February 1, 1896.] 



KNOWLEDGE 



47 



Mars, Saturn, and Uranus are, for the observer's pur- 

 poses, invisible. 



Jupiter is a magnificent object in the evening sky, and 

 is admirably placed for observation, being visible all night 

 long. On the 1st he rises at 3h. 38m. p.m., with a 

 northern declination of 20^ 10', and an apparent equatorial 

 diameter of 46 j'. On the 10th he sets at Oh. oGm. a.m., 

 or half an hour before sunrise, with a northern declination 

 of 20 26', and an apparent equatorial diameter of 46' . 

 On the 20th he sets at 6h. 14m. a.m., or 54m. before sunrise, 

 with a northern declination of 20' 41', and an apparent 

 equatorial diameter of 45|". On the 29th he sets at 

 5h. 36m. A.M., or one hour and a quarter before sunrise, 

 with a northern declination of 20' 5', and an apparent 

 equatorial diameter of 44V'. He is in Cancer during 

 February. The following phenomena of the satellites 

 occur before midnight on the days named, while the planet 

 is more than 8^ above and the Sun 8*^ below the horizon : 

 On the 1st a transit ingress of the first satellite at 

 7h. 17m. P.M., of its shadow at 7h. 80m. p.m. ; a transit 

 egress of the satelHte at 9h. 38m. p.m., and of its shadow 

 at 9h. 50m. p.m. On the 2nd an eclipse reappearance 

 of the first satellite at 6h. 5.5m. 25s. p.m. On the 4th a 

 transit ingress of the second satellite at 9h. 12m. p.m., 

 and of its shadow at 9h. 47m. p.m. On the 5th an 

 occultation disappearance of the third satellite at 6h. 53m. 

 p.m., and its eclipse reappearance at llh. 42m. 31s. p.m. 

 On the 6th an eclipse disappearance of the second satellite 

 at 7h. 48m. 3s. p.m. On the 7th an occultation disap- 

 pearance of the first satellite at llh. 42m. p.m. On the 

 8th a transit ingress of the first satellite at 9h. Im. p.m., 

 of its shadow at 9h. 24m. p.m. ; a transit egress of the 

 satellite at llh. 21m. p.m., and of its shadow at llh. 44m., 

 P.M. On the 9th an occultation disappearance of the first 

 satellite at 6h. 8m. p.m., and its eclipse reappearance at 

 8h. 49m. 593. p.m. On the 10th a transit egress of the 

 shadow of the first satellite at 6h. I3m. p.m. On the 11th 

 a transit ingress of the second satellite at llh. 28m. p.m. 

 On the 12th an occultation disappearance of the third 

 satellite at lOh. 12m. p.m. On the i3th an occultation 

 disappearance of the second satellite at 6h. 32m. p.m., and 

 its eclipse reappearance at lOh. 23m. 35s. p.m. On the 14th 

 a transit ingress of the fourth satelhte at llh. 3m. p.m. 

 On the 15th a transit ingress of the first satellite at 

 lOh. Iflm. P.M., and of its shadow at llh. 19m. p.m. On 

 the 16th an occultation disappearance of the first satellite 

 at 7h. 53m. p.m., and its eclipse reappearance at 

 lOh. 44m. 42s. p.m. On the 17th a transit egress of the 

 first satellite at 7h. 32m. p.m., and of its shadow at 

 8h. 7m. p.m. On the 20th an occultation disappearance 

 of the second satellite at Hh. 49m. p.m. On the 20th a 

 transit egress of the shadow of the second satellite at 

 7h. 12m. p.m. On the 23rd an eclipse reappearance of the 

 fourth satellite at Oh. 22m. 27s. p.m., a transit egress of the 

 third sateUite at 7h. 2m. p.m., an occultation of the first 

 satellite at 9h. 39m. p.m., and a transit egress of the 

 shadow of the third satellite at 9h. 54m. p.m. On the 

 24th a transit ingress of the lirst satellite at 6h. 58m. p.m., 

 of its shadow at 7h. 42m. p.m. ; a transit egress of the 

 sateUite at 9h. I8m. p.m., and of its shadow at lOh. 2m. 

 p.m. On the 25th an eclipse reappearance of the first 

 satellite at 7h. 8m. 17s. p.m. On the 27th an occultation 

 disappearance of the second satellite at llh. 7m. p.m. On 

 the 29th a transit ingress of the shadow of the second 

 satellite at 6h. 54m. p..m., a transit egress of the satellite 

 at 8h. 10m. P.M., and of its shadow at 9h. 49ni. p.m 



Neptune is an evening star, rising about noon on the Ist, 

 with a northern declination of 21 ' 1 2', and an apparent 

 diameter of 2-6". On the 29th he rises at lOh. 14m. a.m.. 



with a northern declination of 21° 13'. He describes a 

 very short retrograde path in Taurus during the month, a 

 little to the south of the 4?- magnitude star t Tauri. A 

 map of the stars near his path will be found in the English 

 Mechanic for August 16th, 1895. 



There are no very well marked showers of shooting stars 

 in February. 



The Moon enters her last quarter at Oh. 38m. a.m. on 

 the 6th ; is new at 4h. 13m. p.m. on the 13th ; enters her 

 first quarter at 9h. 14m. p.m. on the 21st ; and is full at 

 7h. 51m. p.m. on the 28th. There will be a partial echpse 

 of the Moon on the evening of the 28th. The first contact 

 with the penumbra occurs at 5h. 15m. p.m., with the 

 shadow at Oh. 16m. p.m., at 85' from the north point of 

 the Moon's limb towards the east (reckoning for direct 

 image) ; the middle of the eclipse at 7h. 46m. p.m. ; the 

 last contact with the shadow at 9h. 15m. p.m., at 30" from 

 the north point of the Moon's limb towards the west 

 (reckoning for direct image) ; last contact with the 

 penumbra at lOh. 10m. p.m. Taking the Moon's diameter 

 at 1, the magnitude of the eclipse will be 087. The Moon 

 rises at Greenwich at oh. 27m. p.m. 



Cijrss Column. 



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



Communications for this column should be addressed to 

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

 the 12th of each month. 



ANSWERS TO CORRESPONDENTS. 



A Norseman. — All your postcards were received too late 

 to reply to last month. Please send your address for 

 registration nest time you write. Your solutions were 

 correct. 



A. (i. FeUoirx. — Many thanks for your letter, explaining 

 that an alteration of your problem at the last moment gave 

 rise to the si;perfluous solutions. We believe that this is 

 the first unsound problem of yours published in this column. 



THE EIGHT QUEENS PROBLEM. 

 (Continued.) 



We now proceed to remark on the principal features of 

 the table of possible positions given in the -January 

 number : — 



1. Evidently the positions of most frequent occurrence 

 are those beginning a3, ';6, etc. Of course the same 

 would apply to positions beginning aO, fc3, or ending g3, 

 h(i, or g6, hS, for all these are practically the same, the 

 difiference being merely one of right or left, backwards or 

 forwards. 



2. Each of the positions labeUed a, 3, etc 



\ occurs four times in the table of forty-six positions ; it 

 seems, there fore, remarkable that the sj-mmetrical position ui 

 should occur only twi<t: Also that, in both the cases in 

 which it is found, the position is absolutely identical if the 

 board be turned half-way roimd {i.e., two quarter turns). 

 This may be seen at once by referring to the two diagrams 

 ui and cu., in the last number. We beUeve that the 

 coincidence is confined to these two positions. 



8. In three out of the four classes (A, B, C) the squares 

 h7 and h8 are never filled. In other words, a Queen can 

 never be placed on KH7 or KR8 when there is a Queen on 

 QRsq or QK2 or QR3. 



4. We now arrive at the interesting question whether 



