October 



890] 



NATURE 



619 



H. II. Sharland, F.Z.S. ; two Herring GaWs (Larus argenia/us), 

 British, presented by Mr. Joseph White ; a Common Chameleon 

 (^ChamcBleon vulgaris) from North Africa, presented by Mr. 

 V. H. Dadmesh ; a White Pelican {Pelecantts onocrotalus). South 

 European, deposited; a Bay Colobus {Colobus fa-rugineus 9) 

 from West Africa, purchased ; a Large Hill-Mynah {Gracula 

 intermedia) from India, received in exchange. 



OUR ASTRONOMICAL COLUMN. 

 Objects for the Spectroscope. 

 Sidereal Time at Greenwich at 10 p.m. on October 23 = 

 9m. 4s. 



Remarks. 

 (i, 2) Neither of these nebulae have yet had their spectra re- 

 corded. The first is described as "considerably bright; con- 

 siderably large ; irregularly round ; very gradually brighter in 

 the middle " : the second as " pretty bright ; very small ; much 

 elong:ited ; very suddenly much brighter in the middle." 



(3) A star of Group II., the spectrum being described by 

 Duner as "very fine." All the bands 2-9 are very wide, 

 dark, and strongly marked. As the star is a comparatively 

 bright one of this class, a detailed study of its spectrum should 

 be made, special attention being given to the brightness of the 

 carbon flutings, and the pre^-ence or absence of dark lines. 



(4) Secchi thought this star had a spectrum of Group II., but 

 Duner and Gothard describe it as one of the solar type, the 

 latter observer, however, stating that it approaches Group II. 

 According to Duner, D and l> are strong and dark, and several 

 other lines are distinctly visible. At the place of band 2 (the 

 iron fluting) in Group II. stars there is only a narrow and feeble 

 line. It seems probable that the spectrum greatly resembles 

 that of o Tauri, but as the band in the red has disappeared, it 

 is probal'ly a step higher in temperature. A direct comparison 

 with o Tauri, which can now easily be made, might lead to 

 interesting results as to the changes brought about by an increase 

 of temperature in such a star. 



(5) A star of Group IV. The usual observations are required. 



(6) There will be a maximum >>f this variable about October 

 25. The period is short (120-138 days), and the range is from 

 58-6'2 to 67-7 3. The spectrum is an exceptionally fine one 

 of Group II., all the bands being very wide and dark. We do 

 not yet know whether any variations of spectrum accompany the 

 slight chan^fes of magnitude of such a variable as this. 



(7) 'I he spectrum of this variable has not yet been recorded. 

 It is one of considerable range (67-78 to I2'4-I27), and the 

 period is 203 days. As the magnitude at maximum is not small, 

 the observation of the spectrum should not be difficult. There 

 will be a maximum on October 27. A. Fowler. 



Photographs of Nebul.«.— The current number of Comptes 

 rendus (October 13) contains a note by Admiral Mouchez on a 

 photograph of the Ring Nebula in Lyra, obtained at Algiers 

 Observatory by MM. Trepied and Rabourdin. The nebula 

 was given an exposure of six hours, in two evenings of three 

 hours each. The negative obtained is said to be very dense, 

 and a positive copy, enlarged 64 times, has been presented to 

 the Paris Academy. With respect to the photograph. Admiral 

 Mouchez remarked : — " This image of the nebula is certainly the 

 largest that has yet been obtained. It shows, in a very striking 

 manner, the distribution of light in this curious celestial object. 

 We see that a region of maximum light exists at each of the 

 extremities of the minor axis of the elliptical ring. These two 

 maxima are not equal, and in each of the halves of the ring the 

 intensity of the light diminishes gradually up to the extremities 

 of the major axis, where it has the smallest value. These are 

 well- known characteristics of this nebula, and such as may be 

 observed by means of ordinary telescopes. But the photo. 



NO. 1095, VOL. 42] 



graphic observation teaches us other things. In fact, accord- 

 ing to the work done at Algiers Observatory, when we photo- 

 graph this nebula with increasing exposures, the nebulosity does 

 not extend sensibly outside the ring, but spreads more and more 

 towards the centre. On the other hand, when we observe the 

 body in a telescope, we find that the central part of the ring is 

 perfectly separated from the ring itself. The interior of the 

 ring is therefore filled with a material difficult to see, but of 

 which the existence is demonstrated in a certain manner by 

 photography. In fact, the central nebulous star attains an 

 intensity in the present proof nearly equal to that of the feeblest 

 maximum of the ring. 



" At the meeting of July 7, 1890, in presenting to the Academy 

 a photograph of the same nebula obtained at Bordeaux Obser- 

 vatory by MM. Rayet and Courty with an exposure of three 

 hours, I pointed out the probable existence of three, and perhaps 

 four, extremely feeble stars which had never been previously in- 

 dicated, and which formed an almost regular square around the 

 central star in the dark part of the nebula. The existence of at 

 least three of these very feeble stars is now demonstrated with 

 absolute certainty, because of the long exposure, but in the 

 enlarged image they are somewhat confused with the inner edge 

 of the nebula." 



At the same meeting of the Academy (October 13), M. B. 

 Baillaud presented a plate of the region about the Ring Nebula 

 obtained at Toulouse Observatory on September 8, 9, 10, and 

 II, with a total exposure of nine hours. The size of the plate 

 was 9 cm. by 12 cm., and it exhibits about 4800 stars to the 

 naked eye within an area of three square degrees. 



Stars having Peculiar Spectra. — In Astronomischi 

 Nachrichten, No. 2997, Prof. E. C. Pickering notes that photo- 

 graphs of stellar spectra taken by Mr. S. J. Bailey, at Clisica, in 

 Peru, show several stars having peculiar spectra. The following 

 table contains the places of these stars, and a brief description of 

 the spectrum of each : — 



Star. 



Cord. Gen. Cat. 7 191 

 ., ,, 18859 

 ., M 19737 

 „ „ 22855 



Cord. Zone Cat. 36 



S.DM, - 19° 4854 



Anonymous , 



Cord. Gen. Cat. 29232 



Description. 



F line bright. 

 F line brisiht. 

 F line bright. 

 G and h bright. 

 Bright lines. 

 Bright lines. 

 Bright hydrogen lines. 

 Type IV. 



The spectrum of the two stars with " bright lines" is similar 

 to that of the stars discovered by Wolf and Rayet in Cygnus. 



The two variable stars in the above list are new. Their dis- 

 covery resulted from an examination of photographs of stellar 

 spectra at Harvard College Observatory. A comparison of the 

 intensity of the spectrum of the first-named star, situated in 

 Scorpio, with that of others on the same plate, indicated that it 

 fluctuates between magnitudes 7 and ir4. A similar compari- 

 son of the spectrum of the latter variable, situated in Sagit- 

 tarius, with the spectra of other stars near it, shows that between 

 May and October 1889 it decreased from 8-5 to 10-7 magnitude. 

 Both the stars have spectra of the same character as Mira Ceti 

 and other known variables of long period. 



The Photographic Chart of the Heavens.— The In- 

 ternational Committee of the Photographic Chart of the Heavens, 

 will meet at Paris Observatory on March 31, 1891. The last 

 details as to the execution of the work will then be discussed, 

 and it is hoped that all the participating Observatories will be 

 able to begin operations immediately afterwards. 



D' Arrest's Comet. — In the same journal Prof. Krueger 

 points out that the comet discovered by Mr. Barnard of Lick 

 Observatory on the 6th inst., is identical with that of the periodical 

 comet of D'Arrest, for which Dr. Berberich computed an 

 ephemeris {Astronomische Nachrichten, No. 2959). An observa- 

 tion at Strasburg on the loth inst. confirms the identity. 



A New Asteroid. — Dr. J. Palisa, of Vienna Observatory, 

 discovered a new minor planet (^ on the 7th inst. Its 

 magnitude was 14. 



