

ASTRONOMICAL PHENOMENA AND PROGRESS. 



35 



It has long been known that the aphelion-distances 

 of comets are grouped in classes at definite distances 

 from the sun. Tims we know that there is a large 

 group of comets whose aphelion-distance is about the 

 same as the distance of Jupiter from the sun. Jupi- 

 ter's distance is 5 Earth's radii, and there are eleven 

 periodic comets whose aphelion-distance is between 

 4 and 6 Earth's radii. Neptune's distance is 30 ^Earth's 

 radii, and there are six comets whose aphelion-dis- 

 tances vary from 32 to 35 Earth's radii. 



On tabulating the aphelion-distances of all the 

 known elliptic orbits of comets, it was found that in 

 no case was there any grouping of aphelion comet 

 distances which did not agree with the distances of 

 planets, except that beyond the distance of Neptune 

 there were two groupings of comet aphelion-distances, 

 one at 100 Earth's radii, the other at 300 Earth's radii 

 approximately. 



Taking Professor H. A. Newton's theory with re- 

 spect to the introduction of comets into the solar sys- 

 tenij it would follow that the disturbing planet must, 

 at the time when the comet was so introduced, have 

 been somewhere near the position of the comet's aphe- 

 lion. Two hypotheses then present themselves : 1. 

 We may suppose that the planet must have been ex- 

 tremely close to the comet when it introduced it, in 

 which case it would, be necessary to prove that the 

 aphelion-positions of a fair proportion of these comets 

 lie in one plane which passes through the sun. In 

 this case we could determine the dateVhen the planet 

 was in some definite positions, and so might predict 

 its present position ; 2. We may suppose that the 

 planet revolved in some orbit close to the ecliptic, and 

 assume that it attracted the comet into the solar sys- 

 tem, when it was most near to the comet's aphelion- 

 position. 



The details of Professor Forbes's interesting 

 researches can not here be given.* He as- 

 sumes that the comets 1840 IV, 1846 VII, 

 1861 I, and 1861 II, were introduced by a 

 planet whose distance is about one hundred 

 times that of the earth, and whose period is 

 about one thousand years. The estimated po- 

 sition of the planet in 1880 is in longitude 174, 

 and north polar distance 87. Some attempt 

 has also been made to determine the position 

 of the more remote planet, but no satisfactory 

 result has yet been attained. If the bodies 

 really exist, their apparent magnitudes are 

 doubtless very small. 



Comets. On the evening of February 2, 

 1880, Dr. B. A. Gould, Director of the Obser- 

 vatory at Cordoba, South America, noticed a 

 bright stream of light rising from a point be- 

 neath the western horizon. As was supposed 

 when first observed, this luminous beam soon 

 proved to be the tail of a very large comet. 

 From observations at Cordoba, the Cape of 

 Good Hope, and other points in the southern 

 hemisphere, the elements of the orbit were 

 calculated by Dr. Gould, Mr. Hind, and others, 

 with the remarkable result that the comet had 

 actually passed through the sun's atmosphere; 

 the nucleus, in perihelion, having been less 

 than 100,000 miles from the solar surface. It 

 was found, moreover, that the orbit coincided 

 so closely with that of the great comet of 1843 

 as to render it nearly certain that the bodies 

 were identical. 



The second comet of the year was discov- 



* They may be found in Christie's " Observatory " for 

 June, 1880. 



ered, on the 6th of April, by Mr. J. M. Scha- 

 berle, Assistant Astronomer at the Ann Arbor 

 Observatory. It passed its perihelion on the 

 1st of July, at a distance from the sun consid- 

 erably greater than that of Mars in aphelion. 



The comet of Faye, whose period is seven 

 years and five months, was detected by Mr. 

 Common, of England, on the 2d of August. 

 This is its fifth return to perihelion since its 

 discovery, in 1843. 



A comet was discovered by Dr. Lewis Swift, 

 at Rochester, New York, on the night of Au- 

 gust llth. The body, however, on account of 

 cloudy weather for several nights following, 

 was not reobserved, and consequently its orbit 

 is wholly unknown. 



The fifth comet of 1880 was discovered by 

 Dr. Hartwig, of the Strasburg Observatory, 

 on the 29th of September. It was barely visi- 

 ble to the naked eye, and had a tail two de- 

 grees long. It was discovered independently 

 on the following night at Ann Arbor, Mich., 

 by Professor Harrington, and on the 3d of 

 October by Mr. Baxendell, of Southport, Eng- 

 land. Professor Winnecke, of Strasburg, hav- 

 ing discussed the observations of this body and 

 compared them with those of former comets, 

 thinks it probably identical with the cornets 

 of 1382, 1444, 1506, and 1569. The period 

 deduced is sixty-two and one third years. It 

 is regarded, however, as not wholly improb- 

 able that this may be a multiple of the true 

 period. The orbit approaches very near to 

 that of Mercury, and Dr. Winnecke thinks it 

 possible that the former may owe its elliptic 

 form to Mercury's disturbing influence. The 

 elements are as follows : 



Perihelion passage September 6, 1880. 



Longitude of perihelion 88 33' 28" / Mean equi- 



Longitude of ascending node.... 44 33 30 f nox, 18SO. 



Inclination 38 8 56 38,856 



Eccentricity 977T 



Semi-axis major 15'72 



Mean daily motion , 56'93" 



Another comet was detected by Dr. Swift 

 on the night of October 10th. Its apparent 

 diameter was three or four minutes, but the 

 disk was ill defined and irregular in outline. 

 From the first available observations the ele- 

 ments of its orbit were computed by Mr. Seth 

 0. Chandler, Jr., of Boston, Massachusetts. 

 These elements so closely resemble those of 

 the third comet of 1869 that the identity of 

 the bodies can scarcely be doubted. The prob- 

 able period is, therefore, either eleven or five 

 and one half years. The same comet was in- 

 dependently discovered by Mr. Lohse at Du- 

 necht Observatory, England, November 7th. 



Meteors. The shower of meteors radiating 

 from Quadrans, and hence termed Quadrantids, 

 was observed, in 1880, by Mr. E. F. Sawyer, at 

 Cambridgeport, Massachusetts. Between seven 

 and eight o'clock on the evening of January 2d, 

 Mr. Sawyer recorded six meteors of this well- 

 known group. The radiant was in right ascen- 

 sion 227, declination 48 north. The meteors 

 were bright, and their motions rather slow. 



