186 OBSERVATIONS ON THE ZODIACAL LIGUT. 



No. 93. 



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A mn:;' f;ivi inside iiinc. Atmosphere perfectly clear, and sky good down to the horizon. Victoria mountain (Hong- 

 Kong) interferes a little, but not so as to produce any difficulty. I determined to watch this night through, in 

 order 1- see nil the changes of the Zodiacal Light, and to discover how long it would last in the west, and how soon 

 it would appear in the eastern sky. The ecliptic, at this time, is most favorable for the endurance of the Light, 

 belli;;- nearlv vertical to the horizon at midnight, so as to give as little trouble as possible from haziness or the ordi- 

 nary glare along the horizon. I was well rewarded to-night, having had the rare satisfaction of seeing the Zodiacal 

 Light at once, at the east and west, at 12 o'clock. The following are my notes : "At 6" 30 m , twilight not quite past, 

 and the stars imperlectly out; but the Milky Way is clearly distinguishable, and so also is the Zodiacal Light, though 

 the latter is dim. I tried to get its boundaries; but after succeeding in-one or two spots, had to give it up, the Light 

 being so faint as not to give reliable outlines throughout. At 6 h 42" 1 , succeeded; 6" 45 m , could get outlines of Stronger 

 Light. Observations from this on, as in the chart. The Stronger Light was strongest at 7" 45 m ; by 8" 30'" it bad 

 become dim. At !>'' 30'" Stronger Light almost gone; it has ascended, and widened into the Diffuse, which is now 

 very distinct and bright brightest at its lower end. At 11", quite distinct, as high as the Pleiades, its limits nar- 

 rower than before, and running up cone-shaped: brightest at lower end. It perhaps extended up as far as 123 

 Tauri (tip oE the horn), but I was not certain; it rather seemed so to me. At 11" 30"', Light still visible, but dim. 

 Thought, then, it <li<l extend up to 123 Tauri. Boundaries as at 11". It was now simply a paling of the sky. At 

 midnight, still a paling of the sky; boundaries as at 11"; it is, however, scarcely perceptible. Now saw theZodiacal 

 Light also in the cast, for which see morning chart of December 31st, and remarks. At 12" 30', the western Light still 

 seemed to continue; its boundaries as hH'orfc, ^ It was as bright as the extreme edge of the Milky Way, just by 

 Gomeisa, but has a warmer tint than the Milky Way. At I' 1 , it still seemed to be visible appeared not io lie 

 out, but to be sinking with the Pleiades; its limits as before. At 2 h , it had quite gone." 



