198 OBSERVATIONS N THE ZODIACAL LIGHT. 



No. 99. 



JANUARY 4th, 1S54 : MOUSING. 



Lat. 22 18' N.: Lou. 114 10' K. 



Sun rose 6/1. 44m. 



Western Zodiacal Light at midnight and 1 o'clock. Eastern Stronger Light l/i. 40m. Diffuse I1A. Wm. 



2 30 Midnight. 

 40 10 



55 2 30 



5 10 40 



5 IK 50 



6 20 



The western Zodiacal Light continued until l h 23 m of this morning, as is noted in the evening record of January 

 3d. The eastern Zodiacal Light began to appear at IT, though it was but a very faint tinge. I was doubtful of it; 

 but having watched it as it increased in brightness, till at ll h 40' there could be no doubt of it, I think it may be 

 considered certain that it was seen at 11 o'clock. Took boundaries at IT 20 m , &c., as in the chart. As the morning 

 advanced, the Stronger Light seemed to slide to the northward, and it will be seen from the chart that the inclination 

 of the ecliptic to the horizon was then diminishing very rapidly. After 5 h 5 m , I was looking at the Stronger Light, 

 and, not aware that the minutes had passed so rapidly, was not expecting any sinking of the Light yet ; when I noticed 

 suddenly that it was no longer in its late position, but had sunk to c c; on looking at my watch, I found it was the 

 time for it; it was now 5 h 10'. It had also but half its late intensity. This diminishing in height and intensity 

 could have occupied little more than a minute. At 5" 16'" it had got clown to b b. Then, very soon, it began to 

 ascend, also brightening up, till it got one-third of the way from b b to Spica, when it sunk rapidly again, and at 

 5 h 20 m had got to the position given in the chart, a a, also dimming again; thence it rose once more to b b, and at 

 5 26 m had sunk again to a a, brightening and dimming as before; then it ascended once more to b b, brightening 

 as it rose; and at 5" 31 m it was down again to a a. At 5 h 32 m the light broke bounds, and dawn had arrived. In 

 these pulsations, the increase in height and strength of brightness was much slower than the decrease. 



I ought to remark, that, although from 4 h 30" to 5 o'clock, the Stronger Light is quite strong, it has never the great 

 brilliancy of the morning Light in September and October. This will apply also to the intensity in the present 

 evening observations. 



