2WTES ON COMETS.] 



ASTRONOMY. 



069 



1718. This comet was observed at Berlin by Kirch, 

 from January 18th to February 5th. It appeared to be 

 equal to a star of the fourth or fifth magnitude, with a 

 nebulous diameter of 5' or 7'. 



1723. Discovered at Bombay on October 12th, and 

 observed at Lisbon Uud other European stations to the 

 middle of December. It appeared of about the third 

 magnitude, with a very faint tail, not more than 1 in 

 length. 



1729. This comet, which is remarkable in the length of 

 its visibility, and the greatness of its distance from the 

 sun and earth, was discovered at Nimes, by P. Sarabat, 

 on July 31st. It was a small nebulous body, scarcely 

 visible to the naked eye. 



1737. The observations of this comet were made at 

 Paris, Rome, Bologna, Oxford, Lisbon, and also in 

 Jamaica and Madras. 



1 739. This comet was observed at Bologna, from May 

 28th to August 18th. 



1742. First comet. Seen at the Cape of Good Hope 

 on February 5th. It was also seen in Europe in March, 

 and was visible to the naked eye. The length of the tail 

 was 5 to 8. 



1743. First comet. This comet was observed at Bologna, 

 Paris, Vienna, and Berlin. In Berlin, it appears to have 

 been discovered, on February 10th, by M. Grischou. It 

 was a small body. 



1743. Second comet. Observed at Haarlem from the 

 of August to the 13th of September. This comet 



was small, but was seen, notwithstanding, with the naked 

 eye. 



1744. This comet appears to have been discovered at 

 Haarlem on December 9th, 1743, and was seen to March, 

 1744, at several observatories. It was one of the finest 

 bodies which had occurred since the comet of 1080. In 

 February, M. Cassini noticed that the head was divided 

 into two portions. The tail wag also divided shortly after 

 into two branches. 



1747. Discovered at Lausanne, by Cheseaux, on the 

 13th of August, 174(5, and observed there to September 

 22nd. His observations were then interrupted by illness ; 

 but it was last seen on the 23rd of November, near a star 

 in Capricornus. 



1748. The first comet of this year was discovered at 

 Paris about the bitter end of April. It was also observed 

 in South America, and in Pekin in China, as well as the 

 Royal Observatory, Greenwich. It appears to have 

 been a fine object, easily seen with the naked eye, and 

 having a tail 20 3 long. This comet was observed at Paris, 

 by Maraldi, to the 30th of June. 



1748. The second comet of this year was seen at the 

 same time as the first, but in a different part of the 

 heavens. Its nucleus was brighter than the preceding, 

 but there was no appearance of tail. The orbit depends 

 on three approximate observations made at Haarlem, and 

 is consequently very uncertain. 



1757. Observed at Greenwich from September 13th to 

 October 18th. The orbit of this comet is very approxi- 

 mate. 



1758. Discovered in the island of Bourbon on the 

 26th of May, and seen in London on June 18th. Mes- 

 sier first observed the comet on August 15th, and con- 

 tinued his observations to the 2nd of November. It 

 appears to have been a diffused body, equal in diameter 

 to Jupiter. 



1759. Halley's comet, first seen on Christmas day, 

 1758, by Pazlitch, near Dresden, and on the 28th by Dr. 

 Hoffmann. This return is very celebrated in the history 

 of astronomy, as being the first predicted appearance of 

 a comet. Dr. Halley roughly estimated that the time 

 of arriving at its perihelion would be at least one year 

 longer than the interval between the two preceding re- 

 turns. Clairaut, by a laborious calculation of the plane- 

 tary perturbations, fixed its return on the 13th of April, 

 the true time having been determined by Rosenberger, 

 from a minute discussion of all the observations, to have 

 *;ik<m place on March 12th. From the beginning of 

 IT.'i!) to the middle of February, the comet was regularly 

 observed, till it became plunged in the solar rays about 



VOL. L 



! the latter period. On its reappearance, at the end of 

 j March, it was again observed to the 17th of April, till 

 its declination became too great to permit its observation 

 at European stations. It was observed, however, from 

 the 20th of April to the middle of May in southern sta- 

 tions. La Nux, at the Isle of Bourbon, found the 

 length of its tail on March 21st to be 8; on the 28th 

 of March, 25; on May 1st, 33 to 34; and on the 5th of 

 May, 47. It afterwards diminished, till, on the 14th 

 of May, it was not more than 19. It afterwards reap- 

 peared above the European horizon, and was observed in 

 France and Portugal to the 3rd of June. 



1759. The second comet of this year is reckoned in the 

 order of its time of perihelion passage. It was discovered 

 on the 25th of January, 1700, in the constellation Leo, by 

 the celebrated astronomer Messier, and regularly ob- 

 served to the 16th of March. 



1759. The third comet of this year (reckoning, as 

 before, in the order of perihelion passage) was discovered 

 on the 1st January, 1760, by all the astronomers of the 

 French Academy, and observed till the 8th of February. 

 Its motion was exceedingly rapid, being, on the day of 

 its discovery, 2 25' of a great circle in two hours, or at 

 the rate of 29 daily. The diameter of the nebulosity was 

 found to vary from 20" to 30". Its tail was about 4 in 

 length. 



1762. This comet was discovered by Klinkenberg on 

 the 17th of May, and observed by Messier and Maraldi 

 to the 2nd of July. Its appearance at the time of its 

 discovery was similar to a star of the fourth or fifth 

 magnitude, with a slight tail. The nucleus was readily 

 visible to the naked eye, but in a telescope was bright 

 and ill-defined. 



1763. Discovered by Messier on September 28th, and 

 observed to the 25th of November. Its appearance was 

 that of a nebulous star. On the 4th of October, its dia- 

 meter was 7' or 8'. The orbit of this comet gave Pingre 

 considerable trouble. That of Burckhardt is founded on 

 unpublished observations. 



1764. This comet was also discovered by Messier, and 

 observed by him from January 3rd to February llth. It 

 was a bright nebulous object, visible to the naked eye, 

 with a tail 2J in length. 



1766. Discovered by Messier on the 8th of March, 

 when looking for the supposed satellite of Venus, 

 which had created great sensation about this period. 

 It appeared as a small nebulosity, with a luminous 

 centre. 



1766. Second comet. This comet appears to have 

 been discovered by Helfenzriella, of Dillengen, in Suabia, 

 on the 1st of April. On April 9th, it presented a tail 

 from 3 to 4, its nucleus being similar to a star of the 

 fourth magnitude. Pingre supposed that it would be 

 visible after the perihelion passage, which proved to be 

 the oase ; but not, however, in European latitudes. La 

 Nux observed it in the Isle of Bourbon, from April 29th 

 to May 13th. 



1769. This remarkable comet was discovered by Mes- 

 sier, on the 8th of August, and observed by nearly all the 

 astronomers. La Nux observed it at the Isle of Bourbon, 

 from August 26th to September 26th. On September 

 llth, he found its tail by measurement 97 long. Pingre, 

 the same day, measured its length to be 90. On August 

 28th, Dr. Maskelyne noticed its tail as 7 ; Messier as 

 15 ; La Nux and Pingre as 19 to 20. On September 

 9th, Dr. Maskelyne estimated its length 43 ; Messier as 

 55 ; La Nux upwards of 60 ; and Pingre as 75. This 

 comet was also observed after its perihelion passage, from 

 October 24th to the 1st of December. 



1770. First comet. Messier discovered this comet on 

 the 14th of June, and observed it regularly to the 2nd of 

 October. This comet is celebrated for the trouble it has 

 successively given astronomers in the attempts to investi- 

 gate its orbit. Leverrier has recently determined its 

 period to 5 '6 years nearly, but it has never been ob- 

 served since the time of its discovery. 



1770, Second comet. This comet appeared in 1771, on 

 the 10th of January of which year it was seen at Paris by 

 Messier, and at Milan by Boscovicb . It appears, how- 



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