592 



NA TURE 



[April 22, 1886 



{Coturnix californica) from California, a Scarlet Ibis {Eudocimiis 

 ruber) from Para, deposited ; a Roan Kangaroo {Macropus et it- 

 be cens) from South Australia, an Eroded C\Tayiy%{Cinixys erosa) 

 from West Africa, a Merrem's Snake {Liophis inci-remi) from 

 South America, purchased; an Axis Deer [Cennis axis), born 

 in the Gardens. 



OUR ASTRONOMICAL COLUMN 

 Relation of Asteroid Orbits to that of Jupiter. — 

 Prof H. A. Newton, in the American Journal of Science, 

 April i886, points out that the orbits of the asteroids should have 

 a relation to that of Jupiter. For supposing the orbits of the 

 asteroids to be distribiiled in any manner whatever, provided 

 only that they make small angles with the plane of Jupiter's 

 orbit, the action of Jupiter would give to each orbit a motion of 

 its node which would differ for the different orbits, and even- 

 tually the orbits would come to be distributed somewhat sym- 

 metrically about the orbit of Jupiter. And as a matter of fact, 

 the centre of gravity of the poles of the 251 known asteroid 

 orbits, computed as for points of equal weight, lies only 30' 

 froni the pole of Jupiter's orbit ; so that the plane of Jupiter's 

 orbit lies nearer to the mean plane of all the asteroid orbits than 

 any single asteroid orbit does, the nearest orbits being those of 

 Medu'a and Euterpe, inclined to it 46' and 49' respectively. 



In the same periodical Dr. H. Geelmuyden, of Christiania, 

 remarks, relative to Prof. Searle's deduction that the plane of 

 the zodiacal light has some relation to the asteroid orbits 

 (Nature, February 11, p. 350), that "the most northerly 

 point of Jupiter's orbit has the heliocentric longitude l8S°, or 

 with 60° east elongation 178° ; and for matter in the same plane, 

 but nearer the sun, the approxim.ation to coincidence with 160° 

 is still greater." 



The Proposed Change in the Astronomical Day. — 

 M. Raoul Gautier has recently published in the Archives des 

 Sciences Physiijues et Naturclles of Geneva an account of the pro- 

 ceedings of the International Meridian Conference held at 

 Washington in October 1884. Remarking that the resolutions 

 passed at Washington are similar in many respects to those of 

 the Roman Conference of the preceding year, M. Gautier goes 

 on to point out how they differ in the important particular of the 

 manner of reckoning universal time, and that on this account a 

 large number of astronomers have expressed their reluctance to 

 conform to these recommendations, more especially to the sixth 

 resolution (which proposed that the astronomical and nautical 

 days should be arranged everywhere to begin at mean midnight 

 of Greenwich), the adoption of which would involve considerable 

 changes in the astronomical and nautical ephemerides, which are 

 used by all observers and navigators. Astronomers, M. Gautier 

 states, as well as sailors, begin the day at noon ; the former to 

 avoid changing the date in the middle of the night during a series 

 of observations, the latter becau-e they find it convenient to 

 commence the day at the moment when they observe the sun on 

 the meridian. Why then, he asks with some force, oblige them 

 to modify their habits, now of long standing, considering that 

 the fourth resolution passed at the Washington Conference 

 expressly stipulates that the universal day ought not to interfere 

 with the use of local or other standard time where the latter 

 appears desirable ? 



The Pleiades as Seen and as Photographed. — MM. 

 Henry have recently compared their beautiful photographic map 

 of the Pleiades with the map so carefully laid down by M. Wolf in 

 1873-75, •'^"d published in vol. xiv. of the Manoires de I'Obser- 

 vatoire de Paris, and find that the photograph possesses the 

 following advantages over the map made by direct eye-observa- 

 tion. The photograph shows faint objects which are lost to the 

 eye through their proximity to bright stars ; thus the Maia 

 nebula, and another near Electra, have been made evident, as 

 well as details recognised hitherto only by Mr. Common in the 

 Merope nebula. A number of faint companions have also been 

 detected close to several of the brightest stars of the group, and 

 in several cases where M. Wolf had detected a faint companion 

 to a bright star, the photograph has shown that the magnitude 

 of the former was under-estimated. Many more stars are seen 

 on the photograph than are given in M. Wolf's map, the former 

 showing 142 1 stars, the latter 625 ; the aperture of the instru- 

 ment employed being about the same in both cases. A yet 

 more striking instance of the superior sensitiveness of the plate is 



seen in the fact that M. Rayet, in his revision of M. Wolfs map 

 in the pure air of Bordeaux, and with a much more powerful in- 

 strument, added only 151 stars in a region where the photograph 

 gave 338. All the stars observed by M. Wolf are seen in the 

 photograph but ten, and these cannot be found in the sky. 



The Brothers Henry, whilst laying stress on these facts as 

 showing how indispensable a weapon photography has now- 

 become to the astronomer, disclaim the idea of criticising M. 

 Wolf's great work, and completely assent to his opinion, ex- 

 pressed in the Comptei rendus, vol. cii.. No. 9, that the eye of 

 the observer must continue to work at the same time as the 

 sensitive plate ; the latter can never supersede the former. 



ASTRONOMICAL PHENOMENA FOR THE 

 WEEK 1886 APRIL 2i—MAV i 

 /■pOR the reckoning of time the civil day, commencing at 

 Greenwich mean midnight, counting the hours on to 24, 

 is here employed. ) 



Ai Greenwich on April 25 



Sun rises, 4h. 45m; ; souths, iih. S7m. Sl'4s. ; sets, igh. lom. ; 



decl. on meridian, 13° 15' N. : Sidereal Time at Sunset, 



gh. 25 m. 



Moon (at Last Quarter April 26) rises, oh. 57m. ; souths, 



5h. 28m. ; sets, loh. 2m. ; decl. on meridian, 17° 22' S. 



Planet Rises .Souths Sets Decl. on meridian 



Mercury ... 4 16 



Venus 3 25 



Mars 13 19 



Jupiter 15 20 



Saturn 7 51 



* Indicates that th. 



10 37 

 9 6 



20 21 



21 37 

 16 3 



16 58 ... 3 29 N. 



14 47 •.. 4 21 S. 



3 23* ... II 16 N. 



3 54* ... 2 32 N. 



O 15* ... 22 51 N. 



tting is that of the following morning. 

 0:ciillations of Stars by the Moon (visible at Greenwich) 



Corresponding 

 glesfrom ver- 

 :>: to right for 

 verted image 



Mag. 





Reap. 



4 42 



42 288 

 139 175 



28 ... £■' Aquarii 6 ... 3 



29 ... 78 Aquarii ... 6 ... 2 

 April h. 



28 ... 6 ... Mercury at greatest distance from the Sun. 



29 ... 17 ... Venus at greatest elongation frjm the Sun, 



46' west. 



30 ■•• 5 ••• Venus in conjunction with and 0° 19' north 



of the Moon. 



i83t3 



Positions of the Comet Fabry 



R.A. Decl. Log A Bright- 



April 25 ... I 45 25 ... 31 18 N. ... 9-420 ... 315 

 27 ... 2 29 43 ... 24 51 ... 9-355 ... 400 



29 ... 3 20 22 ... 15 22 ... 9-309 ... 465 



Positions of the Comet Barnard 

 1SE6 R A. Decl. Log .i Bright- 



h. m. s. . , nets. 



April 25 ... I 39 50 ... 39 53 N. ... 0-047 ■•• 67 



27 ... I 38 41 ... 40 19 ... 0023 ... 80 



29 ... I 38 8 ... 40 31 ... 9997 ... 94 



The comet positions are for Berlin midnight. 



Variab'c-Slars 

 Star R.A. Decl. 



h. m. „ , h. m. 



R Leporis 4 54-4 ... 14 59 S. ... Apr. 26, o o m 



S Libra; ..; ... 14 54-9 ... 8 4 S 25, 3 26 m 



U Coronae 15 13-6 ... 32 4 N. ... ,, "30, i 53 m 



U Ophiuchi 17 io'8 ... i 20 N , 25, i 31 m 



and at intervals of 20 8 



X Sagittarii 17 40-4 ... 27 47 S. . Apr. 28, 2 20 in 



May I, o Q M 

 W Sagittarii ... 17 57-8 ... 29 35 S. ... Apr. 25, 21 40 m 



,, 29, 2 25 AT 



U .Sagittarii 18 25-2 ... 19 12 S. ... ,, 26, 2 30 m 



,, 29, 2 20 M 



^ Lyrte i8 45-9 ... 33 14 N. ... ,, 29, 2 r 35 J/ 



7) Aquil^ 19 46-7 ... o 7 N. ... ,, 29, 21 40 M 



R Vulpeculre ... 20 59-3 ... 23 22 N. ... ,, 25, w 



5 Cephei 22 24-9 ... 57 50 N. ... May i, o oM 



M signifie 



