ASTRONOMICAL PHENOMENA AND PROGRESS. 



97 



Kirkwood, to the effect that, if an ethereal 

 medium exists, it should have acquired a rota- 

 tory movement in the general direction of that 

 of the planets. 



Mr. Trowbridge also deduces, from the prin- 

 ciple that the invariable plane of the solar sys- 

 tem must be the invariable plane of the primi- 

 tive solar spheroid, the conclusion that the 

 first planetary ring abandoned must have been 

 situated nearly in this plane, and hence, that 

 the outermost planet of the solar system should 

 move in an orbit whose inclination to the 

 ecliptic is nearly the same as that of the prin- 

 cipal plane of the solar system. Now, by an 

 extremely exact determination, M. Lespiault 

 finds the inclination of the invariable plane to 

 be 1 41', while the inclination of the orbit of 

 Neptune the outermost planet yet known is 

 1 46' 59", a correspondence within 6' of a 

 degree, and one that, when we reflect on the 

 necessarily disturbing effect through immense 

 ages of the planetary perturbations, is quite as 

 near as could be anticipated. 



Comets. The most recent enumeration met 

 with of the comets of 1863, reverses the order 

 of those previously given as IV and V of that 

 year, that seen by M. Tempel, November 4th, 

 being now reckoned as Comet IV, and that of 

 M. Backer as Oomet V, of the year in question. 

 The same account credits the discovery of 

 Comet VI of 1863 to M. Eespighi time, De- 

 cember 28th. 



The comet at first designated I, of 1864, 

 was discovered by M. Tempel, July 5th ; its 

 appearance was that of a diffused nebulosity, 

 3'-4' in diameter: perihelion, September 7.05, 

 Marseilles mean time; movement retrograde. 

 August 5th, this comet was seen at Charleston, 

 S. 0., by Acting-Master Tillinghast of the iron- 

 clad Catskill, it being then visible to the naked 

 eye. Comet II light very faint ; July 23d, 

 by Donati, at Florence : its perihelion, October 

 11.088, Berlin mean time ; motion retro- 

 grade. Comet III also very faint ; September 

 9th, by Donati. According to its calculated ele- 

 ments, this comet passed its perihelion before 

 those heretofore known as I and II of the same 

 yea"r. Comet IV December llth, by M. 

 Biicker, at Nauen, near Berlin. Comet V 

 December 30th, by M. Bruhns, at Leipzic : 

 perihelion, December 27.77; motion retro- 

 grade. All these comets may be said to have 

 been telescopic. 



Comet I, 1865, was of large size, visible in 

 the Southern hemisphere, in the months of 

 January and February. As seen at Rio Janeiro, 

 January 24th, the tail was 26 in length. M. 

 Moesta computed its elements, and, February 

 20th, observed a second tail, very faint, branch- 

 ing out to the north from the principal one. 

 Perihelion, January 14.3367. 



Celestial Atlas. M. Ch. Dien, of France, 

 has lately published a celestial atlas, in 20 

 maps, the projection employed corresponding 

 to the development of a sphere of 65 centime- 

 tres in diameter. This atlSs contains more 

 TOL. v.- 1 A 



than 100,000 stars and nebulae, and is believed 

 to surpass in accuracy of detail all its prede- 

 cessors. 



Survey of the Southern Celestial Hemi- 

 sphere. An arrangement has been entered into 

 by which the directors of three Southern ob- 

 servatories, Mr. Pogson at Madras, Mr. Ellery at 

 Melbourne, and Sir T. Maclear at the Cape, di- 

 vide this work among them; the boundaries 

 adopted for five successive zones of the celes- 

 tial hemisphere being, the equator, 20, 40, 

 60, 80 the last zone of course stretching to 

 the pole. The previous catalogues of Taylor, 

 Weisse, and Oeltzen, of stars in southern lati- 

 tudes the two last named embracing from the 

 equator to 31 S., are, by allowing for the 

 precession, to be reducSd to the epoch 1875. 



Sirim. Much interest is at present felt in 

 observations upon this star, especially in view 

 of the question whether Mr. Clark's supposed 

 " companion " star (1862) is really such 

 whether Sirius is indeed one of a multiple 

 group, or again, whether the telescope has 

 actually detected one or more planets attendant 

 on this brilliant orb. Mr. T. H. Safford, of 

 Cambridge Observatory, 1863, infers from the 

 apparent participation of the less brilliant star 

 in the proper motion of Sirius itself, that the 

 former must be physically connected with the 

 latter ; and while concluding that in this com- 

 panion star, probably, the body disturbing the 

 movements of Sirius has been actually found, 

 he urges the continuance for several years of 

 observations and measurements with a view to 

 determine these questions. 



M. Otto Struve, in a communication, May 

 13, 1864, states the result of his observa- 

 tions thus far, on the changes of distance and 

 angle of position of the small star in reference 

 to the large one, to be to the effect that the 

 juxtaposition of. the two stars is more probably 

 accidental; though he does not regard this 

 view as being yet finally established. 



Meanwhile, M. Goldschmidt has recently 

 asserted that, with an object-glass of little 

 more than four inches aperture, he has detected 

 not only Mr. Clark's companion star but five 

 additional stars which he judges to possess a 

 like relation to Sirius. Secchi, at Rome, later 

 detected along with the former also several 

 contiguous luminous points ; but he raises the 

 question whether these may not be illusions 

 such as, possibly, might arise from something 

 in the action of the instrument itself on the 

 light. The question of the possibility of detect- 

 ing planetary systems about some of the fixed 

 stars, first raised by Sir J. Herschel many years 

 ago, is one of intense interest ; but no conclu- 

 sion in the case can as yet be drawn from the 

 observations above mentioned. 



Parallax of Minute Stars. The supposition 

 that the most conspicuous fixed stars were also 

 the nearest, or, in other words, that in intrinsic 

 magnitude and brightness the stellar bodies are. 

 nearly alike, and their apparent differences of 

 magnitude really the effect of differences of dis- 



