Dec. 19, 1889J 



NATURE 



163 



cyrtolite, moiybdite, allaniie, tengeriie, and a new hydrated 

 thorium-yttrium-lead uranate, termed nivenite — have been found. 

 Altogether, this is the richest find of rare earths which has been 

 heard of for some time, and will probably exert a fresh impetus 

 upon the attempts to set our knowledge of the rare-earth 

 elements upon a surer foundation. 



The additions to the Zoological Society's Gardens during the 

 past week include a Ring-tailed Coati {Nasua rufa i ) from 

 South America, presented by Mrs. Petre ; a Common Squirrel 

 {Schirus vulgaris), British, presented by Mri;. S. Stutterd ; a 

 Short-eared Owl {Asia brachyoius) from Hampshire, presented by 

 Mr. E. Hart, F.Z.S. ; two Owen's Apteryx {Apteryx oweni) 

 from New Zealand, presented by Captain C. A. Findlay, R.N.R., 

 R.M.S. S. Ruapehti ; four Common Vipers ( F?^fra berus) from 

 Hampshire, presented by Mr. W. H. B. Pain ; a Marsh Ich- 

 neumon (Herpesies galera) from South Africa, purchased ; a 



Troupial {Xanthosomus frontalis) from Brazil, received in 



exchange. 



OUR ASTRONOMICAL COLUMN. 



Objects for the Spectroscope. 



Sidereal Time at Greenwich at 10 p.m., December 19 = 3h. 

 54m. 45s. 



Name. 



(i) G. C. 826 



(2) y Eridani 



(3) e Persei ... 



(4) 3 Persei ... 



(5) 43 Schj. ... 



(6) .S Tauri ... 



Mag. 



3 

 3 

 3 

 8 

 Var. 



Colour. 



Yellowish-red. 



Yellowish-white. 



Bluish-white. 



Very red. 



R.A. 1890. Decl. 1890. 



Remarks. 



(1) This is described in the General Catalogue as "a globular 

 cluster, very bright, small, round, very suddenly brighter in the 

 middle, barely resolvable (mottled as if with stars)." In 1864 

 Dr. Huggins observed the spectrum, and noted that it was 

 apparently continuous, extending from the orange to the blue, 

 without any traces of either bright or dark lines. It was again 

 observed by Winlock at Harvard College in December 1868, 

 and, strange to say, a bright line spectrum was recorded. " Two 

 distinct bright lines, near each other, and coincident with air- 

 lines A 5020_± and K 4990 ; a third faint line \ 4900 ± " ('• Har- 

 vard College Observations," vol. xiii. Part I, p. 64). These lines 

 were in all probability the three ordinary nebula lines near A 500, 

 495, and 486. Winlock describes the nebula as planetary, and 

 gives exactly the same co-ordinates as those given by Huggins 

 and in the General Catalogue. If both observers really saw the 

 same nebula, the results are highly suggestive of variability ; but 

 even then there is the difficulty of the recorded resolvability. It 

 is quite possible that, in the four years which elapsed between 

 the observations, the spectrum changed from an apparently con- 

 tinuous one to a discontinuous spectrum, by some action similar 

 to that producing variability in such stars as Mira, but at the 

 same time a change of brightness would also be expected, and 

 of this there is no record. In any ca-e, the nebula is well worthy 

 of further examination. 



(2) This star of Group 11. is interesting, as being a connect- 

 ing-link between stars like o Herculis, in which the bands are 

 very wide and dark, and those like Aldebaran, in which there 

 is a line spectrum with only the remnants of the bands in 

 the red. Duner states that the bands 2-8 are visible, but all of 

 them are narrow and pale, b, and presumably D, are very 

 strong. Further observations, with special reference to the 

 lines of hydrogen, are suggested. 



(3) A star, hitherto described as of the solar type, of which 

 the usual observations are required. If the star appears to be 

 of the same type of the sun or Capella, special attention should 

 be directed to the presence or absence of dark carbon flutings. 

 It is highly probable that stars like the sun, in which there is a 

 photographic indication of carbon absorption, will subsequently 

 cool down and become stars of Group VI., in which carbon 



absorption is predominant. If this be the case, all the interme- 

 diate stages of mixed metallic lines and dark carbon flutings 

 should be represented amongst the stars. 



(4) A star of Group IV., of which the usual observations are 

 required. 



(5) This is a star of Group VI. The three ordinary bands of 

 carbon are visible, band 6, near A. 564, being rather pale. A 

 study of Duner's catalogue of the stars of this group shows 

 that some of those in which band 6 is pale give secondary 

 bands, whilst others do not. This appears to be mainly, though 

 not entirely, due to differences of magnitude. Comparative 

 observations with the same telescope and spectroscope, with 

 reference to this point, are suggested. 



(6) Gore states the period of this variable as 378 days, 

 and the magnitudes at maximum and minimum as 9*9 and < 13 

 respectively. The colour is described as trifling, but the spec- 

 trum has not yet been recorded. The maximum will occur on 

 December 28. A. FoWLER. 



Period of U Corona. — Mr. S. C. Chandler {Astronomical 

 yotirnal. No. 205), from the observations of the period of this 

 star, finds an inequality of the same order as those detected in 

 U Ophiuchi and U Cephei, variables of the Algol type. The 

 period appears to be shortening by 0'0036s. from minimum to 

 minimum. The results depend upon forty-five very unequally 

 distributed minima ; thirty-eight, however, lie in the interval 

 1870-74, and afford a basis to work upon. A larger series of 

 observations is required to elucidate Mr. Chandler's hypothesis, 

 which, however, is quite conformable within the limits of the 

 purely accidental errors of the observations that have been 

 investigated. 



Identity of Brooks's Comet {d 1889) with Lexell's 

 Comet 1770. — In the same publication as the above, Mr. 

 Chandler gives some most interesting results of an investigation 

 into the orbits of these comets. The following is a summary of 

 the principal conclusions : — 



(i) The encounter of the comet with Jupiter in 1886 effected 

 a complete transformation of the comet's orbit. Instead of the 

 present seven years' ellipse, it was previously moving in a large 

 one of twenty-seven years' period. 



(2) Several months before reaching its perihelion, it passed, 

 near the beginning of 1886, into the sphere of Jupiter's attrac- 

 tion, and was deflected into a hyperbolic path about that planet, 

 and narrowly escaped being drawn into a closed orbit, as a 

 satellite of Jupiter. 



(3) At the point of closest approach to Jupiter, May 20, 1886, 

 the comet was distant from it only about nine diameters of the 

 planet, passing a little outside of the orbit of the third satellite. 



(4) In 1779, and not before, the comet must have come so 

 near to Jupiter as to pass under his control and experience a 

 radical change of orbit at the point of longitude where Lexell's 

 comet underwent its notable disturbance in that year. More- 

 ever, the elements of Lexell's comet before the disturbance were 

 strikingly similar to those found for the present comet previous 

 to 1886. 



Taking all the points presented into consideration, the argu- 

 ment for the identity of the two comets is overwhelming. A 

 fuller investigation will be made as soon as the observations for 

 the whole apparition have been received. 



Some Photographic Star Spectra. — An examination 

 has been made by Dr. Scheiner of the star spectra photographed 

 at Potsdam i^Astr. Nachr., No. 2923). The wave-lengths of 

 lines in the spectra were determined by comparison with the 

 solar spectrum, and as the probable error of the measures is 

 estimated so small as 0005, the identification of the lines seems 

 beyond doubt. The following are some descriptive results : — 



7 Cassiopeia. Continuous spectrum ; hydrogen lines and D3. 

 bright. 



o CoroncB. The magnesium line at 448 '2 appears as a broad 

 line in this star. 



a LyrcB. Some fine lines, supposed to be due to iron or calcmm, 

 are seen, but have not been measured. 



Sirius. 91 similar fine lines to those in the above star have 

 been measured, and 43 ascribed to iron. Even more of these 

 lines occur in Procyon. 



o AquilcB. The spectrum of this star appears almost identical 

 with that of the sun. 



& Orionis. The hydrogen and other lines appear broad, but 

 are not diffused at the edges as in o Lyras and similar stars. 20 

 lines have been measured from A 4C0 to A 460. 



