124 



Sir David Brewster on the Polarization 



west, the sun's altitude being about 30°. In carrying the bands 

 vertically round, the neutral line, in place of crossing them at a 

 right angle, was the arch of a circle, to which one of the bands 

 was a tangent. The sky was clear, but in a short time a cloud 

 was formed in that place. I had observed the same pheno- 

 menon previously. It indicates a state of the air similar to that 

 which produces mirage. 



1842, February 21.— Barom. 29*44 in. Wind west. The sky- 

 line over both the sea and the land unusually distinct and free 

 from haze. 



Apparent time. 



In zen 



h m 







3 45 p.m. 





3 57 „ 





4 31 „ 





4 37 „ 





5 6 „ 





R= maximum polarization. 

 In horizon. 



Height of neutral point 

 above the antisolar point. 



10 29 

 12 39 



17 40 



18 35 



19 49 



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



5 25 p.m. . . . . 13 26 



5 32 „ .. .. 15 25 



6 21 ,. 30 26! 19 1 



6 55 „ .. .. 18 50 



7 12 „ 30| •• 21 5 



N.B. This and April 8 are the only days on which I was able 

 to observe all the three neutral points and determine 

 their place. 



1842, April 6. — Barom. 30*05 in. Considerable haze. 

 5 23 15 26 



1842, April 8. 









5 30 p.m. 



, m 



, > 



15 26 



5 38 „ 







19 



5 46 „ 







19 



5 52 „ 







19 5 



6 5 „ 



24J 



19! 



21 25 



6 22 ., 



, . 



. , 



20 55 



6 47 „ 



27! 



. , 



20 30 



7 5 „ 



28| 



. . 



19 55 



7 18 „ 



• • 





20 15 



1842, April 13.- 



—Barom. 



30*12 in. 



Fine day. 



5 48 p.m. 





.. 



16 20 



6 20 „ 



29 



22! 



17 55 



6 54 „ 



29! 



. , 



19 40 



7 10 „ 





, . 



19 45 



7 19 „ 



m 



, 



19 4 



7 54 „ 





. . 



22 10 



At 7 h 32 m the maximum polarization was 32J, the greatest 

 ever observed. 



