350 Sir David Brewster on the Polarization 



1842, February 19. — Fine day, with wind. 



Apparent time. 



h m Arago. 



2 58 R=26i° in S.E. horizon, alt. 30°. , 



3 7 Neutral point 2° alt. . . 13 38 



3 20 Secondary neutral point seen. 14 42 

 A , c | Fleecy clouds over neutral point. ) OA A 



4 15 \ nlm° S- hor. P | 20 

 4 40 R= 24^° in zenith plane. .. 19 28 



1842, February 21.— From 4 h 52 m to 4 h 57 m a secondary 

 neutral point to that of Arago was gradually but imperfectly de- 

 veloped*. 



1842, February 22. — Dull cold morning, which cleared up 

 about l h 25 m , when II = 21 J in clear sky, from which clouds 

 had passed. 



o OA j R=25|°in zenith, 22|° near W. and I , K An 



6 J4 ] E. horizon f lb 4U 



3 38 .. .. .. 17 29 



{Negative bands do not touch the sea- ) 

 horizon. Secondary neutral point !> 20 26 

 in the horizon. . . J 



4 2.. 



4 28 



5 8.. 





20 50 

 23 8 

 19 2 



4 6 Pol.ofmoon,R=3°; R=27^°in 



4 24 



5 6 



Babinet. 



zenith. 17 15 

 16 19 

 19 5 



1842, February 24.— Barom. 29 in. 







Arago. 



3 47 .. .. .. 17 20 



2 32 R=26|° in zenith; 27^° in S.E. hor. 



3 51 R = 23|° in zenith, and 25±° at 35° alt. 



N.W. horizon. 



1842, February 25. — Dull day; frost in morning ; cleared up 

 at 4 h 2 m . 



Babinet. 



5 9 R= 28° in zen. ; 26^° in E. and W. hor. 1 7 50 



Arago. 



5 12 .. .. .. 18 5 



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

 as a white spot. 



2 20 The polarization everywhere extremely feeble. Babi- 

 net's neutral point was nearly 75° above the ho- 

 rizon, or about 54° above the sea ! See March 16. 



* See Phil. Mag. vol. xxx. pp. 124, 163, 167. 



