September i, 1892] 



NATURE 



42: 



two Ravens [Corvus corax) from Spain, deposited by Lord 

 Lilford, F.Z.S. ; two Fringed Chameleons (CkamceUon tcenio- 

 bronchus) and a Lobed Chameleon {Chantitleon parvilobus) from 

 Natal, presented by Mr. Charles W. Heaton ; a Black Iguana 

 {Metopoceros cornutus) from West Indies, purchased ; six African 

 Scorpions {Scorpio, sp.inc.) from South Africa, presented by 

 Mr. J. F. Hawtayne. 



OUR ASTRONOMICAL COLUMN. 



Photographic Magnitudes of Nova Kvkigje.— Astro- 

 nomical Journal, No. 269, contains the results of Mr. J. M. 

 Schaeberle's work with regard to the determination of the photo- 

 graphic magnitudes of stars, including also that of Nova Aurigse. 

 The method he has adopted differs from those used by former 

 observers in that the photographic magnitude of a star for any 

 exposure-time is expressed "as a function of the equivalent 

 theoretical aperture which a standard star (Polaris in this case) 

 would require to make the same impre.ssion on the plate in the 

 same time." The particular form which the expression, as ob- 

 tained from this investigation, assumes enables one, after having 

 once adopted the photographic magnitude of the standard star, 

 to determine the theoretical photographic magnitude of any 

 other star without any reference at all to the visual magnitude. 

 As this method had only been applied to bright stars, the ap- 

 pearance of Nova Aurigse suggested a further trial for stars of 

 less magnitude which were visible only in large instruments. 

 On the plates, which were each night exposed, three stars in the 

 region of the Nova, the images of which resembled somewhat 

 that of the Nova in form, size, and density, were selected for 

 the sake of comparison. The magnitudes of these comparison 

 stars were then determined by direct measurement of their 

 images on the standard positive plate, this plate being a second 

 positive from the original negative. The resulting photographic 

 magnitudes for the month of February showed that the light of 

 this new star fluctuated very considerably, confirming the visual 

 observations. 



The following list gives the theoretical magnitudes as ob- 

 tained in this way, the mean time at Mount Hamilton being 

 also added. The exposures up to March 10 were all moderately 

 short, varying from 2 to 128 seconds. 



Comparison Stars of the Planet Victoria.— Dr. Gill, 

 in Astronomische Nachrickten, Nos. 3107-08, communicates an 

 article on the definite places of the stars used for comparison 

 with the planet Victoria in the observations for parallax made in 

 the year 1889. The positions of these stars are now, as he says, 

 " more accurately known than those of any other group of stars 

 in the heavens," and he suggests that they should be advan- 

 tageously used for the determination of optical distortion and 

 scale values of photographic telescopes, and for testing the various 

 methods for the " raccordement des plaques." The positions of 



NO. II 92, VOL. 46] 



the thirty-seven stars are based on 3766 meridian observations 

 of right ascension, and 3771 meridian observations of decli- 

 nation, together with several other observations made with the 

 heliometers at the Cape, Yale, and Gottingen, amounting to 

 1867 measurements of distances, and 151 position angles. In. 

 the first tables which Dr. Gill here gives, are shown the definite 

 places for the Victorian comparison stars computed for the 

 Equinox 1889 90, and Epoch 1889*55. Owing to the com- 

 paratively large quantities that the probable errors of the proper 

 motions amount to. Dr. Gill mentions that it is desirable to 

 obtain photographs for determining scale- value distortion, &c., 

 as soon as possible. Table 2 consists of a comparison between 

 the distances as obtained from definite co-ordinates, and these as 

 measured by Gill, Finlay, Jacoby, Chase, Schur, and Ambronn 

 with the heliometer. 



International Time.— In a small pamphlet, published by 

 Mr. Edward Stanford, a scheme for a systematic regulation of 

 time is discussed by Major the Hon. E. Noel. The principle on 

 which the system he proposes is based is the same as that which is 

 at present in use on the American continent. It consists in divid- 

 ing the earth's surface up into time-zones each covering fifteen 

 degrees, so that they will differ from one another by one hour. 

 In considering the question of the initial-time meridian, there 

 are many points which have to be well borne in mind. In the 

 first instance there must be a first-class observatory, on which 

 every one could depend ; secondly, the contra-meridian, i.e.y 

 that half of the initial meridian in the opposite hemisphere, 

 must fall in a convenient place, by which is meant that 

 it must not cut through a continent or any large tract 

 of land. Another important consideration is the arrange- 

 ment of the time - zones, which must, if possible, be 

 conveniently related to the longitude boundaries as are shown 

 in our maps. Taking these points into account, Major Voel 

 retains Greenwich as the initial for longitude, but selects Rome 

 as our initial for time. On this basis he discusses this scheme 

 with reference to each individual country. The only great 

 country which this arrangement would not suit is France, for 

 she, as is well known, keeps Paris time ; a suggestion put 

 forward here is that France should form a special zone, making 

 her time exactly, instead of approximately, forty minutes after 

 Rome. The folding diagram which accompanies this pamphlet 

 shows a map of the world graduated on this system. From this 

 one sees that the meridian of Rome traverses the centre of the 

 Scandinavian Peninsula, coincides with Copenhagen, passes 

 close to Leipzig, and between Berlin and Munich, while it cuts 

 Italy from north to south. The western boundary of this zone, 

 which is exactly on the fifth meridian west of Greenwich, pisses 

 between Italy and Spain, outside the western frontier of 

 Germany, and skirts the west coast of Norway, while the 

 eastern boundary also traverses convenient points for such a 

 division of time. In considering the scheme as a whole, there 

 is much to be said in its favour ; but as such a question as this 

 deals with so many nations, its development and final adoption 

 cannot take place in a trice, but can only be brought to a head 

 after many yeara' deliberation and debate. 



Co.MET Swift (March 6, 1892). — The ephemeris of Comet 

 Swift is given in Edinburgh Circular, No. 29, and has been 

 computed from elliptic elements supplied by Herr Berberich. 

 This comet in large telescopes is quite a conspicuous object, 

 while in smaller ones it is still visible. The following ephemeris 

 we take from the above-mentioned source : — 



Ephemeris for Berlin Midni([ht. 



h. m. s. 



Aug. 31 



Sept. I 



M 2 



M 3 



„ 4 



M S 



M 6 



„ 7 



04235 ... +5242-6 

 38-3 

 33-6 

 28-5 

 22 9 

 16-9 

 IO-5 

 37 



41 24... 

 40 10 ... 

 3855 ••• 

 37 39 •■• 

 3622 ... 



35 4 • 

 03346 ... 



Log<^. 



0*2693 ... 0*3922 ... o'oSi 



0*2720 ... 0*4004 ... 0*077 



52 



Taking the comet's position for September 2, we find that it 

 will lie very nearly 3^ south of a Cassiopeiae, being in the pro- 

 longation of a line joining the stars \ and C of the same con- 

 stellation. 



