December 1, 1896.] 



KNOWLEDGE. 



287 



lines. Now, as mentioned in the April paper, any sub- 

 ordinate series of double lines will have a constant dififer- 

 ence in wave number between tbe two members of each 

 doublet, a difiference equal to that given by tbe first 

 doublet of tbe principal series. This for helium is 100-7, 

 far too small to be shown on the chart. With the alkaline 

 elements the distance apart of the doublets is roughly 

 proportional to the square of the atomic weight. This 

 would give helium an atomic weight between 5-2 and 5-7 ; 

 parhelium would necessarily be lighter — a view Lockyer 

 challenges, but which would seem borne out by the 

 position of its spectrum, which as a whole lies slightly 

 on the more refrangible side of that of hydrogen ; helium 

 lying further in the same direction, and lithium, the next 

 lightest element, further still. 



THE FACE OF THE SKY FOR DECEMBER. 



By Hekbert Sadler, F.R.A.S. 



SUN SPOTS are increasing in number and magnitude. 

 Conveniently observable minima of Algol occur 

 at llh. 15m. p.m. on the 3rd, 8h. 4m. p.m. on the 

 6th, 9h. 46m. p.m. on the 26th, and 6h. 35m. p.m. 

 on the 29th. 

 Mercury is an evening star towards the end of the 

 month, but his great southern declination will prevent any 

 useful observations in these latitudes. 



Venus is also an evening star, but with great southern 

 declination ; still she may possibly be observed towards the 

 end of the month. On the 16th she sets at 6h. 55m. p.m., 

 or more than three hours after sunset, with a southern 

 declination of 21^ 11' (at noon), and an apparent diameter 

 of 15", just three-quarters of the disc being illuminated. 

 On the 23rd she sets at 7h. 17m. p.m., or nearly three and 

 a half hours after sunset, with a southern declination of 

 18° 52', and an apparent diameter of loh". On the 31st 

 she sets at 7h. 41m. p.m., with a southern declination of 

 15° 45', and an apparent diameter of 16|^", x'ot'^s of the 

 disc being illuminated. During the latter half of December 

 she describes a direct path through Capricornus. 



Mars is an evening star, and is very well situated for 

 observation, coming into opposition with the Sun on the 

 11th. On the 1st he rises at 4h. 12m. p.m., or twenty 

 minutes after sunset, with a northern declination of 

 25° 31', and an apparent diameter of 17J". On the 9th 

 he rises at 3h. 27m. p.m., with a northern declination of 

 25° 89', and an apparent diameter of 17". On the 16th 

 he rises at 2h. 48m. p.m., with a northern declination of 

 25° 39', and an apparent diameter of 16j '. On the 

 23rd he rises at 2h. 10m. p.m., with a northern declination 

 of 25 33', and an apparent diameter of 16". On the 30th 

 he rises at Ih. 36m. p.m., and souths at lOh. 7m. p.m., 

 with a northern declination of 25° 25', and an apparent 



diameter of It 



During the month be describes a 



retrograde path in Taurus. 



.Jupiter is an evening star, and becomes well situated for 

 observation towards the end of the month. On the 23rd 

 he rises at 9h. 47m. p.m., with a northern declination of 

 8° 46', and an apparent equatorial diameter of 45j' • On 

 the 30th he rises at Oh. 19m. p.m., with a northern 

 declination of 8° 4!»'. He is almost stationary in Leo 

 during the month. Both Saturn and Uranus are, for the 

 observer's purposes, invisible. 



Neptune is an evening star, rising on the 1st at 4h. 24m. 

 P.M., with a northern declination of 21° 34', and an 

 apparent diameter of 27 ". On the 30th he rises at 

 2h. 27m. P.M. He is in opposition on the 22nd, and 

 describes a very short direct path in Leo during tbe month. 



December is a fairly favourable month for shooting 

 stars, the chief showers being those of the Geminids on 



December 9th to 12th, the radiant point being in K.A. 

 7h., and north declination 32 , rising about 4h. 10m. 

 P.M., and setting at Ih. 40m. a.m. ; and of the Andromedes, 

 occurring on the evenings of the 26th and 27th, the radiant 

 point being in lb. 40m. E.A. and north declination 43. 



The Moon is new at 5h. 51m. p.m. on the 4th ; enters 

 her first quarter at Oh. 29m. a.m. on the 12th ; is full 

 at 4h. 5m. a.m. on the 20th ; and enters her last quarter 

 at Oh. 9m. p.m. on the 27th. 



♦ 



C!)tss Column. 



By C. D. LococK, B.A.Oxon. 



Communicationa for this column should be addressed to 

 C. D. LococK, Burwash, Sussex, and posted on or before 

 tbe 10th of each month. 



Solutions of November Problems. 



(E. Henry.) 



No. 1. 



1. B to B4, and mates next move. 



No. 2. 

 1. Kt to Kt7, and mates next move. 



Correct Solutions of both problems received from 

 G. G. Beazley, H. Le Jenne, Alpha, H. S. Brandreth, 

 J. M'Robert, G. J. Newbegin, W. D. F. Edwards, G. H. 

 Herbert, Miss Attwood, E. C. WUlis, G. A. F. (Brentwood), 

 A. E. Whitehouse, .J. T. Blakemore, W. H. Stead, W. 

 Clugston, J. E. Simpson, A Norseman, A. S. Coulter, 

 E. W. Brook, L. Pfungst, H. W. Elcum, A. C. Tappenden, 

 H. F. Biggs. 



Of No. 1 only from Eev. F. W. Quilter, D.D., 

 A. St. J. C, A. P. Hyatt. 



A. P. Hyatt. — See answer to A. St. J. C. below. 



Alpha. — The fact that this page has to reach the printer 

 by the middle of the previous month will account for the 

 defect. 



Rev. F. W. Quilter.— After 1. B to QKt7, Black may 

 play anything safely except K to Q2. Probably, therefore, 

 you intended Kt to Kt7. 



A. St. J. C. — If 1. B X P, B moves, there is no mate. 



W. Mason. — By several moves of the Kt at B3 ; in fact, 

 too many. 



]]'. Clu'jstoii. — Thanks for enclosures. Mr. Loyd's idea 

 wants working into a three-mover. Shall be glad to insert 

 your two-mover next month. 



A. C. Tappemhn.— Yes ; we have heard it ascribed to 

 Mr. Loyd. It is very neat. 



./. T. Blakemore. — Many thanks for the problems, which 

 are very acceptable. One is reserved for nest month. 



PKOBLEMST^' 

 No. 1. 

 By J. T. Blakemore. 



Black (7). 



Whiti (111). 



White mates in three moves. 



