222 OBSERVATIONS ON THE ZODIACAL LIGHT. 



No. 111. 



JANUARY 30th, 1654: EVENING. 



Lat. 26 10' N.: Lon. 127 42' E. 



Sun set 5/i. 38im. 



Stronger Light ~h. 50m, &c.: Diffuse, TA. 50m, 

 Sun's Ion. 311 20'. 



There can be no doubt that iJiere are pulsations in the Zodiacal Light. I noticed them last evening (the sky being 

 very clear); but, it being Sunday, made no particular record of them. They were, however, distinctly to be seen; 

 and when I called the attention of one of the quartermasters to them, he very easily made them out. His language 

 about the Light was : " Now it seems to be dying away ;" " now it is brightening again," &c. All this applied, 

 however, only to the Stronger Light: it occurred between 7 h 30'" and 8 o'clock. This evening I was on the careful 

 lookout for them, and, with watch in hand, made record of the changes and their times. Clouds interfered till 7 h 50'", 

 when, this part of the sky having cleared up, I got observations. The pulsations were very distinct; observable, 

 however, only in the Stronger Light. This, at 7 h 50% had its boundaries as in the line b (see chart), and was very 

 bright : at 7' 1 52'" it had suuk to the boundaries marked a, and was very dim : 7 1 ' 54'" had risen to b again, and was 

 bright : 7" 55'" at a, and very dim : 7" 56 at b, and bright : 7" 57 at a, and very dim : 7' 1 SS-^" 1 at b, and bright : 7" 5'J^'" 

 still at b, and bright : it seemed now to be permanent at b; but clouds soon after spread over the sky, and shut out 

 everything from sight. 



These pulsations, in order to be seen, seem to require that the ecliptic should be at a high angle with the horizon ; 

 at which time the Stronger Light is very brilliant. Last evening about 7 h 20 m or 30' n , I overheard one of the quar- 

 termasters, as he was Junking at it, remark to another : " If that was not in the wrong part of the sky, I should say 

 that the sun was just going to rise there." 



