34 OBSERVATIONS ON THE ZODIACAL LKIIIT. 



No. 17. 



JUNE 57th, 1S53, (Monday) : EVENING. 



Lat. 26^ 10' N.: Lon. 127 ' 42' K. 



Sun set G/i. 51Ji. 



Stronger and Diffuse Light at 8h. 30m. and 10A. 30m. 

 Sun's Longitude, 95 o'J'. 



I suspected, from some glances at the Zodiacal Light, last evening, that I was giving it a too contracted boundary; 

 and, this evening, determined on a very careful observation, as the evening was very flue, atmosphere very clear, and 

 the sky unusually brilliant. After looking carefully myself, I called one of the oldest of the quartermasters, and, 

 drawing his attention to the light, I said: "You observe that, over there (pointing to the northward), the sky is 

 bluer and darker." He said "Yes." " You observe also, that up here (along the ecliptic), the stars are not so 

 bright as in the parts you have just been looking at." To this he also assented. " Now I want you to point out, 

 in the sky, the boundary between these two appearances; where the stars begin to lose their brightness, and the 

 sky begins to be less blue." He soon commenced drawing the boundaries, which corresponded exactly with those 

 which I myself had just mentally been giving it, and which are marked in the chart by the line of 8 h 30 m aa. At 

 10 h 30 m it had extended as shown in the chart atbbb. At 8 h 30 m the full extent of the Stronger Light along the 

 horizon was 75. At 10 h 30 m the limits of the Stronger Light were not so well denned ; the light was stronger 

 between the horizon and 48 of Ursa Major, Coma Ber., and 5 Virginia, than it was above. 



