448 OBSERVATIONS ON THE ZODIACAL LIGHT. 



No. 224. 



OCTOBER llth 1854s EVENING, 



Lat. at 7k., 35 24' N. : Lon. 1G5 16' E, 



Sun set 5h. 27m. 



StroDger Light at 7A. 12m. aud 7/i. 37m. : Diffuse 7h. 2 n m. 

 Zenith point at 7h., Lat. 53 25' N. : Lot). 319. 



Clouds ever since last date (September 30th), until this evening, when, soon after sunset, the sky became quite 

 clear and remarkably good for observations; the western horizon being particularly free from haziness down to the 

 water's edge. I was glad of this, as I wished much to have an evening observation at this time under favorable cir- 

 cumstances, and they were now as good as could possibly be. Sky quite clear and brilliant, and the horizon open 

 and clear. The results were interesting. 



I watched carefully from the beginning. After the sun had set, its light lingered above it for some time, equally 

 on each side. This was evidently atmospherical light. Then the light appeared gradually and imperceptibly to 

 slide to the southward ; and, as the darkness increased, at 6 h 55"', a white light, very decided, showed itself within 

 the dotted boundary a a. This light was strong to the horizon, and was different from any thing seen beyond it on 

 the north or south ; although, northwardly, a whitish light continued on near the horizon. By 7' 1 12"' the darkness 

 had become complete, and the light had now changed. I could make out the boundaries b l> b l> ; I thought them 

 pretty distinct, the horizon being still remarkably clear. At 7" 20'", the light bounded by a a had widened, and had 

 become the Diffuse Light, with boundaries (c) as in the chart. (In making out the extreme end of this, I found 

 Jupiter's light troublesome, but believe I have got the true boundaries, notwithstanding.) At 7 h 37 m , I was con- 

 firmed in my belief that I had, at 7" 12 m , got the boundaries of the Stronger Light, by finding that the upper 

 boundary had now slid up to d d, changing its direction in consequence of the change of angle in the horizon. I 

 could see it also extending across the clear interval in the Milky Way. At 7 h 42", Diffuse Light on left of Milky 

 Way now quite decided ; boundaries as before. At 8 o'clock the Light could be seen, but was too dim to give bound- 

 aries. 



