of the Atmosphere. 1 63 



1841, November 25.— Barom. 29*63 in. Splendid day. 





B= maximum 



polarization. 



Height 



of neutral point 



Apparent time, 

 h m 

 10 31 P M. 



In zenith. 



In horizon. 



above the sun. 













3 20 



12 9 „ 



m 



25± 





6 24 



12 26 „ 









12 5 



2 24 „ 



28| 



m 





13 47 



3 10 „ 



. . 



, . 





16 35 



1842, January 29. — Barom. 29*93 in. Fine day ; clear sky ; 

 snow covers the ground partially. 



3 32 27 21£ 16 35 



3 53 .. .. 17 38 



4 8 ., ... 17 51 



1842, February 15. — Bain in morning, then a fine day. 

 4 25 . . . . 21 58 



4 44 . . . . 20 24 



4 55 27\ 22iinS.E.hor.20 30 



At this hour clouds rose in the S., N., and N.E. horizon; a 

 dark band of distant haze 6° or 8° high rose above the sea 

 horizon. 



1842, February 21. — Fine day; wind west. 



4 35 . . . . 18 57 



5 8 . . . . 18 32 



1842, March 2. — A wet day; the place of the sun was seen 

 only as a white spot. The polarization everywhere feeble. 



2 h 20 m . — The neutral point was 75° above the horizon, or 

 about 54° above the sun. The polarization was negative from 

 the neutral point to the horizon beneath the sun, and positive to 

 the horizon opposite to the sun. 



1842, March 16. — Barom. 29*96 in. The sun occasionally 

 shining through a thickish haze in a China-ink sky without any 

 blue ; the wind in the south-west, and slight. 



10b. 45m # — Sun's altitude about 30|° ; the polarization below 

 the sun was negative down to the horizon ; the neutral point was 

 30° above the sun, or more than 60° high ! 



1842, April 5.— Barom. 30*07 in. Splendid sky. 



6 23 30 26| 19 17 



6 58 . . . . 18 46 



7 7 30i . . 15 45 



The polarization was unusually great, equivalent to a rotation 

 of the plane of polarization of about 29° ; it became stronger as 

 it grew darker. 



N.B.- — This day and April 8th were the only days on which I 

 was able to observe the three neutral points and determine their 

 place. (See p. 168.) 



M2 



