402 



NA TURE 



{Feb. 24, 1887 



we learn that during 1S86 Mr. Percy Smith continued the 

 measurement of position-angles and distances of double stars, 

 88 sets of measures having been secured. These stars have been 

 divided into three categories for future re- measurement, viz. 

 rapid binaries, to be ob-erved every year ; slower binaries, to be 

 observed every 4 years ; and long-period binaries, to be observed 

 every 10 years. Mr. SeabroUe himself has continued the 

 measurement of the motion of stars in the line of sight with the 

 spectroscope on the reflector, and has completed 100 sets of 

 measures. These observations, together with the corresponding 

 ones for previous years, have been published in the January 

 number of the Monthly Notices. 



Discovery of a New Comet, \%%id (Barx.\rd 2). — A 

 new comet was discovered on February 15 by jNIr. K. E. Barnard, 

 Nashville, Tennessee. It was very faint, and was moving rapidly 

 in a north-westerly direction. At midnight (local time) its 

 position was R.A. 8h. 4m., Decl. 16° 10' S. 



Probable New Variable. — We learn from Circular No. 15 

 of the Liverpool Astronomical Society, that Mr. Backhouse 

 finds 28 Andromedss to be probably variable within small limits. 

 The observations yet obtained are insufficient to fix the period, 

 which must, however, be short. It is possible that the star is 

 of the Algol type. 



Names of Minor Planets. — Herr J. Palisa has named 

 Minor Planet No. 256 Walpurga. 



Brightness and Mass of Binary Stars. — The current 

 number of the Observatory contains an article on this subject 

 by Mr. \V. H. S. Monck, in which he attempts to deduce 

 the relative brilliancy of those binaries for which the orbits are 

 best determined. Assuming that the mass of the companion- 

 star is very small as compared with that of its primary, he shows 

 that the relative brilliancy of any two pairs of binaries may be 

 found by the following formula : — 



%'®m-& 



where /j I., stand for the total amount of light, as determined pho- 

 tometrically, which we receive from the two pairs respectively ; 

 /"i P2 for their periods ; and Aj a.^ for the angular radii of their orbits. 



By, apparently, a printer's error, the index of ( -! j is omitted 



in the formula in the Observatory. Adopting J Ursje Majoris 

 as his unit of comparison, Mr. Monck finds the brilliancy of 

 y Leonis 93-29 ; of Castor, 38-24 ; 8 Cygni, 3S'52 ; of Sirius, 

 7'I7; 42 Coma;, 279 ; 6 (/) Eridani, 0-20 ; and 61 Cygni, q-oS. 

 It is noteworthy that Prof. E. C. Pickering, in a paper which 

 appeared in the Proceedings of the American Academy of Arts 

 and Sciences, vol. viii. No. i, obtained very similar results for 

 many of the same stars, but by a somewhat different prccess. 

 In both lists 7 Leonis figures at the head, followed by Castor 

 and S Cygni, whilst the smallest values are found for p Eridani 

 and 61 Cygni. The weak point in Mr. Monck's computation is 

 the assumption that the mass of the smaller star is comparatively 

 insensible ; the near equality in magnitude of many of the 

 binaries selected would seem to indicate that the assumption 

 was not a safe one. Mr. Monck repeats Prof. Pickering's 

 suggestion that series of careful measurements should be made 

 between each component of the binary systems and some neigh- 

 bouring stars, so that the ratio of the masses of the two com- 

 ponents may be determined. It is to be hoped that some 

 double-star observers may be induced to take up this interesting 

 subject, now that attention has again been called to its import- 

 ance. The research might also possibly supply us in some cases 

 with a determination of the distance of the binary. 



The Liverpool Astronomical Society. — The Pernam- 

 buco branch of this Society now numbers more than eighty 

 members, and has been accorded permission to elect a local 

 executive. The Emperor of Brazil has been elected a member 

 of the Society. 



ASTRONOMICAL PHENOMENA FOR THE 

 WEEK 18S7 FEBRUARY 27— MARCH 5 

 ^pOR the reckoning of time the civil day, commencing at 

 Greenwich mean midnight, counting the hours on to 24, 

 is here employed. ) 



At Greenwich on February 27 

 Sun rises, 6h. 52m. ; souths, I2h. 12m. 56'os. ; sets, I7h. 34m. ; 



decl. on meridian, 8° 21' S. : Sidereal Time at Sunset, 



4h. 3m. 

 Moon (at First Quarter March 3) rises, 8h. 50m. ; souths, 



I5h. 30m. ; sets, 22h. 21m. ;' decl. on meridian, 7° 9' N. 



Planet 



Souths 



March 



3 ■ 

 5 ■ 



Mercury at least distance from the Sun. 

 Mercury at greatest elongation from the Sun, 



iS" east. 

 Saturn in conjunction with and 3° 29' north 



of the Moon. 



M signifies 



Meteor- Showers 

 Amongst the meteor-showers of the season are the two follow- 

 ing : — Near S Virginis, R.A. 192°, Decl. i°N ; near | Sagittarii, 

 R.A. 280°, Decl. 17° S. The latter radiant gives very swift 

 streak-bearing meteors. 



GEOGRAPHICAL NOTES 

 Two letters have been received in Vienna from Dr. O. Lenz, 

 dated, one from Lake Tanganyika in September, and the other 

 from the River Shire in ]5ecember. This indicates that the 

 Austrian Expedition has taken an unexpected route to the east 

 coast. When Lenz and his companions left Kasonge, on the 

 Upper Congo, on June 30, they made for Tanganyika, arriving 

 at Capt. Hore's station on the west shore on August 7. Crossing 

 to Ujiji, Dr. Lenz found that it u as impossible to proceed north- 

 wards to the Albert Nyanza and Emin Pasha, on account of the 

 Arab raids and the state of things in Uganda. Instead, there- 

 fore, of proceeding eastwards to Zanzibar, he travelled, by land 

 apparently, to the south end of Lake Tanganyika, along the 

 Stevenson road to Lake Nyassa, down that lake to the Shire, 

 and thence by the Zambesi to Quillimane. The two letters 

 will be published in the next number of the Mitleiliuigoi of the 

 Vienna Society, and will doubtless contain a good deal of 

 information of interest. 



Tll'POO Tip, about whom we have heard so much recently in 

 connection with the Emin Pasha expedition, seems to be rather 



