CHAP. III., 5.] 



ASTRONOMY. MR HIND MR LASSELL. 



61 



(279.) 

 Division 

 of the body 

 of the co- 

 met in 

 1846. 



though the perturbations of Jupiter were, as usual, 

 large. 



Biela's Comet has been since recognised in 1846 

 and 1852, but it was not seen in 1839. It does not 

 appear to be admitted that it shows any acceleration 

 due to a resisting medium. Its perihelion distance 

 is, however, considerable. 



At the apparition of 1846 an extraordinary cir- 

 cumstance occurred. When discovered in the end 

 of November 1845 it appeared round and. single. 

 On the 19th December it was observed by Mr Hind 

 to be elongated, and ten days later was seen in Ame- 

 rica (and soon after at Cambridge and elsewhere) to 

 have divided into two seemingly distinct nebulous 

 parts. 1 These continued to subsist and move inde- 

 pendently throughout the remainder of the appari- 

 tion : the real distance of the centres being about 

 150,000 English miles. In 1852 the comet was 

 rediscovered at Rome ; the division into two still 

 subsisting, but the interval of separation being in- 

 creased about eight-fold. 



Besides the comets of Encke and Biela, there are 

 several others which are suspected on good grounds 

 to have periods of from 5 to 7 years, their aphelia 

 all lying in tolerable proximity to the orbit of Ju- 

 piter. But among these the return of only one has 

 yet been verified by observation ; namely, the comet 

 of Faye, which, after passing its perihelion 17th 

 October 1843, returned to it 3d April 1851, within 

 an hour of the time predicted by M. Leverrier. The 

 motion of comets of short period seems to be inva- 

 riably direct or conformable to that of the planets. 

 The inclination of their orbits to the Ecliptic is 

 usually moderate. 



Great Comets of 1811 and 1843. The finest 

 comets of the last hundred years were those of 1811 

 and 1843. The former was observed for a length of 

 time altogether unusual, having been visible from 

 March 1811 to August 1812. There is pretty good 

 reason to think that its period is not much less than 

 3000 years. The comet of 1843 was even more 

 splendid, but its flight was more rapid, and it was 

 not favourably seen in northern latitudes. It was 

 visible at many places in broad daylight when less 

 than 4 from the Sun, and at one time a tail 65 in 

 length could be traced. The circumstance which 

 distinguishes this comet from all others which have 

 been computed is the smallness of its perihelion dis- 

 tance, which was only 3^3 of the radius of the Earth's 

 orbit, or the comet approached the Sun's body within 

 one-seventh of his radius. The solar disk then sub- 

 tended an angle at the comet of 12l, or the glare 

 was equal to that of 47,000 suns as seen by us ! 

 The heat to which the comet was exposed is supposed 



to have exceeded 24 times that concentrated by our 

 most powerful burning-glasses by which even rock 

 crystal has been fused. 2 



MR HIND. Discovery of New Planets. We have 

 spoken in a former section (161), of the discovery of Discovery 

 four small planets or asteroids between the orbits of of new 

 Mars and Jupiter. They were found between the years 

 1801 and 1807- An interval of nearly forty years 

 elapsed without any addition to the members of our 

 system. In 1845 a new asteroid, Astreea, was found 

 by M. Hencke ; the following year was distinguished 

 by the discovery of Neptune under unparalleled cir- 

 cumstances ; and since 1847 every year, down to the 

 present time (1855), has added to our knowledge of 

 the group of asteroids. 



Among the discoverers of these planetary bodies M 

 Mr Hind has been distinguished by frequent success, 

 under circumstances which appeared by no means 

 peculiarly advantageous. This indefatigable obser- 

 ver and computer commenced (I believe) his astrono- 

 mical career as one of the assistants at Greenwich, 

 and afterwards had the sole charge of the private ob- 

 servatory of Mr Bishop, a wealthy citizen of London, 

 together with the use of a fine refractor equatoreally 

 mounted. It is within the Regent's Park, close to 

 the smoke of the metropolis, that Mf Hind has dis- 

 covered a larger number of planetary bodies than 

 any other person living. Next to him M. de Gas- M ;_? e Gas " 

 paris of Naples has been most successful. Unques- 

 tionably the impulse towards these new discoveries 

 has been given by the indefatigable industry of astro- 

 nomers (principally those of Germany), in constructing 

 minutely accurate star-maps. Mr Hind is also advan- 

 tageously known by the discovery of several comets, 

 and by his ingenious observations in sidereal astro- 

 nomy, especially on variable stars. I shall here 

 give a table of the asteroids in the order of discovery 

 as at present known (July 1855). 

 l 



pans. 



Ceres 



2 Pallas 



3 Juno 



4 Vesta 



5 Astraea 



6 Hebe 



7 Iris 



8 Flora 



9 Metis 



10 Hygeia 



11 Parthenope 



12 Victoria 



13 Egeria 



14 Irene 



15 Eunomia 



16 Psyche 



17 Thetis 



18 Melpomene 



19 Fortuna 



1801 Jan. 1 



1802 March 28 

 1804 Sept. 1 

 1807 March 29 

 1845 Dec. 8 



1847 July 1 

 Aug. 13 

 Oct. 18 



1848 April 26 



1849 April 12 



1850 May 11 

 Sept. 13 

 Nov. 2 



1851 May 19 

 July 29 



1852 March 17 

 April 17 

 June 24 

 Aug. 22 



Piazzi. 



Gibers. 



Harding. 



Gibers. 



Hencke. 



Hencke. 



Hind. 



Hind. 



Graham. 



De Gasparis. 



De Gasparis. 



Hind. 



De Gasparis. 



Hind. 



De Gasparis. 



De Gasparis. 



Luther. 



Hind. 



Hind. 



List of the 

 Asteroids. 



1 A similar phenomenon is related by Seneca. See Grant's History of Astronomy, p. 302. 



2 See many other interesting particulars of this comet in Sir J. Herschel's Outlines of Astronomy, arts. ^589, &c. See also in- 

 teresting details on the subject of comets generally in Mr Hind's and Mr Milne's works on comets, and in Mr Grant's excellent 

 History of Physical Astronomy. 



