22 



KNOWLEDGE. 



[January 1, 1894. 



prisms for a spectro-heliograpb, so that one, two, or three 

 might be used as occasion required. The method of forming 

 a magnified image of the second sht on the photographic 

 plate, which we owe to Dr. C. Braun, formerly Director of 

 the Haynald Observatory at Kaloesa, is in some respects a 

 valuable one. Its principal defect— the widening of the 

 K line and the second slit — can be avoided by enlarging 

 the solar image before it enters the spectro-heliograph. 

 In this case, however, it might not be possible to photo- 

 graph the whole image on a single plate. 



The larger solar spectroscope which is to be used with 

 the Yerkes telescope will be specially arranged for the 

 study of the H and K reversals on the solar disc. Among 

 the attachments to be employed for this purpose will be a 

 pair of long slits, arranged to move in the focal planes of 

 the collimator and observing telescope. The method of 

 photographing the K reversal in successive sections of the 

 disc will thus be similar to that hitherto employed with 

 the Kenwood Observatory spectro-heliograph, but the 

 exposure will be made automatically by an electrical 

 device controlled by an astronomical clock. As I have 

 already remarked, the spectro-heliograph for the Yerkes 

 telescope will be arranged on another plan. 



Berlin, December 15th, 1893. 



THE FACE OF THE SKY FOR JANUARY. 



By Herbert Sadler, F.K.A.S. 



SPOTS and faculse continue to appear on the Sun's 

 disc whenever he is visible. Conveniently observ- 

 able minima of Algol occur at lOh. 40m. p.m. on 

 the 10th ; at 7h. 29m. p.m. on the 13th, and at 

 4h. 18m. P.M. on the 16th. 



Mercury is a morning star for the first portion of the 

 month, but owing to his proximity to the Sun and great 

 southern declination he will be very difficult to observe. 

 On the 1st he rises at 7h. Dm. a.m., or Ih. Sm. before 

 the Sun, with a southern declination of i^3° 35', and an 

 apparent diameter of 5", /j/^yths of the disc being illuminated. 

 On the 7th he rises at 7h. 22m. a.m., or lom. before the 

 Sun, with a southern declination of 24'^ 11', i-%\,-ths of the 

 disc being illuminated. After this he is too near the Sun 

 to be observed, coming into superior conjunction on the 

 29th. While visible he passes from Ophiuchus into Sagit- 

 tarius, without approaching any bright star. 



Venus is an evening star, a most brilliant object during 

 the first three weeks of January in the south-western sky. 

 She sets on the 1st at 8h. Om. p.m., 4h. after the Sun, 

 with a southern declination of 13;^°, and an apparent 

 diameter of 34i", -[%%ths of the disc being illuminated. 

 On the 11th she sets at 8h. 2m. p.m., 3h. 50m. after the 

 Sun, with a southern declination of iJ^'Sl', and an apparent 

 diameter of 40^", -,"o%ths of the disc being illuminated. 

 She is now at her greatest brilliancy, that being precisely 

 the same as on January 11th, 188G. On the 21st she sets 

 at 7h. 51m. p.m., or 3h. 30m. after the Sun, with a 

 southern declination of 6*^ 21', and an apparent diameter 

 of 47J", rVo^^s of the disc being illuminated. On the 31st 

 she sets at 7h. 19m. p.m., or 2h. 23m. after sunset, with a 

 southern declination of 4^ 12', and an apparent diameter of 

 S-^i". T^u'^s of the disc being illuminated. Her brightness 

 is now only Vote's of what it was on the Ilth. She 

 describes a looped jmth in Aquarius during the month, 

 being stationary on the 24th. 



Neither Mars nor Uranus rise till after midnight in 

 January ; and as Saturn only rises on the 31st at llh. 2Gm. 

 P.M., we defer an ephemeris of him till next month. 



Jupiter is an evening star, and, with the exception of 



Venus, is the brightest object in the evening sky. He sets 

 on the 1st at 4h. 18m. a.m., with a northern declination 

 of 17° 17', and an apparent equatorial diameter of 45-0". 

 On the 12th he sets at 3h. 28m. a.m., with a northern 

 declination of 17° 15', and an apparent equatorial diameter 

 of 43^". On the 31st he sets at 2h. 16m. a.m., with a 

 northern declination of 17° 27', and an apparent equatorial 

 diameter of 40-9". He is almost stationary in a barren 

 region between the confines of Aries and Taurus during 

 the month. The following phenomena of the satellites 

 occur 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 5h. 24m. p.m., and of its shadow at 

 6h. 24m. p.m. ; a transit egress of the satellite at 

 7h. 36m. p.m., and of its shadow at 8h. 37m. p.m. On 

 the 2nd an eclipse reappearance of the first satellite 

 at 5h. 49m. 42s. p.m. On the 3rd a transit egress 

 of the shadow of the third satellite at 5h. 12m. p.m. On 

 the 7th an occultation disappearance of the second satellite 

 at Oh. 38m. a.m. ; a transit ingress of the first satellite at 

 Oh. 45m. A.M. ; an occultation disappearance of the third 

 satellite at Oh. 48m. a.m. ; a transit ingress of the shadow 

 of the first satellite at Ih. 51m. a.m. ; an occultation re- 

 appearance of the third satellite at 2h. 37m. p.m. ; an 

 occultation disappearance of the first satellite at lOh. Om. 

 P.M. On the 8th an eclipse reappearance of the first 

 satellite at Ih. 16m. 81s. a.m. ; a transit ingress of the 

 first satellite at 7h. 13m. p.m. ; a transit ingress of the 

 second satellite at 7h. 21m. p.m. ; a transit ingress of the 

 shadow of the first satellite at 8h. 19m. p.m., and a transit 

 egress of the satellite itself at 9h. 25m. p.m.; a transit ingress 

 of the shadow of the second satellite at 9h. 83m p.m., 

 and a transit egress of the satellite itself at 9h. 42m. p.m. ; a 

 transit egress of the shadow of the first satellite at lOh. 32m. 

 p.m., and a transit egress of the shadow of the second 

 satellite at ] Ih. 54m. p.m. On the 9th an eclipse reappear- 

 ance of the first satellite at 7h. 45m. 31s. p.m. On the 

 10th an eclipse reappearance of the second satellite at 

 6h. 23m. Is. p.m. ; a transit ingress of the shadow of the third 

 satellite at 7h. 21m. p.m., and its egress at 9h. 14m. p.m. 

 On the 14th an occultation disappearance of the first 

 satellite at llh. 51m. p.m. On the 15th a transit ingress of the 

 first satellite at 9h. 3m. p.m.; of the second satellite at 9h. 50m. 

 P.M. ; a transit ingress of the shadow of the first satellite at 

 lOh. 15m. P.M. ; a transit egress of the first satellite at 

 llh. 16m. P.M. On the 16th a transit egress of the second 

 satellite at Oh. 11m. a.m. ; a transit ingress of its shadow 

 one minute later ; a transit egress of the shadow of the 

 first satellite at Oh. 27m. a.m. ; an occultation disappear- 

 ance of the first satellite at 6h. 19m. p.m., and its eclipse 

 reappearance at 9h. 41m. 24s. p.m. On the 17th a transit 

 egress of the first satellite at 5h. 43m. p.m. ; a transit 

 ingress of the third satellite at 6h. 27m. p.m. ; an occulta- 

 tion reappearance of the second satellite at 6h. 88m. 

 p.m. ; an eclipse disappearance of the second satellite at 

 6h. 43m. 46s. p.m. ; a transit egress of the shadow of the first 

 satellite at 6h. 56m. p.m. ; a transit egress of the third 

 satellite at 8h. 21m. p.m. ; an eclipse reappearance of the 

 second satellite at 8h. 58m. 52s. p.m. ; a transit ingress of 

 the shadow of the third satellite at llh. 22m. p.m. On 

 the 18th a transit egress of the shadow of the third 

 satellite at Ih. 16m. a.m. On the 22nd an occultation 

 disappearance of the first satellite at Ih. 42m. a.m. ; a 

 transit ingress of the first satellite at lOh. 54m. p.m. On 

 the 23rd a transit ingress of the shadow of the first satellite 

 at Oh. 10m. a.m. ; a transit ingress of the second satellite 

 at Oh. 20m. a..m. ; a transit egress of the first satellite at 

 Ih. 7m. a.m. ; an occultation disappearance of the first 

 satellite at 8h. 11m. p.m., and its reappearance from 



