Ml 



ASTRONOMY. 



[NOTES ON COMETS. 



newly discovered object that is observed in an ellipse, 

 ouly slightly eccentric, Las boon classed among tlio 



fig. lit. 



planets ; while those which do not satisfy these conditions 

 are regarded as comets. Ihe comets we have described, 

 while differing in many respects, seem to agree in the 

 great degree of eccentricity of their orbits, and would 

 seem to satisfy the inquirer that they cannot have the 

 same origin. 



Comets generally present the appearance of a brilliant 

 nucleus, surrounded with a nebulosity which extends on 

 one side more or less distant from the centre. This ne- 

 bulous matter is so transparent, that stars, even of small 

 magnitude, can be observed through the tail, and even 

 through its thicker parts. The nebulosity of a comet, 

 therefore, may be regarded simply as an extremely linlit 

 vapour, which accompanies the central nucleus. The 

 rapid changes wliich have been occasionally observed in 

 the form of comets would seem to confirm this impres- 

 sion. For example, Halley's comet was observed with 

 much care by Herschul at the Cape of Good Hope at the 

 end of 1835, and we have already noted the changes he 

 registered ; but the most striking instance of change on 

 record occurred in January, 1846, when Gambart's comet 

 was observed to be separated into two parts, each having 

 formed an independent nucleus, with the usual nebulous 

 accompaniment. When the comet again appeared in 

 1852, the two objects also appeared, but at an increased 

 distance. 



NOTES ON COMETS. 371 B.C. According to Diodorus 

 of Sicily, about the end of the year 371, a comet appeared 

 of prodigious magnitude; which was accompanied at the 

 same time by inundations and an earthquake. Its ap- 

 parent motion was from west to east, but its real motion 

 was probably retrograde. From all recorded circum- 

 stances, it appears when observed to have been near its 

 perihelion, and the inclination of its orbit to have been 

 very great. 



ueca relates that the comet was divided into two 

 portions near the end of its appearance. Stuyck is of 

 opinion that the comet was identical with that of loi,|, 

 but there are no grounds for this supposition. 



344 B.C. At this period, Diodorus relates that Fabius 

 ami Sulpicius, being consuls, on the occasion of Timoleus 

 i-inth undertaking an expedition to Sicily, a burn- 

 ing torch appeared in the heavens the whole night, and 



ed the train of Tiuioleus, even till its arrival in 

 \\ may than infer that it had a considerable 



declination, and that it appeared in the western 



203 B.C. M. Cornelius Cethegus and P. Sempronius 

 --idiunu* being consuls a comet was seen at Sethia, ex- 

 tending from east to west The Chinese annals confirm 



tliis by its appearance, about the month of August, near 

 Ari tiirus. 



171' i:.i-. I'. ]>o M:iille relates that a groat comet ap- 

 peared in China, at tin- und of the Humim-r <.f this year, 

 which had a tail. 



156 B.C. In China, near the end of October, and visible 

 for a period of twenty-one days, a comet in the west, 

 \\hi.-li traversed the constellations of Aquarius, Equuleus, 

 and Pegasus. 



156 B.C. In this year, Seneca relates that, after the 

 death of Demetrius, king of Syria, a comet appeared as 

 large as the sun. At first its appearance was red and 

 fiery, emitting sufficient light to dissipate the darkness 

 of night Gradually, however, its magnitude diminished, 

 till it finally vanished. 



136 B.C. In this year three comets were seen, which 

 all may belong probably to the same body. 



I. S. M. Emilius and C. Hostelius Mancinus being 

 consuls, a burning torch was seen in the heavens at 

 Preneste. 



II. Under the reign of Attains, king of Pcrgamus, 

 who reigned from 138 or 137 to ]32 B.C., a comet was 

 seen, which is supposed to be that of 136 B.C., and which, 

 small at first, gradually increased till it reached the equa- 

 tor. Its tail equalled in length the parts of the heavens 

 whose extent is the " Milky Way." 



III. At the birth of Mithridates, who lived from this 

 year to about 65 B.C., a comet, whose brightness was 

 greater than that of the sun, lasted for about seventy 

 days ; the heavens appeared on fire, and the comet ap- 

 peared to occupy one-fourth part of the sky ; but it is 

 doubtful whether this occurred in this year or 134 B.C. 



133 B c. In this year at Anisterne, the sun was seen 

 during the night, and this lasted for some time ; but it 

 is likely that these appearances were due to the muteon 

 which we so frequently observe. 



48 B.C. Lucian mentions that in this year a terrible 

 comet appeared ; the darkness of the night was illumi- 

 nated by it. In 49 B.C., or probably 48, a comet was 

 seen in China whose paths were extended from ft Cassio- 

 peia through t Cassiopeiffi, till it was lost finally among 

 those stars which never set. 



43 B.C. In the latter part of September of this ye.ir, 

 during the feasts in honour of Venus, a comet was seen 

 which was of great brightness, and was visible in all parts 

 of the earth. It was visible about 5 P. M. , when the. bright- 

 ness of the sun permitted it to bo observed. It is very 

 probable that it was in the sign Leo, with a north latitude 

 of 35 to 40, and that it was identical with the comet of 

 1680. In China, in this year also, a comet was seen in 

 the months of May or June, which was in the constella- 

 tion Orion ; but, if this be the same comet as the pre- 

 ceding, it will not agree with the elements of the comet 

 of 1680. 



SINCE THE CHRISTIAN ERA. 14. According to Dio 

 Cassius, S. Pompeius Magnus, and S. Apuleius being 

 consuls, many comets of the colour of blood were seen to 

 shine. 



39. In the Chinese annals mention is made of a comet 

 in this year, which was visible from the 13th of March 

 ;o the 30th of April, or for forty-nine days. Its path was 

 : rom the Pleiades, through Pegasus, and finally to the 

 "ie;id of Andromeda. 



lid. In China a comet was seen in the constellation of 

 Dapricornus, whose tail was eight degrees in length ; its 

 appearance lasted for fifty days, and it was last observed 

 n the smith of the head of the constellation Scorpio. 



76. Pliny related of a comet being observed this year, 

 which was described by Titus Csesar as having occurred 

 n his fifth consulate. In China it was observed from 

 he Ttli of September, ami was visible for forty days. Its 

 ail was 3 in length, and the path of the comet was from 

 he head of the constellation Hercules to 3 of the east of 



Capricorn. 



117- In the 9th of January of this year a comet was 

 seen towards the west. On January 14th it was 

 near ft Libra 1 and a Equulei ; it afterwards passed to the 

 constellation Musca, 



141. According to the Chinese annals, on March -7th 



