The daily morning journal and courier., 1896-07-31

and this ellipse required a period of seven years and few days to com plete, Carrying back this notion a few years he found that In 1886 the object was very close to Jupiter, so close as to have had the shape of it's orbit modt- fled, Carrying the computation back still further, other notifications in mo- tion were probable until history of the object was secured which was the best possible with the material avail able. The story is this; When Lexell lost sight of his comet 1t was moving in an orbit of about five and one-half years period. This motion brought it within disturbing distance of Jupiter in 17SS, 1t having made an unobserved re- turn to the sun in the meantime. The effect of Jupiters attraction was to turn the comet into an orbit about It. self, so that for eight months it re- mained entangled among it's moons. At that time the attraction which the sun had for the comet was but slightly greater than that of Jupiter for the same object, so that the comet narrow ly escaped being thrown into an orbit about Jupiter, and becoming for greater or less space of time true sa- tellite of his celestial majesty. This, however, did not occur, but 1t has giv- en rise to some new thoughts about sa- tellites, and some investigators have even been led to discuss the question whether the fisth moon of Jupiter, the one which was discovered few years ago by Barnard, might not be in truth some recently captured body which came under the influence of the. planet in much the same way as LexelPs com et
 But after all, the influence of the sun was more potent than that of Jupiter and the comet decided to continue It's course about old Sol, but as parting memento Jupiter bestowed upon 1t such a perturbation as to give its orbit an entirely different shape, long ellipse of twenty-seven years period, the ex- tremity of which extended out toward or quite to the path of Saturn. Through this third and longer orbit the comet moved for number of periods, returning again and again to the sun, until in 1886, little more than three years before it was seen by Brooks, it was again disturbed by Jupiter and turned into its present orbit its fourth one, through which 1t now moves, re- quiring seven years for full circuit. All of this computation was undertak- en by Dr. Chandler, an investigation of much labor and great merit, which was carried out as accurately as the data would permit. The result is not cer- tainty, nor does Dr, Chandler claim it to be such, but 1t is probability which needs further observation of the comet to prove or to dispose of. The observa- tions of the present appearance will go very far toward furnishing material for more refined consideration of the del- | icacies of the problem. The future of l the comet is fairly we'll determined for a number of years, and the returns of 1896, 1903, 1910 and 1917 will probably be l strictly according to schedule. but in | 1921 it will again be close to Jupiter, so close as to be again disturbed. By that time, however, the orbit will be so well determined that the resultant motion will be readily computed.
 | Of course, the presence of a periodi- 1 cal comet in the sky was the cause for | quite little activity among the as- | tronomers, half a dozen of whom took lively interest in the stranger. A spell of cloudy weather followed the discovery of the comet by Brooks in 1 July. 1889, and not until the 22d was it possible to publish any orbits. A pre- | Iiminary one was prepared, which served it's immediate purpose of aiding astronomers in seetting their telescopes upon it. This Is very necessary fea- ture, for the large instruments cannot
 be used to sweep over an indefinite space to find a thing. They must have
 a pretty close position for economy of time and the best work This service is carried on by the Science Observer Circulars of Boston, which stand ready
 to print and circulate the early orbits
 of comets the moment the figures are
 ready to be published.
 In this case the earliest orbit was l computed by Dr. Chandler, while a few
 days later the Rev. G. M. Searle of l Washington and Dr. Chandler each l furnished orbits which followed the ell lipticaI track of the comet For the purpose, of setting telescopes MT. Will liam Bellamy of Boston furnished what
 are technically called ephemerides, be- 1 ing tables which indicate the position of the object in the sky and these were
 continued by Bellamy as long as the comet could be seen. Later, when ob-
 servations were pretty we'll completed,
 Dr. J. Banschinger, an observer at the observatory of Munich, computed a final orbit, using all the data available,
 a thoroughly finished product. pr. Charles Lane Poor of Johns Hopkins
 has interested himself in the considera- ton of the vicissitudes of the comet previous to the discovery by Brooks,
 and as the time approached that it
 would again be possible to see the com-
 ct, he has furnished the necessary data,
 giving probable positions, etc. This
 work has been admirably done.
 The length of time during which the Brooks comet remained visible in the telescope is one of the most remarkable features of the story, for it was seen by
 MT. E. B. Barnard at Lick Observatory more than year and half after Brooks first saw it. This was owing to the fact that the orbit of the comet is a
 great ellipse, large enough to have the
 orbit of the earth lie within it at one end, and for certain distance the
 curves of the two orbits might well be
 described as nearly parallel, though | widely divergent in direction at other points. Having passed the comet at a place where the orbits were nearly par
 allel, opportunities for observation
 were afforded, after which the earth