF A TABLE OF ELEMENTS 
 EFFECTS OF PLANETARY ATTRACTION UPON THEIR 
 MOVEMENTS. 
 
 THE curve described by the generality of comets is 
 in all probability a very excentrical ellipsis, so nearly 
 approaching a parabola, that for those parts of the 
 orbit near the perihelion, where alone the comet is 
 visible from the earth, no sensible difference is caused 
 by the substitution of the latter curve; and accord- 
 ingly, as the calculation in the parabola is so much 
 easier and shorter than in the ellipse, astronomers 
 always employ it to represent the paths of comets in 
 the heavens, and to predict their future positions as 
 viewed from the earth or sun. When one of these 
 bodies has been discovered, and several observations 
 (not less than three) have been obtained, they are 
 submitted to calculation; and the elements of the 
 orbit, as they are termed, are found on the supposi- 
 tion that the real path through space is in a para- 
 bola : with these elements we can find for any parti- 
 cular time, the comet's distance from the earth, and 
 its situation in our heavens, and, in fact, trace its 
 c 2 
 
28 THE COMETS. 
 
 course through the system. The major-axis in this 
 conic section being infinite, we can learn nothing 
 respecting the period of revolution round the sun 
 from such computations ; but for all practical pur- 
 poses they are usually found to be sufficiently exact 
 without having recourse to the ellipse. If we wish to 
 approximate to the periodic time, we must enter upon 
 a much longer investigation, and one which may not 
 always prove satisfactory or trustworthy in the end. 
 Sometimes ellipses with periods widely different will 
 represent the observations of a comet with nearly 
 equal accuracy, none of them perhaps being much 
 preferable to a parabola ; in such a case it is tolerably 
 certain that the revolution is of many centuries' 
 duration, or more probably extends to many thousand 
 years. Still some few comets have been observed, 
 whose apparent paths amongst the stars could be in 
 no wise represented by a parabolic curve : elements 
 which appear satisfactory, for the earlier observations 
 would give places at later periods, deviating several 
 degrees from the true situation of the comet. In such 
 cases astronomers have resorted to the ellipse, and it 
 has been found that the comets are revolving in com- 
 paratively short periods, varying from three to seventy- 
 five years. In fact, of these periodical comets there 
 are two well-marked classes, one having the major- 
 axis not very different from those of the minor 
 planets between Mars and Jupiter, and the other 
 having mean distances rather less than in the case of 
 Uranus. These bodies are amongst the most interest- 
 ing objects in the heavens, and of high importance to 
 the physical astronomer. 
 
ORBITAL ELEMENTS. 29 
 
 The elements, as they are termed, of a parabolic 
 orbit, are five in number : 
 
 1. The time of perihelion passage, or the moment 
 
 when the comet arrives at its least distance 
 from the sun, at the vertex of the parabola. 
 English calculators adopt the meridian of 
 Greenwich, the French that of Paris, and the 
 Germans that of Berlin, in expressing the 
 epoch of arrival at perihelion. 
 
 2. The longitude of perihelion, or the longitude of 
 
 the comet at the time it reaches this point, as 
 viewed from the sun's centre. It is usually 
 reckoned on the ecliptic to the node, and 
 thence on the orbit, so that the differences 
 between the longitudes of the nodes and peri- 
 helia, as commonly given, are arcs of true 
 anomaly. 
 
 3. The perihelion distance, or the distance of the 
 
 comet from the sun at that epoch expressed in 
 parts of the Earth's semi-major axis, taken as 
 unity. 
 
 4. The longitude of ike ascending node of the 
 
 comet's orbit upon the ecliptic, as seen from 
 the sun. 
 
 5. The inclination of the orbit, or the angle 
 
 between the planes of the orbit and of the 
 ecliptic. 
 
 It is also necessary to know whether the comet 
 moves in the order of the signs or in the contrary 
 direction : in the former case its movement is said to 
 be direct ; in the latter, retrograde. 
 
 In an elliptic orbit, in addition to the five elements 
 
30 THE COMETS. 
 
 above named, we require also to know the excentri- 
 city ; from which and the perihelion distance we can 
 ascertain the length of the major-axis, and thence the 
 periodic time. The quantity termed the excentricity 
 in this case is not the linear distance of the centre of 
 the ellipse from the focus, but the ratio of that quan- 
 tity to the comet's mean distance or half the greater 
 axis. Occasionally it is expressed as an angle, which 
 is actually formed by the minor-axis at its extremity 
 on the border of the ellipse, with a line drawn thence 
 to the focus. The greater this angle, the more excen- 
 trical is the orbit. 
 
 Up to the year 1850, the elements of about two 
 hundred comets have been determined with a greater 
 or less degree of accuracy, according to the goodness 
 or otherwise of the observations. Out of this number 
 there are thirty-three which appeared before the end 
 of the sixteenth century, and were chiefly observed in 
 China. In these cases the orbits are founded upon 
 the details preserved in the Chinese annals, which, 
 imperfect and vague as they frequently appear, are 
 yet far superior to the generality of European accounts 
 in these early times. MM. Stanislaus Julien and 
 E. Biot of Paris have added much to our previous 
 knowledge of the early Chinese observations. The 
 first cometary orbit in our catalogue belongs to the 
 body observed and described by Aristotle, 371 years 
 before the Christian era. 
 
 The value of the orbital elements, whether para- 
 bolic or elliptic, is not confined alone to their practical 
 application during the visibility of a comet to trace 
 it amongst the stars, and predict its apparent positions 
 
PLANETAEY ATTRACTION. 31 
 
 at any time ; if it should be found, on comparing the 
 elements of a comet newly discovered with any pre- 
 viously computed, that a great similarity exists between 
 them, it is a strong argument in favour of the identity 
 of the comets to which they refer, and such com- 
 parison affords the most certain means of ascertaining 
 the period of a comet, when it extends to many 
 centuries. The direct solution of the problem of 
 finding the time of revolution frequently fails, from 
 want of a sufficiently long series of observations, and 
 other causes. 
 
 Out of 194 comets calculated before the year 1849, 
 it appears that 94 were direct and 100 retrograde, 
 and that one-third of the whole number have arrived 
 at perihelion between the autumnal equinox and the 
 winter solstice. The perihelion distances are thus 
 distributed : 
 
 'Between O'O and 0'5 . . 54 comets. 
 
 0-5 1-0 . . 95 
 
 1-0 1-5 . . 31 
 
 1-5 2-0 .. 8 
 
 Beyond 2-0 . . 6 
 
 The comet of 1729 had the greatest perihelion 
 distance, = 4*04, and that of March, 1843, the least, 
 being only 0'005678. 
 
 The paths of the comets through the Solar System 
 are usually influenced in a very sensible degree by 
 the attractions of the planets, and especially of 
 Jupiter, which from its great mass has on more than 
 one occasion entirely overpowered for a time the 
 action of the sun, and thereby changed in toto the 
 
82 THE COMETS. 
 
 nature of the comet's path about that luminary. The 
 calculation of the effects of these perturbations is one 
 of great intricacy, and attended with considerable 
 difficulties in practice, and astronomers resort to 
 various artifices to shorten the labour of calculation 
 and simplify the analytical process. Where the 
 amount of attraction exercised by two or more bodies 
 upon a third has to be considered, the problem of 
 finding the effect upon the* motion oi the third 
 becomes exceedingly complicated, and in fact it is not 
 possible to solve it directly. The method in general 
 use at present is virtually as follows : Suppose the 
 effect of the Earth, Jupiter, and Saturn upon the longer 
 diameter of a comet's elliptic orbit is required between 
 January 1 and June 1 i. e., having the value ap- 
 plying to January 1 we wish to find what it would be 
 at the beginning of June. The interval is divided 
 into certain equal periods, and for the middle day 
 of each period, the diurnal variation of every element 
 of the comet's orbit is computed separately for each 
 planet, as if the others did not exist; the variations 
 produced by each are then summed, and give the 
 total change in the element in the adopted unit of 
 time, commonly one day; then by a process which we 
 cannot explain here, the quantities are applied to the 
 assumed value of the longer axis of the ellipse on 
 January 1, having been previously multiplied by the 
 number of days (if a day be the unit of time) in each 
 interval, so as to give the value for the epoch required, 
 or June 1. The accuracy of this method depends 
 mainly upon the judgment exercised by the calculator 
 in shortening his intervals, so as to determine the 
 
HALLEY'S CALCULATIONS. S3 
 
 amount of the diurnal variations with sufficient fre- 
 quency; sometimes intervals of fifty days would be short 
 enough, at others it might be necessary to resort to inter- 
 vals of twelve, eight, or even four days, or less, according 
 as the attraction of the disturbing body varies in a 
 lesser or greater degree in each interval ; because it is 
 assumed that the changes go on uniformly, or nearly 
 so, and consequently that the diurnal variation for 
 the middle day of each interval, if multiplied by the 
 number of days included in it, shall give very nearly 
 the true variation in that interval. By another 
 method, instead of using equal periods of time, the 
 calculations are conducted for equal intervals of the 
 comet's excentric anomaly. These processes, to be 
 fully understood in theory, require an acquaintance 
 with some of the highest branches of mathematical 
 science, while their practical application is so tedious 
 and intricate, that few but the most zealous and ex- 
 pert computers will attempt to manage them. 
 
 We have just alluded to the use of a table of the 
 elements of cometary orbits in identifying returns of 
 the same body. By this comparison of elements the 
 periodicity of at least one comet has been established, 
 and we have strong reasons to suspect it in other 
 cases. In the following chapter we shall briefly 
 describe the circumstances which led our countryman 
 Halley to the first discovery of the periodical return 
 of a comet, while he was occupied in applying New- 
 ton's law of gravitation to the apparently capricious 
 and intricate movements of these bodies; by the 
 application of the Newtonian principles at a vast 
 expense of time and labour, Halley laid the founda- 
 c 3 
 
34 THE COMETS. 
 
 tion upon which cometary astronomy has since risen. 
 We shall endeavour so to arrange our descriptions of 
 this and other comets, that the reader may gain an 
 insight into the kind of interest attaching to this 
 department of the science, and the difficulties with 
 which astronomers have to contend in prosecuting 
 their inquiries respecting these extraordinary bodies. 
 
THE COMETS. 35 
 
 CHAPTER IV. 
 
 THE COMET OF HALLEY. 
 
 AMONGST the comets which particularly attracted the 
 attention of Dr. Halley during his arduous investiga- 
 tions, were those of 1531, 1607, and 1682. 
 
 For the most important observations of the comet 
 of 1531 we are indebted to Peter Apian, astronomer 
 to the Emperors Charles V. and Ferdinand I. of 
 Austria, who observed at Ingoldstadt in Bohemia. 
 His results were published in 1540 in the Astrono- 
 micum Ccesarium, an extremely rare work, which 
 was found with difficulty even so long since as the 
 time of Halley. A fine copy is now preserved in the 
 library of the Eoyal Astronomical Society. The ob- 
 servations were made each evening at the time of 
 transit of the bright star Arcturus over the prime 
 vertical westward, and extend from August 13th to 
 the 23rd, Julian style. The comet was first seen at 
 the end of July, and was visible in some parts until 
 the beginning of September, its motion in the interval 
 being from Leo into Libra. Lavather says it was 
 observed in Italy, Germany, and France, and was of a 
 reddish or yellow colour. Camerarius says it belonged 
 to the class Pogonice. The Chinese astronomers found 
 the comet in Gemini on August 5th, and it was last 
 perceived on the 8th of September in the constellation 
 
36 THE COMETS. 
 
 Virgo ; they describe its course amongst the stars, 
 agreeing in every essential point with the relation of 
 Peter Apian. 
 
 On the llth of September, 1607, the Chinese dis- 
 covered a comet in Gemini, which they finally lost 
 sight of in the sign Scorpio at the beginning of Oc- 
 tober. In Europe it was observed by the celebrated 
 Kepler at Prague, by Longomontanus at Copenhagen, 
 and at Malmoge, in Scania, by William Lower at 
 Ilfracombe, and by our distinguished countryman 
 Harriot. Kepler's observations are found in a work 
 published at Augsburg in 1619, and entitled, De 
 Cometis libelli ires. Professor Eigaud has printed in 
 detail the observations of Lower and Harriot, which 
 had been fortunately discovered amongst the papers 
 of the Earl of Egremont. According to Longomon- 
 tanus, the comet had a pretty long and dense tail in a 
 direction opposite to that of the sun. The head ap- 
 peared of about the size of Jupiter, its colour being 
 livid, and resembling that of Saturn ; the tail was 
 visible from the time the comet was first perceived by 
 Kepler, on September 16th, until the 12th of the fol- 
 lowing month. The head was not quite round ; it had 
 a pale watery light ; the tail long and glittering. 
 Gottfried Wendelin saw the comet till November 5th, 
 and says its form was like that of " a burning lamp," 
 or " a flaming sword/' 7 long. Coruscations of the 
 tail were remarked by Kepler and others. The appa- 
 rent path was through Ursa Major, Bootes, Serpens, 
 and Ophiuchus. 
 
 On the evening of the 15th of August, 1682, Flam- 
 steed's assistant saw a comet at the Royal Observatory, 
 
THE COMET or H ALLEY. 37 
 
 Greenwich. A few days later it was more visible ; 
 the tail 5 long, the diameter of the head about two 
 minutes of arc. On the 21st the tail was 10 long, 
 and bent towards the right. Flamsteed's observations 
 extend to September 9th, when the head was dull, 
 and scarcely visible in the twilight. Halley saw it a 
 day later. Picard found the comet at Paris on August 
 26th; the head then appeared as large as a star of the 
 second magnitude. On the 29th the tail was curved, 
 the concavity on the eastern side. . On September 
 1 1th the head was so confused that it was hot with- 
 out difficulty a luminous point could be perceived. 
 Picard 's observations extend to September 12th. 
 Hevelius, who observed the comet at Dantzic, says 
 it was bright at the end of August, and could be 
 seen all night with a tail from 12 to 16 long. In 
 large telescopes a nucleus of an oval or gibbous form 
 was constantly remarked. On many occasions the 
 tail was not directed exactly /rom the sun. About 
 September 8th a kind of luminous ray or sector was 
 thrown out from the nucleus into the tail, a pheno- 
 menon which appears to have struck Hevelius as very 
 remarkable, and induced him to give a figure, which 
 conveys a better idea of its nature than could have 
 been obtained from verbal description. The same 
 phenomenon was witnessed at a subsequent return of 
 this comet. Besides the observers we have named, 
 Kirch of Leipsic, Zimmerman of Nuremberg, Baert of 
 Toulon, and Montanari of Padua, are amongst those 
 who have left descriptions or observations of this body. 
 Dr. Halley calculated the parabolic elements of the 
 comet of 1682 from Flamsteed's observations, agree- 
 
38 THE COMETS. 
 
 ably to the rules laid down by his friend Sir Isaac 
 Newton ; and having also determined the orbits of the 
 comets of 1531 and 1607, he was immediately struck 
 with their similarity, and suspected, from 'the like 
 situation of their planes and perihelions, that the 
 comets which appeared in the years 1531, 1607, and 
 1682 were one and the same comet, that had made 
 three revolutions in its elliptical orbit/ As some 
 differences existed in the periods and inclinations 
 which Halley thought rather large, he merely hinted 
 his suspicion, when the Synopsis of Cometary Astro- 
 nomy was first given to the world in the year 1705. 
 At a subsequent period he became much more con- 
 vinced of the identity of the comets, and remarking 
 that the next revolution would be sensibly affected by 
 the planet Jupiter, he thought the return to perihelion 
 might be delayed till the beginning of the year 1759. 
 In advising the astronomers of that day carefully to 
 watch for the re-appearance, he expressed a hope that 
 in the event of its return, they would not refuse to 
 acknowledge that its periodicity had been discovered 
 by an Englishman. Nor has posterity attempted to 
 deprive him of the honours which were his due ; his 
 discovery forms an epoch, and an important one, in 
 the history of astronomy. His calculations must have 
 been laborious in the extreme. He assures us him- 
 self they were ' prodigiously' long and troublesome ; 
 but the zeal which induced such an amount of exer- 
 tion was well rewarded by the final result. 
 
 As the time of the comet's return drew nigh, 
 the attention of astronomers was more particularly 
 directed to the probable effects of the attraction of 
 
THE COMET OF HALLEY. 39 
 
 Jupiter and Saturn, hinted at by Halley. The 
 eminent French geometer, Clairault, investigated 
 the theory which it would be necessary to apply 
 in the numerical determination of the disturbances 
 produced by these planets; and having devised a 
 method which appeared to possess all needful accu- 
 racy, he commenced, in conjunction with the cele- 
 brated Lalande and a lady, Madame Lepaute, 
 the immense mass of calculations requisite for the 
 complete attainment of his object. It was neces- 
 sary to compute the distances of the comet from the 
 disturbing planets, Jupiter and Saturn, not only 
 from 1682, when it was last observed, but for the 
 previous revolution, or for a space of more than one 
 hundred and fifty years. This of itself was a most 
 laborious business; but the succeeding part of the 
 work, where the disturbing force of each planet was 
 required for this long period, involved much greater 
 and more intricate calculations. Lalande minutely 
 describes the plan adopted : for six months they com- 
 puted from morning to night, with but little intermis- 
 sion, even, as he states, at meals; and he mentions, as 
 one result of this assiduous attention to the work, 
 that he contracted an illness which remained upon 
 him during the rest of his life. Madame Lepaute's 
 assistance is said to have been so important, that 
 without it they would hardly have completed the in- 
 vestigation before the comet reappeared. However, 
 by dint of these extraordinary exertions, the calcu- 
 lations were brought to a close; and on the 14th 
 of November, Clairault announced to the French 
 Academy of Sciences, as the principal results, that 
 
40 THE COMETS. 
 
 the comet would be retarded by the action of Jupiter 
 no less than five hundred and eighteen days, and 
 one hundred by that of Saturn, making a delay of 
 six hundred and eighteen days; and hence he pre- 
 dicted that the perihelion passage would take place 
 on the 13th of April, 1759. In announcing this me- 
 morable conclusion, Clairault observed that he did so 
 with some diffidence, because the small quantities un- 
 avoidably neglected in the calculations might possibly 
 exercise an influence one way or the other to the 
 amount of one month. Messier had been looking out 
 for the comet during the whole of the year 1758, and 
 many other astronomers searched the heavens for it, 
 after the knowledge of Clairault's important results 
 had reached them. 
 
 It was not destined, however, that a professed as- 
 tronomer should be the first to obtain a glimpse of 
 the wanderer on its return to visit these lower worlds. 
 It was perceived on the night of December 25, 1758, 
 by an amateur astronomer, named Palitzch, a farmer 
 living at Prohlis, near Dresden, who saw it with his 
 telescope of eight-feet focus, and not with the naked 
 eye as frequently stated. The Baron de Zach was 
 personally acquainted with this diligent observer of 
 the heavens, and has corrected several mistakes re- 
 specting him. He possessed a strong sight, and was 
 in the habit of examining the heavens with the 
 naked eye, which has probably given rise to the 
 statement of his having detected the comet without 
 optical aid, at a time when all the astronomers in 
 Europe were seeking for it with their telescopes 
 without success. Palitzch saw the comet again on 
 
THE COMET OF H ALLEY. 41 
 
 the 26th of December; and on the 28th of the same 
 month it was detected by Dr. Hoffman. An astronomer 
 at Leipsic found it on the 18th of January. Messier 
 was much interrupted by cloudy weather, but on the 
 21st he caught a glimpse of the comet, and observed 
 it regularly for the three weeks following. Delisle, 
 then director of the observatory at Paris, would not 
 allow him to give notice to the astronomers of that 
 city, that the long-expected body was in sight, and 
 Messier remained the only observer before the comet 
 was lost in the sun's rays. Such a discreditable and 
 selfish concealment of an interesting discovery, is not 
 likely to sully again the annals of astronomy. Some 
 members of the French academy looked upon Messier 's 
 observations when published as forgeries, but his name 
 stood too high for such imputations to last long, and 
 the positions were soon received as authentic, and 
 have been of great service in correcting the orbit of 
 the comet at this return. 
 
 The inferior conjunction with the sun taking place 
 about the end of February, the comet was too near 
 that luminary to be visible before the last week 
 in March. It was found again by La Nux, at the 
 Isle of Bourbon, on the 26th, and by Messier on the 
 31st ; and Delisle having withdrawn his interdict, the 
 formal announcement of the reappearance of the 
 comet was made on the 1st of April. Towards the 
 end of this month, it again became invisible in 
 Europe, owing to its low situation in the southern 
 heavens, but in the meantime had been recognised 
 and observed at Lisbon, Toulouse, Avignon, and other 
 places. At the time that it was below the horizon in 
 
42 THE* COMETS. 
 
 Europe, observations were taken by La Nux, and by 
 Father Cceurdoux, at Pondicherry. On April 28th, 
 the comet was again found at Lisbon, and a few days 
 afterwards at Paris, and at nearly all the observatories 
 of Europe : this third appearance extended to June 
 3rd, when the comet was finally seen by Messier. Its 
 aspect in 1759 was not so imposing in these parts of 
 the world as some astronomers had anticipated, but 
 this was mainly owing to its position near the vapours 
 of the horizon, when it would otherwise have been 
 most brilliant. In the southern hemisphere, however, 
 it presented a fine appearance, the tail being not less 
 than 47 long on the 5th of May, and very conspi- 
 cuous for some time previous. The perihelion passage 
 took place on the 12th of March, just one month 
 before the time announced by Clairault : a closer 
 coincidence could hardly have been expected, for the 
 masses of Jupiter and Saturn were not accurately 
 known at this epoch, and their perturbing forces could 
 not therefore be exactly determined. Laplace has 
 pointed out that the error, instead of amounting to 
 thirty days, would not have exceeded thirteen, if the 
 mass of Saturn had been as well known then as it is 
 now. 
 
 Halley had departed this life at a good old age, 
 eighteen years before the fulfilment of his prediction, 
 but his name was universally associated with the comet 
 whose return foretold by him had formed so memo- 
 rable an epoch in the history of the science. 
 
 As the next and last reappearance of the comet 
 drew nigh, several of the most eminent mathematicians 
 of Europe undertook the calculation of the effects of 
 
THE COMET O/HALLEY. 43 
 
 planetary attraction on the elements of the orbit, 
 since the year 1759. The great advances which had 
 been made in analysis since that period, and the more 
 accurate knowledge of the masses of the disturbing 
 planets, rendered the solution of the problem in the 
 present case of almost equal interest with the labours 
 of Clairault ; nor were the expectations of a high 
 degree of exactness in the prediction disappointed by 
 the result. In 1817, the Academy of Sciences at Turin 
 proposed the determination of the perturbations of Hal- 
 ley's comet since 1759, for their prize, which was to be 
 open for competition to astronomers of all nations. 
 The late Baron Damoiseau, of Paris, was the successful 
 candidate : his researches are published in the memoirs 
 of the Turin Academy, but we can only give the prin- 
 cipal conclusion. After calculating the effects of the 
 attraction of the larger planets upon the comet's 
 mean motion from 1759, he fixed the ensuing return 
 to perihelion, for the 4th of November, 1835, at eight 
 P.M. Paris time. Some years afterwards, M. Ponte- 
 coulant, another eminent French geometer, investi- 
 gated the problem again, and after applying some cor- 
 rections to his first numbers, he announced as his final 
 result, that the comet would reach its perihelion on 
 November 12 that J7 h Paris time, or about a week 
 later than the epoch assigned by Damoiseau. The 
 most elaborate inquiry relative to the perturbations 
 between 1759 and 1835, is, however, due to Professor 
 Rosenberger, of Halle. Both Damoiseau and Ponte- 
 coulant had omitted the consideration of the influence 
 of several of the planets, and had not fully investi- 
 gated the exact period corresponding to the ellipse 
 
44 THE COMETS. 
 
 described by the comet at its reappearance in 1759; 
 this being the starting point and the foundation upon 
 which much of the accuracy to be expected in the 
 ultimate conclusions depended, it was evidently de- 
 sirable to ascertain it with all possible precision. 
 Rosenberger was therefore induced to commence his 
 labours with a new computation of the perturbations 
 between 1682 and 1759, having deduced elements 
 from the observations of each of those years. He thus 
 obtained a secure basis for the continuation of the 
 work through the next revolution, between 1759 and 
 1835. Not to trouble the reader with more numeri- 
 cal results than are necessary, we shall be content with 
 giving the most important deductions, premising 
 that, besides the influence of the great planets, Jupiter, 
 Saturn and Uranus, this distinguished mathematician 
 included the smaller disturbances produced by Venus, 
 the Earth and Mars, and also pointed out the probable 
 effect upon the next perihelion passage, of a resisting 
 medium in the planetary spaces, such as Professor 
 Encke, of Berlin, had supposed to exist, from certain 
 observed accelerations in successive returns of the 
 periodical comet which bears his name. Omitting at 
 first this latter consideration, the periodic time from 
 1759 to the next return was found to be 28002 days, 
 and the perihelion was fixed for November llth at Oh 
 Paris time. With the computed effect of a resisting 
 medium, this epoch would fall a week earlier, or on 
 November 3rd at 19 h Paris time. The earth hastened 
 the .comet's perihelion passage 15- days, Venus about 
 5 j- days, and Mercury and Mars together nearly one 
 day. Professor Rosenberger's investigation is remark- 
 
THE COMET OF HALLEY. 45 
 
 able for its extraordinary completeness, for the pains 
 taken to include every possible source of perturbation, 
 without regard to the numerical labour, and for the 
 masterly manner in which the whole of the vast work 
 was conducted. Accordingly, astronomers generally 
 have awarded him the palm for the most elaborate 
 and valuable memoir upon this interesting subject. But 
 we have yet to speak of another discussion of the 
 elements and disturbances of the orbit of Halley's 
 comet, by Dr. Lehmann, which, though inferior in 
 several respects to Rosenberger's, has yet very great 
 merit, particularly as regards the extension of the 
 computations to the year 1607. The epoch fixed 
 upon by this astronomer for the comet's arrival at 
 perihelion was the 26th of November, a fortnight 
 later than that announced by Pontecoulant or Rosen- 
 berger. The cause of this difference has been attri- 
 buted to the want of a sufficiently minute attention 
 to the effects of small but progressive changes in the 
 elements between 1759 and 1835, in which matter 
 however, we ought to observe, very much is left to 
 arbitrary arrangement. 
 
 So early as December, 1834, astronomers began to 
 direct their telescopes to that quarter of the heavens 
 where the anxiously -expected wanderer was to re- 
 appear. Dr. Olbers, in an able paper published at 
 the latter end of the same year, had given it as his 
 opinion that the comet might possibly be discovered 
 much sooner than was usually anticipated, and pointed 
 out the track it should pursue in the heavens between 
 December and April following, on two hypotheses as 
 to the time of perihelion passage viz., 183 5, November 
 
46 THE COMETS. 
 
 1st and llth. He supported this opinion by an exa- 
 mination into the circumstances of its previous appa- 
 ritions, and by adducing additional evidence founded 
 on the brightness of other comets, particularly of one 
 which appeared in 1811. A call to arms from this 
 celebrated astronomer was not likely to meet with 
 inattention. Many European observers sought dili- 
 gently for the comet about the expected path in 
 December and January, when the part of the heavens 
 between Auriga and Taurus, where it should have 
 been seen, was most favourably placed for examina- 
 tion, in a dark sky : all their efforts were in vain. 
 Sir John Herschel, also, having received the calcu- 
 lated positions, employed his great reflector at the 
 Cape of Good Hope in searching for the comet during 
 the winter months, but no glimpse of it could be 
 obtained. Similar "sweeps" over the suspicious 
 neighbourhood in March and April following, were 
 equally unavailing, and the reappearance of this 
 region of the heavens, after conjunction with the sun 
 about midsummer, was anxiously awaited. The first 
 glimpse of the comet was obtained by Father Dumou- 
 chel and the astronomers of the Collegio Romano, at 
 Rome, who, aided by their splendid climate and the 
 powerful telescope of the observatory, succeeded in 
 finding the welcome visitant on the morning of the 
 6th of August, close to the computed place, which at 
 this time was in the neighbourhood of the star 
 Tauri. It was a faint, misty object, scarcely discerni- 
 ble with considerable optical power under an Italian 
 sky. The presence of moonlight and unfavourable 
 weather during the next fortnight, delayed the comet's 
 
THE COMET OF HALLEY. 47 
 
 liscovery at other places ; but on the 21st, Professor 
 Struve saw and observed it with the grand telescope 
 it Dorpat, and within the ensuing week it was found 
 3y the astronomers of Vienna, Berlin, Kremsmunster, 
 iltona, Breslau, and Leyden, as well as by Sir James 
 South, Captain Smyth, and Dr. Hussey, in this coun- 
 ,ry. According to the observation at Dorpat on 
 August 20th, the error of Professor Rosenberger's 
 predicted place was only seven minutes of arc in right 
 iscension and seventeen minutes in declination, which, 
 vith succeeding observations, showed that the peri- 
 lelion passage would be retarded till November 16th, 
 >r five days later than the epoch fixed upon by the 
 ibove mathematician. During the first three weeks 
 n September the comet gradually increased in bright- 
 less, but exhibited no indications of a tail. On the 
 23rd it was seen with the naked eye by Professor 
 Struve, and on the following day by Kaiser at Leyden, 
 hough it was not sufficiently conspicuous to attract 
 general attention until the end of the month. The first 
 tppearance of a tail is dated on September 24th. 
 \fter the beginning of October the comet rapidly in- 
 Teased in brightness, and for the five weeks following 
 vas watched with the naked eye in its course through 
 Trsa Major, Hercules, and Ophiuchus. The tail 
 Stained its maximum length about the middle of 
 Dctober, but, as in many previous instances, observers 
 it stations widely distant differ very considerably in 
 ,heir estimation of its actual extent. On the 14th 
 Struve says it was brilliant, and more than 20 long. 
 NText evening it was 24 long at Breslau, and about 
 20 to M. Schwabe, at Dessau. On the 19th it was 
 
48 THE COMETS. 
 
 traced fully 30 from the nucleus, at Madras, and 
 only 15 on the 22nd. After this time it became 
 gradually shorter, and, according to most accounts, had 
 vanished entirely before the comet sank below the 
 south-western horizon, about the time of perihelion 
 passage. Roller continued his observations at Krems- 
 munster till November 22nd. From this date till the 
 30th of December the comet was hidden in the sun's 
 rays, but was again detected by Kreil, at Milan, on 
 the latter day, and observed at some of the more 
 southerly observatories of Europe, and at the Cape of 
 Good Hope, till the middle of May following, when 
 this interesting object was finally lost to view, to 
 return again to these parts of space in the year 1911, 
 a reappearance which few of those who remember its 
 last visit can expect to witness. 
 
 Some very extraordinary phenomena were observed 
 by astronomers in the head of the comet, particularly 
 by Professor Bessel, Sir John Herschel, and Professor 
 Struve. The latter compares the appearance of*the 
 nucleus, about the end of the first week in October, 
 to a fan-shaped flame, emanating from a bright point, 
 and subsequently to a red-hot coal, of oblong form. 
 On the 12th, says the same astronomer, its aspect was 
 astonishing. It appeared like the stream of nre 
 which issues from the cannon's mouth after discharge, 
 when the sparks are driven backward by a violent 
 wind. At moments, the flame was thought to be in 
 motion, scintillations similar to those of the Aurora 
 Borealis being suspected. A second small flame, 
 forming a great angle with the principal one, was also 
 remarked. On the 5th of November, the nebulosity 
 
THE COMET OF HALLEY. 49 
 
 without the flames (two being visible) was shaped like 
 a ' powder-horn' ; its arched form is described as 
 most remarkable. Phenomena of the same kind 
 variously commented upon, under the names of lumi- 
 nous rays, sectors, &c., were observed by the other 
 astronomers we have named, by M. Arago, at Paris, Mr. 
 Cooper, at Markree Castle, and elsewhere. We shall 
 content ourselves with referring the reader, who may 
 wish for further information on the subject, to Struve's 
 Beobachtungen des Halleyschen Cometen, Professor 
 Bessel's Memoir in the Connaissance des Temps 
 for 1839, the Southern Observations of Sir John 
 Herschel, and to the Memoirs of the Astronomical 
 Society, Vol. X., which contains several excellent 
 drawings by Professor C. P. Smyth. The elements of 
 the orbit of the comet at perihelion, in 1835, have 
 been made the subject of a masterly investigation, by 
 the late Hermann Westphalen, whose results will be 
 found in the general table. 
 
 The dimensions of the path of Halley's comet in 
 space, according to the latest calculations, are as 
 follow : 
 
 In parts of the earth's In English 
 
 mean distance. miles. 
 
 Least or perihelion distance . . 0-5866 . . 55,900,000 
 Greatest or aphelion distance . . 35-3660 . . 3,370,300,000 
 Major axis of the orbit .... 35'9526 . . 3,426,200,000 
 Minor axis of the orbit .... 9'1072 . . 867,900,000 
 
 Thus, it will be seen that this body recedes from 
 the sun, to a distance exceeding that of the planet Nep- 
 tune. At the more remote parts of the orbit, it is 
 <**. .vays far removed from the plane of the ecliptic on 
 
 D 
 
50 THE COMETS. 
 
 the south side. Its motion is in the contrary direc- 
 tion to that of the planetary system, or against the 
 order of signs ; and this fact is the more worthy of 
 remark, inasmuch as it affords the only instance of a 
 retrograde periodical comet, with which we are at 
 present acquainted. 
 
 Before concluding our account of Halley's comet, 
 we must briefly review its probable history prior to the 
 year 1531, at which we took our departure. 
 
 In looking back into the history of comets, Halley 
 found that one had appeared in 1456 which gave 
 every indication of identity with the comet of 1682, 
 and the celebrated French cometographer, Pingre, 
 has converted Halley's suspicion into a certainty. It 
 was seen in the month of June, and is described by 
 the historians of the day as great, terrible, of extra- 
 ordinary magnitude, ' training after it a tail which 
 covered two celestial signs/ or was 60 in length. It 
 was beheld with equal awe by the Turks under Ma- 
 homet II., and by the Papal forces, each regarding it 
 as the omen of defeat and of divine displeasure. The 
 nucleus shone like a star, and the tail presented a 
 brilliant golden colour, at times assuming the appear- 
 ance of a flame flickering to and fro. The comet was 
 in perihelion, or nearest to the sun, on the 9th of 
 June. 
 
 The preceding return of Halley's comet took place, 
 as M. Laugier has shown, in the year 1378, when it 
 was discovered both in Europe and in China, though 
 it does not appear to have been so bright as in 1456. 
 It arrived at perihelion on the 9th of November, and 
 therefore followed a track amongst the stars not very 
 
THE COMET OF HALLEY. 51 
 
 different from that pursued in the autumn of 1835. 
 All the circumstances recorded of the comet of 1378 
 in the Chinese annals, are faithfully represented by 
 the elements of Halley's comet. 
 
 In September, 1301, a great comet is mentioned by 
 nearly all the historians of that period. It was seen 
 as far north as Iceland, and is described also in the 
 annals of China. It exhibited a bright and extensive 
 tail, which stretched out from the west towards the 
 eastern parts of the heavens. An anonymous author 
 has left two contradictory observations, one of which 
 cannot be reconciled with the elements of Halley's 
 comet ; but as the Chinese relation agrees extremely 
 well with those elements, and this body was certainly 
 due about 1301, it appears highly probable that it 
 was really the object observed, the perihelion passage 
 taking place about October 22nd. 
 
 The previous apparition is not so well ascertained, 
 but most likely occurred in July, 1223, when it is 
 recorded in an ancient chronicle, that a sign called a 
 comet appeared in the heavens, shortly before the 
 death of Philip Augustus of France, of which event 
 it was generally considered the precursor. Unfor- 
 tunately its position amongst the stars is not stated : 
 we are only told it was visible in the western heavens 
 in the evening twilight. The little that is related of 
 it will agree very well with the elements of Halley's 
 comet ; and as no other is recorded about this year at 
 all likely to have been the same as the one in 
 question, it seems not improbable that our comet 
 appeared in 1223, and reached its perihelion about 
 July. 
 
 D 2 
 
52 THE COMETS. 
 
 In April and May, 1145, a very great comet is 
 mentioned by European historians, which, continued 
 visible a long time. The Chinese saw it towards the 
 end of April, and describe it as of a pale blue colour, 
 with a tail more than 10 long. The course amongst 
 the stars from the end of April to the beginning of 
 July, is perfectly in accordance with the computed 
 track of Halley's comet, supposing the least distance 
 from the sun to have been attained on the 19th of 
 April. This is one of the most certain of our series 
 of returns. 
 
 There is considerable probability in favour of the 
 appearance of the comet in the year of the Nor- 
 man Conquest, or in April, 1066. The famous 
 body which astonished Europe in that year is 
 minutely, though not very clearly, described in the 
 Chinese annals, and its path there assigned is found 
 to agree with elements which have great resemblance 
 to those of Halley's comet. In England it was con- 
 sidered the forerunner of the victory of William of 
 Normandy, and was beheld with universal dread. It 
 was equal to the full moon in size, and its train, at 
 first short, increased to a wonderful length. Almost 
 every historian and writer of the eleventh century 
 bears witness to the splendour of the comet of 1066, in 
 which we are disposed to recognise the comet of Halley. 
 
 Burckhardt, the French mathematician, calculated 
 an orbit for a comet observed in China in 989, closely 
 resembling that of Halley's. The comet is mentioned 
 by several Saxon chronologists, and by Elmacin, in 
 his history of the Saracens. The perihelion occurred 
 on the 12th of September. 
 
THE COMET OF HALLEY. 53 
 
 Another comet recorded by the Chinese in May 
 and June, 837, and probably seen in Europe, affords 
 some indications of identity The perihelion would 
 fall about the beginning of April. This great body 
 must have been a different one from Halley's, if all the 
 accounts, European and Chinese, can be strictly relied 
 upon. 
 
 The preceding apparition is referred by M. Laugier 
 to the year 760, and is well certified by the annals of 
 China. The historians of the western empire tell us 
 that a comet like a great beam and very brilliant was 
 observed in the 20th year of Constantine, first in the 
 eastern heavens, and subsequently in the west for 
 about thirty days. In China it was seen two months. 
 It is assumed that Halley's comet arrived at its least 
 distance from the sun on June llth, and every par- 
 ticular is exactly represented by the elements of that 
 body. The appearance of our comet in 760, is a 
 matter little short of a certainty. 
 
 In 684, Ma-tuan-lin, the Chinese historian, has 
 mention of a comet which was observed in the western 
 heavens, in September and October. This will agree 
 with the course of Halley's, when its perihelion pas- 
 sage falls about the middle of the latter month ; and 
 as the interval agrees well, we may infer that there 
 is a fair probability in favour of the identity of the 
 comets. 
 
 We are disposed to recognise Halley's star, again, 
 in the comet observed by the Chinese in the constel- 
 lations Auriga, Ursa Major, and Scorpio, in 608 ; this 
 being precisely the track of that body if it attained 
 its least distance from the sun about November 1st. 
 
54 THE COMETS. 
 
 The apparition which should have occurred about 
 530 is not well ascertained. It may be remarked, that 
 a great comet recorded by the Latin authors in that 
 year, which was visible, in the western sky, in Ursa 
 Major, offers nothing contradictory to its identity 
 with Halley's, and, in fact, the few circumstances 
 related of it agree much better with the elements of 
 Halley's comet than with those of the great comet of 
 1680, which many astronomers have regarded as the 
 same that appeared in 530, or 531 for some doubt 
 exists respecting the year of appearance. 
 
 We have pretty decisive evidence in favour of the 
 return of the comet in 451, as M. Laugier has shown. 
 It was seen in Europe about the time of the Battle of 
 Chalons, when the Roman general, Aetius, obtained 
 a victory over the armies of Attila, whose ravages had 
 extended to France. The Chinese discovered it on 
 the 17th of May, and followed it on its course till the 
 middle of July, in which interval it had moved from 
 the Pleiades into Leo and Yirgo. The circumstances 
 agree well with the track of Halley's comet, assumed 
 to have been in perihelion on July 3rd. 
 
 In October 373, the annals of China mention a 
 comet in Ophiuchus, which will agree with the position 
 of the same body, if we fix its arrival at the least dis- 
 tance from the sun about the beginning of November. 
 
 In 295, the appearance of this comet is nearly cer- 
 tain : it was observed in China in the fourth moon 
 during its progress from Andromeda into Yirgo. The 
 perihelion passage would take place at the commence- 
 ment of April. 
 
THE COMET OF HALLEY. 55 
 
 There can be little doubt of another return in the 
 year 218, when we have a circumstantial account of a 
 large comet in the catalogue of Ma-tuan-lin, which 
 followed a path exactly in agreement with that of 
 Halley's, when the perihelion falls on or about April 
 6th. It is mentioned by Dion Cassius, who describes it 
 as a very fearful star, extending its tail from the west 
 eastwards. The comet this year traversed the con- 
 stellations Auriga, Gemini, Leo, and Virgo. 
 
 In 141, the Chinese observed a comet, the track of 
 which in the heavens may be represented by elements 
 not very widely different from those of Halley's; it is 
 the only comet recorded about this epoch. 
 
 The preceding apparition took place either in the 
 summer of the year 65, or early in 66. Two Comets 
 are found in the Chinese annals. That of 65 was 
 discovered in July, in the constellation Leo, and con- 
 tinued visible fifty-six days. The second was seen in 
 February following, in Sagittarius and Scorpio, and 
 remained in sight fifty days. This latter body appears 
 most likely to have been Halley's, if the perihelion 
 occurred on January 26th. But it is possible this 
 comet may have appeared in 65, in which case it was 
 not improbably the sword-shaped sign over the city of 
 Jerusalem, recorded as having preceded the commence- 
 ment of the war which terminated in the destruction 
 of the holy city. 
 
 In the year 11 B.C., during the consulate of M. 
 Valerius Messala and P. Sulpicius Quirinus, before 
 the death of Agrippa, a comet is referred to by Dion 
 Cassius, which seemed to be suspended over the city 
 
56 THE COMETS. 
 
 of Rome. The same comet was very closely observed 
 by the Chinese, whose valuable details respecting its 
 path amongst the constellations afford the most satis- 
 factory proof that they belong to the comet of Halley. 
 It passed from Gemini, through Leo, Bootes, Hercules, 
 Ophiuchus, into Scorpio, where it was lost in the sun's 
 rays, fifty-six days after its first discovery. It was in 
 perihelion in the third week of October. 
 
 Previous to the year 11 B.C., the Chinese descrip- 
 tions of comets are too vague to aid us in tracing any 
 more ancient appearances of Halley 's comet, and 
 European writers of these remote times render us no 
 assistance. The series of returns which we have briefly 
 pointed out is most satisfactory as a whole. That of 
 1456 was known to Halley, and the appearances of 
 1378, 760, and 451, were recognised by M. Laugier 
 some years since ; with these exceptions, the whole of 
 the probable returns of the comet prior to 1531 were 
 notified in a paper by the author, which was read 
 before the Royal Astronomical Society, in January, 
 1850.* 
 
 The following is a tabular view of the most probable 
 epochs of perihelion passage. The reader will under- 
 stand that much uncertainty attaches to the result in 
 one or two cases, but the series seems hardly to admit 
 of doubt as to its general accuracy. The most certain 
 appearances previous to 1456 are marked with an 
 asterisk ; and to render the table complete, the peri- 
 helion passages are added down to the year 1835. 
 
 * See Monthly Notices of the Astronomical Society, vol. x., 
 No. 3 
 
THE COMET OF HALLEY. 
 
 57 
 
 The epoch of perihelion passage is expressed 
 
 in years and dec 
 
 mals. The intervals indicate the length of each revolution. 
 
 Year. 
 
 Interval. 
 
 Year. 
 
 Interval. 
 
 
 YRS. 
 
 A.D. 
 
 YKS. 
 
 A.c.*ll'80 
 
 
 989-70 
 
 
 
 77-87 
 
 
 76-55 
 
 A.D. 66-07 
 
 
 1066-25 
 
 
 
 75-17 
 
 
 79-05 
 
 141-24 
 
 
 *1 145-30 
 
 
 
 77-20 
 
 
 78-22 
 
 *218-26 
 
 
 1223-52 
 
 
 
 7699 
 
 
 78-29 
 
 *295-25 
 
 
 1301-81 
 
 
 
 78-59 
 
 
 77-04 
 
 373-84 
 
 
 *1378'85 
 
 
 
 77-66 
 
 
 77-59 
 
 *451-50 
 
 
 1456-44 
 
 
 
 79-34 
 
 
 75-21 
 
 530-84 
 
 
 1531-65 
 
 (o.s.) 
 
 
 77-96 
 
 
 76-14 
 
 608-80 
 
 
 1607-82 
 
 (N.8.) 
 
 
 76-00 
 
 
 74-88 
 
 684-80 
 
 
 1682-70 
 
 
 
 75-64 
 
 
 76-49 
 
 *760-44 
 
 
 1759-19 
 
 
 
 76-82 
 
 
 76-68 
 
 837-26 
 
 
 1835-87 
 
 
 
 74-99 
 
 
 
 912-25 
 
 
 
 
 
 77-45 
 
 
 
 D 3 
 
58 THE COMETS. 
 
 CHAPTER V. 
 
 COMETS OF SHORT PERIOD THE COMET OF ENCKE. 
 
 THE most remarkable of the comets of short period 
 is that known as ENCKE'S ; it is a body of the highest 
 interest to the astronomer, and we shall here recapitu- 
 late briefly the principal points in its history. 
 
 On the 17th of January, 1786, M. Mechain, of 
 Paris, discovered a telescopic comet, near the star /3, 
 Aquarii. It was pretty large and bright, with a sen- 
 sible nucleus surrounded by nebulosity, but without 
 any appearance of a tail. Cloudy weather prevented 
 M. Mechain from observing it, except on January 17th 
 and 19th ; so that no orbit could be deduced from 
 observation. 
 
 Miss Caroline Herschel, sister of the celebrated Sir 
 W. Herschel, detected a comet not far from the star 
 marked y in Cygnus, on the 7th of November, 1795. 
 It was just visible to the naked eye : in the telescope 
 no nucleus was perceptible, but merely a condensation 
 of the nebulous matter near the centre. The comet 
 was observed at Berlin, by Professor Bode, on the llth of 
 November, an amateur astronomer named Carl having 
 announced its visibility ; and on the 14th, M. Bouvard 
 saw it at Paris. The outline of the nebulosity is 
 
THE COMET OF EXCKE. 59 
 
 described as nearly if not quite circular, the greatest 
 apparent diameter amounting to about five minutes 
 of space on tbe day of discovery. The elements were 
 investigated, on the assumption of parabolic motion, 
 by Dr. Olbers, M. Bouvard, and Baron de Zach. 
 
 On the evening of the 20th of October, 1805, a 
 comet was found, almost simultaneously, by M. Pons 
 at Marseilles, Professor Huth at Frankfort, and M. 
 Bouvard at Paris. It was situate in Ursa Major. 
 The perihelion passage occurred about a month after 
 the discovery, and the comet was observed until 
 within a week from this epoch. The parabolic orbit 
 was calculated by MM. Bouvard and Legendre, and 
 Professors Bessel and Gauss. 
 
 M. Pons, of Marseilles, a most industrious observer, 
 detected a telescopic comet on the 26th of November, 
 1818, which remained visible till the 12th of January 
 following. It was speedily found that no parabolic 
 orbit could be made to represent the observations 
 within their probable limits of error, and this circum- 
 stance induced the celebrated calculator, Professor 
 Encke, to undertake the rigorous investigation of the 
 elements. On treating the observations agreeably to 
 the methods of Professor Gauss (but little practised 
 at that time), a most important result was obtained. 
 Professor Encke showed that the real path of the 
 comet must be an ellipse, with a period of about 
 three years and a quarter ; and on looking over the 
 catalogue of comets already observed, it appeared 
 highly probable that the one in question had been 
 previously seen, and was, in fact, identical with the 
 comets of 1786, 1795, and 1805, those years agreeing 
 
60 THE COMETS. 
 
 well with the presumed time of revolution of the 
 comet of 1819. The question could only be definitely 
 settled by calculating the planetary perturbations 
 backward to the respective epochs ; and this enor- 
 mous labour was entered upon by Professor Encke, 
 and completed in the most masterly manner, after 
 close application for about six weeks. It was found 
 that the comet had arrived at perihelion on January 
 30th, 1786; May 19th, 1789; September 4th, 1792; 
 December 21st, 1795 ; April llth, 1799; August 2d, 
 1802; November 22d, 1805; March 12th, 1809; 
 June 26th, 1812; October 13th, 1815; and again on 
 January 27th, 1819. In 1789, 1792, 1799, 1802, 
 1809, 1812, and 1815, it passed through these parts 
 of space without being detected by any observer. The 
 average time of revolution appeared to be about 1208 
 days ; but on allowing for the perturbations of Jupiter, 
 the period still exhibited indications of a gradual dimi- 
 nution since the year 1786, unaccounted for by the 
 disturbances produced by other planets, and too large 
 to be attributed to the effect of any quantities omitted 
 in the calculation. On this interesting point we shal] 
 have more to say very shortly. 
 
 After having thus brought to light the past history 
 of the comet, at the expense of a vast amount of 
 labour, Professor Encke turned his attention to the 
 next return to perihelion, and again undertook the 
 determination of the perturbations produced by plane- 
 tary attraction on the movements of the comet. He an- 
 nounced, as the principal result of his investigations, 
 that the comet would arrive at perihelion on the 24th 
 of May, 1822, after undergoing a retardation of rather 
 
THE COMET OF ENCKE. 61 
 
 more than nine days from the influence of the planet 
 Jupiter. So complete were these calculations that 
 astronomers universally attached the name of ENCKE 
 to the comet of 1819, not only as an acknowledgment 
 of his diligence and success in the performance of 
 some of the most intricate and laborious computations 
 that occur in practical astronomy, but also to mark 
 the epoch of the first detection of a comet of short 
 period, one of no ordinary importance in this depart- 
 ment of the science. 
 
 Owing to the position of the comet in the heavens 
 about the time of perihelion passage in 1822, it was 
 not seen at all in Europe, but there fortunately 
 existed an observatory in full activity at Paramatta, 
 New South Wales, founded and maintained by the 
 munificence of a private individual, Sir Thomas Bris- 
 bane, then Governor of the colony. Mr. Rumker, the 
 present director of the observatory at Hamburg, 
 detected the comet at Paramatta on the 2nd of June, 
 and followed it until the 23rd of that month. His 
 observations enabled Professor Encke to rectify the 
 elements, and predict the time of its next arrival at 
 perihelion with the greater accuracy. He found it 
 should occur on the 16th of September, 1825, and 
 that the apparent path of the comet in the heavens 
 would allow of observations at the European observa- 
 tories. 
 
 Professor Harding, the discoverer of Juno, ob- 
 tained the first glimpse of the wanderer on the 26th 
 of July, 1825, in a position differing from the pre- 
 dicted one by less than three minutes of space. The 
 comet was observed at nearly all the astronomical 
 
62 THE COMETS. 
 
 establishments of Europe until about ten days before 
 the perihelion, when it was lost in the sun's rays. It 
 appeared round and very bright towards the centre, 
 and it was remarked by Professor Argelander in the 
 strong twilight as a small planetary disk, with scarcely 
 any signs of the surrounding nebulosity. 
 
 The next return of the comet, in 1828, excited 
 great interest, as, for the first time since the discovery 
 of its periodicity, the apparent track amongst the stars 
 would be peculiarly favourable to observation in Europe. 
 The epoch of perihelion passage was fixed by Encke 
 on the morning of the 10th of January, 1829. Pro- 
 fessor Struve, employing the magnificent telescope 
 then newly erected at Dorpat by the Emperor of 
 Russia, saw the comet as a very faint nebulosity on 
 the 16th of September, 1828. At Berlin it was seen 
 by MM. Kunowsky and Encke with a much smaller 
 instrument on the 7th, but it was not generally ob- 
 served until the end of the month. 
 
 On November 30th it was visible to the naked eye 
 as a conspicuous star of the sixth magnitude, and a 
 week afterwards was still brighter, so as to be rated 
 with stars of the fifth class. The outline of the 
 nebulosity was not circular, but somewhat elliptical, 
 the major axis, on one occasion, being nearly at right 
 angles to the line joining the sun and comet, which is 
 the usual direction of the tails of these bodies. The angle 
 of position of the longer axis of the elliptic comet in 
 respect to the circle of declination, and counted from 
 the north towards the west, was measured on four 
 evenings by Professor Struve, and on comparing it 
 with the direction of the line joining the sun and 
 
THE COMET OF ENCKE. 63 
 
 comet, he ascertained that the major axis of the comet 
 made the following angles with the radius-vector on 
 the respective days: 
 
 Nov. 7 - - 99-7 I Dec. 7 - - 154 
 Nov. 30 - - 145-3 I Dec. 14 - - 149'4 
 
 The comet was seen at Dorpat and Nismes, until 
 the close of the year 1828, when its gradual approach 
 to the sun's place rendered it invisible. 
 
 The next return to perihelion took place in 
 1832, the calculations of Professor Encke assigning 
 the 4th of May as the epoch of the cornet's arrival at 
 its least distance from the sun. The path in the 
 heavens was again unfavourable to observation in 
 Europe, and only a single glimpse of the wanderer 
 was obtained by Harding, at Gottingen, on the 21 st 
 of August. It was, however, found by Mr. Hen- 
 derson, at the Cape of Good Hope, and by M. Mos- 
 sotti, at Buenos Ayres, at the beginning of June, and 
 their observations were discussed by Professor Encke 
 in a memoir communicated to the Prussian Academy 
 of Sciences, in 1 834 
 
 As the observations of 1832 afforded no satisfactory 
 foundation for any further correction of the elliptic 
 elements, they were carried forward to 1835 by simply 
 taking account of the perturbations produced by the 
 planet Jupiter, which was never very near the comet. 
 The perihelion passage was fixed for the evening of 
 the 26th of August, and notwithstanding the diffi- 
 culties attending observation, owing to the position of 
 the comet amongst the stars, it was seen after the 26th 
 of July by M. Kreil, at Milan, and Professor Bogus- 
 
64 THE COMETS. 
 
 lawski at Breslau. Mr. Maclear saw it at the Cape of 
 Good Hope, on September 14th, and on two other 
 occasions, with a 14-feet reflecting telescope, con- 
 structed by Sir W. Herschel, but no measures could 
 be taken. It looked as he had seen it in England. 
 
 The next visit in 1838 was predicted to take place 
 under circumstances particularly favourable to Euro- 
 pean observers. The comet was discovered with the 
 fine refractor at Berlin, on the 16th of September, 
 and by the Rev. W. R Dawes, with a 5-feet telescope, 
 at Ormskirk, on the 27th of the same month. With 
 these exceptions it was not observed until the middle 
 of October. The least distance of the comet from the 
 earth was O22, and about the end of the first week in 
 November this interesting object could be discerned 
 in the constellation Draco without the assistance of a 
 telescope. When viewed under suitable optical aid, it 
 was found to exhibit a bright nuclear condensation, 
 from which the nebulosity streamed off in a fan-like 
 form, the general outline of the whole being that of a 
 broad parabola. On the 7th of November it was 
 described as a very splendid object, the light being 
 particularly intense and glowing. M. Valz saw it 
 until the middle of December. 
 
 After the publication of the observations taken at 
 the various observatories of Europe in 1838, a most 
 elaborate discussion of the elements was entered upon 
 by Professor Encke, to whom astronomers had been 
 hitherto indebted for their information respecting this 
 comet's returns. One important object of research 
 was, the determination of the mass of the planet 
 Mercury, near which the comet had passed in August, 
 
THE COMET OF ENCKE. '65 
 
 1835. It had been shown by Encke that if Laplace's 
 mass were correct, the effect of the planet's attraction 
 would diminish the geocentric right ascension of the 
 comet on November 2nd, 1838, no less than 58', while 
 the declination would be increased 17'. The observa- 
 tions not having indicated any such enormous devia- 
 tion from the elliptic path, it became evident that a 
 very large error existed in the received mass of the 
 planet ; and it was obviously rather a matter of 
 labour, than difficulty, to deduce from the observa- 
 tions of 1838 a more exact value of that element. 
 The mode of procedure was, to calculate with the 
 utmost nicety the amount of perturbation produced 
 by each of the planets, employing the best values of 
 the masses extant. Then, were there no other cause 
 operating to affect the geocentric positions, the differ- 
 ences between the places rigorously computed from 
 the elements after a consideration of the other pla- 
 netary disturbances, supposed to be exactly known, 
 and those given by the observations, would be due to 
 any error in the presumed attraction of the planet 
 Mercury, and from these numbers the alteration re- 
 quired to bring about a perfect agreement between 
 observation and calculation could be inferred. But 
 it so happened, that another influential disturbing 
 agency was present, the existence of which Professor 
 Encke had already intimated as extremely probable, 
 and without which there appeared no way of account- 
 ing for an acceleration in the times of arrival at 
 perihelion between 1819 and 1838, over and beyond 
 the epochs determined by his researches into the 
 effects of planetary attraction. The comet had been 
 
66 THE COMETS. 
 
 remarked to reach the point of least distance from 
 the sun, at each return, about 2h. 30m. sooner than 
 the time assigned by the calculation. In order to 
 account for this gradual diminution of the period of 
 revolution, Professor Encke supposed that a thin 
 etherial medium pervades the planetary spaces, suffi- 
 ciently dense, however, to produce some impression 
 on a body of such extreme tenuity as the comet in 
 question, but incapable of exercising any sensible 
 influence on the movements of the planets. This 
 supposition has been converted almost into a certainty 
 by the results of more recent observation and calcula- 
 tion, and has received the support of the first autho- 
 rities of the present day. The great difference 
 between the effects of such a medium on the comets 
 of Encke and on the planets, will be evident from 
 what has been stated respecting the pellucid and 
 almost etherial nature of the former. 
 
 It may appear paradoxical at first sight that a 
 medium tending to retard the velocity of the comet's 
 orbital motion should ultimately accelerate its return 
 to perihelion. But this resistance to the comet's 
 movement at any point of the trajectory has the 
 effect of increasing the sun's attraction, and conse- 
 quently of drawing the comet into a smaller orbit 
 than before: the length of the major axis is therefore 
 diminished, and the period of revolution shortened 
 in proportion. This contraction of the orbit must be 
 continually progressing, if we suppose the existence of 
 such a medium, and we are naturally led to inquire 
 what will be the final consequence of this resistance? 
 Though the catastrophe may be averted for many 
 
THE COMET OF ENCKE. 67 
 
 ages by the powerful attractions of the larger planets, 
 particularly Jupiter, will not the comet be at last 
 precipitated on to the sun? The question is full of 
 interest, though widely open to conjecture. 
 
 The constant of resistance, as it is termed by Pro- 
 fessor Encke, was not definitively settled previous to 
 1838, and it therefore became necessary, for the 
 complete solution of the problem, to regard it as a 
 quantity only approximately known, and so leave it 
 open for more exact determination from the observa- 
 tions of 1838. The differences between the observed 
 and computed positions in that year were therefore 
 considered due to the corrections required first, in 
 the assumed mass of Mercury, and, secondly, in the 
 constant of resistance ; and by treating these quanti- 
 ties agreeably to methods commonly practised amongst 
 astronomers, it was found as the principal result 
 that the planet's mass assigned in the Mecanique 
 Celeste of Laplace was far too great, or that it 
 required to be diminished in the proportion of seven 
 to twelve. Thus has a body of such apparent in- 
 significance as Encke's comet enlightened us on 
 more than one point of the highest astronomical 
 interest. 
 
 The elaborate discussion of the elements to which 
 allusion has been made, appeared in Nos. 488-9 of 
 the Astronomische Nachrichten, and the numbers 
 there obtained have been used as the foundation for all 
 subsequent prediction. The comet was expected to 
 become visible again early in 1842, and to reach the 
 perihelion point on April 1 2th. It was found by Dr. 
 Galle at Berlin, on the 8th of February, and observed 
 
68 THE COMETS. 
 
 pretty generally in Europe until the 10th or llth of 
 April. It was found, on its return from the sun, at 
 the observatory, Cape of Good Hope, on May 2nd, and 
 continued visible there for three weeks. It is gene- 
 rally described as round, bright, and so well defined, 
 as almost to exhibit a planetary disc. This agrees 
 with Professor Argelander's description of the comet's 
 appearance in 1825. The strong evening twilight 
 doubtless hid a great portion of the more feeble nebu- 
 losity surrounding the nucleus, only permitting the 
 denser part in the immediate vicinity of the comet's 
 centre to remain visible. The real diameter of this 
 condensed portion appears to have been about 25,000 
 miles. 
 
 The next appearance in the summer of 1845, took 
 place under the most unfavourable circumstances; 
 nevertheless, a very accurately computed ephemeris 
 of its geocentric path was published by M. d' Arrest, 
 of Berlin. Though the attention of astronomers was 
 closely directed to the comet, it was seen in Europe 
 by one observer only, the late Professor de Vico, who, 
 favoured by the clear sky of Rome, observed it on the 
 nights of July 9th and 14th. In America, two ob- 
 servations were procured, the first at Philadelphia, on 
 the 4th, and the second at Washington, on the 10th 
 of the same month. The error of the predicted 
 place was less than 45 seconds of space, a most satis- 
 factory proof that the theory of the comet's move- 
 ments was well understood. 
 
 The next return occurred in the autumn of 1848, 
 when its apparent track in the heavens was such as 
 to allow of extensive observation in these parts of the 
 
THE COMET OF ENCKE. 69 
 
 globe. The comet arrived at perihelion only five 
 days later than in 1805, so that its path amongst the 
 stars was not very different in the two years, and, 
 judging from previous experience, Prof. Encke con- 
 sidered there would be little chance of any exact 
 observations before the commencement of September. 
 It was found by Professor Bond, with the great tele- 
 scope, at Cambridge U. S., on the 27th of August, 
 and by several astronomers during the first week of 
 September. It was last seen by Professor Bond, on 
 the 26th of November. When first visible in large 
 telescopes, it was faint and without any condensa- 
 tion of light. On September 24th, the nebulosity ex- 
 tended over eight minutes of arc, or about 140,000 
 miles. Two days later, a faint brush of light extend- 
 ing from the more condensed part towards the sun, 
 was detected by Professor Bond, and on the 6th of 
 the following month, the same observer found it 
 just visible to the naked eye. On the 22nd it was 
 still distinctly visible without the telescope : the 
 general outline was elliptical, and the light appeared 
 strongest on the side opposite the sun. Early in 
 November, the comet exhibited a tail in the usual 
 direction, extending over a space of between one and 
 two degrees, while the same emanation from the head 
 towards the sun, that had been remarked in Septem- 
 ber, was again observed. The last observation of the 
 American astronomer, on November 26th, was taken 
 after a very close approach to the planet Mercury. 
 About midnight, on the 22nd of that month, the 
 comet was separated from the planet, by only 0'038 
 of the earth's mean distance, or 3,600,000 miles, a 
 
70 THE COMETS. 
 
 much nearer approximation than that of August, 
 1835, from the effects of which the mass of Mercury 
 at present received, was investigated. The observa- 
 tions of 1852, and subsequent years, will, therefore, 
 lead to a more correct value of this element, for they 
 will contain in them, the effects of the planet's pertur- 
 bations, expressed as the mathematician can read them 
 on the comet's geocentric places. 
 
 The last perihelion passage occurred on March 
 14th, 1852, and the comet was seen in the second 
 week of January, and remained visible two months. 
 Early in March, it was very distinct in the strong 
 evening twilight. Its appearance, when best seen 
 this year, was similar to that presented in 1845 ; 
 it resembled a nebulous star, with something of a 
 planetary disc. In 1858, the track of the comet 
 amongst the stars will be more favourable for obser- 
 vation than it was in 1852, or is likely to be in 1855. 
 
 The dimensions of the orbit of Encke's comet are 
 as follow : 
 
 In parts of the earth's 
 
 mean distance. In English miles. 
 
 Aphelion distance - - - - 4-0927 - - - 390,010,000 
 Perihelion distance - - - - 0-3370 - - - 32,120,000 
 
 Minor axis 2-3489 - - - 223,840,000 
 
 Corresponding period of revolution 3'296 years. 
 
THE COMET OF BIELA. 71 
 
 CHAPTER VI. 
 
 COMETS or SHORT PERIOD continued. 
 
 The Comet of Biela. 
 
 ANOTHER very remarkable periodical comet is that 
 usually called BIELA'S, though it has occasionally been 
 termed Gambart's comet. 
 
 On the 8th of March 1772, M. Montaigne of 
 Limoges, discovered a comet in Eridanus which he 
 saw until the 20th of the same month, though for 
 want of proper instruments he could observe it but 
 very imperfectly. 
 
 M. Pons discovered a telescopic comet on the 10th 
 of November, 1805, which was observed until the 9th 
 of the following month. The elements very much 
 resembled those of the comet of 1732, and the iden- 
 tity was hinted at by several astronomers, including 
 Olbers and Gauss. The latter remarked that an 
 ellipse with the greater semi-axis = 2 '8 2 or longer, 
 would agree better with the observations than a para- 
 bola, and his last calculation assigned as the most 
 probable period 1732 days. Notwithstanding this 
 circumstance it does not appear that any prediction 
 of the return of the comet was ventured upon, and 
 
72 THE COMETS. 
 
 the question remained in this state until 1826, when 
 an unexpected discovery again drew attention to the 
 subject. 
 
 On the evening of the 27th of February, 1826, 
 M. Biela, of Josephstadt in Bohemia, detected a tele- 
 scopic comet in the constellation Aries. It presented 
 a small round nebulosity, with a feeble condensation 
 of light towards the centre. The same comet was 
 recognised independently by M. Gambart at Mar- 
 seilles on the 9th of March, when it was situate in 
 Cetus : there was no trace of tail or nucleus, and the 
 diameter did not exceed 1 J'. It was very soon found 
 that the elements bore a striking similarity to those 
 of the comets of 1772 and 1805, and what was more 
 important, that no parabolic orbit would represent 
 with reasonable accuracy the observed path of the 
 comet. Clausen, Biela, and Gambart, determined the 
 elements of elliptic orbits, the period differing but little 
 from 6 '7 years. The identity of the comets of 1772, 
 1805, and 1826, was therefore rendered extremely 
 probable, notwithstanding some calculations by the 
 late Professor Bessel, which appeared to throw a 
 degree of uncertainty on this conclusion, as respects 
 the former year : but as we have already remarked, 
 the comet of 1772 was very imperfectly observed, and 
 was only followed by M. Montaigne during a space 
 of twelve days. 
 
 Supposing the period of revolution about 6 f years, 
 the comet must have appeared in 1778, 1785, 1792, 
 1799, 1813, and 1819, without being perceived, and 
 such was no doubt the case, for the computations of 
 MM. Clausen, Gambart, and others, showed that the 
 
THE COMET OF BIELA. 73 
 
 period could not differ much from 2440 days, and that 
 an ellipse with a major axis corresponding to this time, 
 would represent equally well the observations of 1805 
 and 1826. 
 
 The comet of 1826 was observed by Dr. Olbers and 
 M. Gambart until the end of April. It is generally 
 described as a small circular nebulosity, destitute of 
 tail or nucleus, and a very little brighter towards the 
 centre than at the edges. Soon after the disappear- 
 ance of the comet, Professor Santini, of Padua, under- 
 took the determination of the effects of planetary 
 disturbances on the ensuing return. He ascertained 
 that the most probable value of the periodic time in 
 1826 was 2455-176 days and that the comet had arrived 
 at its perihelion point on March 18th, at ten P.M., Paris 
 time. He then calculated the amount of perturba- 
 tion due to the attraction of the Earth, Jupiter, and 
 Saturn, and found that the next revolution would be 
 shortened 10'023 days by their combined influence, so 
 that the comet should again arrive at perihelion about 
 two o'clock on the morning of the 27th of November, 
 1832. The Baron Damoiseau also entered upon a 
 similar investigation, and was led to infer that the 
 return of the comet would be accelerated by 9 '6 64 
 days, a result not very widely differing from that of 
 Professor Santini. 
 
 In a paper by Dr. Olbers, published at the be- 
 ginning of the year 1 828, the attention of astronomers 
 was directed to the very close approach of the orbits 
 of the earth and comet at the descending node of the 
 latter. In 1805 and 1826 the radius-vector of the 
 comet at the nodal passage was greater than the 
 
 E 
 
74 THE COMETS. 
 
 earth's, and consequently it passed outside our orbit. 
 But in 1 832 Dr. Olbers found that the comet at this 
 moment would be nearer the sun than the earth, 
 and would therefore pass inside our annual path, but 
 at a distance from it of only 0-00033, or less than five 
 terrestrial semi-diameters. Now, on the 8th of De- 
 cember, 1805, when the comet of Biela was near the 
 earth, Dr. Olbers found the apparent diameter sub- 
 tended an angle of 40', whence he concluded that the 
 real semi-diameter of the nebulosity was at least 5 '25 
 radii of the earth, and it thus appeared certain that 
 if the extent of the cometic atmosphere in 1832 were 
 as great as in 1805, and if Damoiseau's calculations 
 were rigorously accurate, a portion of the earth's orbit 
 would be within the nebulosity of the comet at the 
 nodal passage in 1832. The orbital arc, or arc of true 
 anomaly between the descending node and perihelion 
 amounted to 41 45', which the comet would require 
 29*0 days to traverse, and as the calculations had fixed 
 the arrival at perihelion about midnight on the 27th 
 of November, it was thus inferred that the passage 
 through the descending node would take place on the 
 evening of the 29th of October. The heliocentric 
 longitude of the point of the comet's orbit which lies 
 nearest that of the earth is 68 10', and the earth 
 could not reach this point until the morning of the 
 30th of November, or one month after the comet's 
 passage by it. These results, of course, showed that 
 there was no ground for alarm, at least in 1832, as 
 the two bodies would pass through the dangerous 
 neighbourhood so long after each other. If the peri- 
 helion passage had occurred at eight P.M. on the 28th 
 
THE COMET OF BIELA. 75 
 
 of December, an extremely near approach, if not a 
 collision, of the earth and comet must have taken 
 place on the last day of November. 
 
 Though astronomers were satisfied the comet would 
 not approach within many millions of miles from the 
 earth, it was not so with the general public. Con- 
 siderable alarm was excited on the continent as soon 
 as Gibers' results were known, and the comet of 1832 
 was even anticipated as the destined agent in the 
 destruction of our globe. It was argued that if a 
 retardation of about one month in the arrival at peri- 
 helion should take place, the most disastrous conse- 
 quences must follow a line of reasoning which, 
 though possibly correct in itself, was altogether inad- 
 missible under the circumstances. The periodic time 
 corresponding to the ellipse actually described by the 
 comet at its visit in 1826 was known, without a greater 
 error than one day, and the effect of planetary attrac- 
 tion had also been determined with all requisite accu- 
 racy. The date fixed for the perihelion passage, No- 
 vember 27th, could not therefore be well subject to a 
 larger error than one day at the utmost. All fear 
 of collision or dangerous proximity was evidently 
 groundless. 
 
 The first glimpse of the comet at its reappear- 
 ance was obtained by the observers of the Collegio 
 Romano at Rome, on the 23rd of August. It was 
 observed by Sir John Herschel, with his twenty-feet 
 reflector, at Slough, on the 23rd of September, but at 
 this time neither Professor Harding, with a 10-feet 
 reflecting telescope, nor M. Nicolai with a 4J-feet 
 achromatic, by the celebrated Fraunhofer, could dis- 
 E 2 
 
76 THE COMETS. 
 
 tinguish it. The excessive faintness of the comet may 
 be readily conceived. About the end of the third 
 week in October it became more generally visible, 
 and was last seen at the Cape of Good Hope, on the 
 3rd of January, 1833. It was always faint, with but 
 little central condensation, and was at no time per- 
 ceptible without a good telescope. The comet arrived 
 at perihelion only twelve hours before the computed 
 time, a much closer fulfilment of prediction than 
 could have been expected. Professor Santini, on a 
 revision of his calculations, and after allowing for the 
 attraction of Venus and Mars, which he had previously 
 neglected, ascertained that the time elapsed between 
 the perihelion passages of 1826 and 1832, was 
 2444*7027 days, his earlier computations having given 
 24451528 days. He then investigated the effects of 
 planetary disturbances on the ensuing appearance, 
 and found it would retard the comet l d 17 h , so that 
 the perihelion passage would occur on the 23rd of 
 July, 1839, about noon, Greenwich mean time. The 
 longitude of the comet in perihelion, as seen from the 
 sun, is 110, which differs only 10 from the geocentric 
 longitude of the sun on the 23rd of July ; and the 
 comet's motion being direct, it is always too near this 
 luminary to be easily detected when the perihelion 
 takes place about this time. It passed through these 
 parts of space in 1 839 without being perceived in any 
 part of the earth, and the next return, in 1846, was 
 therefore anticipated with the greater interest. The 
 calculations of Professor Santini, to whom we are 
 indebted for nearly the whole of our knowledge of 
 the comet's movements since 1826, indicated an acce- 
 
THE COMET or BIELA. 77 
 
 leration of the ensuing arrival at perihelion by 31'884 
 days, the influence of the planet Jupiter being very 
 considerable, not only on the periodic time, but like- 
 wise on the inclination of the plane of the orbit to 
 that of the ecliptic, which was diminished 37' in the 
 interval between 1839 and 1846. The perihelion 
 passage was fixed for about nine p.m. Greenwich time, 
 on the llth of February, 1846, and it was found the 
 comet would remain visible a long time, and thus 
 afford an opportunity of correcting the theory of its 
 motion, by long-continued observation. 
 
 The powerful telescopes which are now happily 
 found in many of the European observatories were 
 employed in the search for the wanderer, as the time 
 of its return drew near. It was discovered the same 
 evening, November 28th, by Professor Encke at 
 Berlin, and Signer De Vico at Rome ; Professor 
 Challis saw it on the 1st of December with the great 
 Northumberland telescope at Cambridge, but it was 
 not generally recognised till the third week in 
 December, and was last seen on the 27th of April at 
 the observatory of Bonn. 
 
 A phenomenon which created no little astonishment 
 amongst astronomers, took place at this reappearance 
 of Biela's cornet. When it first became visible in the 
 large refractors of Berlin, Cambridge, &c., it presented 
 a faint nebulosity, almost if not perfectly circular in 
 form, with but slight condensation towards the centre. 
 On the 19th of December it was remarked to be 
 somewhat elongated or pear-shaped, but this circum- 
 stance merely induced a passing notice, such distor- 
 tions being not unfrequently noticed in telescopic 
 
78 THE COMETS. 
 
 comets. Within a fortnight of this date, however, the 
 comet had actually separated into two distinct nebu- 
 losities, which travelled along in company for more 
 than three months. The circumstance was remarked 
 independently by various astronomers, but the division 
 appears to have been first perceived in America on 
 the 29th of December. At the end of January and 
 until the end of March the two comets were very 
 generally observed : Mr. Otto Struve thought he could 
 just distinguish the companion on the 16th of April, 
 when the principal comet was observed for the last 
 time with the great Equatorial at Pulkova. The 
 apparent distance between the centres of the two 
 nebulosities was at first little more than two minutes, 
 but subsequently it increased to about seven times 
 that quantity, and each head or comet exhibited a 
 short tail in the usual direction, while something very 
 like a stellar point was observable in each. The com- 
 panion comet was even the brighter of the two about 
 the 12th of February, but did not continue so more 
 than three or four days. The real distance between 
 the comets has been calculated by Professor Planta- 
 mour for different days : we subjoin some of his 
 results, expressed in English miles, instead of semi- 
 diameters of our globe : 
 
 1846. Miles. 
 
 February 10 - - - 149,800 
 
 February 17 - - - 153,560 
 
 February 26 - - - 156,660 
 
 March 3 - - - 157,240 
 
 March 16 - - - 155,770 
 
 March 22 - - - 154,200 
 
 The maximum distance attained on the 3rd of 
 
THE COMET OF BIELA. 79 
 
 March was therefore about two-thirds of the moon's 
 mean distance from the earth. The angle of position 
 of the line joining the two heads in respect to a fixed 
 point, altered very little, according to Professor Plan- 
 tamour's researches. 
 
 Biela's comet reappeared at the end of August, 
 1852, and continued visible about three weeks. Pro- 
 fessor Secchi, of Rome, detected, on September 16th, 
 a fainter comet near the above, which it preceded by 
 two minutes of time in right ascension, being 30' 
 south. This object was considered to be, in all pro- 
 bability, the second part of the chief comet; and, if 
 so, it had evidently become a distinct body, since its 
 real distance from the other must have exceeded 
 1,250,000 miles. The morning twilight greatly in- 
 terfered with observations this year. 
 
 The dimensions of the orbit of Biela's comet in 
 1846 were as subjoined : 
 
 In parts of the earth's 
 
 mean distance. In English miles 
 
 Aphelion distance - - 6-1926 - - - - 590,100,000 
 
 Perihelion distance - - 0-8564 - - - - 81,600,000 
 
 Minor Axis - - - - 4*6060 - - - - 438,900,000 
 
 The corresponding time of revolution is 6'617 years. 
 
80 THE COMETS. 
 
 CHAPTER VII. 
 
 OTHER COMETS OF SHORT PERIOD FATE'S, DE VIGORS, 
 BRORSEN'S, D'ARREST'S. 
 
 I he Periodical Comet of Faye. 
 
 NEARLY a quarter of a century after the discovery of 
 the periodicity of Encke's comet, another object of 
 great interest was brought to light by M. Faye, one 
 of the astronomers attached to the Observatory of 
 Paris. On the 22nd of November, 1843, he detected 
 a telescopic comet in the northern part of the constel- 
 lation Orion, which was visible till the 10th of April 
 following. It exhibited a bright star-like nucleus, 
 with a short, fan-shaped tail, in the usual direction, 
 but was never bright enough to be discovered without 
 optical aid. The incompatibility of the track which 
 the comet was pursuing with the assumption of para- 
 bolic motion, appears to have been independently 
 remarked about the same time by Professor Arge- 
 lander of Bonn, Dr. Goldschmidt of Gottingen, and 
 Professor Henderson, late director of the Royal Ob- 
 servatory at Edinburgh, who occupied themselves in 
 the investigation of the true curve described by the 
 comet. This was speedily found to be an ellipse, with 
 a period of revolution of about 7J years, or rather 
 
THE COMET OF FA YE. 81 
 
 longer than in the case of Biela's comet. A good deal 
 of speculation followed with regard to the identity of 
 the new comet with one observed by Messier in 1770, 
 which was known to have suffered enormous pertur- 
 bations through the attraction of Jupiter. The ques- 
 tion was not set at rest till after the appearance of a 
 complete memoir on the subject, by M. Leverrier, 
 who, in tracing the past history of the comet of Faye, 
 has proved that it could not have been the same as 
 that of 1770, designated the ' lost comet;' but it must, 
 notwithstanding, have been a denizen of our system 
 for at least ninety-six years previous to its discovery 
 by Faye. It is possible that in its descent towards 
 the sun in 1747, when it passed close to the planet 
 Jupiter, the action of this vast globe may have de- 
 flected the comet into its present orbit, and this is the 
 least remote period at which disturbances to the 
 amount necessary to produce a great change could 
 have occurred. 
 
 - M. Le Verrier predicted that Faye's comet would 
 again reach its perihelion on the 3rd of April, 1851, 
 at midnight, but its path amongst the stars would 
 not be so favourable for observations in Europe as at 
 the previous appearance. True to the prediction, the 
 comet was in sight with the large telescope under the 
 direction of Professor Challis, at Cambridge, and 
 actually attained its least distance from the sun at the 
 very hour named by the French mathematician some 
 years beforehand, having suffered a retardation of be- 
 tween seven and eight days, chiefly through the influ- 
 ence of Jupiter, as M. Le Verrier had calculated. The 
 exact length of the comet's revolution in 1843 was 
 E 3 
 
82 THE COMETS. 
 
 2,718 days, and the elements necessary to construct 
 the orbit at that epoch are as subjoined : 
 
 In parts of earth's 
 mean distance. In English miles. 
 
 Aphelion distance - - 5*9310 - - - - 565,200,000 
 Perihelion distance - - 1'6926 - - - - 161,300,000 
 Minor axis - - - - 6'3368 - - - - 603,880,000 
 
 The other elements will be found in the catalogue 
 of orbits (1843, III.) 
 
 The comet of Faye may be expected to arrive at 
 perihelion again in October, 1858. 
 
 The Periodical Comet of De Vico. 
 
 On the 22nd of August, 1844, Father de Vico dis- 
 covered a telescopic comet at the Collegio Komano at 
 Rome, which continued visible in powerful telescopes 
 until the end of the year. About the third week in 
 September it was just discernible with the naked eye, 
 and under slight optical aid had a very beautiful ap- 
 pearance, the nucleus being bright and star-like, and 
 a short tail of a bluish tinge, extending in the direc- 
 tion opposite that of the sun. It was soon found by 
 M. Faye and others that the observations would not 
 agree with the assumption of parabolic motion, and on 
 investigating the real nature of the conic section 
 described by the comet it was ascertained to be an 
 ellipse with a periodic time of about five and a half 
 years. The elements have been calculated by Dr. 
 Brlinnow, with due regard to the influence of plane- 
 tary attraction during the interval over which the 
 observations extend, and his results show that at the 
 time of perihelion passage the length of the comet's 
 
THE COMET OF DE Vico. 83 
 
 revolution was 1993 days. The same computer has 
 carried on the inquiry to the return in the spring of 
 1850, but it happened very unfortunately that when 
 the comet was near enough to the earth to be other- 
 wise discerned, it was always lost in the sun's rays, the 
 geocentric positions of the sun and comet at perihelion 
 being nearly the same, and continuing so for some 
 months, on account of the apparent direct movement 
 of both bodies. 
 
 At the next visit, in the summer of 1855, the comet 
 will be more favourably located in the heaveos, and 
 astronomers will look forward with some interest to 
 this re-appearance, as the time and track are likely to 
 be predicted with great accuracy. Dr. Briinnow cal- 
 culates that it will be in perihelion on the evening of 
 August 6, 1855. 
 
 The eminent geometer, M. Le Verrier, has shown 
 that there is strong reason to think the comet of De 
 Vico identical with one observed in 1678, by La Hire, 
 and recorded in the Histoire Celeste of Lemonnier. 
 The comet of that year was seen near the ecliptic in 
 the constellation Aquarius, and the positions given by 
 the observer do not lay claim to any degree of exact- 
 ness. M. Le Yerrier proves that elements closely re- 
 sembling those of De Vico's comet will accord suffi- 
 ciently well with La Hire's observations, and hence 
 the identity of the cornets becomes extremely probable. 
 At one time it was thought to be the same comet that 
 appeared in 1585, which was attentively watched by 
 Tycho Brahe, but the computations of MM. Le Yerrier 
 and Peters render this very unlikely, notwithstanding 
 a similarity in the elements. 
 
84 THE COMETS. 
 
 The dimensions of the orbit described by the peri- 
 odical comet of De Vico in 1844, were as follows : 
 
 In parts of the earth's 
 
 mean distance. In English miles. 
 
 Aphelion distance - - - - 5-0194 - - - 478,300,000 
 Perihelion distance - - - - 1-1890 - - - 113,300,000 
 
 Minor axis 4-8860 - - - 465,600,000 
 
 Corresponding period of revolution 5*469 years. 
 
 The periodical Comet of Brorsen. 
 
 On the 26th of February, 1846, Mr. Brorsen, of 
 Kiel, in Denmark, discovered a telescopic comet in 
 the constellation Pisces, which has been found to re- 
 volve round the sun in about 5 J years. It was nearest 
 to the earth on the 27th of March, and at that time 
 appeared as a large roundish nebulosity, without any 
 indications of nucleus or tail. The observations were 
 not very numerous, and, towards the latter part of the 
 series were separated by a long interval, for which 
 reasons the elements of the orbit, and, particularly, 
 the periodic time, could not be exactly ascertained. 
 The epoch of the ensuing arrival at perihelion was, 
 therefore, liable to some uncertainty, and was fixed 
 by one able calculator on September 26th, 1851, and 
 by another about the middle of November. The 
 comet, we believe, was sought for on both suppositions, 
 with more than one of the larger telescopes of the 
 present day, but was not found. It was expected to 
 be fainter than in 1851, and if it arrived at its least 
 distance from the sun in September or earlier, might 
 very easily escape observation. It is to be hoped that 
 observers will be more successful in their search for 
 the comet early in the year 1857. 
 
THE COMET OF D'AKREST. 8 
 
 There seems a probability that the present remark- 
 able form of the orbit is owing to the influence of 
 the planet Jupiter, near which the comet must have 
 passed in May, 1842, as the author has shown by 
 calculation. When it has been again observed, so as 
 to discover the precise length of revolution at the 
 time it was visible in 1846, and thus secure a good 
 starting point, it will be possible to determine very 
 precisely, what effects followed this close appulse, and 
 thus to find the periodic time, and other elements of the 
 comet's orbit, before it passed so near the system of 
 Jupiter. Such inquiries are amongst the most in- 
 teresting in the whole science of astronomy, though 
 involving a long and laborious application of very 
 abstruse and intricate formulae. 
 
 Dr. Briinnow, who has paid much attention to the 
 movements of this comet, gives strong reasons for 
 disputing its identity with the comets of 1532 and 
 1661, long supposed to be the same, though the three 
 orbits have a striking resemblance to each other, as 
 the reader may see by comparing the numbers in our 
 general table. We subjoin the dimensions of the 
 orbit of Brorsen's comet. 
 
 In parts of the earth's 
 
 mean distance. In English miles. 
 
 Aphelion distance - - - - 5 6429 - - - 537,750,000 
 Perihelion distance - - - - 0-6501 - - - 61,950,000 
 
 Minor axis 3-8307 - - - 365,100,000 
 
 The corresponding period is 2039 days, or 5-581 years. 
 
 The Periodical Comet of D 'Arrest. 
 
 On the 27th of June, 1851, Dr. D'Arrest of Leip- 
 zic discovered a faint telescopic comet in the constel- 
 
86 THE COMETS. 
 
 lation Pisces. As early as July 8th it was remarked 
 by this astronomer that the course the comet was pur- 
 suing did not appear reconcileable with a parabolic 
 curve, and as observations were multiplied it became 
 evident that the true orbit was elliptic, and that the 
 time of revolution round the sun extended only to a 
 few years. The latest investigation gives a periodic 
 time of 2353 days (6*441 years), the comet having 
 arrived at its least distance from the sun on the morn- 
 ing of July 9th. It was always extremely faint and 
 small, without nucleus or tail, and was not observed 
 more than three months. The elements do not re- 
 semble those of any former comet in a sufficient 
 degree to justify the supposition of identity. Dr. 
 D'Arrest has remarked that the comet was for a con- 
 siderable period in the vicinity of the planet Jupiter 
 in 1849 : it may eventually be found to have under- 
 gone large perturbations from the attraction of this 
 great globe, which possibly may have given rise to its 
 present limited path about the sun. The following 
 numbers, exhibiting the dimensions of the orbit of 
 D'Arrest's comet in 1851 must be received with some 
 caution, as the observations have not yet been fully 
 discussed : 
 
 Aphelion distance - - 5*7497 or 547,900,000 miles. 
 Perihelion distance - - 1-1740 or 111,900,000 
 Minor axis of orbit- - 5-1960 or 495,200,000 
 
PERIODICAL COMETS. 87 
 
 CHAPTER VIII. 
 
 PERIODICAL COMETS (continued) OF six COMETS, 
 
 PROBABLY WITH SHORT PERIODS LEXELL^S COMET 
 IN 1770 COMETS WHICH APPEAR TO REVOLVE 
 ROUND THE SUN IN ABOUT 75 YEARS OTHERS 
 TO WHICH LONGER PERIODS HAVE BEEN ASSIGNED. 
 
 (1.) Comets which were probably describing small 
 elliptical orbits at the time they were observed, 
 but ivhose periods are not yet accurately deter- 
 mined. 
 
 IN this class of comets we shall briefly notice, in chro- 
 nological order, six of these bodies which should 
 probably be included amongst those of short period, 
 but respecting which our knowledge is not yet suffi- 
 ciently exact to enable us to predict the time of re- 
 appearance. In fact, the first five may be considered 
 lost, until they are either accidentally rediscovered, or 
 until it has been shown that they have been deflected 
 from their former orbits by the attraction of the larger 
 planets. 
 
 I. A comet observed somewhat roughly in February 
 1743, at Paris, Berlin, Vienna, and Bologna, appears 
 to have been periodic, as the apparent places cannot 
 be represented on the supposition of parabolic motion. 
 
88 THE COMETS. 
 
 Clausen, founding his calculations on the observa- 
 tions of Zanotti at Bologna, makes the time of revo- 
 lution 5-436 years. This comet was seen in Ursa 
 Major and Leo. 
 
 II. The comet detected by Messier at Paris on the 
 8th of April, 1766, and afterwards observed by La 
 Nux at the Isle of Bourbon, was undoubtedly moving 
 in an ellipse of moderate length of revolution. Burck- 
 hardt made the periodic time a little over five years 
 (5-025 years). 
 
 III. A comet discovered by Mr. Pigott, at York, 
 on the 19th of November, 1783, has had elliptical 
 elements assigned to it by the same computers ; the 
 period being 5 -61 3 years. 
 
 IV. The small comet detected by Pons on the 12th of 
 June, 1819, and roughly observed at Marseilles and 
 Milan, was doubtless one of short period. Professor 
 Encke finds the time of revolution 2052 days, or 5.618 
 years, but it has not been recognised since 1819. 
 Clausen conjectures that it may be the same as 
 that of 1766, the elements having undergone con- 
 siderable changes from the attraction of the larger 
 planets, which is by no means an unlikely event. 
 
 Y. Another small and faint comet discovered in the 
 same year, by Blanpain at Marseilles, on November 
 the 28th, to which Encke assigns a period of 1757 
 days, or 4f years, subject, however, to greater uncer- 
 tainty than in the former case, owing to the greater 
 errors which exist in the observations. The late Pro- 
 fessor De Vico, of Rome, computed the amount of per- 
 turbation due to the influence of the planet Jupiter up 
 to the year 1836, and found that the comet should 
 
LEXELI/S COMET. 89 
 
 have returned to perihelion towards the end of August 
 in that year, if Encke's numbers were correct. No 
 comet was found, nor has it been recognised since the 
 year 1819. Clausen suggests that this may have been 
 the comet which was observed in February 1743, as 
 noticed above. 
 
 VI. The comet found by Dr. Peters, at Naples, in 
 June, 1846, and followed until the end of July, is 
 supposed to be periodical. The time of revolution is 
 15*89 years, according to D* Arrest, and 12 '85 years 
 agreeably to the calculations of the discoverer, who 
 thought his result was uncertain to the extent of one 
 year. In this case, we may expect the re-appearance 
 of the comet between 1858 and 1860, the most pro- 
 bable epoch we can fix upon being the spring of 1859. 
 It was always small and faint, and with the exception of 
 a single observation at Rome, was observed only at 
 Naples. The six comets which we have included in 
 the present class all move in the same direction as the 
 earth. In four cases the inclination of the orbit to 
 the plane of the earth's path is less than eleven degrees, 
 the perihelion distance being in each instance within 
 the orbit of our globe. The comets of 1783 and 1846, 
 which have much larger inclinations, have their peri- 
 helia nearer to the orbit of the planet Mars. 
 
 (2.) Lexell's Comet of 1770. 
 
 There is one body which we should perhaps have 
 included in the above division, had not the interest 
 attaching to the form of its orbit when last observed, 
 and its extraordinary history, claimed for it something 
 more than a passing mention. We allude to the re- 
 markable comet discovered in June 1770, by Messier 
 
90 THE COMETS. 
 
 of Paris. "When first perceived, it was pretty bright, 
 its nucleus shining like a star, and resembled the 
 nebula between the bow and head of Sagittarius. 
 
 On July 1st, it had greatly increased in apparent 
 size, and though no tail was visible, the white nebu- 
 losity surrounding the nucleus extended over a space 
 of 2i-, or more than five times the diameter of the 
 moon. At this time the comet was very near the 
 earth, as we shall presently notice more particularly. 
 It continued visible till the beginning of October, when 
 it had become very small and faint. Several astro- 
 nomers, and amongst them MM. Pingre and Prosperin 
 endeavoured to represent the apparent track of the 
 comet in the heavens by means of parabolic elements, 
 but without success. M. Lexell of the Academy of 
 Sciences at St. Petersburg has the merit of having 
 first pointed out the true form of the orbit described 
 by the comet. He proved that a period of seven 
 years was too long, and finally arrived at the conclu- 
 sion that the true periodic time, in 1770, was five years 
 and seven months. These results were not obtained 
 until 1778, or two years after the comet should have 
 returned, supposing Lexell to be correct in the length 
 of a revolution. At that time a very close search was 
 kept up by Messier and others for new comets, and it 
 was supposed that the one in question must have 
 escaped observation during its descent towards the 
 sun, in 1776, owing to its proximity to that luminary 
 a very likely event. During the course of his re- 
 searches, Lexell remarked that the comet must have 
 made a very close approach to the planet Jupiter, at the 
 end of May, 1767, when the distance between the two 
 
LEXELL'S COMET. 91 
 
 bodies was probably only -g-g-o-th of the comet's distance 
 from the sun, and hence it appeared the influence of the 
 planet was three times greater than that of the sun : 
 the motion of the comet at this part of the ellipse 
 being comparatively slow, it was exposed for a con- 
 siderable period to the disturbing action of Jupiter. 
 These circumstances, Lexell thought, would give rise 
 to most important changes in the form of the comet's 
 path round the sun, so that the small ellipse in which 
 it was moving when visible from the earth in the 
 summer of 1770, might have been the result of Jupi- 
 ter's powerful attraction. 
 
 Another re-appearance of the comet, on the suppo- 
 sition of a periodic revolution of five years and seven 
 months, would fall due about the month of August, 
 1781, and Lexell, in drawing attention to this fact, 
 gave a series of ephemerides to facilitate the comet's 
 discovery. In the same memoir he pointed out a 
 close appulse between Jupiter and the comet, which 
 would take place after the aphelion passage, or about 
 August 23rd, 1779, when he found the action of the 
 planet would exceed that of the sun 225 times, and 
 hence it was possible the path of the comet might 
 again suffer a total change. Though astronomers 
 searched the heavens diligently about the time of the 
 expected reappearance, the comet was not seen, and, 
 according to the results deduced by Lexell, it was 
 inferred that the comet had again been deflected 
 from its course by the overpowering attraction of the 
 planet Jupiter, and moved after this encounter in a 
 very different, though unknown, orbit. The labours 
 of Lexell in clearing up the history of this body were 
 
92 THE COMETS. 
 
 so great, that by most authorities it has been called 
 ' LexelUs comet/ 
 
 Nothing further was known respecting it until the 
 year 1806, when Burckhardt, an eminent French 
 calculator, verified LexelFs calculations ; and subse- 
 quently, at the request of Laplace, investigated the 
 effects of Jupiter's action upon the comet in 1767 
 and 1779, with the help of formulae devised by 
 Laplace, and published in the Mecanique Celeste. 
 JBurckhardt's conclusions were received with great 
 interest by astronomers, and we believe every confi- 
 dence has been placed in them until the subject of 
 periodical comets was taken up so ably by Le 
 Yerrier four or five years since. Of the main facts 
 there can be no doubt: the comet certainly twice 
 encountered the planet, in 1767 and 1779, and on each 
 occasion must have been deflected from its previous 
 course into an orbit widely different, but Le Yerrier 
 shows that the elements could not be determined from 
 the observations of 1770 with sufficient accuracy to allow 
 of a rigorous computation of the disturbances due to the 
 influence of Jupiter in 1779, and consequently that 
 the numbers which Burckhardt assigned for the orbit 
 after the great perturbations in that year were not 
 certain, while with respect to the elements calculated 
 by the same mathematician prior to the close appulse 
 of Jupiter and the comet in 1767, it was stated that 
 some errors must have crept into the computations, 
 the numbers in the Mecanique Celeste being thereby 
 entirely vitiated. Having said thus much, we will 
 subjoin the principal results of Burckhardt's re- 
 searches, on account of their historical interest, and 
 
LEXELL'S COMET. 93 
 
 the great notoriety they have obtained, and will then 
 more particularly allude to the investigations of Le 
 Verrier, which furnish us with some very interesting 
 conclusions. 
 
 The great perturbations of 1767 took place between 
 the middle of January and May. In the latter month 
 the comet was moving in an ellipse, with a periodic 
 time of 2050 days ; but before the 18th of January, 
 according to Burckhardt, its time of revolution was 
 48 j- years ; the mean distance from the sun was 13 J 
 times the radius of the earth's orbit ; and the comet 
 could never approach that luminary within 480 
 millions of miles, at which distance there would be 
 no chance of seeing it from our globe. Hence it 
 was inferred that the non-appearance of the comet 
 prior to 1770 was fully accounted for. To ascertain 
 the effect of Jupiter's attraction upon the orbit in 
 1779, Burckhardt started with numbers corrected for 
 the small deflection caused by the near approach of the 
 earth and comet in 1770, assuming a periodic time of 
 2043 days, when the large disturbances commenced 
 about the end of June, 1779. Following similar 
 methods to those used in the former case, he con- 
 cluded that the comet escaped from what was termed 
 the sphere of activity of the planet early in October, 
 1779, and at this epoch it was moving in an ellipse, 
 with a revolution of rather more than 16 years, and 
 a perihelion distance of 3,f times the semi-diameter 
 of the earth's orbit, and at such a distance there would 
 be no hope of our ever seeing it again. We must 
 mention, as one result of Burckhardt's researches, 
 that the earth diminished the time of the comet's 
 
94 THE COMETS. 
 
 revolution in June and July, 1770, more than two 
 days. Its reaction upon the earth was quite insensible, 
 and Laplace considered its mass must be less than 
 3-oVo- of that of our planet, or its influence might have 
 been perceptible upon the solar tables. 
 
 M. Le Verrier communicated the principal results 
 of his researches on the comet of 1770 to the Paris 
 Academy of Sciences in May 1848. It is found that 
 the observations of Messier in 1770 do not suffice to 
 determine exactly the length of the major axis of the 
 comet's orbit, and consequently of its period of revo- 
 lution during the time it was visible, whence it is im- 
 possible to assign the exact amount of perturbation 
 which the elements would undergo in 1779, since the 
 computed positions of the comet in its orbit at that 
 epoch may not be the true ones, and the effect of 
 Jupiter's attraction will remain uncertain, as the real 
 distances between the two bodies is to a certain degree 
 indeterminate. But M. Le Verrier proceeds to show 
 that the elements as a whole, subsequent to the year 
 1779, are far from being arbitrary; if one of them be 
 assumed, there exist only two systems of values for the 
 other five elements, and hence we have a ' criterion' 
 by which to judge of the possible identity of the comet 
 of 1770 with any other that has appeared since that 
 year. In this way it is found that the comets of Faye, 
 De Yico, and Brorsen (all of short period) are quite 
 distinct from Messier's. In a similar way M. Le 
 Verrier assigns limits between which the elements 
 prior to 1767 must have fallen, and with the help of 
 his formulae he is able to show that not any of the 
 ancient comets can have been identical with the one 
 
LEXELI/S COMET. 95 
 
 in question. It is remarked that some error exists in 
 Burckhardt's calculation, as the perihelion distance 
 before the commencement of the year 1767 could not 
 have exceeded three times the radius of the earth's 
 orbit, and much more probably was comprised between 
 1*5 and 2. The inclination of the comet's path to 
 the ecliptic before the great perturbations of 1767 
 might have amounted to 37, though less than 2 when 
 Messier observed in 1770. The final conclusion from 
 M. Le Verrier's investigations is that the comet of 
 1770 may be considered lost until it is accidentally 
 rediscovered in the ordinary course of searching for 
 these bodies, when his formulae will enable the astro- 
 nomer to recognise in the new comet that interesting 
 wanderer. 
 
 The comet of Lexell has made a nearer approach 
 to the earth than any other on record. Dr. Clausen 
 of Dorpat, has shown that the distance between the 
 centres of the two bodies about five o'clock on the 
 evening of July 1st, was only 363 semi- diameters of our 
 globe, or rather more than 1,400,000 miles. At this 
 time, as we have already remarked, the nebulosity 
 surrounding the nucleus subtended an angle of 2 23', 
 whence it would appear that the real diameter of the 
 comet was 59,000 miles. 
 
 Before concluding we may state that a part of the 
 calculations of Burckhardt have been very lately per- 
 formed again by Dr. Briinnow, who considers his re- 
 sults confirmatory of those in the Mecanique Celeste. 
 
96 THE COMETS. 
 
 (3) On certain comets which appear to revolve 
 round the Sun in about 75 years. 
 
 There are four comets besides that known as Hal- 
 ley's, which have periods a little over 70 years, and 
 consequently, mean distances rather less than the 
 radius of the orbit of Uranus ; this singular circum- 
 stance, notwithstanding the difficulties which present 
 themselves in the way of such an inference, would 
 almost lead us to conclude that they have had a com- 
 mon origin at some distant epoch, when a great 
 comet had been separated into several parts, either 
 by collision with one of the larger planets or other 
 cause. We are not, however, to be understood as 
 advocating the probability of such an event, though 
 one able writer has endeavoured to show by cal- 
 culation, the possibility that three out of the four 
 comets may at some past time, have formed a much 
 larger one, which exploded in the neighbourhood 
 of the planet Mars. The comets we are about to 
 notice, all move according to the order of signs, or in 
 the same direction as the earth, with large inclinations 
 to the ecliptic ; in these respects they differ from the 
 comet of Halley. We shall take the four in the order 
 of discovery. 
 
 I. A comet discovered by Pons in July, 1812, in 
 the constellation Lynx, and, shortly after, visible to 
 the naked eye, with a conspicuous tail. 
 
 II. The comet of Olbers, detected by that active 
 astronomer on the 6th of March, 1815, and observed 
 till the end of August. The periodic time has been 
 well determined by -the late Professor Bessel, who 
 
COMETS OF LONG PERIOD. 
 
 97 
 
 finds that the comet will again arrive at perihelion in 
 February, 1887. The action of the planets will 
 hasten its return no less than two years. 
 
 III. The comet discovered at the Collegio Ro- 
 mano, at Rome, by De Vico, on the 20th of February, 
 1846, and just visible without the telescope, early in 
 March. 
 
 IV. A comet found by Brorsen, in July, 1847, 
 and observed till the middle of September. 
 
 We subjoin the numbers required for constructing 
 the orbits of these interesting bodies, merely remark- 
 ing that the quantities are far more exact in the case 
 of Gibers' comet, than in the others, owing to the 
 researches of Professor Bessel. The distances, &c., 
 are expressed in semi-diameters of the earth's orbit : 
 the periods in years and decimals. 
 
 Pnmpf 
 
 Aphelion 
 
 Perihelion 
 
 Minor 
 
 Period of 
 
 
 Distance. 
 
 Distance. 
 
 Axis. 
 
 Revolution 
 
 Pons, 1812*. . % f . 
 
 33-414 
 
 0-777 
 
 10-192 
 
 70-68 yrs. 
 
 Gibers, 1815 . . . 
 
 34-055 
 
 1-213 
 
 12-854 
 
 74-05 
 
 De Vico IV., 1846 . 
 
 34-351 
 
 0-664 
 
 9-550 
 
 73-25 
 
 Brorsen III., 1847 . . 
 
 35-071 
 
 0-488 
 
 8-273 
 
 74-97 
 
 The other elements will be found in the general table. 
 
 * The author drew attention to this singular group of comets 
 in the Astronomische Nachrichten some time since, instancing 
 the comets of Olbers, De Vico, and Brorsen, but, by an over 
 sight, omitting that of Pons, which was soon after added by 
 Professor Stephen Alexander, of New Jersey, U. S. While 
 these sheets are passing through the press, it is announced that 
 the comet discovered in June, 1852, by Dr. Westphal, at Got- 
 tingen (the last in our general table), has a periodic time of about 
 sixty-nine years, and may therefore belong to the above group. 
 This body has also direct motion and a large inclination. 
 
 F 
 
98 THE COMETS. 
 
 (4.) Comets to which Long Periods of Revolution 
 have been assigned. 
 
 In addition to the comets of short period there are 
 many for which ellipses with much longer revolutions 
 have been calculated at various times, these we shall 
 place in a class by themselves. It is, however, to be 
 understood that in some instances there is a high 
 degree of probability attaching to the periodic times ; 
 while in others, the numbers attributed are to be 
 regarded as little better than the mere results of cal- 
 culation, or as affording no trustworthy idea of the 
 true time of revolution. For the sake of a methodical 
 arrangement, we will take these comets in chrono- 
 logical order, and endeavour at the same time to 
 distinguish between the probable &nduncertain periods. 
 
 1680. Professor Encke, from elaborate investiga- 
 tions, found the shortest probable revolution of the 
 great comet of this year, 805 Julian years, while the ob- 
 servations might be pretty well represented by suppos- 
 ing a hyperbolic orbit. This body approached very near 
 the sun, and passed over a great angle of true anomaly 
 before it was visible after perihelion passage ; conse- 
 quently, the heliocentric arc traversed during the ob- 
 servations was very small, and errors of observation, 
 otherwise insignificant, are enormously exaggerated 
 in the final elements. Little dependence, therefore, 
 can be placed upon any results of computation for this 
 comet.* 
 
 * See a paper, by the author, on the * Supposed Period of 
 Revolution of the Great Comet of 1680,' read before the Royal 
 Astronomical Society, in March, 1852, and published in their 
 4 Monthly Notices.' .. 
 
COMETS OF LONG PERIOD. 99 
 
 1683. A revolution extending to 190 years is 
 assigned by Clausen's calculations, upon the data fur- 
 nished us by Flamsteed, the first astronomer royal at 
 Greenwich. Very uncertain. 
 
 1763. Burckhardt made the time of revolution of a 
 comet in this year, 7334 years, while Lexell found it 
 1137 years. The great difference between these num- 
 bers is of itself sufficient proof that little or no de- 
 pendence can be placed upon either. 
 
 1769. Some years since the late Professor Bessel, 
 of Konigsberg, investigated the elements of the fine 
 comet of 1769 : he considered the most probable 
 period 2090 years, but showed that what might 
 be regarded as insignificant errors of observation, would 
 suffice to diminish the time of revolution to 1692, 
 or to increase it to 2673 years. Other calculators 
 have occupied themselves with the discussion of the 
 observations of this comet, but their deductions are 
 superseded by the more probable conclusions of Bessel. 
 
 1807. Professor Bessel, in a classical memoir on 
 the subject, makes the duration of a sidereal revolu- 
 tion 1714 years, which may be considered at least an 
 approximation to the truth. 
 
 1811. The first or great comet of 1811 is stated by 
 Argelander to have had a period of 3065 years at the 
 time it was observed. On this point the reader is re- 
 ferred to the following chapter. 
 
 1811. The second comet of this year, which was 
 discovered by Pons on November 16th, and seen for 
 three months, is computed by Nicolai to have a period 
 of 875 years, and with some degree of probability. 
 
 1822. Professor Encke finds a revolution of 
 F 2 
 
100 THE COMETS 
 
 years for the fourth comet of 1822, detected by Pons 
 at Marlia on July 13th, and observed subsequently at 
 various places in Europe and also in New South 
 Wales. 
 
 1825. The great comet of this year has a revolution 
 of 4386 years, according to Professor Hansen. This 
 result doubtless admits of correction, as there are large 
 outstanding differences between the calculated and 
 observed places of the comet. 
 
 1840. The fourth comet discovered by Dr. Bre- 
 micker at Berlin, is found by Mr. Gotze to have a 
 period of 344 years, which time he considers to be 
 correct within ten years. This conclusion deserves 
 confidence. 
 
 1844. On the 7th of July a comet was discovered 
 by M. Mauvais at Paris, which remained visible in 
 powerful telescopes until April of the following year. 
 During this interval it was observed with all the accu- 
 racy of which modern instrumental means admit, and 
 the rigorous discussion of the whole series of observa- 
 tions might, therefore, be expected to conduce to some 
 results closely approximating to the truth. After an 
 elaborate and masterly inquiry, Professor Plantamour, 
 of Geneva, finds a periodic time of 102,050 years ! 
 subject to an uncertainty of about 3090 years. This, 
 of course, is one of those instances where it is impos- 
 sible to determine the length of a comet's revolution, 
 owing to the slight deviation of the orbit from a para- 
 bola. We may be certain, however, that it extends 
 to many thousands of years. 
 
 1845. A comet found by Colla, at Parma, early in 
 June, and visible to the naked eye soon after, is pro- 
 
COMETS OF LONG PERIOD. 101 
 
 bably periodical. From a similarity between the ele- 
 ments of this body and those of the comet observed 
 by Tycho Brahe, in 1596, Dr. D'Arrest was led to 
 suspect their identity, and has accordingly tried how 
 a period of 249 years (the interval between 1596 and 
 1845), would agree with the observations: his infer- 
 ence is, that the agreement is sufficiently close to 
 warrant an opinion that the comets were the same. 
 
 1846. De Vico's third comet. Dr. Jelinek, of 
 Prague, assigns a period of 2720 years, which is stated 
 to be uncertain within 400 or 500 years. 
 
 1846. Brorsen's second comet. Dr. Wichmann, of 
 Konigsberg, was led to infer, from his own observa- 
 tions, that the length of a revolution was about 401 
 years, while Mr. Oudemanns makes it 500 years. A 
 closer investigation might, perhaps, lead to more 
 exact numbers : the elliptical character of the orbit 
 is certain. 
 
 In the next chapter we shall notice more fully 
 several of the comets included in the present section. 
 
102 THE COMETS. 
 
 CHAPTER IX. 
 
 A BEIEF NOTICE OF SOME OF THE MOST REMARKABLE 
 COMETS THAT HAVE BEEN OBSERVED FROM THE 
 EARLIEST TIMES TO THE PRESENT DAY. 
 
 ABOUT A.C 134, at the time of the birth of Mithri- 
 dates the Great, a very splendid comet made its 
 appearance, according to Justin, and remained visible 
 seventy days. Its brilliancy is compared to that of 
 the sun ; the tail covered a fourth part of the heavens, 
 and was four hours in rising. There is strong reason 
 for supposing this fine comet the same as the one 
 observed in China, from July to October, A. c. 134, in 
 the northern and eastern heavens, with a train ex- 
 tending past the zenith. Some writers have conjec- 
 tured that the comet of Justin may have been that 
 now known as Halley's, but there is pretty decisive 
 evidence to the contrary. 
 
 A.D. 178. A remarkable comet was observed by the 
 Chinese in the autumn. The nucleus had a reddish 
 tinge, and moved from the constellation Virgo, through 
 Ophiuchus and Serpens into Eridanus in about eighty 
 days. The tail, at one period, was between 50 and 
 60 in length. Few comets have described a longer 
 track in the heavens, and continued visible to the 
 naked eye during a. longer period than that of 178. 
 
REMARKABLE COMETS. 103 
 
 389. A comet is mentioned by contemporary histo- 
 rians which almost equalled in brilliancy the planet 
 Venus. They describe the head as composed of seve- 
 ral small stars; the tail was sword-shaped, and the 
 whole phenomenon resembled a burning lamp, with 
 the flame extending upwards from the horizon. The 
 sight of this ' prodigy" is said to have inspired the 
 greatest terror. 
 
 582. According to the Chronicle of Idatius, a large 
 comet appeared in this year. ' It was surrounded by 
 a thick darkness, and situated in a kind of opening ; 
 it shone in the midst of the darkness/ It was accom- 
 panied by a tail of surprising magnitude, which re- 
 sembled the smoke of a distant conflagration, and 
 was observed in the western heavens about the first 
 hour of the night, or soon after sunset. 
 
 615. A comet was seen in China in the sixth 
 moon, or about July. It was of a dusky colour, and 
 during the night the upper extremity of the tail had 
 a kind of vibratory motion : the length of the train 
 was between 50 and 60. This is, perhaps, the first 
 distinct mention of coruscations in the tail of a comet. 
 
 891. A great comet was observed both in Europe 
 and China, in May, 891 ; its path was from Ursa 
 Major, through Bootes into Ophiuchus and Serpens. 
 The Chinese say the tail was 100 long, and it is 
 described by European historians as of astonishing 
 magnitude and brilliancy. 
 
 1402. A very splendid comet made its appearance 
 
 in the spring of this year. Judging from the vague 
 
 accounts left us by eye-witnesses, we may infer that it 
 
 fas one of the finest comets recorded in history. It 
 
104 THE COMETS. 
 
 was observed in Italy between the west and north, 
 with a tail directed towards the north-east. It in- 
 creased daily in size and brightness as it approached 
 the sun. On Palm Sunday, March 19th, and two fol- 
 lowing days, its increase was c prodigious/ On Sun- 
 day the tail was ' twenty- five fathoms long/ on Mon- 
 day, fifty, and the same day one hundred ; on Tues- 
 day more than two hundred. These numbers enable 
 us to estimate the relative length on different days. 
 After March 21st, the comet was not seen in the even- 
 ing in Italy, but it was observed near the sun, which 
 it preceded. The brightness was such that the light 
 of the sun did not prevent its being seen at mid-day. 
 It caused great terror amongst the ignorant, who 
 considered it the presage of many evils to men in 
 general. The comet was observed in Japan, but 
 unfortunately we have no account of it in the Chi- 
 nese Annals. A second comet appeared in the same 
 year, about the end of spring, in the western heavens : 
 it was bright and clear, with a tail ' like a long pike/ 
 stretching out towards the east. After sunset its 
 brilliancy is described as most intense. It was seen 
 day and night, and moved from the west eastwards. 
 1 This prodigy/ says Ducas, l was remarked in the 
 Indies, in Chaldea, Phrygia, Persia, Asia Minor, 
 Thrace, in the country of the Huns, Dalmatia, Italy, 
 Spain, Germany, and in all the countries bordering 
 upon the ocean. This wonderful phenomenon conti- 
 nued until the autumnal equinox, and did not dis- 
 appear till the sun was already advanced in the sign 
 Libra ; it was termed Lampadias.' Other historians 
 mention the second comet of 1402, which could have 
 been but little inferior to the first in splendour. 
 
REMARKABLE COMETS. 105 
 
 72. The most celebrated comet of the fifteenth 
 century, was that which became visible early in De- 
 cember, 1471, but was especially remarked about the 
 third week in January of the following year. Towards 
 the 20th of this month it increased to an astonishing 
 size, throwing out a tail of prodigious length, and pre- 
 senting altogether a spectacle, which, in the language 
 of the age, is described as very horrible, and causing 
 universal dread. There was one European observer, 
 however, who viewed it in a different light, and 
 through whose account of its apparent path in the 
 heavens, Dr. Halley was enabled to compute the ele- 
 ments of the real orbit. Regiomontanus discovered 
 it on the 13th of January, amongst the stars of Virgo, 
 under the sign Libra. The motion of the head was 
 very slow at first, but became much more rapid as it 
 passed through Bootes. About January 21st, it tra- 
 versed an arc of 40 of a great circle, being then about 
 the middle of Cancer. Its after course was between 
 the poles of the equator and ecliptic, through Ce- 
 pheus, Cassiopea, Andromeda, and Pisces into Cetus, 
 where it disappeared about the end of February. 
 When nearest the earth on the 21st of January, it 
 was visible in full daylight, and its tail stretched across 
 the heavens : it was distant from our globe at this 
 time less than 3,350,000 miles. The Chinese have a 
 long account of the position with respect to the stars 
 on different days. The comet moved very nearly in 
 the same plane as the earth. 
 
 1577. The comet of this year deserves mention 
 chiefly on account of its having been the object of 
 Tycho Brahe's investigation on the parallax of these 
 F 3 
 
106 THE COMETS. 
 
 bodies. On the day of discovery if exhibited a curved 
 tail 22 in length. The Chinese describe it as of a 
 bluish colour, with a white vapour about 10 long. 
 Tycho Brahe concluded there was no sensible parallax, 
 and, therefore, that the comet must have been situated 
 far beyond the moon. 
 
 1618. Several comets were observed in this year, 
 but the finest was that discovered by Kepler, Longo- 
 montanus, Gassendi, and many other astronomers, 
 about the end of November. The tail was of unusual 
 length, exhibiting coruscations, especially to Longo- 
 montanus on December 10th, when it extended over an 
 arc of no less than 104, ' cum vibratione enormi.' 
 The comet was observed by our countryman Harriot, 
 whose results have been discussed by Professor Bessel. 
 Cysat remarked a circular nucleus in the centre of the 
 head about 2' diameter. 
 
 1652. Hevelius attentively observed the comet of 
 this year. It was of a pale and livid colour, but 
 almost equalled the moon in size, according to the 
 judgment of Hevelius and Comiers. 
 
 In 1661, 1664, and 1665, fine comets were visible. 
 The last two form the subjects of a great folio volume, 
 in the Theatrum Cometicum of Stanislaus Lu- 
 bienietski. Both exhibited tails, but if we may depend 
 on the drawings, the train in the comet of 1664 
 proceeded directly from the nucleus, without an en- 
 velope, while that of 1665 presented an extensive 
 envelope, which, partly encircling the nucleus, formed 
 the origin of a somewhat lengthy tail. 
 
 1680. The famous comet which astonished the 
 world at the close of the year 1680, and beginning of 
 
REMARKABLE COMETS. 107 
 
 1681, was discovered by Godfrey Kirch, at Coburg, 
 in Saxony, on the 14th of November, in the constel- 
 lation Leo. It was noticed before the end of the 
 same month at various places in Europe and America. 
 The perihelion passage took place on the 18th of 
 December, and the comet was lost in the sun's rays 
 about ten days previously : nevertheless it had exhi- 
 bited a very imposing appearance, with a tail varying 
 from 15 to 30 long. After perihelion, however, 
 about the 20th of December, when it became visible 
 in the evening sky, it was the object of universal 
 attention, the train extended over a vast arc of the 
 sky, frequently appearing from 70 to 90 in length, 
 and sensibly curved at the extremity so as to resemble 
 an enormous sabre. The nucleus presented itself 
 under various forms. By some it was described as a 
 confused mass of light not particularly bright to the 
 naked eye. In the telescope it was like a ' burning- 
 coal/ The tail was the most remarkable feature, and 
 its situation in the heavens was such as to render its 
 whole length distinctly visible, especially during the 
 first fortnight in January, 1681. The comet was ob- 
 served in all parts of the world, and was last seen 
 by Sir Isaac Newton with a seven-feet telescope 
 on the 19th of March. This great mathematician 
 having devised methods of representing the apparent 
 motion of comets by parabolic curves, calculated the 
 elements of the orbit for the one in question, as did 
 also his friend and assistant Dr. Halley. The results 
 showed that the comet at its perihelion passage, al- 
 most grazed the sun's surface, so close did it approach 
 to that luminary, and this remarkable circumstance 
 
108 THE COMETS. 
 
 gave rise to much speculation as to the probable 
 consequences of such proximity to the great origin 
 of heat and light. Dr. Halley, on searching the cata- 
 logues of ancient comets, considered he had found 
 three which gave signs of identity with that of 1680, 
 viz., those of 1106, 531 and B.c. 43, and his inferred 
 time of revolution 575 years has long been accounted 
 the true period of that comet. Since his time, how- 
 ever, much more information relative to these ancient 
 comets has been discovered in the various European 
 chronicles, and in the annals of China ; the tendency 
 of this additional evidence is adverse to Halley's con- 
 clusion, but it would lead us far beyond our limits to 
 discuss the question at length. In 1818, Professor 
 Encke collected together all the observations he could 
 find on the comet of 1680, and after a most complete 
 investigation, he ascertained that the probable period 
 of revolution resulting from the observations, is no 
 less than 8800 years, but the uncertainty of the data 
 is such that they may be satisfied within their pro- 
 bable limits of error, by an ellipse with a periodic 
 time of 805 years, or, by an hyperbolic orbit. Flam- 
 steed's and Newton's observations alone give a period 
 of 3164 years. It is clear, therefore, that no definite 
 knowledge of the length of the comet's excursion into 
 space can be obtained from the observations, and 
 notwithstanding Whiston's fanciful theory of the 
 comet's past movements, based, upon a presumed 
 revolution of 575 years, and the conjectured identity 
 of this body, with the prodigy which appeared at the 
 time of the destruction of Troy, or the brilliant star 
 
REMARKABLE COMETS. 109 
 
 during the reign of Ogyges, the testimony of history 
 is against the supposed revolution of Halley. 
 
 1744. The most splendid comet of the eighteenth 
 century, appeared in this year. It arrived at perihe- 
 lion at the beginning of March, and during the pre- 
 vious month formed a very conspicuous object in the 
 western sky. On the 7th of February the tail was 
 20 long ; the head seemed pretty round on this day, 
 but on the 1 1th it was oblong in the direction of the 
 tail, and was divided by a black line into two parts, 
 the northern one much smaller than the other, with 
 a coma brighter than the tail. This singular figure 
 disappeared on the following days. On February 15th, 
 the tail was divided into two branches ; the eastern 
 portion 7 or 8 long, the western 24. On the 23rd 
 it became curved, the convexity on the west side. On 
 the 7th of the same month, the light of the comet 
 equalled that of Jupiter at his greatest brilliancy, 
 and on the llth was little inferior to Venus. On the 
 day of perihelion passage, the head was prodigiously 
 bright, it was seen with the telescope in broad day- 
 light, and many persons followed it with the naked 
 eye, some time after the sun had risen. This splendid 
 object was observed by nearly all the astronomers of 
 the time, and gave occasion for many dissertations on 
 comets. Cheseaux affirms that six tails were visible 
 at one period, but the most eminent observers in 
 England and France have no mention of such an 
 extraordinary phenomenon. 
 
 1769. Another remarkable comet appeared in the 
 autumn of this year, and was watched by our astro- 
 
110 THE COMETS. 
 
 nomer royal Dr. Maskelyne, and by M. Messier, at 
 Paris. About the middle of September, the tail at- 
 tained a length of between 90 and 100, exhibiting 
 undulations of light, and a curvature towards the 
 extremity. The extent of the train varied considerably 
 according to different observers, but the discordances 
 between their estimated lengths are evidently owing 
 to atmospherical circumstances. Professor Bessel has 
 fully investigated the elements of the comet of 1 I 769. 
 
 1807. The comet of this year was distinctly visible 
 to the naked eye, and was examined with the power- 
 ful reflectors of Sir William Herschel. It had a well 
 defined planetary disk of a circular form, the diameter 
 of which was determined by Sir William to be 
 about 538 miles. The real length of the tail on 
 October 18th, was nine millions of miles, though 
 owing to the effect of foreshortening it did not appear 
 above 3J long. The researches of Professor Bessel 
 assign a periodic revolution of 1714 years, but it may 
 possibly be as long as 2157 years, or may not extend 
 over more than 1404 years. 
 
 1811. The first or great comet of 1811 is perhaps 
 the most famous of modern times. Independently of 
 its great magnitude, the position of the orbit and 
 epoch of perihelion passage were such as to render it 
 a very splendid circumpolar object for some months. 
 It was detected with the aid of the telescope by 
 M. Flaugergues, at Viviers, on the 26th of March, 
 1811, and was last seen by Wisniewski, at Neu- 
 Tscherkask in the south of Russia, on the 17th of 
 August, 1812. In the autumnal months of 1811, 
 the bright nucleus and tail became visible soon after 
 
REMARKABLE COMETS. Ill 
 
 the shades of evening closed in, and continued so 
 throughout the night, the high northern declination 
 causing the comet to appear constantly above the 
 horizon in these latitudes. The tail was longest about 
 the end of the first week in October ; it then extended 
 over an arc of 25, and was 6 broad. According to 
 the observations of M. Bouvard, the tail was divided 
 into two branches after the end of August, making 
 an angle of little less than 90 with each other. Sir 
 W. Herschel paid close attention to this comet : he 
 distinctly saw a well-defined planetary disk involved 
 in the nebulosity forming the head, and by accurate 
 measurement determined its real diameter to be 
 about 430 miles. This disk was of a pale ruddy 
 colour; the surrounding nebulosity greenish or bluish 
 green. "When the comet was examined with high 
 magnifiers, the appearance of a stellar nucleus va- 
 nished, and the light was spread, though not uni- 
 formly. The real length of the train about the middle 
 of October was upwards of one hundred millions of 
 miles, and its breadth about fifteen millions. Accord- 
 ing to the calculations of Professor Argelander, the 
 most complete that have been made, the period of 
 revolution at the epoch of perihelion in 1811, was 
 3065 years, subject to no greater probable error than 
 43 years.* But on computing the variation of the 
 greater axis due to the attractions of the larger 
 planets up to May, 1827, he ascertained that the 
 revolution would be shortened even in this brief 
 interval by no less than 177 years, or that the periodic 
 
 * The following numbers, which deserve confidence, repre- 
 sent the dimensions of the orbit of the comet of 1811 in that 
 
112 THE COMETS. 
 
 time corresponding to the end of May 1827, was about 
 2888 years. How much further it may be altered, 
 will probably be left for determination by those who 
 may be interested in its return. Another comet was 
 observed in 1811, but it was very far inferior to the 
 first in splendour. 
 
 1819. In July of this year, a fine comet suddenly 
 became visible in the constellation Leo. M. Caccia- 
 tore, of Palermo, assures us it exhibited phases simi- 
 lar to a crescent moon, during part of its visibility, 
 and that the crescent was not always on the same 
 side of the nucleus. This remark proves that the 
 phase could not have been owing to reflected light from 
 the sun, such as produces the varied phases of Mer- 
 cury and Venus, and M. Arago has drawn particular 
 attention to this fact. The tail extended about 7 
 from the nucleus. The observed path of this comet 
 is very well represented by a parabolic curve, so that 
 the period of revolution, if the real orbit be elliptical, 
 must extend to many centuries, and perhaps to some 
 thousands of years. 
 
 1825. In July, 1825, a comet was discovered inde- 
 pendently by M. Pons, at Marseilles, and M. Biela, 
 at Josephstadt, which continued visible until the 
 
 year, and afford a striking idea of the enormous distances to 
 which some of these bodies travel. 
 
 Aphelion distance - 421-015 or 40,121,000,000 miles 
 Perihelion distance - 1'035 or 98,700,000 mile*. 
 Minor axis ... 41 '76 
 
 This comet therefore recedes from the sun to a distance of four- 
 teen times that of the planet Neptune. 
 
REMAKKABLE COMETS. 113 
 
 middle of July, 1826. It was most conspicuous at the 
 beginning of October, when the head was approaching 
 our southern horizon. The tail appeared about 15 
 long, and was divided into two branches. On the 
 6th of this month, Professor Santini saw the nucleus 
 composed of three bright points. The period of revo- 
 lution of this fine comet, is probably not less than 
 4000 years. It is known as the ' great comet of 
 1825/ several others having appeared in the same 
 year. 
 
 1843. The finest comet of the present century 
 was that which made its appearance at the end of 
 February, 1843. On the 28th of that month it was 
 observed in full daylight near the sun, at Guadaloupe 
 y Calvo, in Mexico ; at Portland, in the United States 
 of America ; on board the East India Company's ship, 
 Owen Glendower, off the Cape of Good Hope ; and 
 at Parma, Bologna, Genoa, and other places in Italy. It 
 presented a most splendid appearance during the first 
 week in March throughout the southern hemisphere, 
 but when it became suddenly visible above the horizon 
 in these latitudes, about the 17th of that month, its 
 brilliancy had very much diminished : nevertheless the 
 tail still covered an arc of the heavens of no less than 
 40, and was curved towards the extremity. Undula- 
 tions similar to those recorded in the trains of some of 
 the great comets of past times were generally remarked. 
 The suddenness of its apparition in this country added 
 not a little to the interest which such an object was 
 certain to excite. No accounts from more southern 
 latitudes reached us for some days, and even astrono- 
 mers were somewhat puzzled as to the nature of the 
 
114 THE COMETS. 
 
 strange ray of light which, rising above the clouds 
 or haze of the western horizon, soon after sunset, 
 stretched over the south-west sky towards the constel- 
 lation Lepus through more than 35. The nucleus of 
 this comet is described as small, but extremely bright, 
 of a golden hue, of the colour of Venus, or reddish, 
 according to different observers. On the llth of 
 March it exhibited a well-defined planetary disk, 
 which, by accurate measurement, must have exceeded 
 4500 miles in diameter. The average length of the 
 tail in March was about 35, but on the evening of 
 the 3rd a faint ray extended as far as 65 from the 
 nucleus. At this time the train is described by an 
 observer at Brazil as of a brilliant silver colour, but 
 with a streak of a bright golden hue running directly 
 into it from the head to an extent of four or five de- 
 grees. Early in the month it was divided into two 
 branches, which subsequently united into one long 
 narrow stream of light. 
 
 The orbit of this comet approaches closer to the sun 
 than that of any other hitherto observed, not excepting 
 the famous comet of 1680. According to the most 
 trustworthy calculations, the perihelion distance was 
 only 538,500 miles; therefore the centre of the comet 
 would be distant from the surface of the sun's globe 
 less than 96,000 miles ! 
 
 Several comets have been mentioned as probably 
 identical with the great one of 1843, and in particular 
 those of 1668 and 1689, which exhibited tails of 
 unusual length. If it were one and the same comet 
 that appeared in 1668, 1689, and 1843, the period of 
 revolution could differ but little from twenty-two 
 
KEMAEKABLE COMETS. 115 
 
 years. But, independently of the primd facie impro- 
 bability of this short period, the evidence afforded by 
 the history of comets in past ages is decidedly against 
 it. Neither is the period of thirty-five years, sug- 
 gested by some astronomers, more probable, for the 
 comet of 1106 which was cited as strongly supporting 
 this time of revolution, could not possibly have been 
 the same as the comet of 1843, since historians agree 
 in stating that it was observed for some time in the 
 northern heavens, a circumstance perfectly irrecon- 
 cilable with the elements of the latter body, which 
 can only remain about three hours north of the eclip- 
 tic. Calculation shows that the paths of the comets 
 of 1668 and 1689 might be tolerably well represented 
 by the orbit of the comet of 1843, but equally well, 
 in the former case, and much nearer in the latter, 
 by numbers altogether different, so that we can come 
 to no definite conclusion on the subject. 
 
116 THE COMETS. 
 
 CHAPTER X. 
 
 ON THE EXPECTED GREAT COMET. 
 
 ONE of the grandest comets mentioned in history is 
 that which made its appearance in the middle of the 
 year 1264. It is recorded in terms of wonder and asto- 
 nishment by nearly all the historians of the age : no one 
 then living had seen any to be compared to it. It was 
 at the height of its splendour in the month of August, 
 and during the early part of September. When the 
 head was just visible above the eastern horizon in the 
 early morning sky, the tail stretched out past the mid- 
 heaven towards the west, or was fully 100 in length. 
 Both Chinese and European writers testify to its 
 enormous magnitude. In China the tail was not 
 only 100 long, but appeared curved in the form of a 
 sabre. Its movement was from Leo, through Cancer 
 and Gemini, into Orion. It continued visible until 
 the beginning of October, historians generally agree- 
 ing in dating its last appearance on the 2nd of October, 
 or 'on the night of the death of Pope Urban IV, 
 of which event it seems to have been considered 
 the precursor. It would lead us beyond the limits of 
 the present work, were we to attempt to discuss the 
 
EXPECTED GREAT COMET. 117 
 
 rude accounts which have descended to us ; we must, 
 therefore, content ourselves with stating that some 
 rough approximations to the elements have been 
 attempted in the first instance by Mr. Dunthorne, in 
 the middle of the last century, and subsequently by 
 M. Pingre, the well-known French writer upon the 
 history of comets. 
 
 In 1556, at the latter end of February, or early in 
 March, a comet became visible in the zodiacal constel- 
 lation Virgo. It was closely watched at Vienna, by 
 Paul Fabricius, astronomer at the court of the Emperor 
 Charles V., and we have a rudely executed map of its 
 path amongst the stars in the Book of Prodigies, 
 Omens, &c., published by Lycosthenes or Conrad 
 Wolfhardt, at Nuremburg, in the year of the comet's 
 appearance. It was not nearly so conspicuous as that 
 of 1264, but still is described as a ' great and brilliant 
 star/ Its course lay through Virgo and Bootes, past 
 the pole of the heavens, into Cepheus and Cassiopea, 
 where it was last seen about the end of the third week 
 in April, according to European authorities, though 
 the Chinese observers, who paid great attention to 
 comets, did not lose sight of it till the 'second day 
 of the fourth moon' corresponding to May 1 Oth old 
 style : they discovered it on the 1st of March, a little 
 below the equator, amongst the stars of Virgo. 
 
 Our countryman Dr. Halley, the second astronomer 
 royal, calculated the elements of the comet of 1556, 
 from the observations of Fabricius, and gave them, with 
 many others, in his synopsis of Cometary Astronomy, 
 which was published early in the eighteenth century. 
 Owing to the imperfect nature of these observations, 
 
118 THE COMETS. 
 
 his elements were not considered so exact as those of 
 other comets he had calculated, since it appeared dif- 
 ficult to reconcile the whole series with any rigorous 
 computation. Mr. Dunthorne, some fifty years later, 
 was induced to try the determination of an orbit for 
 the comet of 1264, having at his command two defi- 
 nite observations of position, purporting to have been 
 made at Cambridge by Friar Giles, besides the rude 
 descriptions to be met with in English and Foreign 
 chronicles of that age. His results were so similar to 
 those Halley had given for the comet of 1556, that 
 he was immediately led to conclude the bodies of 
 these years were identical, and the period being pro- 
 bably about 292 years, he surmised that a reappear- 
 ance might be expected about 1848. Mr. Dunthorne's 
 memoir on this subject was read before the Koyal 
 Society of London, and is published in their transac- 
 tions. 
 
 About twenty years later, M. Pingre very mate- 
 rially strengthened the evidence in favour of this 
 conclusion. He collected together at a great expense 
 of time and trouble all the accounts he could find in 
 the chronicles and histories of the thirteenth century 
 relative to the comet of 1 264, and was successful in 
 finding many that were unknown to Mr. Dunthorne, 
 and contained valuable information on the subject of 
 his inquiry. The result of an elaborate memoir com- 
 municated to the Paris Academy of Sciences in 1760 
 is, that the paths of the comets of 1264 and 1556 
 may be represented with tolerable accuracy, consi- 
 dering the nature of the observations, by elements 
 very closely similar ;- and hence he regarded those 
 
EXPECTED GKEAT COMET. 119 
 
 bodies as identical, and coincided with Mr. Dunthorne 
 in anticipating its reappearance about the year 1848. 
 This interesting and valuable paper of M. Pingre's is 
 to be found in the memoirs of the Paris Academy for 
 1760. 
 
 Between the years ,1843 and 1847, the author of 
 these pages investigated the question of identity anew, 
 taking as his groundwork, the chart of the path of the 
 comet of 1556, in the work of Lycosthenes already 
 mentioned. After correcting one or two pretty mani- 
 fest errors, which are not noticed by Pingre, the fol- 
 lowing orbit was finally fixed upon as the best the 
 observations would afford. 
 
 Passage through perihelion in 1556, on April 22nd, at 
 Oh. 34m. p.m. mean time at Greenwich, according to the Julian 
 style of reckoning : 
 
 Place of the perihelion upon the orbit .... 274. 15' 
 
 Longitude of the ascending node 175.26' 
 
 Inclination of the orbit to the ecliptic .... 30. 12' 
 
 Distance from the sun in perihelion, 0*505, or about 
 48 millions of miles. 
 
 The apparent path of the comet amongst the fixed 
 stars deduced from the above elements, agreed so well 
 with that actually observed by Paul Fabricius, that 
 no doubt could remain as to their being a fair approxi- 
 mation to the truth. It became then a matter of 
 great interest to ascertain how these elements would 
 represent the particulars recorded of the comet of 
 1264. Supposing no great perturbations to have 
 taken place in the interval, the agreement between 
 calculation and observation should be pretty close. 
 
120 THE COMETS. 
 
 The only point upon which any difficulty could re- 
 main, was the time of perihelion passage in 1264?, and 
 this was satisfactorily settled by a European obser- 
 vation, cited by Thierri of Yaucouleurs in a poem 
 upon the life of Pope Urban IV., and a Chinese obser- 
 vation some three weeks later, which were found to 
 be strikingly confirmatory of each other. 
 
 Supposing the other elements the same as in 1556, 
 allowing only for the precession of the equinoxes in 
 the interval of 292 years, it was found that the path 
 which the comet should have followed in the heavens, 
 was very like that which historians and chronologists 
 ascribe to the grand comet of 1264. This body would 
 become visible about the middle of July, gradually 
 assuming a more imposing appearance towards the 
 middle of August, after which it would recede from 
 the earth and sun, and therefore become fainter, as 
 we are assured was the case. It would traverse Leo, 
 Cancer, Gemini, Orion, and Eridanus, and might 
 finally vanish in the latter constellation at the begin- 
 ning of October. Hence the author concluded that 
 the comets of 1264 and 1556 were very probably the 
 same, and a return to perihelion might be expected 
 about the middle of the nineteenth century. 
 
 We have now to mention a most important inves- 
 tigation relative to the comets in question, by 
 M. Bomme, of Middelburg, in the Netherlands, which 
 has but very recently come into the hands of astro- 
 nomers. At a vast expense of time and labour, 
 ^. Bomme has calculated the effects that will be pro- 
 duced on the period of the comet's return (supposing 
 Che identity established) by the united attraction of 
 
EXPECTED GREAT COMET. 121 
 
 the planets Jupiter, Saturn, Uranus and Neptune, 
 and partially of the Earth, Yenus, and Mars. In a 
 work of this nature, we can give no idea of the methods 
 upon which the computations have been conducted, 
 and shall therefore merely state the principal results, 
 premising that M. Bomme first assumed the elements 
 given by Halley for 1556, and subsequently those of 
 the author, which were unknown to him at the com- 
 mencement of his researches. M. Bomme appears to 
 give a preference to the latter, but on this point some 
 caution should be observed. 
 
 With Dr. Halley 's elements, it was found that at 
 the time the cornet was visible in 1264, it was moving 
 in an ellipse with a periodic time of 112,469 days, or 
 308 years, but perturbations owing to planetary attrac- 
 tion quickened the return of the comet by no less 
 than 5903 days, so that it was in perihelion in April, 
 1556, and at that time the revolution corresponding 
 to the elliptical arc described, was 112,943 days. 
 Starting again from this epoch, M. Bomme ascertained 
 that the next revolution should occupy 111,146 days, 
 bringing the comet to its perihelion on the 22nd of 
 August, 1860, at which time the revolution will be 
 113,556 days. 
 
 With the author's calculations, on which, as above 
 stated, M. Bomme seems disposed to rely, as being 
 the best of several sets of elements, it was found 
 that in 1264, the ellipse described by the comet had 
 a period of 110,644 days, or 302'922 years, and that 
 planetary disturbances expedited its return by 4077 
 days. At the time it was visible in 1556, its mean 
 motion corresponded to a period of 308169 years. 
 
 G 
 
122 THE COMETS. 
 
 i 
 
 The present revolution should be shortened by per- 
 turbations 3828 days, or 10*48 years, and the comet 
 should again reach its perihelion on the 2nd of 
 August, 1858, the revolution belonging to the major 
 axis at that epoch, being 308-784 years. 
 
 Hence it appears that there is an uncertainty of 
 two years (between August, 1860, and August, 1858) 
 in the time of the next arrival in these parts of space, 
 according as the elements of Dr. Halley or those of 
 the author are employed, and we may here remark 
 that the computations upon the observations of Fa- 
 bricius, seemed to establish the position of the longer 
 axis of the ellipse, a most important point, within 4, 
 which may be regarded as the extreme amount of 
 probable error. This is about the difference between 
 the longitudes of perihelion in the two orbits, and it 
 may therefore be inferred that the 2nd of August, 
 1858, will probably be within two years of the time 
 of the next perihelion passage: nearer than this it does 
 not appear possible to approximate in the present state 
 of our knowledge. The deviation of 4 in the position 
 of the longer axis of the orbit, causes large differences 
 in the comet's distances from the disturbing planets, 
 and consequently in the estimation of their attractive 
 force at the various epochs, which accounts for the 
 great discordances in the final results. 
 
 Such, then, is the present state of this interesting 
 problem, and we have now to look forward to the 
 period 1856 1860 for a confirmation, or otherwise, of 
 the opinions of those astronomers who have occupied 
 themselves with these investigations. M. Bomme's 
 elaborate researches have fully accounted for the non- 
 
EXPECTED GKEAT CoME-r. 123 
 
 arrival of this grand comet at the time originally fixed 
 upon by Dunthorne, Pingre, and others. 
 
 It is an important circumstance, as bearing on the 
 question of identity of the comets of 1264 and 1556, 
 that about 289 years anterior to the former epoch, or 
 A.D. 975, a comet of great apparent magnitude was 
 visible, which may very possibly have been the same. 
 It was observed in Europe from August to October, 
 during the reign of John Zimisces. The Chinese saw 
 it about the middle of July, and traced its course 
 through Hydra, Leo, Cancer, Gemini, and Taurus, 
 into Aries, where it was lost after a visibility of three 
 days. It exhibited a tail 40 in length, and was evi- 
 dently a comet of unusual brilliancy. Supposing the 
 elements fixed by the author for 1556, it is found that 
 the observed track may be very closely represented, 
 the perihelion passage being assumed to take place 
 early in August, 975. A comet observed in China in 
 the summer of 683, and one seen in the circum- 
 polar heavens, A.D. 104, present some indications of 
 identity with the grand comet of 1264 and 1556, but 
 the accounts we possess are too vague to admit of 
 anything more than conjecture. 
 
 G 2 
 
A CATALOGUE 
 
 OF THE 
 
 CEBITS OF ALL THE COMETS 
 
 HITHERTO COMPUTED, 
 B.C. 370 TO A.D. 1852. 
 
126 
 
 THE COMETS. 
 
 
 .2 S 
 
 c3 
 
 1 -2 
 
 PH ^ 
 
 r-H o oo TJ-I <rq i 
 >O oq 10 "* >>: < 
 T-H o o" o'ooooooo'oooooooo'o 
 
 
 o o 
 
 ooo ooooo 
 
 J CO iO CO 
 
 i-H O 05 t^ t^ 00 CO 
 
 - 
 
 ooooooooooooooooo 
 
 CO 
 
 c^ 
 
 J.ol 
 
 000 
 
 So 
 
 oOCOCOi ir-HiOiOCOCO iO^CO 
 r-Hi(C<C<|r-l (?qCO t-H(M 
 
 o o 
 
 r-H CO 
 CM 
 
 & 
 
 1 
 
 g 
 
 i-H <n CO 
 
 ^o oooooooooooooooo 
 
 -O lOOOOOt-iOCiOOt-COCOOiOOO 
 
 <?q O t^ rH 00 00 T-H T-H 
 
 OO^T-HT-HT li-HC5COCOC<|COrHOT lOOl>- 
 
 CM r-l <?q i 1 
 
 o^ 
 
 ti CM 
 
 00 C5 t>cO CO OO O r-t rH 1O r-n 
 
 MCO 
 
 T^ ft 
 
CATALOGUE OF ORBITS. 
 
 127 
 
 
 
 s 
 
 ooo ooooooi-i O'O'OOOOO'CM'OOOOOOOOO 
 
 o o o o 
 
 CM CO 
 
 CO CO 
 
 o o o o o 
 
 rH r I XO CM 
 
 o o o o o o o o o o o o o c5 o o o 
 
 CM CO 
 
 i I *O CM i I 
 !> J>- i I CM "*< CO 
 
 CO 
 
 ooo 
 
 OOO 
 CO CO 
 
 ooo 
 
 OOOO 
 >^CO 
 
 oooooo o o o o o o o o o o o o o o o o o 
 
 GO ^^ rH C*^ CO r"H 
 
 CO 
 
 i CO i i 1O 
 
 oooooooooooooooooooooooo 
 
 OOCSOCMOOOOOt-rH 
 
 i ( CO 
 
 co 
 
 COrHCM^OO'iOOOOCrsiO ^^ 
 
 CMCM I-HCMCMCO co 
 
 CM 
 
 r I CO r- 1 
 
 CM 
 
 CO S 
 
 CM rH 
 
 CM i I rH IO rH 
 T-H CM i I T-H CM 
 
 <M CM CM CM 
 
 CM r- 1 CM r I 
 
 r ^ 
 
 > s 
 
 S B O ,w C5 
 
 C5 rH t- 
 
 C5 O CO 
 CM CO CO 
 
 *O CO 
 
 oo 
 
 co co ' co co 
 
 co to 
 
 00 , CM 
 
 O ^O T-H CM 
 
 OT o co co 
 
128 
 
 THE COMETS. 
 
 
 
 Excentricity. 
 
 QO 
 
 oo 
 
 CO 
 
 
 fc- 
 
 CO 
 05 
 
 
 O CO I-H IO i t CM i-H 10000000*00 
 ^i It-i 1 Oi rH Ci O 1O 
 
 OOOOOOOOOOr-ir-iOOOOOOOOOO 
 
 tio 
 
 i 1 <7<J O5 
 
 CDOOT 100 
 IO r 1 C<JrH<M 
 
 . 
 CO 
 
 cending 
 Node. 
 
 ooo 
 
 i-H CM i H rH CO CM<7<I T i r- 1 r-H CO CO 
 
 Longitude 
 of 
 Perihelion. 
 
 i I I-H. C<| 
 
 ^HOi lOOOCOOO 
 t t-OOr-l (M 
 
 <~ % fe 
 J3 Pi45 
 
 ^ a * 
 ..2^ 
 
 i^-s^ 
 
 S rfl QQ 
 
 5 B I 
 
 ^a 
 
 I CM rH CM i-H T I 
 
 r-H i ti-HCMCMi i <M CM 
 
 i 1 CM CM CM CM i-H r-l 
 
 .- CM CO i?O lOOt^OCM i>O .O iCO^O 
 ^JCOCO 1O lOt^OOOO CO Oi OiOi 
 <IO^O '^Ci 'lOiOOO 'JO 'O 'iOiO 
 
 b- iOO CM 
 
 O I-H >O 
 CO 'CO CO 
 

 CATALOGUE OF ORBITS. 
 
 129 
 
 d fl 
 
 f til If 
 
 Slj 
 
 CO 
 CM 
 O 
 
 O 
 
 CM Oi 
 ^ 1-1 O 
 iO O t- 
 
 00 CM -* 
 
 01 C5 C<1 
 O5 t^ CO 
 O5 ?O OO 
 O5 O5 Oi 
 
 O O O 
 
 S3 
 
 
 Oi CiOOS 
 
 ^i-Ht- 
 
 tOi-H-^ 
 
 OOO 
 
 o i i <N o 
 
 co o o oo 
 
 lO 
 
 o 
 
 o os o 
 
 O^HOOOOOr-Hr-iOOOOOOOOOOOOOOOr-iO 
 
 OOOOOOOOOCOCiOOQOOOO^OtOiOOOOiOOit^O 
 
 COr-l CO <M i I -tf ^H(M(?q i ICO i-H -^H CO <M i I 
 
 i-HT-Hr-ico^tH<?q 
 
 i I <M CO CO 
 
 i i^ioi ico 
 
 CO<?lt>- ^O 
 
 rHlC5<Mi inH 
 
 t-H CO 
 
 CO 
 
 asiOt^^OO^COOiOCDO-^O 
 i-H COi-H CO-rJl rH CO i I 
 
 CO 
 
 i I CO CO (M (M CO CM 
 
 CM<Mr-lrH 
 
 CO 
 
 co "* -^ ^ oo i i 
 CM CM CM CM 
 
 CM 
 
 i-H CM 
 
 
 -II 
 
 ^ IO 00 i CM t~ OO 
 
 CO CO CO 
 
 <M CO 
 
 Cs , lOOOOii iCMCOt-OOCOCs 
 
 N C*- ^fj i v_? I WM <TJ ^T viJ US i ^> U<J VJJ r I M ^iJ t> UU C^3 CS 
 
 t^t-t^ |OO JOOOOOOOOOO |OiC5C5OOOOi ICMCM 
 
 G 3 
 
130 
 
 THE COMETS. 
 
 OO 
 
 o 
 
 CO 
 
 t 
 
 
 
 CO t^ 
 CO CO 
 
 00 O5 
 CO CO 
 
 CO CO 
 * * 
 
 o o 
 
 OO 
 CO 
 
 GO c<j 
 
 CO ^H 
 
 00 iO 
 
 01 CS 
 O5 O5 
 
 
 
 I 
 d I 
 
 fc 
 
 i lOOOiOOi ilo^oO *O> -* CO *O CO )O IO i 
 
 cocqt-coiooorHi icq oooxot>- 1 d^-^i< 
 
 ^oooooooooc4oooooooorHG>d 
 
 00 
 
 i 1 rH ^ <M CO 
 
 t-OOCOrHCOrHrHt- 
 
 ndin 
 ode. 
 
 co 
 
 o 
 
 rH 
 
 CO 
 
 lOO 
 COCO 
 
 Longitude 
 of 
 erihelion. 
 
 'CO 
 t>. 
 
 (MiOCOCOCO^OrHCO 
 
 o 
 
 i trHC^C<| 
 
 111 
 
 e l 
 
 1 1 
 
 CO(7<|COrHrH rH-^rHlOrHrHCOr ' 
 
 ' lOOOO 
 
 iiiiiiiiliSiiiiiliiiii 
 
 '"'(MCOi 
 ICOCOl 
 
 1 It-fc- 1 
 

 CATALOGUE OF ORBITS. 
 
 131 
 
 r-H CO CO 00 IO O S 
 
 OOCOO5O5 Ci OO OCO -rH 
 
 O5 r-H CO -^ICO^CM O5 -rH CO CO 
 
 -^1 ^ rH OO T^l CO rH O5 CM O5 *O "^1 CO 
 
 ** CM *O CO CO O5 05 CO CO 00 O5 O50O OO 
 
 co as oo oo oo o o o t- CM as co t- ^^ 
 
 OOO5t>.t>.i>. OOOiCO O Oi O CO CO 
 
 O^OOO rHrHOO rH O OO O 
 
 IJ _ 
 
 rHCMOOiOCOiOr-H^t-COOOO51>COOOO^T lOCMCOOOCMOrH 
 
 CMCOO5t^CO^COCMCO^COOOOOOOr-ICOCMOOO^ICOOO^COOOrHai 
 lO^OOCM^^^OOCOCOCOi lCOCMCOCOiOJOrH^XOl>.COI^^OOO 
 
 ^iOCOrHCOCOCO^OC5asOOSrH'^t>-OiOt>-O5^H^Ht>.t I^CO-*CO 
 
 lO^^^HlOCOlOt-OS^OOCOCOCOCOCOCOCi^rHCO^tO 
 iO ^COCOCOCMrHr Ir-HCOr ICMCOCM ^rHiO"* rHCOCOiClrH 
 
 o oo o 
 
 "^l "^4 CO rH rH rH 
 
 CO CO rH rH CO ^O CM CM rH CO "^f* CO 
 
 r-H r- 1 
 
 CM T-HrHrHrHrH CMCMrHr-H rHrH CM COrHrH 
 
 r-H r-H rH r-H rH rH CM rH CM rH CM rH CO ^O T-H CO "^1 ^O ^^ CO CM "^1 
 
 j^T^rHCOCOCOCMrHrHr-H" CO CMCMCM^ r- 1 CM rH rH 
 
 rH O5 
 
 rH CM r- 1 rH r-H ~ ~i IT iCMCM'rHrHrH CNCM' 
 
 rHr-HCM t-H rH r-H CM rH T IT I rH^COCM CM rH i I CM CM CO rH 
 
 p-^ ^ ^ If a "^ o ^.o o > J J 
 
 M M M 
 
 CO C5 O 
 CO CO I CO b- 
 
 CM i CO -^ O5 O i rH I CO 
 i^. t- t- t- 00 GO OO 
 
 CO , b- 
 00 00 
 
132 
 
 THE COMETS. 
 
 *a *c8 *3 
 
 S^H rSJI 
 
 
 
 
 
 o 
 W W 
 
 
 id i I CO 
 
 co i i CM 
 
 CO CM GO 
 1^ ^ GO 
 ^ CO GO 
 CO t^ -* 
 i>. OS GO 
 
 000 
 
 I I 
 I I 
 
 T-H O 
 CO i I 
 t- GO 
 
 i IGOCM 
 
 000 
 
 i-H i I CM O 
 
 T^H -rH GO CM CO 
 
 ^H I-H OS 
 CO CO CM 
 
 rHCOCOCOr-H CMCO 
 
 i lCM^OCMCOCOi-HOO-*CO 
 
 ,co co co 
 
 .CO 
 O 
 
 CM 
 
 CO 
 O CO r-i 
 
 iO I-H 
 
 .j c* (-^ <-*J IN ^N ^i^ r 
 
 r-H i I ^ rH CM i-H CO 
 "^^ i H CM CO 
 
 CO "^i i-H CO "^n T-H 
 
 CO CO -^ CM I-H -*i CM 
 
 CO 
 
 VN K^ W4 ^^/ u 1 ^ ^** s^rf 
 
 u^c-t^cocooscoo^o 
 
 COr-Hi-HCM l-HCMi-HCO 
 
 CO I-H CM CO 
 
 i i t- CO 
 
 CO I-H CO 
 
 CO ^ CO CM -^ CM 
 
 rH COCM 
 
 -00 OS 
 
 OSCMOCOi-HCOCOlOGOlOi-HCOCMOS^^COOCOCMOOCO 
 
 Oi CMCOiOi-Ht^COCOCMl>-l>-tOOS^tlOCO OSOOCO'^i^O 
 
 i I CM i I CM I I r-H i-H i-H r-H CO i I r-H 
 
 PA 
 
 s.i.1 
 
 . 1C CO CO GO 
 ^CM r-H *0 
 
 ICO i I CM CO^COCOi-HCOCOCMCMCO 
 
 OOl>-lOCOCOO^iOOOSCM!-HCOiOi-HCOi itOCM 
 i-H i-H CMi-H i I r-H i-Hi-H CM r- ( CM i I rH 
 
 | __ lC q,_ l ^-(CM(Mi *<M 
 
 GO GO i I CM OS ^ T-H J>T c> GO O5 CO I-H 
 CM CM CM CO CM r (CM 
 
 hJ M 
 
 = : l I 
 
 . * . ^ . " t T 
 
 OS OS 
 
 OSOSOSOS 
 
 OS I O O O O 
 t^ ' GO GO CO CO 
 
CATALOGUE OF ORBITS. 
 
 133 
 
 I 
 
 1 '111 11 -I 
 
 ^tiiif iif 1 ill Illiilf 
 
 CO CO !> OS CM 
 *O CO <M O rH 
 
 01 CO I-H ^H 
 "* O O l>- JO 
 O iO O C<1 ^H 
 
 01 Oi Oi OO 1O 
 C5 O5 C5 Oi C5 
 O O O O O 
 
 t- CO 
 
 Oi 05 
 
 CO CO 
 Ci C5 
 O O 
 
 o *o 
 
 O^ "^^ 
 rH t^ 
 
 tO GO 
 
 o o 
 
 ootoi looascoi i^^HiO 
 COT icoait^t^aaioioto 
 ooo^oooococococo 
 as o co co co co as o o o to t- 
 
 ^ 
 
 13,4 
 
 o T i co co co t-- oo o 10 co oo 
 
 CO 
 
 r-HtOrH (MC^ 
 
 COCO<MrH 
 
 COCOCOOO 
 t-HOOi I t 1O i I CO 
 
 rHrHrHCOr-HCO 
 
 co 
 
 co 
 
 -H co 
 
 CO 
 
 CO tOrHCOCO 
 
 i-H G^ 5^(7<1 
 
 COrH^(^rHCOlOCOrHG<J^(^OO 
 <M (M "^ 1O rH^iOrHlO^COCO 
 
 COC^fr^C^^lOCSiOCOtOCOt^-C^ 
 
 (7qcqrH(?q T-H <M r- 1 
 
 r^otfod'<^<^ eC *cTcCc'5feCcrcr' 
 
 (Mi I rH rH rH rHrHrHrHrH rH(jq<M CM CM<MrH(M(?q CMrH 
 
 W S w M M S M S M MM>; M SH 
 
 cot^oo, lOrH. . , <j?i eo i MS <D 00 i o> . 7 4 1 ~ l *** i t 
 
 000 I 1-4 vH. r-trHrHrHr-HrH (N(M 
 
 oooooo' 'cooo 1 'Gooo'oo'oooo'oo 1 'ooco 1 ' 
 
THE COMETS. 
 
 pq 
 
 p p tf ft ft tf ft ft rt ft 
 
 r-H IO 
 
 i- 
 
 iO O b- 
 
 00 O5 <M 
 OO CO t>. 
 00 CO iO 
 -* iO O 
 ^ O5 -rH 
 OO O5 J>- 
 
 O 
 
 iC *O CO 
 ^=H 00 
 CO (M OO 
 
 t>. o co 
 
 <M ^ CS 
 
 C5 HH Oi 
 
 C5 00 Oi 
 ^ 
 
 
 r-lT 100 
 
 i (OOC^ 
 
 rHOO OiOOOi-HCOCSair I 
 
 r-n O O r-i rH O O O ft O CM O O O O O O O O O O 
 
 T iCO(MOO 
 
 -CO i-HCOCOCO^^<MCOCO 
 
 11 CO ^ -^ CO 
 
 (MlOOO^O 
 CM CO CO <M 
 
 O 
 CO 
 
 ndi 
 
 OO^(MOCO 
 r-ICOrHrH i 1 
 
 CO <M <M ) i 
 
 T I CO CO 
 
 fr-t>-OC5C5rHi (CO 
 CM i( CO <M <M <M iO 
 
 COOOr-H-^COOOCO 
 (Mi iCOi iCOCMCMCO 
 
 of 
 
 rihe 
 
 -t- O 
 
 i i co 
 
 <Mt>-Or-iiOr-i 
 
 co <Mco 
 
 
 CO 
 
 Oi 
 
 r-lOi lb-l>.r (rHCi 
 COCOCOiOi 1 r-H r-H IO 
 
 O t>- <M (M O 
 
 iOlO' 1 r-l , 1 
 
 (N i-H CM CM CO 
 
 I-H <?q <M 
 
 
 III 
 
 CO ^l 
 
 cq <M 
 
 oo oo 
 
 oo 
 
 (M CO 
 00 00 
 
CATALOGUE OF ORBITS. 
 
 135 
 
 CM 
 TH 00 
 rH CO 
 
 CO C* to O 
 to O b- to 
 CO C5 b- O 
 
 O co i i CM 
 tO b- to O 
 
 H/i CO ^H O 
 
 GO 05 oq o 
 O O O rH 
 
 CO r-l 
 
 CO ^H 
 
 oo co 
 
 00 CM 
 b- CO 
 
 OS O5 
 
 05 05 
 O O 
 
 CO ^H 
 O 
 
 O5 
 
 CM O <M 
 
 tO O5 O5 
 
 00 b- OO 
 
 O^ "^^ Oi 
 
 CO ^ O5 
 
 O5 GO O5 
 
 O O 
 
 00 CO O5 ** O5 O5 CO 
 O5 CM CO to CO to OO 
 b- CO CO O tO to O 
 T H Oi C^J iO ^O C^ CO 
 O to CO CO b- b- O5 
 ^^ iO ^O *O ^ ^H O^ 
 
 o to to to co co os 
 
 rH O O O O O O 
 
 rH rH O rH O O 
 
 o o 
 
 CO CO CO t> to Ci CO !> CO CO 
 
 r ICOCMtOlOtOrH 
 
 CO 
 
 CO CM rH ^tHrH 
 
 ^CNOOCOCOOO^to^HOi 
 
 COI>.-^CMC^tOCOtOCOrH 
 CO Cq CO CM CO CO rH 
 
 COCOCOOO^t-rHrHt-t-CiCSOSCOCOrH 
 
 cocooo^coo totoooocococo 
 
 CMCMrHCMCOCM T IT I CM CM CM 
 
 rHlOOrHCOCMCOrHb-rH OOCMOrHO5J -,,_., 
 
 i tOCO^CMCOCMrH rHrHCMCOCMrHCOCOCMCMCOCMCMCOCOCM 
 
 rHCMrHCMCMCMrHCOrHrH 
 
 CO i I CO CM CM CM CM 
 
 CO CO 
 
 COCMCM^tOCOOOCMOO COC^^^OOCMOSOOrHCOrHrHrHrHOO 
 
 CMrH rHrH CM rH CM rHrH CM rH (jq^Mr-lrH 
 
 CO "^^ to i i OO ^^ 
 
 co co co co 
 
 I m 
 
 oo oo oo 
 
 GO 00 
 
 B > ~ B ^ 
 
 II CM i CO 
 
 ^ ^ 
 
 I GO I OO 
 
 00 
 
136 
 
 THE COMETS. 
 
 WWb 
 
 i . . Si -i 
 g.l'S'SlI 
 
 (ii k^ .* *i ? ^ a* "^r? 
 
 ptfpqppppppptfp 
 
 CM CO O O tO rH 
 
 co CM co o oo co cs 
 
 CO O O CO OO "* OO 
 -* -rH O -* CO CM O 
 
 t^ <M t- ^H co CM CM 
 
 OS tO 05 OS CO CO 
 
 3 
 
 OO OJ t>> i>- t>- OS OS t>- 
 
 d d d d d d d d 
 
 10 
 o 
 
 CO CO 
 
 co co 
 
 rH 00 
 
 CM OO 
 
 
 
 
 o co os oo CM oo 
 
 OtO^O^tot^COCM^CM^iCOCSI>. 
 
 <MrHCOCOOrHt>.-^OrHt>.COCMCOt>.^CO) IrHt^rH 
 lOrHlO-^rHi tOOOCOOOCOCOCOt^OOCOOOtO^t^- 
 
 tOtOOtOOOCOOOtoiOtOCOCOt^COCMCOCOCMrHOOCO 
 
 O O O rH O O O rH O O O O O rH rH rH O O ^ CM* rH rH 
 
 o 
 
 Oi CO l>. rH 
 
 CM^OCOOSOO^HCOCOrHCOCMCOO 
 -CM COCOCOtO CO tOtOtOrH-rfHto 
 
 rH CM ^ rH 
 
 COCOOCOrHlOt-CO^I 
 
 -co co to CM -rH to CM co 
 
 CO CO 00 00 CO 
 
 coiotocM^tioorHcrscooot^ 
 
 CO CMrH^COCOCOCM 
 
 rHOOiOSOOCiCMCO 
 I t- CO 00 
 
 o o to to 
 
 COCOOOOOtocOCOCM 
 
 os co 
 
 "CO CM "* 
 
 rH OO CO 
 
 DCO rH CO 
 
 rH CO 
 
 U5 
 
 CO 00 00 
 
 CO CO 
 CO CM 
 
 OS rH 00 CO CO OS tO 
 CO 'T^ ^O G^ CO 
 
 OS -*H 
 
 1O rH 
 
 rH O CO rH 
 
 co -^ CM co 
 
 ^ rH IO CO 
 
 CO rH 
 CO rH 
 
 o co co oo CM 
 
 ^ CO CO rH rH 
 
 CM CM t b r* O 
 
 O O i>- t CO CO 
 
 rH rH rH CM 
 
 00 rH rH OS t>- CO t- 
 CM tO -^ ^ tO ^ rH 
 
 O rH 
 
 CO CO 
 CM'CM 
 
 rH CO CO 00 
 
 CM t~ t>- CO 
 
 rH CO 
 
 %<*% 
 
 ^.O CM OS 
 -t I CO CO 
 
 O OS 
 
 O CO rH 
 OOO OS OS 
 rH CM 
 
 O5 CO CO rH 
 
 <^ T^H to OS ^^ 
 CM CM rH rH 
 
 CM OO 00 t- t^ CM OS 
 
 CM CM CM CM co ^ 
 
 Oi CO CO 
 O rH rH 
 
 o CM os 
 os oo co 
 
 CM 
 
 to -* o o o o ^ 
 
 CO tO tO tO rH CO CO 
 
 t O *O rH l>- i^ rH 
 
 CO rH CO rH *<*! 
 
 O CM 00 CO rH rH CO 
 
 ^H CO OS t^ ^ CM -^ 
 CM rH CM * CM 
 
 CO -* 
 CM ^ 
 
 00 CO CO O 
 
 CM to 
 
 r I 
 
 tO CM 
 
 CM t^ OS 00 CO l>. rH 
 ^ to to to CO 
 
 CO !> 00 CM CO rH CM 
 CM rH rH <M 
 
 CO CO CO 00 ^ t- t^ 
 
 CM to CM co rH co 
 
 CM 
 
 CO CO 00 O 
 
 * 
 
 M V^c 
 
 "* I OO 
 
 oo 
 
 H? M 
 
 ill! I I I I M 
 
CATALOGUE OF ORBITS. 
 
 137 
 
 J__>- 
 
 D' Arrest. 
 G. Rumker. 
 Sonntag and 
 Quirling. 
 
 ^ rH 
 
 j . "i 1 $ *B "i $ $> . 
 
 8 & fc E -2 ^ L E ^ -3 8 ^ 
 
 11 w J 1 1^ 3 *1 * 1 1 
 
 P3 <u ^> *x o o Lp ^ %, kP o & o w 
 
 RPHr^ft^5Cr > r^ftP > GQrH 1 cy2^ 
 
 ij Atftf 
 
 ftftftftPPPftPftfiQtfA 
 
 (M 
 
 o 
 
 s 
 s 
 
 1 5 . 
 ~l 
 
 O O CM IO CO CO 
 OO O O5 rH CM IO 
 CM CO rH OO Jt- t- 
 
 oo oo o oo co ^ 
 
 t^ fr- IO O t^ CM 
 
 "* O5 IO CO -HH O5 
 OO O5 IO CO OO ^ 
 00 
 
 ] O O5 CO 
 
 ! 05 05 05 
 
 I t- O5 05 
 f OO CM rH 
 
 i' ^f co co 
 
 COCOCMCOO5rHCOCOOOCOCMlOCMCO 
 Ot-COCOCOlO^O505COCO^tHOO 
 l>-O5O5-HH^rHlOO5COrHrHt^lOrH 
 COlOlOO5O5OOCOO5t-GO^COOlO 
 COO5rHGOOOOlOCOrHO5rHCOO5CM 
 
 J O 
 
 OOrHOOrHOrHrHOOOOrH 
 
 10 rH 
 
 CM IO IO 
 
 00 -* 
 rH CM 
 
 23 
 
 1 
 
 CO^HO5CMO500t-OCMt-^H^H-HHCM 
 CO ^O O i~H CO "^^ r~H ^O *^H ^O ^O CO 
 
 OOCMO5O5lOCMlOrHCOCOO5l>.CMOO 
 lOlOrH CMIO^IO 1O1O 
 
 COlOb-COCOOOOrHCOt-COCOOOO 
 rHOOCOCOCOCO^rHrHCOt^rH^^tl 
 
 O5 CO O5 
 ^ IO (M 
 
 OO IO CM 
 ftf IO CO 
 
 O5 O rH 
 05 rH 
 CO rH CM 
 
 CM^HCOOOOCO^lOOt->-rHCMlO 
 rHlOlO^l lOCMCOCMrHCOCMCMCM 
 
 CMCMCMrHCMCMO5Ot>-O51OCOOOCO 
 CMrHCOCOCOlOlOCOCM CMCM i 1 
 
 -r^ 10 CM o o CM 10 05 oo co ^ -^H t>- co 
 
 COrHOCOCOOSOO-^CM^COrH^H 
 COCMCM CMCMrHCM COCOCO 
 
 CO rH 05 
 rH CO 
 
 cq co ^ 
 
 rH CM CO 
 
 05 * 
 t- t^ rH 
 CM CO 
 
 OOlO'*OOOOO'rHOCOCMOOCMCOCO 
 
 I 1 CM rH lOlO^^lOrH COrH 
 
 t>.^COCOCOCOCOCMO5CMlOrHOCM 
 ^rH-rfrl CMrH^lOrH-rtHlO rH 
 
 t>-COlOt^t^COO5O5CMrHOOt^OOO 
 lOCOCOCOCOl>-OO-^CMrHCOlOOO^ 
 rH CMCMCMCM COCOCOrHCM 
 
 CM ^ CO 
 CO T* rH 
 
 COrH^OCOOOOlOOOOCMOOCMCO 
 ^CMlOrHlOCMrHlO^ICMrHlOlO 
 
 CMOOrH^-^CMOOrHCOt^OSOOCOlO 
 
 11 
 
 rH ^H 
 
 05 ^H 00 
 "&J "^ 
 
 1 mfam 
 
 COO5COOOOOCOO5COOOCOO-^O5CM 
 (Tq.-HCM CMrH CMCOrHrHr-i 
 
 S : ?3 
 
 2 '2 
 
 IO5 i V i O rH i 7 i CM "T* 
 -* 10 10 10 
 oo 1 ' ' oo oo ' > ' oo ' 
 
 1 1 i-H i 1 I 1 
 
NOTES 
 
 TO THE 
 
 CATALOGUE OF COMETARY ORBITS. 
 
 B.C. 
 
 370. Elements assigned by Pingre from the account given 
 by Aristotle. 
 
 136. The orbit of this comet is founded upon the Chinese 
 observations which have recently become known 
 in Europe. Like most of those which follow, and 
 are based upon the Chinese records, it is necessa- 
 rily open to a good deal of uncertainty. 
 68. From Chinese observations. 
 
 11. Elements assigned on the supposition of the identity 
 of this comet with that now known as Halley's. 
 The orbit given in the American Almanac for 
 1847, and copied into Encke's recent edition of 
 Gibers' Abhandlung, will not represent the obser- 
 vations as published in M. Biot's Catalogue. 
 
 A.D. 
 
 66. The few circumstances related by the Chinese respect- 
 ing this comet, may be represented either by the 
 orbit in the Catalogue, or by carrying back the 
 elements of Halley's comet to the epoch. 
 
140 THE COMETS. 
 
 141. From Chinese observations. The similarity between 
 the elements of this comet and that of 1066 is 
 pretty certain probably an appearance of the 
 comet of Halley. 
 
 240. Chinese observations. The elements somewhat 
 doubtful. 
 
 539. Chinese observations. 
 
 565. Chinese observations on two different suppositions 
 respecting the comet's distance from the earth, at 
 the first and third observations. 
 
 568. Also founded upon the Chinese records. It is 
 perhaps, however, the most certain orbit deduced 
 from these authorities, as the comet approached 
 very near the earth, and was observed several 
 months. 
 
 574. Chinese observations : the elements are open to 
 much uncertainty. 
 
 770. Chinese observations : rather uncertain, but the 
 general character of the orbit is decided. 
 
 837. These elements belong to the first or grand comet 
 of this year : they appear to represent the obser- 
 vations, Chinese and European, as well as could be 
 reasonably expected. 
 
 961. The observations of this comet, recorded in the 
 Chinese annals, are amply sufficient to give a very 
 fair idea of the real path in space. 
 
 989. Chinese observations : probably an appearance of 
 
 Halley's comet. 
 
 1066. The famous comet which astonished Europe in the 
 year of the Norman conquest ; very likely the 
 comet of Halley, which was due about this epoch; 
 the orbit assigned is very similar. 
 
 1092 1 
 
 10Q7 i -^ rom * ne Chinese observations. 
 
NOTES TO THE CATALOGUE. 141 
 
 1231. Calculated by Pingre on the European and Chinese 
 records. We find there is a great likeness between 
 the elements of this comet and those calculated 
 for the comet of 1746, observed only by Kinder- 
 manns. 
 
 1264. A grand comet, supposed to be identical with that 
 
 of 1556. Pingre*'s is the most satisfactory orbit. 
 
 Mr. Dunthorne's depends on a recital by Friar 
 
 Giles, of Cambridge, containing several manifest 
 
 - contradictions. 
 
 1299. Chinese observations. 
 
 1301. Probably an appearance of Halley's comet. M. 
 Laugier has been led to a different orbit, from in- 
 cluding two observations purporting to have been 
 taken by Friar Giles, at Cambridge; but there is 
 some doubt respecting them. 
 
 1337. A very fine comet, and the first which appears on 
 Halley's list, in his Synopsis of Cometary Astro- 
 nomy. The elements there given were founded 
 upon the particulars related of this body by Nice- 
 phoras Gregoras, the Byzantine historian. The 
 Chinese annals, more recently known in Europe, 
 contain a more decisive account, and it is upon 
 this authority that the orbits of Pingre", Laugier, 
 and the author, have been computed. 
 
 1351. A few Chinese observations without latitudes. 
 Yery uncertain. 
 
 1362. ) Chinese observations; uncertain, particularly in 
 
 1366. / 1366. 
 
 1385. Chinese observations; but they are sufficiently 
 definite to give a general notion of the orbit. 
 
 1433. Chinese observations : tolerably certain. 
 
 1456. The celebrated comet of Halley. The elements are 
 partly adapted to the observations left by Eben- 
 
142 THE COMETS. 
 
 dorffer and others. The comet was observed also 
 in China. 
 
 1457. European observations a mere approximation. It 
 appears certain that the perihelion distance was far 
 greater than in the case of any other ancient 
 comet. 
 
 1468. Chinese observations j but the orbit must be open 
 to a good deal of uncertainty. 
 
 1472. One of the most splendid comets recorded in his- 
 tory. M. Laugier's elements are based upon a 
 minute recital of particulars relating to the motion 
 and positions of the comet, found in the Chinese 
 annals. It approached veiy near the earth, and 
 the plane of its orbit appears to have been nearly 
 coincident with that of the ecliptic. 
 
 1490. Chinese observations. The elements have some 
 resemblance to those of the comet found by Bre- 
 micker, in October, 1840, and which, according to 
 Gotze's calculation, should have appeared at the 
 latter end of the fifteenth century ; but it does 
 not appear easy to reconcile the observations of 
 1490 with the elements of the comet of 1840 
 probably the bodies were not identical. 
 
 1506. Chinese observations : elements somewhat uncer- 
 tain. 
 
 1531. The comet of Halley, observed in this year by 
 
 Peter Apian, at Ingoldstadt ; and likewise in 
 China. 
 
 1532. It is still uncertain whether this comet is identical 
 
 with that observed by Hevelius in 1661. The 
 elements of Halley and Olbers are very like those 
 of the comet of 1661 ; but Mechain, who dis- 
 cussed this question at considerable length, gives 
 an orbit materially different. It was not re- 
 
NOTES TO THE CATALOGUE. 143 
 
 observed about the year 1790, as anticipated by 
 most astronomers. 
 
 1533. There is no comet whose elements are subject to 
 greater doubt than that seen by Apian in 1533, 
 as a comparison of the results of Olbers and 
 Douwes will prove. Both orbits, according to 
 Olbers, represent the few observations recorded, 
 and it appears impracticable at present to decide 
 between them. 
 
 1556. Generally supposed to be a re-appearance of the great 
 comet of 1264. The elements calculated by the 
 author are the results of a close examination of the 
 observations of Fabricius and others, and appear to 
 represent all the circumstances recorded of the 
 comet with sufficient accuracy. 
 
 1558. From the observations of the Landgrave of Hesse 
 and Cornelius Gemma. 
 
 1577. The elements of this comet were first calculated by 
 Halley ; but the orbit given in the Catalogue is 
 the result of a new discussion of Tycho Brahe's 
 observations, by Dr. Woldstedt. 
 
 1580. This comet was roughly observed by Tycho Brahe; 
 the positions are frequently uncertain to ten minutes 
 of arc, and the elements are consequently some- 
 what doubtful. Halley also computed an orbit 
 upon Msestlin's observations. 
 
 1582. Three observations only by Tycho. The elements 
 are uncertain, but the first set is to be preferred. 
 
 1585. Both orbits have been recently computed, in order 
 to decide the question of the identity of this comet 
 with that found by M. de Vico, in August, 1844. 
 Dr. Peter's elaborate paper upon the comet is pub- 
 lished in the Astronomische Nachrichten. The 
 observations of Tycho Brahe and Rothmann are 
 
144 THE COMETS. 
 
 perfectly represented by a parabola ; and according 
 to Le Terrier, there is no probability in favour of 
 the identity. 
 
 1590. Founded upon Tycho's observations, which were 
 reduced anew by the author. 
 
 1593. From the observations of Bipensis at Zerbst. 
 
 1596. The elements have been recently calculated by M. 
 Talz and the author, in consequence of an apparent 
 similarity between the comet of 1596 and that of 
 June, 1845. Halley had previously calculated the 
 elements upon Mosstlin's observations, and M. 
 Pingre" upon Tycho's. Both the new determina- 
 tions are founded upon the details left by the 
 Danish astronomer. 
 
 1607. The celebrated comet of Halley. 
 
 1618. (i.) Pingre"'s orbit depends upon the somewhat im- 
 perfect observations of Kepler. 
 
 1618. (n.) This splendid comet was one of the finest 
 ever observed. The elements were calculated by 
 Bessel from the observations of Harriot, Longo- 
 montanus, and others. Halley had previously de- 
 termined the orbit. 
 
 1652. A fine comet observed by Hevelius. It would be 
 worth while to reduce his observations more accu- 
 rately,, and work out another set of elements. 
 
 1661. Formerly supposed to be identical with the comet 
 of 1532 ; but this is now doubted. Halley first 
 assigned elements in his Synopsis of Cometary As- 
 tronomy. Mechain's will be more exact. Observed 
 by Hevelius. 
 
 f The orbits of these fine comets were calculated 
 I by Halley from the observations of Hevelius. 
 ' \ Lubienietski wrote a folio volume upon them, 
 1 in which are found many observations, inferior, 
 however, in accuracy to those of Hevelius. 
 
NOTES TO THE CATALOGUE. 145 
 
 1668. Calculated from the positions laid down in a chart 
 of the comet's path in the heavens, by Father F. 
 de Gottignies, of Goa. This has been supposed 
 to be identical with the grand comet of March, 
 1843. The elements are very uncertain. Either 
 of the orbits given in the Catalogue will represent 
 approximately the apparent track of the comet. 
 The chart has been re-published at Rome, under 
 the title 'Estratto delle osservazioni fatte sulla 
 Cometa del 1668.' 
 
 1 672 ) 
 
 valJ V From the observations of Hevelius at Dantzic. 
 
 1677. j 
 
 1678. Observed roughly by Lahire at Paris. It is con- 
 
 sidered to have been an appearance of the periodical 
 comet of De Yico by Le Verrier, who has shown 
 that elements closely approaching those of that 
 body will satisfy all the particulars recorded of the 
 comet in 1678. These elements are given in the 
 preceding table. 
 
 1680. The celebrated comet which led Newton to the 
 study of cometary astronomy. The elements in 
 the Catalogue are the results of Encke's masterly 
 investigation, published in the Zeitsclwift fur As- 
 tronomic, 1818. 
 
 1682. The comet of Halley. Rosenberger's last orbit, in 
 
 which perturbations are taken into account. 
 
 1683. Elliptic elements computed by Clausen from a new 
 
 reduction of Flamsteed's observations at our Royal 
 Observatory. The periodic time found by this 
 astronomer is 190 years ; but little dependence can 
 be placed upon a result of this kind. 
 
 1684. Observed by Bianchini at Rome. 
 
 1686. Observed in Europe in September, but previously 
 (in August) in the East Indies. 
 H 
 
146 THE COMETS. 
 
 1689. A fine comet observed very roughly by Father 
 Richaud at Pondicherry ; and by Beze and Comille 
 at Malacca, &c. 
 
 1695. Observed still more imperfectly than that of 1689, 
 in the southern hemisphere. The elements were 
 calculated by Burckhardt, upon manuscript obser- 
 vations preserved in the Depot de la Marine at 
 Paris. 
 
 1698. Somewhat roughly observed by Lahire and Cassini 
 at Paris. TIalley does not give the orbit with 
 much confidence. 
 
 1699. Observed by Cassini and Maraldi at Paris, and by 
 Fontenay at Pekin. 
 
 1701. Calculated by Burckhardt from the observations of 
 
 Fathers Pallu and Thomas, at Pau and Pekin re- 
 spectively. 
 
 1702. Observed in April and May at Paris, Berlin, and 
 Rome, but not very accurately. The inclination 
 of the orbit is very small. 
 
 1706. Observed at Paris by Cassini and Maraldi. 
 
 1707. Found at Bologna by Manfredi and Stancari on 
 
 November 25, and four days later by Cassini and 
 Maraldi at Paris. If this comet had reached its 
 perihelion about fourteen days later, it would have 
 passed very near the earth at the end of October. 
 
 1718. From Kirch's observations, which Argelander has 
 reduced anew. 
 
 1723. Discovered first at Bombay on October 12th; and 
 observed after the 20th in England by Halley, 
 Bradley, and Pound, and in various other parts of 
 Europe. The orbit has been recently calculated 
 by Sporer, from a new reduction of the observations. 
 
 1729. Discovered by Father Sarabat at Nismes, on July 
 31, and observed until the 18th of January, 1730. 
 
NOTES TO THE CATALOGUE. 147 
 
 The orbit is remarkable for the enormous perihelion 
 distance, far exceeding that of any other comet 
 hitherto calculated. The first orbit is hyperbolic. 
 
 1737. (i.) Observed and calculated by Bradley. Also by 
 Cassini at Paris, and Manfredi at Bologna. The 
 comet appears to have been first seen at Spanish- 
 town, Jamaica, on the 6th of February. 
 
 1737. (n.) Observed at Pekin, but only approximately. 
 
 1739. Chiefly observed by Zanotti at Bologna, where it 
 was discovered on the 28th of May. 
 
 1742. Seen in all parts of Europe, but first detected at 
 the Cape of Good Hope on the 5th of February. 
 
 1743. (i.) Very imperfectly observed, after the 10th of 
 February, at Berlin, Paris, Bologna, and Vienna. 
 Clausen thought this comet might be identical 
 with the fourth of 1819. His calculations assign 
 a period of about 5 years. 
 
 1743. (11.) Observed only by Klinkenberg, at Haarlem, 
 after August 18th. The positions given are liable 
 to considerable errors. 
 
 1744. The finest comet of the eighteenth century. The 
 elements have been calculated by a great number 
 of astronomers, but those we have given in the 
 Catalogue appear entitled to most reliance. The 
 comet was discovered by Kliukenberg, at Haarlem, 
 on the 9th of December, 1743. 
 
 1746. Calculated by the author from the rough indica- 
 
 tions afforded by Kindermanns, who, strangely 
 enough, appears to have been the only observer of 
 this comet. It must have passed very near the 
 earth. The similarity between the elements of the 
 comets of 1231 and 1746 is striking. 
 
 1747. Discovered by Cheseaux, at Lausanne, in Switzer- 
 land, August 13th, 1746, and observed only in that 
 
 H 2 
 
148 THE COMETS. 
 
 year ; but the perihelion passage did not take place 
 until March, 1747. 
 
 1748. (i.) Observed by Maraldi at Paris, and by Bradley 
 at Greenwich ; also at Pekin. The positions de- 
 termined at our Royal Observatory may perhaps 
 lead to a more exact orbit. As far as we are 
 aware, they have not as yet been thoroughly dis- 
 cussed. 
 
 1748. (n.) Three observations only, by Klinkenberg, at 
 Haarlem, reduced and calculated by Bessel. 
 
 1757. Bradley's are undoubtedly the best observations 
 
 of this comet : they extend from September 13th 
 to October 18th, and are well represented by a 
 parabolic orbit, notwithstanding the small angle of 
 inclination and direct motion. 
 
 1758. Discovered by La Nux, at the Isle of Bourbon, 
 
 on the 26th of May, and observed in Europe till 
 the 2nd of November. The orbit depends on the 
 observations of Messier at Paris. 
 
 1759. (i.) The famous comet of Halley ; its first predicted 
 reappearance : was discovered by a Saxon farmer, 
 named Palitzch, on the 25th of December, 1758, 
 but not generally observed until April following. 
 The elements are the results of the masterly calcu- 
 lations of Rosenberger and Lehmann, and apply 
 to the moment of perihelion passage, the effects of 
 planetary perturbations being taken into account. 
 
 1759. (n.) Discovered by Messier, January 25th, 1760, in 
 Leo. Perihelion passage in the previous year. 
 
 1759. (in.) First seen at Lisbon on January 7th, and very 
 generally observed on the following night. The 
 comet approached near the earth, and its apparent 
 motion was unusually rapid. On the 8th of 
 January it was moving at the rate of 29 of a great 
 circle daily. 
 
NOTES TO THE CATALOGUE. 149 
 
 1762. Detected by Klinkenberg May 17th, and observed 
 until the beginning of July. The elements, like 
 those of most comets of the eighteenth century, 
 have been calculated by many astronomers ; but 
 the best set is that of Burckhardt, given in the 
 Catalogue. 
 
 1763. Both our orbits are elliptic ; in the first the period 
 is 7334, and in the second 1137 years: these 
 numbers are to be regarded merely as the results 
 of calculation. Pingre says he spent more time 
 over this comet than any of the others he had cal- 
 culated, but could not arrive at any satisfactory 
 conclusions. It was discovered at Paris, by Messier, 
 on the 28th of September. 
 
 1764. Also detected by Messier, on the 3rd of January. 
 1766. (i.) Discovered by Messier on March 8th, and ob- 
 served on the eight following days only. 
 
 1766. (n.) A remarkable comet, as exhibiting a deviation 
 from parabolic motion. It was seen by Messier 
 at Paris, on April 8th, and observed on the four 
 following days, but had been previously discovered 
 by Father Helfenzriede at Dillengen, on the 1st. 
 La Nux observed it at the Isle of Bourbon, after 
 perihelion passage, from April 29th to May 13th. 
 The periodic time assigned by Burckhardt is 1835 
 days, or 5*025 years ; but the comet has not been 
 recognised at any subsequent time. 
 
 1769. A great comet discovered by Messier on the 8th of 
 August, and observed until the 1st of December. 
 Amongst the numerous astronomers who watched 
 this comet was Dr. Maskelyne, of Greenwich, and 
 his description is amply sufficient to convey a 
 notion of its magnitude and splendour. The ac- 
 counts furnished by Pingre and others, which give 
 it even a more imposing aspect, have been already 
 
150 THE COMETS. 
 
 noticed. Bessel's orbit is the result of an elaborate 
 investigation published in 1808. He finds the 
 most probable period 2090 years ; but supposing 
 errors of 5" only in the observations employed, it 
 may be extended to 2673 or diminished to 1G92 
 years ; hence the observations leave us in doubt as 
 to the true period of the comet in 1769, to the 
 extent of nearly 1000 years. 
 
 1770. (i.) The celebrated comet of 1770 : discovered by 
 Messier on the 14th of June. At the beginning 
 of July it approached very near the earth. Burck- 
 hardt, Clausen, and Le Terrier, have distinguished 
 themselves by their investigations relative to this 
 comet. The latest results are those of Le Yerrier, 
 which were obtained at a vast expense of time and 
 labour, such as few but that eminent mathema- 
 tician and astronomer would have had the courage 
 to meet. 
 
 1770. (n.) This comet did not appear till January, 1771, 
 
 but the perihelion passage occurred in November, 
 1770. It was observed at Paris, at Milan, and at 
 the Isle of Bourbon by La Nux. 
 
 1771. Discovered by Messier, at Paris, on April 1st. Of 
 
 all the comets hitherto observed, that of 1771 
 affords the most decisive indications of hyperbolic 
 motion. Encke found it impossible to represent 
 the observations within their probable limits of 
 error by any other curve, a conclusion previously 
 arrived at by Burckhardt. 
 
 1772. The first recorded appearance of the Comet of Riela. 
 
 Bessel assumed a periodic time of 33 years, and 
 adapted the other elements accordingly. Gauss' 
 orbit was obtained by direct calculation. 
 
 1773. Discovered by. Messier on the 12th of October, 
 
NOTES TO THE CATALOGUE. 151 
 
 and observed for six months. Burckhardt found no 
 sensible deviation from a parabola. 
 
 1774. Detected at Limoges by Montaigne, on August 
 llth. Burckhardt's elements are hyperbolic^ and 
 depend upon Messier's observations of September 
 20th, October 8th and 25th. 
 
 1779. Discovered by Bode at Berlin, on the 6th of 
 January, and also by Messier at Paris, on the 18th, 
 without previous knowledge of Bode's observa- 
 tions. Many orbits have been calculated : Pros- 
 perin computed three an ellipse, a parabola, and 
 a hyperbola. Zach's elements, which we have 
 entered in the Catalogue, are probably amongst the 
 most exact. 
 
 1780. (i.) Discovered by Messier, on the 26th of October. 
 
 Cliiver recalculated the orbit at the request of Dr. 
 Olbers, with the view of ascertaining if there were 
 any probability in favour of a presumed identity 
 of this comet with the third of 1827; but not- 
 withstanding the striking similarity in the ele- 
 ments, this does not appear likely, as the obser- 
 vations are well represented by a parabola. The 
 period in Cliiver's ellipse is 75,320 years ! 
 
 1780. (n.) Detected on the same day, October 18th, by 
 
 Montaigne and Olbers, in Ophiuchus, and but very 
 imperfectly observed on three days only. The 
 orbit is therefore somewhat uncertain. 
 
 1781. (i.) Found by Mechain on the 28th of June. 
 1781. (u.) Also discovered by Mechain, at Paris, on 
 
 October 9th, near 8 Cancri. It was visible to 
 the naked eye, and approached pretty near the 
 earth. Mechain's elements satisfy all the obser- 
 vations well. 
 1783. Discovered by our countryman, Pigott, at York, 
 
152 THE COMETS. 
 
 on the 19tli of November. The comet exhibits 
 decided indications of elliptic motion. The period 
 assigned by Burckhardt is 5-613 years, but this 
 may probably be improved upon by a rigorous 
 discussion of the observations, which appears very 
 desirable. 
 
 1784. First seen by La Nux, at the Isle of Bourbon, on 
 
 December 15th, 1783, and found at Paris on the 
 24th of the following month. Last observed on 
 May 26th. 
 
 1785. (i.) Found by Messier and Mechain, on January 7th. 
 
 1785. (11.) Discovered by Mechain, on March llth. 
 
 1786. (i.) Found on the 17th January, by the same 
 
 diligent astronomer. It is the first observed 
 appearance of the comet of Encke. Only two 
 observations were procured. 
 
 1786. (u.) Discovered by Miss Caroline Herschel, sister 
 
 of Sir William Herschel, on August 1st, and 
 observed till the 26th of October. 
 
 1787. Found April 10th, by Mechain, at Paris. 
 
 1788. (i.) Detected by Messier, on November 25th. 
 1788. (n.) The second comet discovered by Miss Her- 
 schel, at Slough, near Windsor, December 21st. 
 
 1790. (i.) Also discovered by the same lady on the 7th of 
 
 January, but only imperfecjbly observed on four 
 
 occasions : the elements are consequently merely 
 
 approximate. 
 1790. (n.) Perceived by Mechain, on January 9th, two 
 
 days after Miss Herschel's discovery of the first 
 
 comet of 1790. 
 1790. (in.) Discovered at Slough, by Miss Herschel, 
 
 A pril 1 7th, and observed till the end of June. 
 1792. (i.) Discovered on the 15th of December, 1791, by 
 
 Miss Herschel, but the perihelion passage did not 
 
 take place till the following year. 
 
NOTES TO THE CATALOGUE. 153 
 
 1702. (11.) Discovered by Mechain and Piazzi, 011 the 
 10th of January, 1793; the perihelion occurring 
 in the previous year. 
 
 1793. (i.) Discovered by Messier, on September 27th, and 
 last seen on January 7th, 1794. 
 
 1793. (n.) A remarkable comet discovered by Perny, on 
 the 24th of September. Burckhardt assigns a 
 period of 12-13 years, and leaves it doubtful 
 whether this comet was identical with that of 
 1783 or not. Dr. D' Arrest, of Leipzig, has 
 recently reduced the observations anew, and finds 
 the orbit given in the table : period 422 years. 
 
 1795. The Comet of Encke, detected at this appearance on 
 the 7th of November, by Miss Caroline Herschel, 
 at Slough. 
 
 1796. Discovered by Olbers, at Bremen, on the 31st of 
 
 March. 
 
 1797. A rather conspicuous comet, discovered nearly 
 simultaneously, on August 14th, by Bouvard at 
 Paris, Miss Herschel at Slough, and by Mr. S. 
 Lee at Hackney. 
 
 1798. (i.) Discovered by Messier, April 12th. 
 
 1798. (n.) Found at Paris, by Bouvard, on December 
 
 6th ; and at Bremen, by Olbers, on the 8th ; it 
 was not seen after the 12th, so that the orbit is 
 not very accurately determined. 
 
 1799. (i.) Discovered by Mechain, on August 6th. 
 1799. (n.) Also discovered by the same astronomer, on the 
 
 26th of December, and observed for ten days. 
 Mechain thought it might be identical with the 
 comet of 1699, but the inclinations differ con- 
 siderably. 
 
 1801. Discovered almost simultaneously by Pons, at Mar- 
 seilles, and by Messier, Mechain, and Bouvard, at 
 H 3 
 
154 THE COMETS. 
 
 Paris, on the 1 2th of July, in Camelopardus. The 
 observations are not very exact. 
 
 1802. Discovered by Pons, on August 26th, in Ophiuchus, 
 and two days subsequently by Mechain 
 
 1804. Discovered by Pons, on March 7th, and observed 
 
 for about three weeks. Bouvard found it on the 
 10th, and Olbers on the 12th. It was situate in 
 the constellation Yirgo. 
 
 1805. The third appearance of Enclce's Comet. Discovered 
 
 on the same morning, October 21st, by Pons at 
 Marseilles, Bouvard at Paris, and Huth at Frank- 
 fort, in Ursa Major : it was then visible without 
 the telescope, 
 
 1S06. (i.) The second appearance of BieMs Comet. Dis- 
 covered by PODS, on the 10th of November, 1805. 
 It became visible to the naked eye. 
 
 1806. (n.) Discovered by Pons, November 10th, and last 
 
 seen on the 12th of February, 1807. 
 
 1807. The Great Comet of this year was found at Castro 
 
 Giovanni, in Italy, by an Augustine monk, named 
 Parisi, on the 9th of September, and eight days 
 later by the indefatigable Pons, at Marseilles. 
 It was observed until the 27th of March, 
 1808. Bessel's elements are the result of a 
 masterly investigation, in which all the observa- 
 tions deserving of confidence were included. The 
 periodic time assigned by this astronomer is 1714 
 years. 
 
 1808. (i.) Discovered by Pons on March 25th, and by 
 
 Wisniewsky, at St. Petersburg, on the 29th, near 
 the north pole of the heavens, in Camelopardus. 
 1808. (u.) Also discovered by Pons, June 24th, and 
 roughly observed for ten days at Marseilles. The 
 elements, though more than sufficient to identify 
 
NOTES TO THE CATALOGUE. 155 
 
 the comet if it should re-appear, are not very exactly 
 ascertained. 
 
 1810. Discovered on August 22nd, by Pons, in Camelo- 
 
 pardus, but only approximately observed, the right 
 ascensions exhibiting material errors, according to 
 Bessel's comparison with his elements. 
 
 1811. (i.) The Grand Comet. "We have already given a 
 
 particular account of this splendid comet, which 
 was first perceived by Flaugergues, at Yiviers, on 
 the 26th of March, and observed till the 17th of 
 August, 1812, by Wisniewsky, at Neu-Tscherkask. 
 Many ellipses have been calculated, in all of which 
 the period extends to more than 3000 years. 
 Bessel's orbit was corrected by Argelander, whose 
 results deserve the greatest confidence. 
 
 1811. (n.) Another fine, though much less conspicuous 
 
 comet, discovered by Pons, on the 1 6th of Novem- 
 ber, in Columba, and observed for three months. 
 Nicolai has thoroughly discussed the observations, 
 and assigns a periodic time of 875 years. 
 
 1812. Discovered by Pons, on the 20th of July, in Lynx. 
 
 Encke has assigned elliptical elements, the period 
 being 70*68 years. Early in September the comet 
 was distinctly visible to the naked eye. It was 
 seen till the end of that month. 
 
 1813. (i.) Discovered by Pons, on the 4th of February. 
 1813. (n.) Discovered April 3rd, by Pons, at Marseilles, 
 
 and by Harding at Gottingen. It became very 
 bright, and visible to the naked eye. 
 
 1815. The Go met of Olbers, discovered by that great 
 astronomer at Bremen, on March 6th, and last 
 observed on the 26th of August. Bessel makes 
 the periodic time, in 1815, 74-049 years, and 
 Nicolai, 74-789 years; but the former having cal- 
 
156 THE COMETS. 
 
 ciliated the perturbations onward to the next 
 perihelion, finds that it will be expedited con- 
 siderably, and will occur about February 9th, 
 1887. 
 
 1816. Discovered by Pons, at Marseilles, on the 22nd of 
 January. There is only one accurate observation, 
 taken at Paris on February 1 ; the others are 
 merely approximate. The elements were communi- 
 cated by Buckhardt, in a letter to Olbers, and have 
 only recently appeared in print, through the in- 
 strumentality of Dr. D' Arrest. 
 
 1818. (i.) Discovered by Pons, on December 26th, 1817, 
 but the perihelion passage occurred in the following 
 year; it was considered by Pons the faintest of all 
 the comets he had found. It was seen at Bremen 
 till May 1st. 
 
 1818. (n.) Discovered by Pons, on November 29th, in 
 
 Hydra; and by Bessel, on December 22nd, in 
 Cygnus, without knowledge of the previous dis- 
 covery. It moved very rapidly, and approached 
 pretty near the earth. Rosenberger computed a 
 hyperbolic orbit. 
 
 1819. (i.) A memorable appearance of the Comet ofEncke, 
 when its periodicity was detected, and since which 
 its returns have been regularly predicted. It was 
 discovered by Pons, on the 26th of November, 
 1818, but the perihelion did not take place till the 
 end of January in the following year. 
 
 1819. (n.) The Great Comet. Discovered in various parts 
 of Europe, on the 1st and 2nd of July, having 
 made its appearance rather suddenly above the 
 north-west horizon, in the constellation Lynx. A 
 parabola satisfies all the observations well: they 
 
NOTES TO THE CATALOGUE. 157 
 
 extend to October 20th. The comet was distinctly 
 visible to the naked eye, with a bright tail and 
 nucleus. 
 
 1819. (in.) The first of two remarkable comets observed 
 in this year, both of which exhibit every indication 
 of elliptic motion in orbits of very short period. 
 It was discovered by Pons on June 12, and ob- 
 served till July 19th. Encke assigns a period of 
 revolution of 2052 days, or 5-618 years. 
 
 1819. (iv.) Found by Blainpain, at Marseilles, on Novem- 
 ber 28th, and observed at Milan till the 25th of 
 January, 1820. The orbit appears decidedly 
 elliptical, and Encke makes the duration of a revo- 
 lution 1757 days, or 4 -8 10 years. Clausen thinks 
 this comet may be identical with the first of 1743. 
 
 1821. Discovered by Pons, at La Marlia, near Lucca, and 
 by Nicollet, at Paris, on the 21st of January; and 
 subsequently at various other observatories. It 
 was observed in Europe before the perihelion pas- 
 sage until March 7th, and was seen from April 1st 
 to May 3rd, by Captain Basil Hall, at Valparaiso. 
 The chief peculiarity of the orbit is the smallness 
 of the perihelion distance. 
 
 1822. (i.) Discovered by Gambart, at Marseilles, on May 
 
 12th, by Pons on the 14th, and by Biela on the 
 16th: it was situate in Auriga. It was visible 
 until the end of June. 
 
 1822. (n.) The first predicted reappearance of the Comet 
 of Encke, which was found by Riimker, at Para- 
 matta, New South Wales, on the 2nd of June, and 
 observed till the end of the month. It was not 
 seen in Europe. 
 
 1822. (in.) Found by Pons, at La Marlia, on the morning 
 
158 THE COMETS. 
 
 of May 31st, in Pisces. Its apparent motion was 
 very rapid, and it was soon lost below the horizon 
 in Europe. 
 
 1822. (iv.) Discovered by Pons, on the 13th of July, in 
 the constellation Cassiopea, and observed till Octo- 
 ber 22nd in Europe. Gambart saw the comet on 
 July 1 Gth. Ellipses have been calculated by Encke, 
 and by Riimker from his own observations at 
 Paramatta, extending to November llth. The 
 period given by Encke is 5444 years, while that 
 assigned by Riimker is 1816 years. Encke's orbit 
 is doubtless the most exact that has been computed. 
 
 1823. A fine comet, discovered in various parts of Europe, 
 
 at the end of December, and observed till the end 
 of March, 1824. This comet is remarkable as 
 having exhibited a tail directed towards the sun, 
 in addition to another in the usual position. 
 
 1824. (i.) Discovered at Paramatta, by Kiimker, on the 
 
 15th of July, in Leo, and observed there until the 
 llth of the following month. It was not seen in 
 Europe. 
 
 1824. (n.) Discovered at Chemnitz, by Scheithauer, on 
 the 23rd of July, in Hercules; by Pons on the 
 following day; and at later periods by Gambart 
 and Harding. Observed at Naples till the 25th 
 of December. The orbit was hyperbolic, according 
 to Encke. 
 
 1825. (i.) Discovered by Gambart, at Marseilles, on May 
 
 19th, in Cassiopea ; and last seen by Kiimker, at 
 Paramatta, on the 15th of July, in Leo. The 
 elements resemble those of the third comet of 
 1790; but as the observations are well represented 
 by a parabolic orbit, the comets can hardly be 
 identical. 
 
NOTES TO THE CATALOGUE. 159 
 
 1825. (n.) Discovered by Pons, at Florence, on the 9th of 
 August; and a fortnight later, by Harding, at 
 Gottingen. It was last observed on August 26th, 
 in Orion. The orbit is almost perpendicular to 
 the plane of the ecliptic. 
 
 1825. (ra.) The Comet of Encke. Found by Yalz, at 
 Nismes, July 13th, and subsequently observed at 
 nearly all the observatories of Europe. 
 
 1825. (iv.) The Great Comet 0/1825; or, as it was called 
 at first, ' the Comet in Taurus.' It was found by 
 Pons on the 15th, and by Biela on the 19th of 
 July; was observed in Europe before the peri- 
 helion passage until the middle of October, when 
 it had become bright, with a conspicuous tail; 
 afterwards at Paramatta, by Riiinker, till the 20th 
 of December; and re-discovered in Europe at the 
 beginning of April, and followed by the astro- 
 nomers of Florence until the 8th of July. Hence 
 the observed arc extends over a whole year an 
 unusually long period. Hansen calculated several 
 elliptical orbits : that we have given is founded on 
 observations considerably distant from each other. 
 The periodic time is 4386 years. This, how- 
 ever, may possibly be corrected by a more rigorous 
 investigation, but it is certain that the revolution 
 extends to many centuries. 
 
 1826. (i.) The famous Comet of Biela which was recog- 
 
 nised as a comet of short period at this appear- 
 ance. It was found by Biela, at Josephstadt, on 
 the 27th of February, and at Marseilles by Oam- 
 bart, on the 9th of the following month. The 
 orbit in the Catalogue is founded on a great 
 number of observations. 
 1826. (ii.) Discovered by Pons on November 7th, 1825, 
 
160 THE COMETS. 
 
 in Eridanus, in which constellation it remained 
 until finally lost sight of about April llth. The 
 orbit is chiefly remarkable for the great perihelion 
 distance. It appears to differ in no material 
 degree from a parabola. 
 
 1826. (in.) Discovered by Flaugergues, at Viviers, on 
 the 29th of March, and observed by him only till 
 the 6th of April. The comet approached very 
 near to the earth, but notwithstanding this cir- 
 cumstance, the elements are open to great uncer- 
 tainty. The discoverer calculated an orbit widely 
 different from Cliiver's, which, however, is un- 
 doubtedly most correct. 
 
 1826. (iv.) Discovered by Pons on August 7th, and a 
 week later by Gambart. It was seen until the 
 latter end of November. The path of this comet 
 crosses the ecliptic at a point not very far distant 
 from the earth's orbit. 
 
 1826. (v.) Discovered by Pons, October 22nd, by Clau- 
 
 sen on the 26th, and by Gambart on the 28th. 
 The comet passed over the sun's disc on the 18th 
 of November, but was not seen at that time. It 
 was observed until the first week in January, 1827. 
 
 1827. (i.) Discovered by Pons, on December 26th, 1826. 
 1827. (n.) Also discovered by Pons, on June 20th, and 
 
 likewise by Gambart, at Marseilles. Continued 
 visible about one month. 
 
 1827. (in.) Discovered by Pons, on August 2nd. It 
 was at first supposed that this comet was iden- 
 tical with the first of 1780 ; but Cliiver's elliptical 
 orbit, which has a period of 2610 years, is against 
 this idea. The true path in space appears to be 
 very nearly a parabola. The comet was observed 
 until the middle of October. 
 
NOTES TO THE CATALOGUE. 161 
 
 1829. The Comet of Encke. The perihelion passage falls 
 in 1829; but the observations were made in the 
 previous year. Struve detected it on September 
 16th, in Aries, and saw it until the 27th of De- 
 cember. At the end of November it was dis- 
 tinctly visible to the naked eye. The elements in 
 the Catalogue are undoubtedly very exact. 
 
 1830. (i.) This comet was discovered in the southern 
 hemisphere, on the 17th of March, and was then 
 conspicuous to the naked eye, with a somewhat 
 lengthy tail. Gambart found it on April 20th, and 
 it was observed in Europe till the 17th of August. 
 The best elements are those of Hadenkamp and 
 Mayer, calculated chiefly upon the accurate obser- 
 vations taken by Bessel at Konigsberg. The 
 parabola is preferable to the ellipse. 
 
 1830. (n.) Discovered about the 7th of January, 1831, 
 by several persons, without the telescope, and ob- 
 served for two months. It exhibited a tail and 
 bright nucleus. 
 
 1832. (i.) The Comet of Encke. Discovered on June 
 1st, by Mossotti, at Buenos Ayres, and on the fol- 
 lowing day by Henderson, at the Royal Observa- 
 tory, Cape of Good Hope. Harding also saw it 
 at Gottingen, on the 21st of August, but it was 
 not observed elsewhere in Europe. 
 
 1832. (n.) Discovered by Gambart, at Marseilles, July 
 19, and ten days later by Harding. It was ob- 
 served till the end of August. 
 
 1 832. (in.) The Comet of Biela. Its first predicted re- 
 appearance. Discovered at the Collegio Romano, 
 at Rome, on the morning of August 24th, and 
 seen by Sir John Herschel about a month later ; 
 but it was not generally observed till October. 
 
162 THE COMETS. 
 
 The last observation is by Henderson, at the Cape 
 of Good Hope, on the 3rd of January, 1833. The 
 best observations are those at K onigsberg and Dorpat . 
 
 1833. Discovered by Dunlop, at Paramatta, New South 
 
 "Wales, at the end of September, in Libra, and 
 observed only to the middle of October. 
 
 1834. Discovered by Gambart, at Marseilles, on March 
 
 7th, and a fortnight later by Dunlop, at Paramatta. 
 Observed till the middle of April. 
 
 1835. (i.) Detected by Boguslawski, at Breslau, on the 
 
 20th of April. The best elements are those of 
 W. Bessel, son of the great astronomer. 
 
 1835. (n.) The Cornet of Encke. Found July 22nd, by 
 Kreil, at Milan, and observed also by Boguslawski, 
 on the 30th. It was seen by Maclear at the Cape 
 of Good Hope, from September 14th to 24th, with 
 a telescope of Sir W. Herschel's ; but no observa- 
 tions could be made. 
 
 1835. (in.) The famous Comet of Hattey. Discovered at 
 the observatory of the Collegio Romano, at Rome, 
 by the director, Dumouchel, on the 5th of August, 
 but not generally found until the 21st or 2 2nd. 
 It was last seen in Europe by Lament, on the 
 17th of May, 1836 ; having been observed at 
 nearly all the astronomical stations in the world. 
 The elements of Westphalen are founded upon the 
 fine series of observations taken by Bessel at 
 Konigsberg, Struve at Dorpat, and by Herschel 
 and Maclear at the Cape of Good Hope. 
 
 1838. T/ie Comet of Encke. Observed by Galle, at Berlin, 
 on September 16th, and followed until the end of 
 November. About the 7th of the latter month 
 it was just perceptible to the naked eye. 
 
 1840. (i.) Discovered -by Galle, at Berlin, on December 
 
NOTES TO THE CATALOGUE. 163 
 
 2nd, 1839, in the constellation Virgo, and observed 
 till February 8th. The comet exhibited a short 
 tail, and was rather bright in the telescope towards 
 the end of the year. The calculations of Peters 
 and O. Struve assign a hyperbolic orbit ; but 
 the observations are well represented by a para- 
 bola. 
 
 1840. (IT.) Discovered by the same astronomer on the 
 25th of January. It was much fainter than the 
 first comet of this year. The elaborate computa- 
 tions of Loomis and Plantamour prove that the 
 period must extend to many centuries. Loomis 
 makes it about 2423 years, and he finds the ellipse 
 far preferable to the parabola. 
 
 1840. (in.) A third comet, also discovered by Galle, at 
 Berlin, on the 6th of March, on the confines of 
 Pegasus and Cygnus ; the last observation dates 
 three weeks later, and was taken at Pulkowa. 
 The elements resemble those deduced by Burckhardt 
 from Chinese observations of the comet of 1097. 
 It is possible that the same body may have ap- 
 peared in 1097 and 1840. 
 
 1840. (iv.) Discovered at Berlin by Bremicker, on the 
 27th of October, 1840, in the constellation Draco. 
 It was always faint, and invisible without the 
 telescope ; the observations extend to the middle 
 of February, 1841. Gotze has shown that the 
 orbit is certainly elliptical, and the period which 
 agrees best with the whole course of observations 
 is 344 years, subject to an uncertainty of about 
 eight years. 
 
 1842. (i.) The Comet of Encke. Found by Galle, at Ber- 
 lin, on the 8th of February, and observed last in 
 America, on April llth. It appeared as a round 
 
THE COMETS. 
 
 bright planetary disc, the nebulosity being doubt- 
 less hid in the strong evening twilight. 
 
 1842. (n.) Discovered at Paris, by Laugier, on the 28th 
 
 of October, in Draco, and observed until the end of 
 November. It was always small and faint. 
 
 1843. (i.) The Great Comet of 1843, the finest of the pre- 
 
 sent century. Seen near the sun's limb on the 
 28th of February in America, Italy, and off the 
 Cape of Good Hope ; and throughout the southern 
 hemisphere during the early part of March. It 
 became visible in Europe about the middle of 
 this month, and was last seen near the west hori- 
 zon, at Berlin, on the 15th of April. The orbit 
 is remarkable for its small perihelion distance. The 
 period in Hubbard's ellipse is 376 years. 
 1843. (n.) Discovered at Paris by Mauvais, on the 3rd of 
 May, on the borders of the constellations Pegasus 
 and Cygnus, and observed till the beginning of 
 October. The calculations of Gotze assign a hyper- 
 bolic orbit, but the parabola suffices for the accu- 
 rate representation of the observed path. 
 
 1843. (in.) Discovered by Faye, at Paris, on the 22nd of 
 
 November, in Orion, and last seen at Pulkowa, 
 with the grand telescope of the observatory, on 
 April 10th, 1844. This remarkable comet is found 
 to revolve in an elliptic orbit, slightly inclined to 
 the ecliptic, in about 2718 days : it was again in 
 perihelion on April 3rd, 1851. Le Terrier's ele- 
 ments depend on all the observations deserving of 
 confidence. Professor Challis re- discovered this 
 comet in November, 1850. 
 
 1844. (i.) Discovered by De Yico, at the Collegio Romano, 
 
 on the 22nd of August, and observed till the end 
 of the year. This comet is also found to be perio- 
 
NOTES TO THE CATALOGUE. 165 
 
 dical, its revolution extending to 1993 days. The 
 return in 1850 was not observed, owing to the 
 comet's unfavourable position in the heavens. 
 1844. (n.) Discovered at Paris, by Mauvais, on July 7th, 
 and at Berlin, by D' Arrest, on the 9th. It was 
 observed until the 10th of March, 1845. Professor 
 Plantamour has rigorously investigated the ele- 
 ments, and finds a revolution considerably over 
 100,000 years ! or the orbit is not sensibly different 
 from a parabola. This result is the more important 
 in the present case, because the comet was ob- 
 served at a considerable distance on each side of 
 the perihelion. 
 
 1844. (in.) Seen at the Cape of Good Hope on the 18th 
 
 of December, and on the following night in New 
 South Wales. It was conspicuous in the southern 
 hemisphere for the three weeks following this date, 
 and at the beginning of February was observed in 
 Europe. The last observation was made on the 
 12th of March, 1825. 
 
 1845. (i.) Discovered on the 28th of December, 1844, by 
 
 D' Arrest, in the constellation Cygnus, and observed 
 till the end of March. It came pretty near the 
 earth, but was not visible without the telescope. 
 The orbit appears nearly parabolic. 
 
 1845. (n.) Discovered by De Yico, at Rome, on the 25th 
 of February, and on March 6th, by Faye, at Paris : 
 observed till the latter end of April. It was small, 
 and invisible to the naked eye. 
 
 1845. (m.) Discovered at Parma, by Colla, on the 2nd ot 
 June, and very distinct to the unassisted eye for a 
 fortnight subsequently. It exhibited a tail about 
 2 J long, and divided by a dark line into two 
 branches. The identity of this comet with that of 
 
166 THE COMETS. 
 
 1596 appears probable, and D' Arrest's orbit is cal- 
 culated on this supposition. 
 
 1845. (iv.) The Comet of Endue, which was so unfavour- 
 
 ably situated in the morning twilight that only 
 three observers succeeded in finding it : De Yico 
 saw it at Rome, and it was also observed at Phila- 
 delphia and Washington. 
 
 1846. (i.) Discovered by De Yico at Rome, on the 24th of 
 
 January, in Eridaiius, arid observed by Argelander 
 till May 1st. The best elements are those of 
 Jelinek, who finds an elliptical orbit with a period 
 of revolution extending to 2721 years: this is the 
 most probable period, but the observations leave it 
 uncertain between 2319 and 3255 years. The 
 comet was in perihelion two days before the dis- 
 covery. 
 
 1846. (11.) The Comet of Mela. Found on the 28th of 
 November at Berlin and Rome, and observed till 
 the end of April, 1846. For an account of the 
 extraordinary phenomena exhibited by the comet 
 at this appearance, see Chapter VI. 
 
 1846. (in.) A remarkable periodical comet discovered by 
 Brorsen at Kiel, in Denmark, on February 26th, in 
 the constellation Pisces. It was observed till April 
 22nd. The elements were soon ascertained to be 
 elliptical, independent calculations by Briinnow, 
 Goujon, and the author, agreeing as to the short 
 period of revolution, which is about 5J years. The 
 comet was not seen in the autumn of 1851, when 
 it must have returned to perihelion, owing pro- 
 bably to its faintness in the morning twilight. 
 
 1846. (iv.) Discovered by De Vico, on February 28th, in 
 Cetus, and by Bond at Cambridge, U.S., on the 
 26th; observed till the beginning of May. This 
 
NOTES TO THE CATALOGUE. 167 
 
 comet is also periodic, the revolution extending 
 to 72 or 73 years, according to Yan Deinse and 
 Peirce. 
 
 1846. (v.) Discovered on the 2 9 oh of July by De Vico at 
 Rome, and two hours later by the author in Lon- 
 don. It was observed at Bonn till the 18th of 
 October; was always small and faint, and appeared 
 to move in an orbit differing in no sensible degree 
 from a parabola. Argelander's elements are very 
 exact. 
 
 1846. (vi.) Discovered at Naples by Peters on the 26th 
 of June, and observed there till July 21st. De 
 Yico was the only astronomer, besides the disco- 
 verer, who was fortunate enough to find this comet. 
 The calculations of Peters and D' Arrest agree in 
 assigning a short period of revolution. According 
 to the former astronomer, whose investigation is 
 somewhat more complete, the period given by the 
 observations is 12-8 years; but is uncertain to the 
 extent of about one year. 
 
 1846. (vn.) Discovered by Brorsen, on the 30th of April, 
 and on the following day by Wichmann, at 
 Konigsberg. It was pretty conspicuous about the 
 middle of May, and was observed at Leyden till 
 June 12th. Wichmann considered the periodic 
 time about 401 years, while Oudemanns makes it 
 500 years. 
 
 1846. (vni.) Discovered by De Yico, on September 23rd, 
 in Ursa Major, and observed about the middle of 
 October at Konigsberg. A parabola satisfies the 
 few observations that were taken of this comet 
 very well. 
 
 1847. (i.) Discovered in London, by the author, on the 
 
 6th of February, in the constellation Cepheus, and 
 
168 THE COMETS. 
 
 observed before the perihelion passage till March 
 24th, when it was bright enough to be visible in 
 the strong morning twilight. Also observed at 
 noon-day, close to the sun, on March 30th, and 
 after the perihelion passage till the 24th of April, 
 at Berlin and Markree. The elements are pro- 
 bably elliptical to a very sensible degree, but as 
 no thorough investigation has yet been undertaken, 
 we cannot give any fair approximation to the 
 period ; still it may be safely stated at several 
 centuries. 
 
 1847. (n.) Discovered by Colla, at Parma, on May 7th, 
 and observed till the end of the year. It was 
 always very faint, and invisible without a good 
 telescope. The orbit is remarkable for the great 
 perihelion distance. 
 
 1847. (HI-) Detected at Moscow, by Schweizer, in the 
 constellation Cassiopea, on the 31st of August, and 
 observed with the great telescope at Pulkowa till 
 the 28th of November. O. Struve calculated an 
 elliptic orbit, but the parabola of Schweizer repre- 
 sents the observations much more satisfactorily. 
 
 1847. (iv.) Discovered by Mauvais, at Paris, on July 
 4th, on the borders of Cepheus and Ursa Minor, 
 and observed with powerful instruments until the 
 middle of April, 1848. The observations through- 
 out this long interval afford no indications of 
 ellipticity. This comet was in perihelion very 
 nearly at the same time as that found by Schweizer, 
 but as the best orbits give a slight priority to the 
 latter, we have termed it the third comet of 1847, 
 though discovered after Mauvais'. 
 
 1847. (v.) Found by Brorsen, July 20th, at Altona, in 
 Aries, or on the, confines of Aries and Triangulum, 
 
NOTES TO THE CATALOGUE. 169 
 
 and observed by Riimker till September 12th. 
 Several astronomers determined elliptical elements, 
 and D' Arrest, from the whole series of observa- 
 tions, found the periodic time about 75 years. 
 
 1847. (vi.) Discovered by Miss Maria Mitchel, at Nan- 
 tucket, United States, near the north pole of the 
 heavens, on October 1st ; by De Yico, at Home, 
 on the 3rd; by the Rev. W. R. Dawes, at Gran- 
 brook, Kent, on the 7th ; and by Madame 
 Riimker, at Hamburg, on the llth. It was 
 visible to the naked eye as a hazy-looking star, 
 and in the telescope presented a large mass of 
 nebulous matter without nucleus, but accompanied 
 by a short tail. The comet was last seen at 
 Konigsberg, by Wichmann, on January 3rd, 1848. 
 The orbit is not sensibly different from a para- 
 bola. 
 
 1848. (i.) Discovered by Petersen, at Altona, on August 
 
 7th, in Auriga, and observed till the 25th of the 
 same month. 
 
 1848. (n.) A return of the Comet of EncJce, which was 
 observed from August 27th till the end of No- 
 vember. 
 
 1849. (i.) Also discovered by Petersen, on October 26th, 
 
 1848, in the constellation Draco, but the peri- 
 helion passage did not take place till 1849, so that, 
 according to our plan of arrangement, the comet 
 belongs to the latter year. It was observed at 
 Geneva by Plantamour, until the 26th of January, 
 
 1849. The observations are very closely repre- 
 sented by a parabolic curve. 
 
 1849. (n.) Discovered by Goujon, at Paris, on April 
 15th, in the constellation Crater, and observed at 
 Liverpool and Berlin until the 22nd of September. 
 I 
 
170 THE COMETS. 
 
 There are no indications of ellipticity, Weyer's 
 parabolic elements agreeing well with the whole of 
 the observations. 
 
 1849. (in.) Discovered by Schweizer on April llth, in 
 
 Corona Borealis, and a few hours later by Bond, at 
 Cambridge, United States ; also at Markree, by 
 Graham, on the 14th. Observed last before the 
 perihelion, by Valz, at Marseilles, on May 9th ; 
 detected again by Bond, on August 24th. D' Arrest 
 finds an elliptical orbit, with a period of 8375 
 years ; hence it is certain that the third comet of 
 1849 cannot be identical with the second of 1748, 
 as was at first conjectured. 
 
 1850. (i.) Discovered at Altona, by Petersen, on May 
 
 1st, nearly in the position in which the same 
 astronomer detected the first comet of 1849. It 
 became very distinct to the naked eye early in 
 July, exhibiting a bright nucleus and a tail several 
 degrees in length. D' Arrest's elements, which 
 are parabolic, satisfy all the observations before 
 the perihelion passage with considerable accuracy. 
 
 1850. (n.) Discovered by Mr. G. P. Bond, at Cam- 
 
 bridge, United States, on the 29th of August, and 
 about a week later by Brorsen, at Senftenberg, 
 and other European observers ; it was never very 
 bright. 
 
 1851. (i.) The first appearance of the Comet of Faye 
 
 since the discovery of its periodicity in 1843. At 
 this apparition it was always extremely faint, and 
 quite beyond the power of any but the very largest 
 telescopes in existence. Professor Challis found it 
 with the Northumberland equatorial, at Cam- 
 bridge. 
 1851. (n.) Discovered by D' Arrest, at Leipzic, on the 
 
NOTES TO THE CATALOGUE. 171 
 
 2 7th of June, and soon ascertained to be periodical 
 (see Chapter VII). It remained visible till the 
 beginning of October, but was always very small 
 and faint. 
 
 1851. (in.) Found by Brorsen, at Senftenberg, on the 1st 
 of August, and observed till November. The 
 observations indicate no sensible deviation from a 
 parabolic orbit. 
 
 1851. (iv.) Also discovered by Brorsen, on October 22nd, 
 
 and then pretty bright, with a double tail the 
 shorter branch turned towards the sun. It be- 
 came rapidly fainter. 
 
 1852. (i.) A reappearance of Enckes Comet, which was 
 first observed at Mr. Bishop's private observatory, 
 Regent's Park, London, on the 9th of January; 
 observations were continued until March. 
 
 1852. (u.) Detected by Chacornac, at Marseilles, May 
 15th, and by Petersen, at Altona, on May 17th, 
 when it was very small and faint. It subsequently 
 passed near the north pole of the heavens. The 
 elements will be approximate only. 
 
 1852. (in.) Found by "Westphal, at Gottingen, on June 
 27th, and subsequently by Peters, at Constanti- 
 nople. The orbit is an ellipse, with a period of 
 about 70 years. 
 
ERRATUM. 
 Page 43, for November 12 that, read November Ybth at. 
 
INDEX. 
 
 N.B. The Notes to the Catalogue of Orbits, being arranged 
 in the chronological order of the Comets, are not included 
 in the following Index. 
 
 PAGE 
 
 Alexander on the comet of 1812 97 
 
 Apian, his observations 11 
 
 on Halley's cornet 35 
 
 Apparent tracks, length of 6 
 
 Arago on the light of comets 24 
 
 on the chance of collision with the earth ... 26 
 
 Argelander, observations on Encke's comet .... 62 
 calculations for Paye's comet 80 
 
 on that of 1811 99,111 
 
 Bessel on Halley's comet 48, 49 
 
 on that of Gibers 96 
 
 on the comets of 1769 and 1807 99, 110 
 
 Biela's comet in 1772, observed by Montaigne ... 71 
 
 in 1805, by Pons 71 
 
 periodicity suspected .... 71 
 
 in 1826, its discovery by Biela .... 72 
 
 period determined by Clausen, 
 
 Biela, and Gambart .... 72 
 missed at several appearances between 
 
 1772 and 1826 72 
 
 appearance in 1826 73 
 
 Santini and Damoiseau calculate the time 
 
 of the return in 1832 73 
 
 near approach to the earth's path ... 73 
 
174 INDEX. 
 
 PAGE 
 
 Biela's comet, anticipated collision with the earth ... 75 
 
 1 in 1832, first seen at Borne 75 
 
 its telescopic appearance ... 76 
 
 stars seen through it .... 23 
 
 Santini's further calculations for 1839 . 76 
 
 why missed in 1839 76 
 
 Santini predicts the time of perihelion 
 
 passage in 1846 77 
 
 in 1846, its discovery that year .... 77 
 
 becomes double 78 
 
 distance between the two parts . 78 
 
 in 1852, both parts found at Borne ... 79 
 
 dimensions of orbit, and period of revolu- 
 tion 79 
 
 Blanpain discovers a comet 88 
 
 Bomme on the comet of 1264 and 1556 120 
 
 Bouvard discovers and calculates a comet 59 
 
 Brisbane, his observatory at Paramatta 61 
 
 Brorsen, his third comet in 1847 97 
 
 his second comet in 1846 101 
 
 Brorsen's comet in 1846 84 
 
 in 1851, not observed 84 
 
 cause of the present form of its orbit ... 85 
 
 Brunnow's calculations 85 
 
 dimensions of orbit, and period 85 
 
 Brunnow on De Vico's comet 82 
 
 on Lexell's 95 
 
 Burckhardt on Lexell's comet 92 
 
 on the comet of 1763 99 
 
 Cacciatore observed phases in a comet 22 
 
 Challis rediscovered Faye's comet 81 
 
 Cheseaux, his observation of the comet of 1744 . . . 109 
 
 Clairault's calculations relative to Halley's comet . . 40 
 
 Clausen calculated Biela's 72 
 
 on that of 1743 88 
 
 . 1819 88 
 
 . on Lexell's comet 95 
 
 Colla finds a comet 100 
 
INDEX. 175 
 
 Collision of a comet with the earth, probability against 
 
 the . . . 26 
 
 Colours of comets ' 9 
 
 Coma 8 
 
 Comet of A.C. 370 described by Aristotle 12 
 
 13-1 in the time of Mithridates ... 10 
 
 43 108 
 
 11, supposed to be Halley's .... 55 
 
 A.D. 60, its long visibility 5 
 
 64, its long visibility 5 
 
 66, 55 
 
 133, 12 
 
 141, supposed to be Halley's .... 55 
 
 178, its long track in the heavens . . 12, 103 
 
 218, probably Halley's ...... 55 
 
 247, its long visibility 5 
 
 295, probably Halley's 54 
 
 373, 54 
 
 389, equalled Venus in -brilliancy . . . 103 
 
 390, 12 
 
 418, seen during a total, eclipse of the sun 9~ 
 
 451, probably Halley's 54 
 
 479, 15 
 
 530 and 531, 108 
 
 582, like a distant conflagration . . 14, 103 
 
 608, 53 
 
 615, coruscations first observed . . 14, 103 
 
 684, 22, 53 
 
 760, probably Halley's 53 
 
 813, 22 
 
 837, alarmed Louis I. of France ... 1 
 
 its remarkable tail 12 
 
 near approach to the earth ... 26 
 
 891, its lengthy tail 103 
 
 912, 15 
 
 989, probably Halley's 52 
 
 1066, 52 
 
 1106, 8, 108, 115 
 
176 INDEX. 
 
 PAGE 
 
 Comet of A.D. 1145, probably Halley's 52 
 
 1223, 51 
 
 1232, 15 
 
 1264, (see Expected great comet). ... 12 
 
 1340, 15 
 
 1362, 12 
 
 1402, splendid comets of this year 8, 15, 26, 103 
 
 1456, Halley's 2, 12, 15, 50 
 
 1472, observed by Eegiomontanus . . 26, 105 
 
 1531, (Halley's) 35 
 
 1556, (see Expected great comet) ... 2 
 
 1577, Tycho Brahe investigated its paral- 
 lax 11, 105 
 
 1607, (Halley's) 36 
 
 1618, its brilliant aspect 8 
 
 . nucleus like bright points . . . 10 
 
 _ . its immense tail 15, 21, 106 
 
 1652, equal to the moon in size . . .10, 106 
 
 1661, 10,106 
 
 1664 10,106 
 
 1665, 106 
 
 1668, 114 
 
 1680, its imposing aspect ... 10, 12, 106 
 
 immense train 21 
 
 near approach to the sun . . . . 106 
 
 supposed identity with several an- 
 
 cient comets 107 
 
 Encke's calculations 98, 108 
 
 conjectures of Whiston and others 108 
 
 1682, (Halley's) 36, 37 
 
 1683, its revolution 99 
 
 1684, 26 
 
 1689, 15, 114 
 
 1729, its great perihelion distance . . . 4, 31 
 
 its long visibility 5 
 
 short track in the heavens .... 15 
 
 1742, near approach to the earth ... 26 
 
INDEX. 177 
 
 PAGE 
 
 Comet of A.D. 1743, probably periodical 87 
 
 1744, its brilliant appearance, and double 
 
 tail 9, 10, 21, 22, 109 
 
 1759, (Halley's) 41 
 
 1763, Burckhardt's calculations .... 99 
 
 1766, probably periodical 88 
 
 1769, 13, 15, 21, 22, 99, 109 
 
 1770, (see Lexell's comet] 
 
 1773, its long visibility 5 
 
 1779, 26 
 
 1780, 18, 19, 24 
 
 1783, probably periodical 88 
 
 1798, 18 
 
 1805, 26,59 
 
 1805, (Biela's) 71 
 
 1807, observed by Herschel, and calculated 
 
 by Bessel 18, 99, 110 
 
 , . Schroter's measures of its diameter 20 
 
 1811, the great comet . 18, 19, 21, 23, 99, 110 
 
 - second of this year 18, 99, 112 
 
 1812, found by Pons in July .... 96, 97 
 
 1815, (see Olberss comet) 
 
 . 1819, the great comet 18, 22, 112 
 
 1819, found by Pons in June, probably 
 
 periodical 88 
 
 1819, found by Blanpain in November, 
 
 probably periodical 88 
 
 1819, (see EncJce's comet] 
 
 1822, its length of revolution .... 99 
 
 1822, (see EncJce's comet} 
 
 1824, with two tails 11 
 
 1825, the great one 5, 6, 100, 112 
 
 1825, (see EncJce's comet] 
 
 1826, (Biela's) 72 
 
 1826, observed by Flaugergues .... 26 
 
 , 1S28, (see EncJces comet] 
 
 1832, (see EncJce's comet) 
 
 K2 
 
178 INDEX. 
 
 PAGE 
 
 Comet of A.D. 1832, (see Bielas comet] 
 
 1835, (see Halleys comet) 
 
 184), Galle's second 24 
 
 1840, Bremicker's 100 
 
 1842, (see Enclces comet} 
 
 1843, visible in full sunshine . . . . 9, 113 
 
 its tail 13, 15, 22 
 
 real diameter of the nucleus ... 18 
 
 close approach to the sun . . . . 113 
 
 supposed identity with several others 114 
 
 1843, (see Fayes comet} 
 
 1844, found by Mauvais in June . . 5, 101 
 
 1844, (see De Vico's comet) 
 
 1845, found by Colla in June ... 18, 100 
 
 1845, in southern hemisphere .... 12 
 
 1845; (see EncJce's comet) 
 
 1846, (see Brorsens comet) 
 
 1846, on the various comets of this 
 
 year 19, 23, 101 
 
 1846, found by Peters 89 
 
 1846, found by De Vico, Feb. 20 ... 97 
 
 1847, (Hind's) seen in full daylight, 9, 18, 19, 21 
 
 1847, Colla's 5 
 
 - Mauvais' 5 
 
 found by Brorsen 19 
 
 1847, (see Brorsen' s comet) 
 
 1848, (see EncTces comet} 
 
 1851, (see Fayes comet) 
 
 1852, found by Westphal in June, its peri- 
 odicity (note) 97 
 
 Cysat on the comet of 1618 10, 15 
 
 Damoiseau calculates the return of Halley's comet . . 43 
 
 on Biela's 73 
 
 D'Arrest, his ephemeris of Encke's 68 
 
 his calculations relative to Peters' comet . . 89 
 
 D'Arrest's comet in 1851 . 85 
 
 period, and dimensions of orbit 86 
 
INDEX. 179 
 
 PAGE 
 
 Dawes observed Encke's comet 64 
 
 Delisle concealed Messier's discovery of Halley's comet 41 
 
 De Yico found Encke's comet, 1845 68 
 
 found Biela's in 1846 77 
 
 his comet of 73 years' period 97 
 
 De Vice's comet, in 1844 82 
 
 in 1850, not seen, and why .... 83 
 
 expected in 1855 83 
 
 same as that of 1678 83 
 
 not the one of 1585 83 
 
 dimensions of orbit, and period . . 84 
 
 Dumouchel first perceives Halley's comet in 1835 . . 46 
 
 Dunthorne on the comet of 1264 117, 118 
 
 Duration of visibility of various comets 4 
 
 Elements of the orbit 27, 29 
 
 their use 33 
 
 Encke finds Biela's comet, 1845 77 
 
 on the comets of 1819 88 
 
 on the comet of 1680 98 
 
 on that of 1822 99 
 
 Encke's comet, in 1786, observed by Mechain ... 58 
 
 in 1795, observed by Miss Herschel . 58 
 
 . in 1805 59 
 
 in 1818, discovered by Pons .... 59 
 
 in 1818, Encke discovered its periodicity 59 
 
 perihelion passages between 1786 and 
 
 1819 60 
 
 Encke's calculations 60 
 
 why so named 61 
 
 in 1822, detected by Eiimker ... 61 
 
 in 1825, found by Harding .... 61 
 
 appears as a small planetary disk . . 62 
 
 in 1828, generally observed, telescopic 
 
 appearance 62 
 
 in 1 828, variable dimensions . ... 20 
 
 in 1832, seen by Harding, Henderson, 
 
 and Mossotti 63 
 
180 INDEX, 
 
 PAGE 
 
 Encke's comet in 1835, observed in Europe and at 
 
 the Cape of Good Hope 63 
 
 in 1838, first perceived at Berlin, tele- 
 scopic appearance 64 
 
 variable dimensions 20 
 
 Encke's further calculations .... 64 
 
 approached near the planet Mercury 
 
 in 1835 64 
 
 affords a knowledge of the mass of 
 
 Mercury 65, 69 
 
 proves the existence of a resisting 
 
 medium 66 
 
 indicates an error in Laplace's mass of 
 
 Mercury 67 
 
 in 1842, discovered at Berlin ... 67 
 
 real diameter 68 
 
 in 1845, observed at Rome and in 
 
 America 68 
 
 in 1848, telescopic appearance ... 69 
 
 near approach to Mercury . 69 
 
 in 1852 70 
 
 dimensions of the orbit, and period of 
 
 revolution 70 
 
 Envelope . 8 
 
 Expected Great Comet 116 
 
 Fabricius, observations of a comet in 1556 . . 117, 119 
 
 Faye calculated De Vico's comet 82 
 
 Faye's comet in 1843 80 
 
 not that of 1770 81 
 
 Le Verrier's calculations 81 
 
 in 1851 81 
 
 period and dimensions of orbit ... 82 
 
 Galle, on a comet found by 24 
 
 Gambart found Biela's comet in 1826 72 
 
 Goldschmidt, calculations on Faye's comet .... 80 
 
 Gotze on Bremicker's comet 100 
 
 Halley's comet, ancient appearances 
 
 11 A.C. and A.D. 66, 141 and 218 . . 55 
 
INDEX. 181 
 
 Halley's comet, ancient appearances 
 
 in 295, 373, 451, and 530 54 
 
 in 608, 684, 760, and 837 53 
 
 in 989, 1066 and 1145 52 
 
 in 1223 and 1301 51 
 
 in 1378 according to Laugier .... 50 
 
 in 1456, its fine appearance .... 50 
 
 in 1531, observed by Apian .... 35 
 
 . in 1607, observed by Kepler .... 36 
 
 ^ in 1682, observed by Flamsteed ... 36 
 
 periodicity discovered and return pre- 
 dicted 38 
 
 _ Clairault's calculations 39 
 
 reappears in 1758 40 
 
 in 1759 41 
 
 . calculations of Damoiseau .... 
 
 Pontecoulant and R-osenberger ... 43 
 
 calculations of Lehmann 45 
 
 sought after in 1834 45 
 
 in 1835, discovery by Dumouchel, its 
 
 course through the heavens ... 46 
 
 in 1835, remarkable form 48 
 
 dimensions of the orbit in 1835 ... 49 
 
 diameter of the disk in 1836 . . 18, 19 
 
 . table of the epochs of perihelion passage 57 
 
 Hansen on the comet of 1825 100 
 
 Harriot, his observations of Halley's 36 
 
 Head of a comet 7 
 
 subject to changes of magnitude . . 19 
 
 Henderson observed Encke's comet 1832 63 
 
 ' calculated E aye's 80 
 
 Herschel, Miss Caroline, discovered the comet of Encke 
 
 in 1795 58 
 
 Sir W., his observations on the comets of 
 
 ] 807 and 1811 18,110,111 
 
 Sir John, his opinion respecting comets . . 23 
 
 sought for Halley's 46 
 
182 INDEX, 
 
 PAGE 
 
 Herscliel, Sir John, his observations on the same . 48, 49 
 
 observed Biela's 75 
 
 Hevelius, his account of various comets . . 10, 15, 37, 106 
 
 Jelinek on a comet in 1846 101 
 
 Kepler on various comets 13, 15, 21, 36, 106 
 
 Kirch discovered the great comet of 1680 107 
 
 Lalande, his calculations relating to the return of 
 
 Halley's comet 39 
 
 La Nux, observations of a comet in 1769 . . . . 13,16 
 
 of Halley's in 1759 41 
 
 of one in 1766 88 
 
 Laugier on ancient returns of Halley's . . 50, 53, 54, 56 
 Lehmann, calculations respecting Halley's comet . . 45 
 Lepaute, Madame, her laborious calculations for 
 
 Halley's comet 39 
 
 Le Terrier, researches on Faye's comet 81 
 
 on De Vico's 83 
 
 on that of 1770 92, 94 
 
 Lexell's comet, in 1770, discovered by Messier ... 89 
 calculations of Pingre, Pros- 
 perm and Lexell ... 90 
 
 not seen in 1776 90 
 
 near approach to the planet Jupiter 90 
 
 expected in 1781, but not observed . 91 
 
 Burckhardt's calculations .... 92 
 
 Le Terrier's investigations .... 94 
 
 its near approach to the earth ... 95 
 
 Briinnow confirms Burckhardt's cal- 
 culations 95 
 
 Long-period comets 98 
 
 Lycosthenes, his chart of the path of a comet in 1556 . 117 
 Maclear observes the diameter of Halley's comet ... 18 
 Maskelyne, observations on comet of 1769 . . . 13, 110 
 
 Mechain, discovery of a comet by 58 
 
 Messier, his discoveries 41, 88, 89 
 
 Montaigne, found Biela's in 1772 71 
 
 Newton, his law of gravitation applied to comets . 33, 38, 107 
 
INDEX. 183 
 
 PAGE 
 
 Noon-day, comets seen at 8 
 
 Nucleus, 7 
 
 planetary 9 
 
 description of, in several comets 10 
 
 real dimensions of, in comets 18 
 
 Number of comets 3 
 
 of those calculated 30 
 
 of direct and retrograde comets 31 
 
 Olbers on various comets 24, 26, 45, 59, 73 
 
 Olbers's comet in 1815 5.. 18, 96 
 
 Oudemanns calculated a comet in 1846 101 
 
 Palitzch, the Saxon farmer, discovered Halley's comet . 40 
 
 Perihelion distances, distribution of the 31 
 
 greatest and least 31 
 
 Periods of about 75 years, comets revolving in ... 96 
 
 Perturbations from planetary attraction 31 
 
 Peter's comet in 1846 89 
 
 Phases occasionally observed 22 
 
 Physical constitution of comets 23 
 
 Picard, his observations 37 
 
 Pigott, discovery of a comet 88 
 
 Pingre, observations of the comet of 1769 13 
 
 on Halley's in 1456 50 
 
 researches on the comet of 1264 and 1556 . . 118 
 
 Plantamour, his computations respecting Biela's in 1846 78 
 
 on the period of a comet 100 
 
 Pons, various cometary discoveries, 59, 71, 88, 96, 99, 100, 112 
 
 Pontecoulant, calculations on Halley's comet ... 43 
 
 Resljiiiber, on a star seen behind a comet by ... 23 
 
 Rosenberger, his calculations relating to Halley's comet 43 
 
 Riimker discovered Encke's in 1822 61 
 
 Santini, researches on Biela's comet 73, 76 
 
 Schroter, his measures of the comet of 1807 .... 21 
 
 Secchi rediscovered Biela's in 1852 79 
 
 Short-period comets 87 
 
 Smyth, Captain W. H., on Halley's comet .... 47 
 
 Smyth, Professor C. P., drawings of the same ... 49 
 
INDEX. 
 
 PAGE 
 
 Struve on Halley's comet .......... 48 
 
 - found Encke's in 1828 ......... 62 
 
 Struve, O., on the companion of Biela's comet ... 78 
 
 Superstitious ideas regarding comets ...... 1 
 
 Tail, definition . ............. 7 
 
 - turned from the sun .......... 11 
 
 - apparent length of, in various comets .... 12 
 
 - coruscations of the ........... 14 
 
 curvature in the ........... 15 
 
 - real length of, in various comets ...... 21 
 
 Telescopic comets, their usual aspect ...... 7 
 
 Valz last observed Encke's comet in 1838 ..... 64 
 
 Wichmann, on the period of a comet ...... 101 
 
 Zach knew Paliztch, the discoverer of Halley's comet 
 
 in 1759 40 
 
 THE END. 
 
STANDARD BOOKS 
 
 PUBLISHED BY 
 
 JOHN W. PAKKEE & SON, LONDON. 
 
 Cloister Life of the Emperor 
 
 Charles the Fifth. By WILLIAM STIRLING, 
 M.P. 8s. 
 
 Critical Biographies. By GEORGE 
 
 HENKY FRANCIS. Sir Kobert Peel Right 
 Hon. B. Disraeli Lord Brougham Lord 
 John Russell. Is. each. 
 
 Wellington, from a French Point of 
 
 View. By JOHN LEMOINNE, one of the Con- 
 tributors to the Journal des Debuts. Is. 
 
 Principles of Political Economy. 
 
 By J. STUART MILL. Second Edition. Two 
 Volumes. Octavo. 30s. 
 
 Essays on Unsettled Questions of 
 
 Political Economy. By the same. 6s. 6d. 
 
 System of Logic. By the same. 
 
 Cheaper Edition. Two Volumes. 25s. 
 
 On the Methods of Observation and 
 
 Reasoning in Politics. By G. Cornewall 
 Lewis. Two Volumes. Octavo. 28s. 
 
 On the Influence of Authority in 
 
 Matters of Opinion. By the same Author. 
 Octavo. 10s. 6d. 
 
 Lectures on the History of Moral 
 
 Philosophy in England. By W. WHEWELL, 
 D.D., Master of Trinity College, Cam- 
 bridge. 8s. 
 
 History of the Whig Ministry of 
 
 1830. By J. ARTHUR ROEBUCK, M.P. 
 Vols. I. and II. to the passing of the Re- 
 form Bill. Octavo. 28s. 
 
 History of Normandy and of Eng- 
 land. By Sir FRANCIS PALGRAVE. Vol. I. 
 Octavo. 21s. 
 
 Yarronianus; a Critical and His- 
 torical Introduction to the Ethnography of 
 Ancient Italy, and the Philological Study 
 of the Latin Language. By J. W. DONALD- 
 SON, D.D., Head Master of Bury School. 
 Second Edition, considerably enlarged. 
 
 The New Cratylus ; Contributions 
 
 towards a more accurate Knowledge of 
 the Greek Language. By the same Author, 
 Second Edition, octavo, much enlarged. 
 
 18s. 
 
 Great Britain One Empire. On the 
 
 Union of the Dominions of Great Britain, 
 by Inter-communication with the Pacific 
 and the East, via British North America. 
 With suggestions for the Profitable Colo- 
 nization of that Territory. By CAPTAIN 
 M. H. SYNGE, R.E.With Maps, 3s. Gd. 
 
 Manual of Geographical Science. 
 
 PART THE FIRST, 10s. 6d., containing 
 
 MATHEMATICAL GEOGRAPHY, 
 by Rev. M. O'BRIEN, Professor of Natural 
 Philosophy in King's College. 
 
 PHYSICAL GEOGRAPHY, by D. T. 
 ANSTED, M. A., F.R.S., Professor of Geology 
 in King's College. 
 
 CHARTOGRAPHY, by J. R. JACKSON, 
 F.R.S., late Secretary of the Royal Geo- 
 graphical Society. 
 
 THEORY OF DESCRIPTION AND 
 GEOGRAPHICAL TERMINOLOGY, by 
 Rev. C. G. NICOLA Y, Librarian of King's 
 College. 
 
 Atlas of Physical and Historical 
 
 Geography, to accompany the MANUAL OF 
 GEOGRAPHICAL SCIENCE. Engraved by J.W. 
 LOWRY, under the direction of Professor 
 ANSTED and Rev. C. G. NICOLA Y. 5s. 
 
 Leaves from the Note-Book of a 
 
 Naturalist. By W. J. BRODERIP, F.R.S. 
 10s. 6d. 
 
 Discourse on the Studies of the 
 
 University of Cambridge. By ADAM SEDG- 
 wiCK.M.A., Woodwardian Professor. Fifth 
 Edition, enlarged. (770 pages.) 12s. 
 
 Elements of Logic. ByR.WHATELr, 
 
 D.D., Archbishop of Dublin. Small Octavo, 
 4s. Gd. Library Edition, 10s. 6d. 
 
 Elements of Rhetoric. By the same 
 
 Author. Small Octavo, 4s. Gd. Library 
 Edition, 10s. 6d. 
 
 History of the Inductive Sciences. 
 
 By W. WHEWELL, D.D., F.R.S., Master 
 of Trinity College, Cambridge. Second 
 Edition, revised. Three Vols. 2 2s. 
 
 Philosophy of the Inductive Sciences. 
 
 By the same Author. Second Edition. 
 Two Volumes. Octavo. 30s. 
 
 Indications of the Creator Theolo- 
 gical Extracts from History and Philo- 
 sophy of Inductive Sciences. By the same. 
 5s. Gd. 
 
 Bacon's Advancement of Learning. 
 
 A Cheap Edition, carefully Revised from 
 the first Copies, with References to Works 
 quoted, and a few Notes. 2s. 
 
 Principles of Imitative Art. Eour 
 
 Lectures delivered before the Oxford Art 
 Society. By GEORGE BUTLEII, M.A., late 
 Fellow of Exeter College, Secretary. 6s. 
 
STANDARD BOOKS PUBLISHED BY 
 
 Elements of Morality. By Dr. WHE- 
 
 WELL. Cheaper Edition. Two Volumes. 15s. 
 
 Meliora ; or, Better Times to Come. 
 
 Edited by Viscount INGESTRE ; and con- 
 taining Papers by Hon. F. Byng, Viscount 
 Goderich, Dr. Guy, Rev. Dr. Hook, Henry 
 Mayhew, Hon. and Rev. S. G. Osborne, 
 &c. &c. 5s. 
 
 English Synonyms. Edited by R. 
 
 WHATELY, D.D., Archbishop of Dublin. 
 Second Edition, enlarged. 3*. 
 
 On the Study of Words ; Lectures 
 
 by R. C. TRENCH, B.D., Examining Chap- 
 lain to the Bishop of Oxford. 3s. 6d. 
 
 History of the Royal Society, com- 
 piled from Original Authentic Documents. 
 By C. R. WELD, Assistant-Secretary of the 
 Royal Society. Two Volumes. Octavo. 30s. 
 
 The Comets ; a Descriptive Treatise 
 
 upon those bodies, with a condensed ac- 
 count of the numerous modern discoveries 
 respecting them, and a table of all the calcu- 
 lated Comets from the earliest ages. By 
 J. RUSSELL HIND, Foreign Secretary of the 
 Royal Asti'onomical Society of London. 
 
 An Astronomical Vocabulary ; being 
 
 an Explanation of all terms in use amongst 
 Astronomers at the present day. By the 
 same Author. Is. 6d. 
 
 Cycle of Celestial Objects. By 
 
 Captain W.H. SMYTH, R.N..F.R. 8., Foreign 
 Secretary of the Royal Society. Two Vols. 
 Octavo, with Illustrations. 2 2s. 
 
 Manual of Chemistry. By W. T. 
 
 BRANDE, F.R.S., Professor of Chemistry in 
 the Royal Institution. Sixth Edition, much 
 enlarged, and embodying all Recent Dis- 
 coveries. Two large Volumes. 2 5s. 
 
 Dictionary of Materia Medica and 
 
 Pharmacy. By the same Author. 15s. 
 
 Principles of Mechanism. By R. 
 
 WILLIS, M. A., F.R.S., Professor of Natural 
 Philosophy, Cambridge. 15s. 
 
 Mechanics applied to the Arts. By 
 
 H. MOSELEY, M.A., F.R.S., one of Her 
 Majesty's Inspectors of Schools. 6s. 6d. 
 
 Lectures on Astronomy. By same 
 
 Author. Third Edition. 5s. 6d. 
 
 Elements of Meteorology. By the 
 
 late Professor DANIELL. With Plates. 
 Two Volumes. Octavo. 32s. 
 
 On Thunderstorms, and on the 
 
 means of Protecting Buildings and Shipping 
 against the Effects of Lightning. By SIB 
 W. SNOW HARRIS, F.R.S. 10s. 6d. 
 
 Connexion of Natural and Divine 
 
 Truth. By BADEN POWELL, M.A.,F.R.S., 
 Professor of Geometry, Oxford. 9s. 
 
 Undulatory Theory as applied to the 
 
 Dispersion of Light. By the same Author. 
 Octavo. With coloured Chart. 9s. 
 
 Mathematical Tracts. By G. BID- 
 DELL AIRY, M.A., F.R.S., Astronomer 
 Royal. Third Edition. Octavo. 15s. 
 
 Lectures on the Principles and 
 
 Practice of Physic. By T. WATSON, M.D. 
 Third Edition. Two Volumes. Octavo. 34s. 
 
 On the Diseases of the Kidney : their 
 
 Pathology, Diagnosis and Treatment. 
 By GEORGE JOHNSON, M.D., Assistant- 
 Physician to King's College Hospital. 14s. 
 
 Physiological Anatomy and Phy- 
 siology of Man. By Dr. TODD and W. BOW- 
 MAN, F.R.S. Part IV., Section .1., 7s. 
 Part III., 7s. Vol I., 15s. 
 
 The Philosophy of Living. By HER- 
 BERT MAYO, M.D. Cheaper Edition, with 
 Additions. 5s. 
 
 Management of the Organs of Di- 
 gestion in Health and in Disease. By the 
 same Author. Second Edition. 6s. 6d. 
 
 Lunacy and Lunatic Life, with Hints 
 
 on the Personal Care and Management of 
 those afflicted with Derangement. 3s. 6d. 
 
 German Mineral Waters : and their 
 
 rational employment for the Cure of certain 
 Chronic Diseases. By S. SUTRO, M.D., 
 Physician of the German Hospital. 7s. Gd. 
 
 m, Languor, and Palsy. By J. 
 
 A. WILSON, M.D., Physician to *St. George's 
 Hospital. 7s. 
 
 Gout, Chronic Rheumatism, and In- 
 flammation of the Joints. By R. B. TODD, 
 M.D., F.R.S., Physician of King's College 
 Hospital. 7s. 6d. 
 
 Minerals and their Uses. By J. R. 
 
 JACKSON, F.R.S. With Frontispiece. 7s. 6d. 
 
 Lectures on Dental Physiology and 
 
 Surgery. By J. TOMES, F.R.S., Surgeon- 
 Dentist to the Middlesex Hospital. Octavo. 
 With 100 Illustrations. 12s. 
 
 Use and Management of Artificial 
 
 Teeth. By the same Author. With Illus- 
 trations. 3s. 6d. 
 
 Practical Geology and Mineralogy. 
 
 By JOSHUA TRIMMER, F.G.S. Octavo, with 
 Two Hundred Illustrations. 12s. 
 
 Practical Chemistry for Farmers and 
 
 Landowners. By the same Author. 5s. 
 
JOHN W. PARKER AND SON, WEST STRAND. 
 
 Practical Geodesy. By BUTLER 
 
 WILLIAMS, C.E. New Edition, with 
 Chapters on Estate, Parochial, and Rail- 
 road Surveying. With Illustrations. 12s. 6d. 
 
 Manual for Teaching Model-Draw- 
 ing ; with a Popular View of Perspective. 
 By the same Author. (Under the Sanction 
 of the Committee of Council on Education.) 
 Octavo, with shaded Engravings. 15s. 
 
 Instructions in Drawing. Abridged 
 
 from the above, 3s. 
 
 Chemistry of the Crystal Palace : a 
 
 Popular Account of the Chemical Pro- 
 perties of the Chief Materials employed 
 in its Construction. By T. GRIFFITHS. 5s. 
 
 Chemistry of the four Ancient Ele- 
 ments. Bythesame. Second Edition. 4s. 6d. 
 
 Recreations in Chemistry. By the 
 
 same. Second Edition, enlarged. 5s. 
 
 Recreations in Physical Geography. 
 
 By Miss R. M. ZORNLIN. Fourth Edi- 
 tion. 6s. 
 
 World of Waters; or, Recreations 
 
 in Hydrology. By the same Author. 
 Second Edition. 6s. 
 
 Recreations in Geology, By the 
 
 same Author. Third Edition. 4s. 6d. 
 
 Recreations in Astronomy. By Rev. 
 
 L. TOMLINSON, M. A. Third Edition. 4s. 6d. 
 
 Summer Time in the Country. By 
 
 Rev. R. A. WILLMOTT. Second Edition. 5s. 
 
 Shipwrecks of the Royal Navy. Com- 
 piled from Official Documents. By W. O. S. 
 GILLY. With a Preface by DR. GILLT, 
 Canon of Durham. Second Edition. 7s. 6d. 
 
 The Earth and Man; or, Physical 
 
 Geography in its Relation to the History of 
 Mankind. By PROFESSOR GUYOT. Slightly 
 abridged.with Corrections and Notes. 2s. 6d. 
 
 Danger of Superficial Knowledge: 
 
 A Lecture. By J. D. FORBES, F.R.S., Pro- 
 fessor of Natural Philosophy, Edinburgh. 2s. 
 
 Introductory Lectures delivered at 
 
 Queen's College, London. 5s. 
 
 The Saint'sTragedy. By C. KINGSLE Y, 
 
 Rector of Eversley. Cheaper Edition. 2s. 
 
 Schiller's Complete Poems. At- 
 tempted in English, by EDGAR ALFRED 
 BOWRING. 6s. 
 
 Jesuit Executorship ; or, Passages 
 
 in the Life of a Seceder from Romanism. 
 An Autobiography. Two Volumes, Post 
 Octavo. 
 
 Yeast: a Problem. By C. KINGSLEY, 
 
 Rector of Eversley. Reprinted from 
 Fraser's Magazine. Cheaper Edition. 
 
 5s. 
 
 The Upper Ten Thousand : Sketches 
 
 of American Society. By A NEW YORKER. 
 Reprinted from Fraser's Magazine. 5s. 
 
 College Life in the Time of James 
 
 the First, as illustrated by an Unpublished 
 Diary of Sir Symonds d'Ewes, Bart. 5s. 
 
 Brampton Rectory: or, the Lesson 
 
 of Life. Second Edition. 8s. 6d. 
 
 Compton Merivale: another Leaf 
 
 from the Lesson of Life. By the Author 
 of Brampton Rectory. 8s. 6d. 
 
 John Sterling's Essays and Tales. 
 
 Edited, with Life, by Archdeacon HARE. 
 Two volumes, with Portrait. 21s. 
 
 The City of God ; a Vision of the 
 
 Past, the Present, and the Future. By 
 E. BUDGE, Rector of Bratton. 8s. 6d. 
 
 Chronicles of the Seasons; a Course of 
 
 Daily Instruction and Amusement, selected 
 from the Natural History, Science, Art, 
 Antiquities, and Biography of our Father- 
 land. In Four Books, 3s. 6d. each. 
 
 The Merchant and the Friar; or, 
 
 Truths and Fictions of the Middle Ages. 
 By Sir F. PALGRAVE. Second Edition. 3s. 
 
 Crusaders ; Scenes, Events, and Cha- 
 racters from the Times of the Crusades. 
 By T. KEIGHTLEY. 7s. 
 
 The Lord and the Yassal; a Eamiliar 
 
 Exposition of the Feudal System. 2s. 
 
 French Revolution; its Causes and 
 
 Consequences. By F. M. ROWAN. 3s. 6d. 
 
 Labaume's History of Napoleon's 
 
 Invasion of Russia. 2s. 6d. 
 
 Historical Sketch of the British 
 
 Army. By G. R. GLEIG, M.A., Chaplain 
 General to the Forces. 3s. 6d. 
 
 Family History of England. By 
 
 the same Author. With numerous Illus- 
 trations. Three Volumes. 6s. 6d. each. 
 
 School History of England, abridged 
 
 from Gleig's Family History of England ; 
 with copious Chronology, List of Contem- 
 porary Sovereigns, and Questions. 6s. 
 
STANDARD BOOKS PUBLISHED BY 
 
 Familiar History of Birds. By E. 
 
 STANLEY, D.D., Bishop of Norwich. Fifth 
 Edition, with numerous Illustrations. 5s. 
 
 Domesticated Animals. By MARY 
 
 ROBEBTS. 3s. 6d. 
 
 Wild Animals. By the same. 3s. 6d. 
 Amusements in Chess. By C. TOM- 
 
 LINSON. 4s. 6d. 
 
 Musical History, Biography, and 
 
 Criticism. By GEORGE HOGAKTH. Two 
 Volumes. 10s. 6d. 
 
 Ullmann's Gregory of Nazianzum. 
 
 A Contribution to the Ecclesiastical His- 
 tory of the Fourth Century. Translated 
 by G. V. Cox, M.A. 6s. 
 
 Neander's Julian the Apostate and 
 
 his Generation: an Historical Picture. 
 Translated by G. V. Cox. M.A. 3s. 6d. 
 
 Dahlmann's Life of Herodotus, 
 
 drawn out from his Book. With Notes. 
 Translated by G. V. Cox, M.A. 5s. 
 
 Student's Manual of Ancient His- 
 tory. By W COOKE TAYLOK, LL.D. Fifth 
 Edition. 10s. 6d. 
 
 Student's Manual of Modern History. 
 
 By the same Author. Fifth Edition, with 
 New Supplementary Chapter. 10s. Gd. 
 
 Historyof Mohammedanism. Cheaper 
 
 Edition. By the same Author. 4s. 
 
 History of Christianity. By the 
 
 same Author. 6s. 6d. 
 
 History of the Holy Sepulchre. By 
 
 Professor WILLIS. Reprinted from Wil- 
 liams's Holy City. With Illustrations. 9s. 
 
 The Holy City; Historical, Topo- 
 graphical, and Antiquarian Notices of 
 Jerusalem. By G. WILLIAMS, B.D., Fellow 
 of King's College, Cambridge. Second 
 Edition, with numerous Illustrations and 
 Additions, and a plan of Jerusalem. Two 
 large Volumes. 2 5s. 
 
 *** The Plan is published separately, with a 
 Memoir, 9s. ; or Mounted on Rollers, 18s. 
 
 Notes on German Churches. ByW. 
 
 WHEWELL.D.D., Master of Trinity College, 
 Cambridge. Third Edition. 12s. 
 
 The Six Colonies of New Zealand. 
 
 By W. Fox. 3s. With large Map by Ar- 
 rowsmith, 4s. 6d. 
 
 Handbook for New Zealand. Recent 
 
 Information, compiled for the Use of In- 
 tending Colonists. 6s. 
 
 View of the Art of Colonization. 
 
 By E. GIBBON WAKEFIELD. Octavo. 12s. 
 
 Travels in the Track of the Ten 
 
 Thousand Greeks; a Geographical and 
 Descriptive Account of the Expedition of 
 Cyrus. By W. F. AINSWORTH. 7s. Gd. 
 
 Travels and Researches in Asia 
 
 Minor, Mesopotamia, Chaldea, and Ar- 
 menia. By the same Author. TwoVols., 
 with Illustrations. 24s. 
 
 Gazpacho ; or, Summer Months in 
 
 Spain. By W- G. Clark, M.A., Fellow of 
 Trinity College, Cambridge. Cheaper 
 Edition. 5s. 
 
 Auvergne, Piedmont, and Savoy: 
 
 a Summer Ramble. ByC.R.WELD. 8s. Gd. 
 
 Wanderings in the Republics of 
 
 Western America. By GEORGE BYAM. 
 With Illustrations. 7s. 6d. 
 
 Hesperos; or, Travels in the West. 
 
 Two Volumes. By Mrs. HOUSTOUN. 14s. 
 
 Commentary on the Cuneiform In- 
 scriptions of Babylonia and Assyria. By 
 Lieut.-Colonel RAWLINSON. Octavo. 3s. 
 
 Port Phillip in 1849. By Dr. GLUT- 
 
 TERBUCK, Nine Years Resident in the 
 Colony. With a Map. 3s. 
 
 Charters of the Old English Colonies 
 
 in America. With Introduction and Notes. 
 By S. LUCAS, M.A. 4s. 6d. 
 
 Canterbury Papers. Nos. I. to VIII. 
 
 6d. each; in a wrapper, 4s. Nos. IX. and 
 X., 1*. No. XI., with Four Views of the 
 Canterbury Settlement, Is. Gd. 
 
 Lectures on the Characters of our 
 
 Lord's Apostles. By a Country Pastor. 
 3s. Gd. 
 
 Lectures on the Scripture Revela- 
 tions respecting Good and Evil Angels. By 
 the same Author. 3s. 6d. 
 
 View of the Scripture Revelations 
 
 respecting a Future State. Sixth Edition. 
 By the same Author. 5s. 
 
 Twenty-five Village Sermons. By 
 
 C. KINGSLEY, jun., Rector of Eversley. A 
 Cheaper Edition, 3s. Gd. 
 
 Churchman's Theological Dictionary. 
 
 By R. EDEN, M.A., Chaplain to the Bishop 
 of Norwich. Second Edition. 5s. 
 
 The Gospel-Narrative according to 
 
 the Authorized Text, without Repetition 
 or Omission. With a Continuous Exposi- 
 tion, Marginal Proofs in full, and Notes. 
 By J. FORSTER, M.A., Her Majesty's Chap- 
 lain of the Savoy. Fourth Edition, 12s. 
 
JOHN W. PARKER AND SON, WEST STRAND. 
 
 Statutes relating to the Ecclesiasti- 
 cal and Eleemosynary Institutions of Eng- 
 land, Wales, Ireland, India, and the Colo- 
 nies ; with Decisions. By A . J. STEPHENS, 
 M.A., F.R.S. Two large Volumes, with 
 copious Indices, 3 3s. 
 
 The Natural History of Infidelity 
 
 and Superstition in Contrast with Chris- 
 tian Faith. Bampton Lectures preached 
 before the University of Oxford. By J. E. 
 RIDDLE, M.A., Minister of St. Philip's, 
 Leckhampton. Octavo, 12s. 
 
 Manual of Christian Antiquities. By 
 
 the same. Second Edition. 18s. 
 
 Luther and his Times. By the same 
 
 Author. 5s. 
 
 Churchman's Guide to the Use of 
 
 the English Liturgy. By the same Author. 
 3s. 6d. 
 
 First Sundays at Church. By the 
 
 same Author. Fifth Edition. 3s. 6d. 
 
 Exposition of the Thirty-Nine 
 
 Articles, Historical and Doctrinal. By E. 
 H. BROWNE, M.A., Prebendary of Exeter. 
 The First Volume. Octavo. 10s. 6d. 
 
 The Churchman's Guide; an Index 
 
 of Sermons and other Works, arranged 
 according to their subjects. By JOHN 
 FORSTER, M.A. Octavo. 7s. 
 
 The Early Christians. By the Rev. 
 
 W. PRIDDEN, M.A. Fourth Edition. 4s. 
 
 The Book of the Fathers, and the 
 
 Spirit of their Writings. 9s. 6d. 
 
 Babylon and Jerusalem: a Letter 
 
 addressed to Ida, Countess of Hahn-Hahn. 
 From the German, with a Preface. 2s. 6d. 
 
 History of the Church of England. 
 By THOMAS VOWLEE SHORT, D.D., Lord 
 Bishop of St. Asaph. Fifth Edition. Oc- 
 tavo. 16s. 
 
 History of Popery; the Origin, 
 
 Growth, and Progress of the Papal Power ; 
 its Political Influence, and Eifects on the 
 Progress of Civilization. 9s. Od. 
 
 Elizabethen Religious History. By 
 
 H. SOAMES, M.A. Octavo. 16s. 
 
 History of the Christian Church. 
 
 By Dr. BURTON, Professor of Divinity, 
 Oxford. 5s. 
 
 Outlines of Sacred History. 2s. 6d. 
 Outlines of Ecclesiastical History, 
 
 before the Reformation. By the Rev. W. 
 HOARE, M.A., late Fellow of St. John's 
 College, Cambridge. 2s. 6d. 
 
 Church of St. Patrick ; an Inquiry 
 
 into the Independence of the Ancient 
 Church of Ireland. By W. G. TODD, A.B. 
 4s. 
 
 Civil History of the Jews. By 
 
 O. COCKAYNE, M. A., King's College. 4s. 6d. 
 
 Cudworth on Freewill; now first 
 
 Edited, with Notes, by J. ALLEN, M.A., 
 Archdeacon of Salop. 3s. 
 
 Guericke's Manual of the Antiquities 
 
 of the Christian Church. Translated and 
 Adapted to the Use of the English Church, 
 by A. J. W. MORRISON, B.A., Master of 
 Grammar School, Truro. 5s. 6d. 
 
 Garrick's Mode of Reading the 
 
 Liturgy. With Notes, and a Discourse on 
 Public Reading. By R. CULL. 5s. 6d. 
 
 Memoir of Bishop Copleston, with 
 
 Selections from his Diary and Corres- 
 pondence. By W. J. COPLESTON, M.A., 
 Rector of Cromhall. 10s. 6d. 
 
 Life of Archbishop Usher. By C. R. 
 
 ELRINGTON, D.D., Regius Professor of 
 Divinity, Dublin. Portrait. Octavo. 12s. 
 
 Life of Archbishop Bancroft. By 
 
 the late Dr. D'OTLT. Octavo. 9s. 
 
 Memoirs of the Life, Character, and 
 
 Writings, of Bishop Butler. By T. BART- 
 LETT, M. A., Rector of Kingstoiie. 12s. 
 
 Lives of Eminent Christians. By 
 
 R. B. HONE, M.A., Archdeacon of Wor- 
 cester. Four Volumes. 4s. 6d. each. 
 
 Bishop Jeremy Taylor; his Prede- 
 cessors, Contemporaries, and Successors. 
 By Rev. R. A. WILLMOTT. Second Edition. 
 5s. 
 
 Lives of English Sacred Poets. By 
 
 the same Author. Two Vols. 4s. 6d. each. 
 
 Life and Services of Lord Harris. 
 
 By the Right Hon. S. R. LUSHINGTON. 
 Second Edition. 6s. 6d. 
 
 Notes on the Parables. By R. 
 
 C. TRENCH, B.D., Examining Chaplain to 
 the Bishop of Oxford. Fourth Edition. 
 Octavo. 12s. 
 
 Notes on the Miracles. By the 
 
 same Author. Third Edition. 12s. 
 
 St. Augustine's Exposition of the 
 
 Sermon on the Mount. With an Essay on 
 St. Augustine as an Interpreter of Scripture. 
 By R.C. TRENCH, B.D. Second Edition. 7s. 
 The Essay separately, 3s. 6d. 
 
STANDARD BOOKS PUBLISHED BY 
 
 Literature of the Church of England; 
 
 Specimens of the Writings of Eminent 
 Divines, with Memoirs of their Lives and 
 Times. By R. CATTEBMOLE, B.D. Two 
 volumes. Octavo. 25s. 
 
 Essays on Peculiarities of the Chris- 
 tian Religion. ByR.WHATELT.D.D., Arch- 
 bishop of Dublin. Cheaper Edition. 7s. 6d. 
 
 Essays on Difficulties in the Writings 
 
 of the Apostle Paul. By the same Author. 
 Cheaper Edition. 8s. 
 
 Essays on Errors of Romanism. 
 
 By the same. Cheaper Edition. 7s. Gd. 
 
 Essays on Dangers to Christian Faith 
 
 from the Teaching or the Conduct of its 
 Professors. By the same Author. 10s. 
 
 The Contest with Rome. A Charge 
 
 delivered in 1851 ; with Notes, especially 
 in answer to Dr. Newman's recent Lec- 
 tures. By J. C. HABE, M.A., Archdeacon 
 of Lewes. Octavo. 10s. 6d. 
 
 Mission of the Comforter. By the 
 
 same. Second Edition. Octavo. 12s. 
 
 The Victory of Faith. By the same 
 
 Author. Second Edition. 6s. 
 
 Parish Sermons. By the same 
 
 Author. Two Series. Octavo. 12s. each. 
 
 The Old Testament. Nineteen Ser- 
 mons on the First Lessons. By F. D. 
 MAUBICE, M.A., Chaplain of Lincoln's 
 Inn. 6s. 
 
 The Church a Family: Sermons on 
 
 the Occasional Services of the Prayer- 
 Book. By the same Author. 4s. Cd. 
 
 The Prayer Book; specially con- 
 sidered as a Protection against Romanism. 
 By the same Author. 5s. 6d. 
 
 The Lord's Prayer. Nine Sermons. 
 
 By the same Author. Third Edition. 2s.6d. 
 
 The Religions of the World, and 
 
 their Relations to Christianity. By the 
 same Author. Cheaper Edition. 5s.. 
 
 Lectures on the Epistle to the 
 
 Hebrews. By the same. 7s. 6d. 
 
 Christmas Day, and other Sermons. 
 
 By the same Author. Octavo. 10s. 6d. 
 
 Sequentise ex Missalibus, Anglicis, 
 
 Gallicis, Germanicis Desumptae. Collegit, 
 recensuit, notulasque addidit JOANNES M. 
 NEALE, A.M., Collegii Sackvillensis Custos. 
 
 Ordo Saeclorum; a Treatise on the 
 
 Chronology of the Holy Scriptures. By 
 H. Browne-, M. A., Canon of Chichester. 20s. 
 
 Observations on Dr. Wiseman's 
 
 Reply to Dr. Turton's Roman Catholic 
 Doctrine of the Eucharist Considered. By 
 T. TUBTON, D.D., Bishop of Ely. 4s. 6d. 
 
 James's Treatise on the Corruptions 
 
 of Scripture, Councils, and Fathers, by the 
 Prelates, Pastors, and Pillars of the Church 
 of Rome. Revised by J. E. Cox, M.A., 
 Vicar of St. Helen's, Bishopsgate. 12s. 
 
 Fullwood's Roma Ruit. The Pillars 
 
 of Rome Broken. New Edition, by C. 
 HABDWICK, M.A., Fellow of St. Catha- 
 rine's Hall, Cambridge. Octavo. 10s. 6d. 
 
 The Scriptural Character of the 
 
 English Church considered. With Notes. 
 By DEBWENT COLEBIDGE, M.A., Principal 
 of St. Mark's College Octavo. 12s. 6d. 
 
 College Lectures on Ecclesiastical 
 
 History. By W. BATES, B.D., Fellow of 
 Christ's College, Cambridge. Second 
 Edition. 6s. 6d. 
 
 College Lectures on Christian An- 
 tiquities, and the Ritual. By the same 
 Author. 9s. 
 
 Hints for an Improved Translation 
 
 of the New Testament. By J. SCHOLE- 
 FIELD, M.A., Professor of Greek, Cam- 
 bridge. Third Edition. 3s. 6d. 
 
 Choral Service of the Church : an 
 
 Inquiry into the Liturgical System of the 
 Cathedral and Collegiate Foundations of 
 the Anglican Communion. By J. JEBB, 
 M.A., Rector of Peterstow. 16s. 
 
 The Personality of the Tempter, 
 
 By C. J. VAUGHAN, D.D., Head Master of 
 Harrow (School. Octavo. 7s. 6d. 
 
 Sermons preached before the Uni- 
 versity of Oxford. By C. A. OGILVIE, D.D., 
 Canon of Christ Church. Octavo. 5s. 
 
 Lectures on the Prophecies, proving 
 
 the Divine Origin of Christianity. By A. 
 M'CAUL, D.D., Professor of Divinity in 
 King's College, London. Octavo. 7s. 
 
 The Messiahship of Jesus. The 
 
 Concluding Series of WABBUBTONIAN Lec- 
 tures. By DB. A. M'CAUL. 7s. 
 
 Two Series of Discourses. I. On 
 
 Christian Humiliation. II. On the City 
 of God. By C. H. TEBEOT, D.D., Bishop 
 of Edinburgh. Octavo. 7s. 6d. 
 
JOHN W. PARKER AND SON, WEST STRAND. 
 
 College Chapel Sermons. By W. 
 
 WHEWELL, D.D., Master of Trinity College, 
 Cambridge. 10s. 6d. 
 
 The Liturgy as it is, illustrated in 
 
 a Series of Practical Sermons. By H. 
 HOWARTH, B.D., Rector of St. George, 
 Hanover Square. Second Edition. 4s. 6d. 
 
 Practical Sermons, by Dignitaries 
 
 and other Clergymen. Edited by J. C. 
 CROSTHWAITE, M.A., Rector of St. Mary- 
 at-Hill. Three Volumes. Octavo. 7s. 
 each. 
 
 Short Sermons for Children, illus- 
 trative of the Catechism and Liturgy. By 
 the Rev. C. A. JOHNS, B.A. 3s. 6d. 
 
 The Calling of a Medical Student; 
 
 Four Sermons preached at King's College, 
 London. By E. H. PLUMPTRE, MA., 
 Chaplain and Divinity Lecturer. Is. 6d. 
 
 Butler's Three Sermons on Human 
 
 Nature, and Dissertation on Virtue. With 
 Preface and Syllabus, by W. WHEWELL, 
 D.D. Second Edition. 3s. 6d. 
 
 Butler's Six Sermons on Moral 
 
 Subjects. With Preface and Syllabus, by 
 Dr. WHEWELL. 3s. 6d. 
 
 Village Lectures on the Liturgy. 
 
 By W. PALIN, Rector of Stifford. 3s. 6d. 
 
 CLASSICAL TEXTS, 
 Carefully Revised. 
 
 ECMENIDES. Is. 
 
 C^SAR de BELLO GALLICO. I. to IV. Is. 6d. 
 CICERO de SENECTUTE. Is. 
 CICERO de AMICITIA. Is. 
 CICERO de OFFICIIS. 2s. 
 CICERO pro PLANCIO. Is. 
 CICERO pro MILONE. Is. 
 CICERO pro MUR-ENA. Is. 
 CICERONIS ORATIO PHILIPPICA SECUNDA. Is. 
 DEMOSTHENES IN LEPTINEM. Is. 
 DEMOSTHENES AGAINST APHOBUS and ONETOB. 
 Is. 6d. 
 
 EURIPIDIS BACCHvE. Is. 
 
 EXCERPTA ex ARRIANO. 2s. 6d. 
 
 EXCERPTA ex LUCIANO. 
 
 EXCERPTA ex TACITI ANNALIBUS. 2s. 6d. 
 
 HORATII SATIRE. Is. 
 
 HORATII CARMINA. Is. Gd. 
 
 HORATII ARS POETICA. Gd. 
 
 OVIDII FASTI. 2s. 
 
 PLATONIS PH^EDO. 2s. 
 
 PLATONIS MENEXENUS. Is. 
 
 PLATONIS PH^DHUS. Is. 6d. 
 
 PLUTARCH'S LIVES of SOLON, PERICLES, and 
 
 PHILOP(EMEN. 23. 
 
 SOPHOCLIS PHILOCTETES, with Notes. 2s. 
 SOPHOCLIS CEoiPus TTBANNUS, with Notes. 
 
 2s. 6d. 
 
 TACITI GERMANIA. Is. 
 TACITI AGRICOLA. Is. 
 TERENTII ANDRIA. Is. 
 TERENTU ADELPHI. Is. 
 VIRGILII GEORGICA. Is. 6d. 
 
 Arundines Cami, sive Musarum Can- 
 
 tabrigiensium Lusus Canori, collegit atque 
 edidit HENRICUS DKUB.Y, M.A. Fourth 
 Edition. 12s. 
 
 Agamemnon of ^Eschylus, the Text, 
 
 with a Translation into English Verse, and 
 Notes. By J. CONINGTON, M.A., Fellow of 
 University College, Oxford. 7s. 6d. 
 
 ^Eschylus translated into English 
 
 Verse. With Notes, Life of ^Eschylus, and a 
 Discourse on Greek Tragedy. By Professor 
 BLACKIE, of Aberdeen. Two Volumes. 16s. 
 
 Phsedrus, Lysis, and Protagoras of 
 
 Plato. Translated by J. WRIGHT, M.A., 
 Master of Sutton Coldfield School. 4s. 6d. 
 
 Homeric Ballads : the Text, with 
 
 Metrical Translations and Notes. By the 
 late Dr. MAGINN. 6s. 
 
 Tacitus, the ^Complete Works, with 
 
 a Commentary, Life of Tacitus, Indices, 
 and Notes. Edited by Professor RITTER, 
 of Bonn. Four Volumes. Octavo. 28s. 
 
 Aristophanis Comcedise Yndecim, 
 
 cum Notis et Indice Historico, edidit 
 HVBEBTVS A. HOLDEN, A.M Coll. Trin. 
 Cant. Socius. Octavo. 15s. The Plays 
 separately, Is. each. 
 
 Aulularia andMensechmei of Plautus, 
 
 with Notes by J. HILDYAHD, B.D., Fellow 
 of Christ's Coll., Camb. 7s. 6d. each. 
 
 Antigone of Sophocles, in Greek and 
 
 English, with Notes. By J. W. DONALDSON, 
 D.D., Head Master of Bury School. 9s. 
 
 Pindar's Epinician Odes, revised and 
 
 explained; with copious Notes and Indices. 
 By Dr. DONALDSON. 16s. 
 
 Becker's Gallus ; or, Roman Scenes 
 
 of the Time of Augustus, with Notes and 
 Excursus. Translated by F. METCALFE, 
 M.A. Second Edition. 12s. 
 
 Becker's Charicles ; or Illustrations 
 
 of the Private Life of the Ancient Greeks. 
 Translated by F. METCALFE, M.A. 12a. 
 
 Speeches of Demosthenes against 
 
 Aphobus and Onetor, Translated, with Ex- 
 planatory Notes, by C. RANN KENNEDY, 
 M.A., Fellow of Trin. Coll., Camb. 9s. 
 
 Selection from Greek Verses of 
 
 Shrewsbury School. By B. H. KENNEDY, 
 D.D., Head Master of Shrewsbury School. 
 8s. 
 
 Select Private Orations of Demo- 
 sthenes: with Notes. By C. T. PENROSE, 
 M.A., Master of Sherborne School. 5s. 
 
 Frogs of Aristophanes; with English 
 
 Notes. By the Rev. H. P. COOKESLEY. 7s. 
 
 Classical Examination Papers of 
 
 King's College. By R. W. BROWNE, M.A., 
 Professor of Classical Literature. 6s. 
 
PUBLISHED BY JOHN W. PARKER AND SON. 
 
 Fables of Babrius. Edited by G. C. 
 
 LEWIS, M.A. 5s. 6d. 
 
 Cambridge Greek and English Tes- 
 tament. Edited by Professor SCHOLEFIELD. 
 Third Edition. 7s. 6d. 
 
 Cambridge Greek Testament. 3s. 6d. 
 Sacred Latin Poetry; with Notes 
 
 and Introduction. By R. C. TRENCH, 
 B.D. 7s. ; or 14s. bound in antique calf. 
 
 Commentary on the Acts of the 
 
 Apostles. By W. G. HUMPHRY, B.D., Ex- 
 amining Chaplain to the Bishop of London. 
 Octavo. 7s. 
 
 Pearson's Lectures on the Acts of 
 
 the Apostles and Annals of St. Paul. 
 Edited in English, with a few Notes, by 
 J. R. CROWFOOT, B.D., Divinity Lecturer 
 of King's College, Cambridge. 4s. 
 
 Greek Text of the Acts of the 
 
 Apostles; with English Notes. By H. 
 ROBINSON, D.D. 8s. 
 
 Bceckh's Public Economy of Athens. 
 
 Translated by G. C. LEWIS, A.M. 8vo. 
 18s. 
 
 Schleiermacher's Introductions to the 
 
 Dialogues of Plato. Translated by W. 
 DOBSON, M.A., Fellow of Trinity College, 
 Cambridge. 12s. 6d. 
 
 Hebrew Grammar. By the late 
 
 CHR. LEO, of Cambridge, 12s. 6d. 
 
 New Hebrew Lexicon. Part I. 
 
 Hebrew and English. Part II. English 
 and Hebrew. With Grammar, Vocabu- 
 lary, and Grammatical Analysis of the 
 Book of Genesis. Also a Chaldee Gram- 
 mar, Lexicon, and Grammatical Analysis 
 of the Chaldee Words of the Old Testa- 
 ment. By T. JARRETT, M.A., Professor 
 of Arabic, Cambridge. Octavo. 21s. 
 
 Guide to the Hebrew Student. By 
 
 H. H. BERNARD, Teacher of Hebrew, 
 Cambridge. 10s. 6d. 
 
 The Psalms in Hebrew, with Critical, 
 
 Exegetical, and Philological Commentary. 
 By G. PHILLIPS, B.D., Fellow and Tutor 
 of Queen's College, Cambridge. Two 
 Volumes. 32s. 
 
 Elements of Syriac Grammar. By 
 
 G. PHILLIPS^ B.D. Second Edition. 10s. 
 
 Practical Arabic Grammar. By 
 
 DUNCAN STEWART. Octavo. 16s. 
 
 Analysis of the Text of the History 
 
 of Joseph By A. OLLIVANT, D.D., Lord 
 Bishop of Llandaff. 6s. 
 
 Edited for the Syndics of the Cambridge 
 University Press. 
 
 Works of Dr. Isaac Barrow. New 
 
 Edition, compared with original MSS., and 
 enlarged with materials hitherto unpub- 
 lished. 
 
 Grotius De Jure Belli et Pads. 
 
 With the Notes of Barbeyrac and others ; 
 acompanied by an Abridged Translation 
 of the Text. By W. WHEWELL, D.D., 
 Master of Trinity College, and Professor 
 of Moral Philosophy in the University. 
 Two Volumes, Octavo. 
 
 The Octavius of Minucius Felix ; 
 
 with an Introduction, Analysis, and English 
 Notes, by the Rev. H. A. HOLDEN, M.A., 
 Fellow of Trinity College. 
 
 Theophili Episcopi Antiochensis 
 
 Libri tres ad Autolycum. Edidit Prole- 
 gomenis Versione Notulis Indicibus In- 
 
 StrUxitGULIELMUSGlLSONHuMPHRY,S.T.B. 
 
 Collegi Sanctiss. Trin. Ap. Cantabrigienses 
 Socius. 6s. 
 
 Sanderson De Obligatione Consci- 
 
 entiae - Prselectiones Decem Oxonii in 
 Schola Theologica Habitse. With English 
 Notes, including an abridged Translation 
 by W. WHEWELL, D.D., Master of Trinity 
 College. Octavo. 9s. 
 
 The Homilies, with various Readings, 
 
 and the Quotations from the Fathers given 
 at length in the Original Languages. Edited 
 by G. E. COHRIE, B.D., Master of Jesus 
 College, and Norrisian Professor of Divinity. 
 Octavo. 10s. 6d. 
 
 Pearson on the Creed. Revised and 
 
 Corrected by TEMPLE CHEVALLIER, B.D., 
 Professor of Mathematics, Durham. 12s. 
 
 In this edition the folio of 1669 has been taken 
 as the principal model of the text, and the 
 quotations from the Fathers have been verified 
 throughout. The passages from the Habbiiiical 
 writings and Chaldee paraphrases have been 
 carefully collated. 
 
 Twysden's Historical Vindication of 
 
 the Church of England in point of Schism. 
 Edited, with the Author's MS. Corrections, 
 by Professor CORRIE. 7s. 6d. 
 
 Archbishop Usher's Answer to a 
 
 Jesuit; with other Tracts on Popery. 
 Octavo. 13s. 6d. 
 
 Dr. Hey's Lectures on Divinity. 
 
 Third Edition. Two Vols. Octavo. 30s. 
 
 Wilson's lUustration of the Method 
 
 of Explaining the New Testament. Edited 
 by T. TURTON, D.D., Bishop of Ely. 8s. 
 
 

 14 DAY USE 
 
 RETURN TO DESK FROM WHICH BORROWED 
 
 LOAN DEPT. 
 
 This book is due on the last date stamped below, or 
 
 on the date to which renewed. 
 Renewed books are subject to immediate recall. 
 
 REC'D 
 
 APR 17 '64 -k 
 C'D LD 
 
 INTERUBRARYLOAN 
 JUN 1 2 1981 
 
 V. OF CALIF. PE 
 
 
 
 LD 2lA-'50m-ll,'62 
 (D3279slO)476B 
 
 General Library 
 
 University of California 
 
 Berkeley 
 
, 
 
 .A 
 
 263255 
 
 UNIVERSITY OF CALIFORNIA LIBRARY