158 



NATURE 



[Dec. 13, 1888 



OUR ASTRONOMICAL COLUMN. 



Comet 1888 e (Barnard, September 2). — The follow- 

 ing ephemeris for this comet for Greenwich midnight is in 

 continuation of that given in Nature, vol. xxxix. p. 1 14 : — 



Dec. 



The brightness on September 2 has been taken as unity. 



The spectrum of the comet presents no very interesting feature, 

 as it is mainly continuous, with but little evidence of the bright 

 hydrqcarbon bands. 



Y Cygni. — Although it is only just two years since Mr. 

 ■Chandler discovered this variable, and Vut comparatively few 

 minima have therefore yet been observed — the fewer that the 

 ■star seems to have been unaccountably neglected by European 

 observers — yet some strange and strongly-marked anomalies 

 have already been observed in its period. Although the light- 

 •curve is of such a shape as to enable the minima to be determined 

 with much precision, the variations in brightncFS proceeding with 

 relatively great rapidity, and Mr. Chandler had therefore be- 

 lieved that the period he had deduced from his 1886 and 1887 

 observations could not be more than a second or two in error, 

 he found, when the star came again under observation in the 

 spring of 1888, that the ephemeris required a correction of four 

 or five hours, and this difference increased until, in the October 

 just past, it had amounted to nearly seven hours. Dividing all the 

 ■observations into five groups, they give the following values for 

 !the period : — 



the smallness bf the telescope used — only 34 inches aperture — 

 is borne in mind, and are valuable from their number and 

 the completeness of the series which they form. The 1887 

 observations were made with Dr. Terby's new telescope of 

 8 inches aperture, which has given excellent proof of its go: d 

 quality. 



On one occasion (1884 February 16) Dr. Terby was fortunate 

 enough to watch the shadow of the first satellite pass over a 

 bright white spot. The shadow lost none of its blackness in 

 the transit, .showing that the white spot was in no perceptible 

 degree self luminous. 



85 Pegasi. — Some recent observations which Mr. Burnham 

 has obtained of this close and difficult dout le, dis:overed by 

 him in 1878, have enabled Mr. ^z\\^ft\i^x\?: {Gould' s Astronomical 

 Journal, No. 185) to compute an approximate orbit, from which 

 it appears that the star has a period of 22*3 year.«, and an 

 eccentricity of 0-35, and that it passed through pcriastron at 

 the beginning of 1884. The other elements are — 



The observations from which these periods have been deduced 

 -include five minima determined by Mr. Sawyer, three by Mr. 

 Yendell, and thirteen by Mr. Chandler himself. Using his own 

 •observations alone, he has roughly represented them by the 

 following elements: 1889 January 25, 5h. 39 -6m. (G. M.T. ), 

 -f id. I2h. om. 0-I2S. (E - 519) + 0-245. (E - 519)- ; the 

 ■elements being referred to epoch 519 on account of the con- 

 -venience of the period at that time being so nearly commen- 

 ■surate with a solar day. But these elements leave residuals far 

 too large to be regarded as errors of observation, whilst the 

 iengtheriing of the period, half a second between two successive 

 recurrences, is entirely unpaialleled in amount by the irregulari- 

 ties in other Algol variables. Mr. Chandler considers that 

 this change is far more likely to be periodic, and of short period, 

 than secular, and it is therefore specially to be desired that 

 •obFervers will follow it with all attention, for the complete know- 

 ledge of its changes must throw much light on the whole subject 

 ■of variation of the Algol type. At present the minima occur 

 soon after sunset, for England, on December 17, and every third 

 following day, and shortly before sunrise on December 19, and 

 ■every third following day. It is to be hoped that English ob- 

 servers will give a most persi.'-tent attention to this star, now so 

 clearly a most important one. 



Recent Sketches of Jupiter.— Vol. xlix, of ihe MJwohrs 

 ■couronnh of the Royal Academy of Sciences of Belgium, con- 

 tains a valuable series of observations of Jupiter by Dr. F. Terby, 

 •of Louvain. This series, which contains his observations from 

 1882 to 1885, is in continuation of a former memoir, which 

 appeared in vol. xlvii. of the same publication, and is soon to be 

 followed by a third containing the results of his work in 1887. 

 In this present memoir Dr. Tei-by has made some first efforts 

 towards the identification of details on the surface of Jupiter in 

 ■successive rotations, a work which he considers he has been able 

 to carry on more successfully in his third series. The present 

 memoir is illustrated by 100 sketches of the planet, which, if cf 

 no great beauty or minuteness of detail, are very creditable when 



70° -3 

 306°- 1 



i = 68° -6 

 a = o"-96 



From observed position-angles and distances of the third star, 

 C, the following result has been obtained for the relative proper 

 motion of 85 Pegasi, viz. annual motion being i"-305 and its 

 direction 140° 2o'-4, or in R.A. and Decl., Aa = -h o"-833 ; 

 A5 = - i"-cc5. The comparison star, C, would appear to have a 

 slight proper motion also, as these values differ Somewhat from 

 those obtained for 85 Pegasi by Argelander, Madler, and 

 Briinnow. 



ASTRONOMICAL PHENOMENA FOR THE 



WEEK 1888 DECEMBER 16-22. 



/T7OR the reckoning of time the civil day, commencing at 

 ^ Greenwich mean midnight, counting the hours on to 24, 



is here employed.) 



At Greenwich on December 16 



Sunrises, 8h. 3m. ; souths, iih. 56m. 7-73.; sets, I5h. 50 n. : 

 right asc. on meridian, I7h. 38-3m. ; decl. 23° 22' S. 

 Sidereal Time at Sunset. 2ih. 33m. 



Moon (Full on December 18, 11 

 22h. 48m, ; sets, 6h. 43m. 

 4h. 32-5m. ; decl. 18° 23' N. 



rises, i5h. 3m.; souths, 

 right asc. on meridian, 



