168 Sir David Brewster on the Polarization 



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



Apparent time. Distance of neutral point 



h in from sun. 



12 27 Neutral point seen distinctly below the sun. 

 12 27 . . . . • 15°25' 



12 53 .. .. 14 40 



12 56 .. .. 15 45 



4 13 .. .. 15 35 



4 33 .. .. 15 22 



N.B. All the three neutral points were observed and their 

 places ascertained this day, and also on April 8. 



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

 8 51 Neutral point distinctly seen below the sun. 



11 6 .. .. 12 



1842, April 8. 



2 7 The neutral point below the sun beau- 



tifully seen. Estimated distance 



from the sun 16 



1842, April 15 and 17. 



3 Neutral point below the sun distinctly seen. 

 3 30 .. 



1842, April 20. — Barom. 30*02 in. Very fine day; wind west. 



12 10 .. .. 11 20 

 12 37 .. .. 10 40 



2 21 .. .. 12 



3 45 .. .. 12 35 



The maximum polarization was very great. 



1842, April 25. — Thin hazy clouds before the sun. 



1 11 Sun's alt. 45^°. Alt. neutral point below sun 34°. Dis- 



1842, April 26.— Barom. 30*08 in. Not a cloud in the sky 

 from morning till night. 



11 1 

 11 46 



3 30 



3 35 



4 10 



12 15 

 12 30 



14 35 



15 5 

 17 45 



1842, April 27. — Barom. 30"04 in. Singularly fine sky. 



10 45 . . . . 12 5 



12 12 A fog from the sea has just come on, and has driven the 

 neutral point beneath the horizon, the bands being ne- 

 gative all the way to the horizon. 

 1 20 The fog has diminished. The neutral point is now seen 

 near the horizon, playing up and down from 4° to 6° 

 above the horizon, as the fog becomes denser or rarer ! 



