November, 1913. 



KNOWLEDGE. 



425 



variable stars are being made to the total, 

 now well over 4,000, and that only 1,400 of these 

 have lettered names, it would greatly benefit 

 astronomy and be to the credit of astronomers if some 

 international consensus of opinion were obtained, and 

 a definite and, as far as possible, a permanent scheme 

 were evolved from the present confusion. 



In Chambers's "Handbook of Astronomy," Vol. 

 Ill, page 271, we read: " Argelander's very crude 

 and unsatisfactory nomenclature (Astr. Nachr., XL, 

 959, 1855, May 3) has been followed, but at no 

 very distant period it will have to give place to 

 something more artistic." And he wrote as long ago 

 as in 1865 : " The time seems arriving when it will 

 be imperatively necessary to adopt a new nomen- 

 clature for variable stars. The present system, 

 besides being inartistic, is gradually, and not very 

 slowly either, drawing to a natural termination." 



This period has undoubtedly arrived, and, whether 

 or not Professor E. C. Pickering's scheme is more 

 artistic, it is certainly very convenient, of great 

 utility, capable of indefinite expansion, and with 

 some modifications, might very well hold the field. 



To show how compact and convenient Professor 

 Pickering's method is we shall conclude this article 



by giving a sample of the form in which Professor 

 Pickering has arranged a table for all the variable 

 stars with letters (to 1907). The whole catalogue of 

 lettered stars can be given on four or five pages. 

 Here is a sample (see Table 81). 



The first star R Andromedae has R.A. h 18 m and 

 Dec. + 38°; RT Andromedae has a note ; SR, TR, 

 TS are not used, only letters in direct sequence; 

 thus, for Cygnus, there are no stars for XR to XW, 

 YR to YZ, or ZR to ZY. All the stars under 

 Antlia have south declinations, also most of those 

 under Aquarius. There seems no valid reason why 

 letters and Professor Pickering's notation should not 

 be applied immediately a discovery — with sufficient 

 verification — in the star's light is announced; we 

 should get rid of the second, fourth, and fifth 

 variations in nomenclature and two different epochs. 

 Even if the star should eventually prove to be non- 

 variable no harm would be done; in 1920, 1930, 

 1940, or even every five years from 1915, the 

 catalogues could be swept clean of those spurious 

 variable stars and the letters appropriated for others. 

 The order of the letters is no longer coincident 

 with the order of discovery, and no chronological 

 significance would be disturbed. 



NOTES. 



ASTRONOMY. 



By A. C. D. Crommelin, B.A., D.Sc, F.R.A.S. 



YERKES PARALLAX D ETERM I NATIONS.— The 

 Astrophysical Journal for July contains a further series of 

 parallax determinations by Messrs. Slocum and Mitchell. 

 Only four stars on the present list have parallaxes notably 

 exceeding their probable errors, and three of these are faint. 

 /uOrionis has a parallax of -"036; Groningen VII, number 20 

 (RA 16 h 21 m , N. 48°-6), whose magnitude is only 10-7, has a 

 P.M. of l"-22 and parallax -"125 ; an anonymous star, RA 

 17" 33 m , N. 18°-6, magnitude 9-1, has parallax -"108, PM 

 T"36. Curiously enough, there are two other ninth-magnitude 

 stars close to it which also have large, though not identical, 

 P.M.'s, but their parallaxes are insensible. The remaining 



parallax is an 11-3 magnitude star near 17 Lyrae, whose P.M. 

 is 1 • "75, parallax -"124 ; its intrinsic lustre must be extremely 

 small ; if its surface were of the same brightness as our Sun's 

 its size would be comparable with Jupiter's. 



WESTPHAL'S COMET.— This comet, which appeared in 

 1852, has now been detected on its return by M. Delavan at 

 the La Plata Observatory, Argentine Republic, of which 

 Professor Hussey is Director. It was seen at Greenwich on 

 September 30th, when it was of eighth magnitude and about 3' 

 in diameter, with distinct central condensation. On November 

 1st its place will be roughly R.A. 20 h 38 ra , N. 24° 50'; 

 November 11th R.A. 20 h 33 m , N. 31° 7'. The following are the 

 elements: Perihelion Passage, 1913, November 26-1, Omega 

 57i°, Node 346$°, Inclination 40° 57', Perihelion Distance 

 1-25, Period 61 • 12 years. The perihelion passage is about a 



