38 



KNOWLEDGE 



[February 1, 1892. 



Comet, since its return in 1886, Dr. von Haerdtl, of 

 Vienna, has made a re-investigation of its motions and 

 found no evidence of any such eifect of a supposed 

 resistance. The suggestion, however, will give some 

 additional interest to observations of the Comet at its 

 a,pproaching return to perihelion. 



THE FACE OF THE SKY FOR FEBRUARY. 



By Herbert S.4dler, F.R.A.S. 



THE Sun's disc, when visible, should be examined for 

 spots and faeula?. The following are conveniently 

 observable minima of some Algol-type variables 

 (<;/'. " Face of the Sky," for .January). U Cephei. 

 — February 4th, oh. 55m. p.m. ; February 9th, 

 5h. 34m. P.M. Algol. ^ — February 2nd, 5h. 41m. p.m. ; 

 February 19th, lOh. 36m. p.m. ; February 22nd, 7h. 23m. 

 P.M. X Tauri. — February 1st, lOh. 11m. p.m. ; February 

 5th, 9h. 3m. p.m.; February 9th, 7h. 55m. p.m.; February 

 13th, 6h. 48m. p.m. ; February 17th, 5h. 40m. p.m. 



Mercury is a morning star during the first portion of the 

 month, but owing to his great southern declination and 

 proximity to the Sim is very badly situated for observation. 

 He rises on the 1st at 6h. 46m. a.m., or 5Gm. before the 

 Sun, with a southern declination of 22*^ 26', and an 

 apparent diameter of 51", -xg^-ijths of the disc being illumi- 

 nated. On the 6th he rises at 6h. 52m. a.m. , or 42m. before 

 the Sun, with a southern declination of 21° 44', and an 

 apparent diameter of 6", xoV^li? of the disc being illuminated. 

 After this date he is too near the Siui to be visible. Venus 

 is an evening star, and is now becoming a conspicuous 

 object in the western sky. On the 1st she sets at 7h. 47m. 

 P.M., 3h. Im. after the Sim, with a southern declination of 

 7° 14', and an apparent diameter of 12|", i^/oths of the 

 disc being illuminated. On the 29th she sets at 9h. 15m. 

 P.M., with a northern declination of 7° 18', and an apparent 

 diameter of 14i", tVo^'^s °^ ^-^^ disc being illuminated, and 

 the brightness of the planet being rather less than one-half 

 of what it will be at its greatest at the beginning of -June 

 and middle of August next. Venus is in conjunction with 

 .Jupiter at lOh. 14m. a.m. on the 6th, the geocentric distance 

 separating the limbs of the two planets being only 18^", but 

 the phenomenon occurs after sunrise in Europe. The two 

 planets, however, will present a most beautiful appearance 

 in the western sky in England on the evenings of the 5th 

 and 6th. At 7h. p.m. on the 5th Venus will be about 

 38' s.p. .Jupiter, and at the same hour on the next evening 

 she will be about 21^' «./'. .Jupiter, the field of view on 

 both evenings, with a low power, being a singularly jn'etty 

 one. During the month Venus passes from Aquarius into 

 Cetus, but without approaching any conspicuous star. 

 Mars is, for the purposes of the observer, invisible ; and as 

 Uranus does not rise till after midnight at the beginning 

 of February, we defer an ephemeris of this j)lanet until 

 next month. 



Jupiter is still visible, close to the S.W. horizon, but he 

 is so rapidly approaching the Sun that our ephemeris of 

 him only extends over the first third of the month. On 

 the 1st he sets at 8h. 16m. p.m., S^h. after the Sun, with 

 an apparent equatorial diameter of 34J", and a southern 

 declination of 5° 8'. On the 10th he sets at 7h. 52m., or 

 2h. 49m. after sunset, with an apparent equatorial diameter 

 of 33f ", and a southern declination of 4° 20'. The following 

 phenomena of the satellites occur while Jupiter is more 

 than 8° above, and the Sun 8° below, the horizon. On 

 the 1st a transit egress of the shadow of the fourth satellite 

 at 6h. 7m. p.m. On the 2nd a transit egress of the shadow 

 of the first satellite at 6h. 52m. p.m. On the 4th a reap- 



pearance from occultation of the third satellite at 6h. 51m. 

 P.M., and its eclipse disappearance at the same instant. On 

 the 8th a transit egress of the second satellite at 5h. 54m. 

 P.M. ; while visible he describes a short du-ect path in 

 Aquarius. 



Saturn is an evening star, rising on the 1st at 9h. p.m., 

 with a northern declination of 2° 19', and an apparent 

 equatorial diameter of 18'6" (the major axis of the ring 

 system being 42'8" in diameter, and the minor 2-5"). On 

 the 29th he rises at 7h. p.m., with a northern declination 

 of 3'^ 3', and an apparent equatorial diameter of 19'1" (the 

 major axis of the ring system being 44" in diameter, and 

 the minor 1-9"). The following phenomena of the satellites 

 may be observed (the times are given to the nearest quarter 

 of an hour) ; — February 2nd, 4ih. a.m., Tethys, eclipse 

 disappearance. February 3rd, lOh. p.m., Dione, eclipse 

 disappearance. February 4th, 2h. a.m., Tethys, eclipse 

 disappearance. February 5th, ll^h. p.m., Tethys, eclipse 

 disappearance. February 8th, l|^h. a.m., shadow of Rhea 

 in central transit. February 9th, 0|h. a.m., shadow of 

 Titan m central transit ; 4h. a.m.. Titan in inferior con- 

 junction with centre of Saturn, 9-9" south. February 10th, 

 ofh. A.M., Rhea, eclipse disappearance. February 12th, 

 3h. A.M., Dione, eclipse disappearance. February 17th, 

 2|h. A.M., shadow of Rhea in central transit ; 4^h. a.m.. 

 Titan, eclipse disappearance. February 19th, 4|-h. a.m., 

 Tethys, eclipse disappearance. February 20th, 2h. a.m., 

 lapetus in inferior conjunction with the centre of the planet ; 

 Tethys, eclipse disappearance. February 22nd, llh. p.m., 

 Tethys, eclipse disappearance. Febrftary 23rd, 2h. a.m., 

 Dione, eclipse disappearance. February 24th, 8ih. p.m., 

 Tethys, eclipse disappearance ; 11-1-h. p.m., shadow of Titan 

 in central transit on Saturn. February 25th, l|h. a.m.. 

 Titan skirts southern limb of planet. February 26th, 

 3Jh. a.m., shadow of Rhea in central transit. During the 

 month Saturn describes a short retrograde path in Virgo, 

 without approaching any naked-eye star. 



Neptune is still visible during the working hours of 

 the night, rising on the 1st at lib. 40m. a.m., with an 

 apparent diameter of 2-6", and a northern declination of 

 19° 48'. On the 29th he rises at 9h. 39m. a.m., with a 

 northern declination of 19° 49'. During February he is 

 almost stationary just north-west of « 'Tauri, and about 

 the middle of the month he will be observed to be about 

 80" «./'. a 9i magnitude star. 



There are no well-marked showers of shooting stars in 

 February. 



The Moon enters her first quarter at 9h. 39m. a.m. on 

 the 5th ; is full at 7h. 38m. p.m. on the 12th ; enters her 

 last quarter at Oh. 15m. a.m. on the 21st; and is new at 

 3h. 47m. A.M. on the 28th. She is in perigee at 9-2h. a.m. 

 on the 1st (distance from the earth 226,765 miles) ; in 

 apogee at 9-8h. a.m. on the 17th (distance from the earth 

 251,845 miles) ; and in pei'igee at ll-8h. a.m. on the 28th 

 (distance from the earth 223,660 miles). The greatest 

 western libration is at 2h. 46m. a.m. on the 9th, and the 

 greatest eastern at 9h. 48m. p.m. on the 23rd. 



Cljcss Column. 



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



All communications for this column should be addressed 

 to the " Chess Editor, Knowledge Office," and posted before 

 the 10th of each month. 



The solution of the Four-Move Problem in the January 

 number is necessarily withheld till its publication in the 

 Chess- Monthli/. 



