206 OBSERVATIONS ON THE ZODIACAL LIGHT. 



No. 103. 



JANUARY llth, 1854: MORNINS. 



. Lat. 22 18' N.: Lon. 114 10' E. 



Sun rose G/i. -tOm. 

 Stronger Light at 4A. Om. Diffnso 4A. Om. 



4 40 SO 



5 



5 2 



6 7 

 5 12 



5 14 



6 16 



Moon did not set till almost 4 o'clock. At 4 h got boundaries; and also at 5 h , as in chart. After 5 h , was carefully 

 on the watch to see if there would be any pulsations. Morning very clear. Atmosphere transparent; every thing 

 favorable for good observations. My notes run thus: " 4 h 40', Stronger Light very strong and bright; 5 h 2 m , it h'as 

 sunk, and has dimmed; 5 h 7, sunk lower, dimmed to half its former brightness; 5 h 12 m , has risen, and has just sunk 

 again (for its latter place, see chart); 5" 14" 1 , up again, and has brightened; 5 h 16 m , is up now to Libras ; 5 h 22 ra , 

 breaks bounds, and dawn has come. In breaking bounds, it spreads first and most rapidly towards the north ; then 

 southwardly." These are my notes for so it seemed to me; but, after all, these pulsations may only be seeming 

 ones. I do the best I can, in watching carefully, and recording what appears to be. One thing I can say with cer- 

 tainty: namely, that there is first a sudden and very rapid sinking down of the Stronger Light, with a dimming to 

 about one-half of its late intensity; and then, a little while before dawn, a rising again of the Stronger Light, with 

 an increase of brightness, though not coming up to its former strength. Of so much I can be positive. 



This morning I concluded to watch after dawn had come ; for the Light, though spread over the whole eastern sky, 

 was yet strongest at the central line of the late Zodiacal Light; as if, while the sunlight had now reached our atmo- 

 sphere, and was reflected from it, the reflection was still strongest from the substance giving the Zodiacal Light. At 

 5 1 ' 25 m a little of this was still left say from 38 Libras down; 5 h 28 m , some slight trace of it still remained; 5 b 30, 

 all gone ; sky uniform . 



All this corresponds conversely to the first appearing of the Zodiacal Light in the evening sky, as I have often 

 described it; the time when I suddenly become conscious that I am looking on the true Zodiacal Light, corresponding 

 to the morning period just before the time when the Light breaks bounds, and becomes mingled with the dawn light 

 i. . light from our atmosphere. 



