Page:Encyclopædia Britannica, Ninth Edition, v. 6.djvu/220

Rh 192 COMET Though there is great probability of the identity of this comet with &quot;Wmnecke s comet (No. VII.), it is preferable at present to treat of these bodies separately. The comet of 1 766 was undoubtedly moving in an elliptical orbit of no long period, as was established by Burckhardt after a great amount of computation, but the obser vations were not sufficiently precise to allow of the length of revo lution being found with exactness. IV. TempeVs Comet. 1873, II. T 1873, June 25 3777 e 0-544156 1873-0 a 2-94954 Period.. 5 066 years. Direct. Q, 120 54 9 i 12 43 20 Discovered by Tempel at Milan, 1873, July 3. The marked deviation from a parabolic orbit was soon independently noticed in England and on the Continent. It does not appear that there is any record of this comet having been observed prior to the year 1873. V. De Vice s Co-met. 1844, I. T 1844, September 2 4779 TT 342 30 48 ) 1844, ft 63 49 38 Sept. 1. i 2 54 46 e 0-617372 a 3-10045 Period. .5-459 years. Direct. Discovered by De Vico at Rome, 1844, August 22. Notwith standing the elaborate calculation of the orbit by Professor Briinnow, the comet has not been detected since 1844. The researches of M. Leverrier make it highly probable that this body is identical with the comet observed by Lahire at Paris in 1678, though it was not detected at any one of the many returns to perihelion which must have taken place in the interim. VI. Br or sens Comet. T 1873, October 10-2694 .116 2 50 .101 12 38 . 29 24 13 1870-0 1846, III. e 0-808560 a 3-10556 Period.. 5 473 years. Direct. Discovered by Brorsen at Kiel, 1846, February 26, and since ob served at several returns, including the last in 1873, to which year, it will be seen, the above elements apply. The comet appears to have been detected at its first passage of the perihelion in the present orbit, the form of which is evidently due to a very near approach to the planet Jupiter in May 1842. A first approximation to the elements previous to this encounter with Jupiter has been given by the late Professor D Arrest. VII. Winnecke s Comet. 1858, II ( = 1819, III. =1766, II. ?) T 1875, March 12-1765. e 0741013 a 3-20081 Period. .5-727 years. .276 .111 . 11 37 51 29 43 17 4 1875-0 Direct. A comet discovered by Professor Winnecke, 1858, March 8, was soon found to be moving in an elliptical orbit of short period, and to be identical with the third comet of 1819, to which Encke had assigned a revolution of 5 62 years. The two appearances of 1819 and 1858 have since been connected, from calculation of the per turbations produced by the planet Jupiter, by Clausen, so that there is no possible doubt of the identity of the comets of these years. According to Clausen s computation, the intermediate perihelion passages took place, 1825, February 5; 1830, August 21 ; 1836, March 3; 1841, September 13; 1847, March 29; and 1852, October 11, the comet being missed at every return. Our elements are for the last appearance in 1875. (See No. III.) VIII. rigott s Comet. T 1783, November 19-930-1 .50 .55 .45 17 25 40 31 6 54 1783-0 1783. e 0-552456 a 3-26066 Period...5-888 years. Direct. Certainly a comet which, at the time it was detected by Pigott (of variable-star celebrity) at York, 1783, November 19, was moving in an orbit with short period of revolution. This was first established by Burckhardt about the year 1819, but the most accurate orbit will be that of Professor Peters of Clinton Observatory, New York, who has used improved solar places. His orbit is given above. The comet has not been observed since 1783, but Peters has pointed out that with a major axis differing very little from that he had found, the comet might have encountered the planet Jupiter at some one of the aphelion passages subsequent to 1783, and thus have under gone an entire change of orbital elements. IX. TempeTs Comet. (1.) T 1867, May 23-9204 (2.) T.... 236 9 24 101 10 10 6 24 36 .1873, May 9 01 34 237 78 9 38 42 44 39 44 13 1867-0 1873-0 1867, II. e 0-509706 o 3-18903 Period.. 5 695 years. Direct. e.... 0-461999 a 3-28895 Period.. 5 965 years. Direct. Discovered by Tempel in April 1867 ; the periodicity established at the same appearance. We have here given orbits both for that year and for the next return in 1873, on account of the heavy perturbations which the elements suffered from the attraction of Jupiter, near to which the comet passed about the aphelion passage. It will be seen that the node was thereby thrown back more than 22, the inclination increased 3J, and the revolution lengthened upwards of three months. The least distance between the planet and comet was about 32, the earth s mean distance being taken as unity. X. Biela s Comet. The periodicity of this comet was ascertained on its discovery in February 1826 by Biela, at Josephstadt, Bohemia, and independently by Gambart at Marseilles about ten days later. Both discoverers remarked the similarity of elements to those of the comets of 1772 imperfectly observed by Montaigne at Limoges, and the first comet of 1806. Clausen s calculations showed that the period of revolution between 1772 and 1826 had been about 6 years, the comet having escaped observation at the intermediate returns, excepting that of 1806, when it was detected by Pons. Professor Santini of Padua has principally occupied himself with the investigation of the motions of this comet, and more recently the late Professor Hubbard of Washington. The comet was observed at its re-appearance in 1832, but missed in 1839, from proximity to the sun s place. At the next return in 1845-6 it was again found, and at this appear ance a remarkable separation into two distinct nebulosities took place under the eyes of astronomers. In 1852 both components were re-observed, and were found to have considerably widened their distance from one another. At the return to perihelion in 1859, there was no possibility of observations from unfavourable position in the heavens ; but in 1866, according to calculation, which in volved accurate determination of the planetary perturbations, its track seemed likely to favour observation, yet, notwithstanding long and minute search, the comet was not found, nor was anything seen of it as a comet in 1872. In this year, however, there occurred an extraordinary shower of meteors at the end of November, which beyond doubt were moving in the orbit almost identical with that of Biela when last observed. Subjoined are the elements of the two nebulosities forming the comet at the last appearance iu 1852 : 1852, September 23 -0443 (A.) T.... ir 109 ft 245 53 13 i 12 33 11 (B.) T..... 1852, September 23-7259 l852 .109 .245 . 12 9 10 52 15 33 26 1852-0 e 0-755838 a.. . 3-52479 Period. .6-618 years. Direct. e 0-755872 a 3-52537 Period.. 6 -6 19 years. Direct. XL D Arrest s Comet. T 1877, May 10-3325 e 0-627805 , // a 3-54139 T 319 15 } igso-O Period.. 6 664 years. a1J Q 98 ( ioou &quot; T- i. 14o y zo ) Direct. i 15 43 9 Discovered by D Arrest at Leipsic, 1851, June 27 ; he suspected a marked deviation of the orbit from a parabola as early as July S, and elliptical elements were very fairly determined at this first observed visit. MM. Villarceau and Leveau of Paris have prin cipally occupied themselves with the motions of this body, which, like others of the group, approaches very near to the orbit of Jupi ter, thereby at times undergoing considerable perturbation. This was the case in 1861, when the distance between the two bodies was only 36, so that the elements we have given above for 1877 are materially different from what they were in 1851 ; the period of revolution is now about 100 days longer than when the comet was discovered. It was observed in 1857-58 and in 1870, but missed at the intermediate return. XII. Faycs Comet. T 1873, July IS 4866 e 5573S3 , // a 3-80138 TT 50 253) 1fi70 . Period... 7 -41 2 years. Q 209 38 57 j ia/U Direct. i 11 21 50
 * ....306 9 43