178 



KNOWLEDGE 



[September 1, 1898. 



I entirely agree with Mr. Maunder as to the compara- 

 tive shallowness of the layer about the sun which causes 

 ijeneral absorption, as compared with that which causes 

 selective absorption. It seems probable that the layer 

 causing general absorption is not a gaseous layer, but is a 

 stratum above the photosphere which is rendered partially 

 opaque by the presence of small solid or liquid particles. — 



A. C. E.^NYARD.l 



THE FACE OF THE SKY FOR SEPTEMBER. 



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



SOME magnificent spots have lately appeared on the 

 Sun's disc. Conveniently observable minima of 

 Algol occur at lOh. 11m. v.si. on the 3rd ; 7h. Om. 

 P.M. on the 6th ; llh. 52m. p.m. on the 23rd ; and 

 8h. 41m. P.M. on the 26th. About the end of the 

 month the Zodiacal light is visible in the east before 

 sunrise. 



Mercury is a morning star, and is well situated for 

 observation during the first portion of the month. He 

 rises on the 1st at Sh. 40m. a.m., or Ih. 33m. before the 

 Sun, with a northern declination of 14° 46', and an 

 apparent diameter of 6', I'^ths of the disc being illuminated. 

 On the 3rd he rises at 3h. 48m. a.m., or Ih. 30m. before 

 the Sun, with a northern declination of 13° 57', and an 

 apparent diameter of 5|', y'jj^ths of the disc being illu- 

 minated. The planet is now at about its greatest bright- 

 ness. On the 9th he rises at 4h. 25m. a.m., or Ih. Im. 

 before the Sun, with a northern declination of 10° 30', and 

 an apparent diameter of 5^", i^-jths of the disc being 

 Illuminated. After this he gets too near the Sun to be 

 readily observed. He is in superior conjimction on the 

 20th. While visible. Mercury describes a direct path 

 through Leo, without approaching any conspicuous star 

 very closely. 



Venus is an evening star, but her proximity to the Sun 

 and her increasing southern declination render her rather 

 difficult to observe. She sets on the 1st at 7h. 48m. p.m., 

 or 57m. after the Sun, with a southern declination of 

 4° 3', and an apparent diameter of 12J", x',;^ths of the disc 

 being illuminated. On the 17th she sets at 7h. 9m. p.m., 

 or Ih. after the Sun, with a southern decUnation of 12° 0', 

 and an apparent diameter of 13", youths of the disc being 

 illuminated. On the 30th she sets at (ih. 46m. p.m., or Ih. 

 5m. after the Sun, with a southern declination of 17° 41', 

 and an apparent diameter of 14^", about f ths of the disc 

 being illuminated. At this time her brightness is about 

 fiJ^ths of what it will be about the middle of .January, 1894. 

 Venus is in conjunction with Saturn at 3h. a.m. on the 

 2nd, Venus being nearly 2° south of Saturn. During the 

 month Venus passes through part of Virgo into Libra, but 

 does not approach any bright star. She will be occulted 

 by the Moon on the 13th, but the phenomenon will not be 

 visible in England. 



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

 purposes, invisible. 



•Jupiter is getting every night more favourably situated 

 for observation. He rises on the 1st at 9h. 21m. p.m., or 

 2h. 35m. after sunset, with a northern declination of 

 19° 19', and an apparent equatorial diameter of 41-0", the 

 phase on the p limb amounting to 0'4". On the I8th he 

 rises at Hh. 16m. p.m., or 2h. 9m. after sunset, with a 

 northern declination of 19° 24', and an apparent equatorial 

 diameter of 43i". On the 30th he rises at 7h. 28m. p.m., 

 or Ih. 47m. after sunset, with a northern declination of 

 19° 20', and an apparent equatorial diameter of 44iJ ", 

 the phase licing still perceptible. During the month Jin 



describes a very short looped path in Taurus. The following 

 phenomena of the satellites occur while .Jupiter is more 

 than 8° above and the Sun 8° below the horizon : — A 

 transit ingress of the shadow of the first satellite at 

 lOh. 23m. P.M., on the 2nd ; a transit egress of the shadow 

 of the second satellite at Oh. 43m. a.m., on the 8rd ; a 

 transit ingress of the satellite itself at Ih. 8m. a.m., and 

 its transit egress at 3h. 25m. a.m. On the 4th a transit 

 ingress of the third satellite at Oh. 51m. a.m. and its transit 

 egress at 2h. 14m. a.m. ; an occultation reappearance of 

 the second satellite at lOh. 31m. p.m. On the 5th a 

 transit ingress of the shadow of the first satellite at 

 4h. 29m. A.M. On the 6th an eclipse disappearance of the 

 first satellite at Ih. 39m. 18s. a.m. ; an occultation re- 

 appearance of the satellite at 5h. 9m. a.m. ; a transit 

 ingress of the shadow of the first satellite at lOh. 58m. 

 P.M. On the 7th a transit ingress of the first satellite at 

 Oh. 18m. A.M. ; a transit egress of its shadow at lb. lOm. 

 A.M. ; a transit egress of the satellite at 2h. 29m. a.m., and 

 an occultation reappearance of the same satellite at 

 llh. 37m. P.M. On the 10th a transit ingress of the shadow 

 of the first satellite at Oh. 58m. a.m. ; its transit egress at 

 3h. 19m. A.M. ; a transit ingress of the satellite itself at 

 3h. 39m. A.M. ; and a transit ingress of the shadow of the 

 third satellite at llh. 13m. p.m. On the 11th a transit 

 egress of the shadow of the third satellite at Oh. 57m. a.m. ; 

 an eclipse reappearance of the second satellite at lOh. 23m. 

 15s. p.m., and its occultation disappearance at lOh. 45m. p.m. 

 On the 12th an occultation reappearance of the second 

 satellite at Ih. Im. a.m. On the 13th an eclipse disappear- 

 ance of the first satellite at 3h. 33m. lis. a.m. On the 

 14th a transit ingress of the shadow of the first satellite at 

 Oh. 52m. A.M. ; a transit ingress of the satellite itself at 

 2h. 9m. A.M. ; a transit egress of the shadow at 3h. 4m. 

 A.M. ; of the satellite at 4h. 20m. a.m. ; and an eclipse 

 disappearance of the satellite at lOh. Im. 41s. p.m. On 

 the 15th an occultation reappearance of the first satellite 

 at Ih. 28m. a.m. ; a transit egress of its shadow at 9h. 32m. 

 p.m. ; and a transit egress of the satellite itself at lOh. 48m. 

 p.m. On the 17th a transit ingress of the shadow of the 

 second satellite at 3h. 34m. a.m. On the 18th a transit 

 ingress of the shadow of the third satellite at 3h. 13m. 

 A.M., and an eclipse disappearance of the second satellite 

 at lOh. 44m. 43s. p.m. On the 19th an eclipse reappearance 

 of the second satellite at Oh. 58m. 39s. a.m. ; an occultation 

 disappearance of the satellite at Ih. 13m. a.m. ; and its 

 reappearance from occultation at 3h. 28m. a.m. On the 

 20th a transit egress of the second satellite at 9h. 30m. 

 P.M. On tl'.e 21st a transit ingress of the shadow of the 

 first satellite at 2h. 45m. a.m. ; a transit ingress of the 

 satellite itself at 3h. 59m. a.m. ; a transit egress of its 

 shadow at 4h. 68m. a.m. ; an occultation disappearance 

 of the third satellite at lOh. Om. p.m., and its reappearance 

 from occultation at llh. 23ni. p.m.; and an echpse dis- 

 appearance of the first satellite at llh. 55m. 43s. p.m. 

 On the 22nd an occultation reappearance of the first 

 satellite at 3h. 17m. a.m. ; a transit ingress of its shadow 

 at 9h. 14m. p.m. ; a transit ingress of the satellite itself at 

 lOh. 20m. p.m. ; and a transit egress of its shadow at 

 llh. 26m. P.M. On the 23rd a transit egress of the first 

 satellite at Oh. 37m. a.m., and its reappearance from 

 occultation at 9h. 45m. p.m. On the 26th an eclipse 

 disappearance of the second satellite at Ih. 20m. 4s. p.m. ; 

 its reappearance at 3h. 33m. 57s. a.m. ; and its occultation 

 disappearance at 3h. 38m. a.m. On the 27th a transit 

 ingress of the second satellite at 9h. 40m. p.m. ; a transit 

 egress of its shadow two minutes later. On the 28t]i a 

 transit egress of the second satellite at Oh. Im. a.m. ; a 

 transit ingress of the shadow of the first satellite at 



