POLARISATION OF THE ATMOSPHERE. 273 



1842, October 20.— Barom. 29-62. Fine day; cold. 



Apparent Time. Arago. 



4 h 15 m R=26i° near S. horizon. Clouds in zenith. 14° 46' 



1842, October 21. 



Apparent Time. Arago. 



4 h 49 m Neutral point above a cloud. 18° 13' 



1842, October 24.— Barom. 29*33. Rain in the morning; cold. 



Apparent Time. Arago. 



4 h 28™ 18° 46' 



Babinet. 

 4 32 R = 27° maximum polarisation in zenith plane. 21° 59' 



1842, November 9.— Barom. 29 -06, after a storm of wind and rain. 



Apparent Time. Arago. 



4 h 41 ra Polarisation of moon in S. horizon 25J°. 17° 20' 



1842, November 14.— See " Edinburgh Transactions," vol. xxiii. pp. 218, 226. 

 1842, November 15.— Barom. 2972. Hard frost in morning. 



Apparent Time. Arago. 



2 h 12 m Secondary neutral point in horizon. 17° 50' 



1842, November 20, 21.— See " Edinburgh Transactions," vol. xxiii. pp. 219, 226. 

 1842, November 27. — Barom. 29*15, rising. A dark band along the horizon. 



Apparent Time. 



3 h 57 m R=27° in zenith, and 18|° in horizon. 



Arago's secondary neutral point in horizon, and primary one consider- 

 ably up. 



1842, December 3.— Barom. 29*95. Fine day. 



Apparent Time. 

 12 h 46 m Arago's neutral point not risen. 



12 46 R=27J° maximum polarisation in zenith, 20|° in hor. 



Arago. 



2 16 R=28|° maximum polarisation in zenith, 18|-° in hor. 19° 20' 

 4 23 24 22 



Babinet. 

 4 28 20° 15' 



1842, December 17. — Barom. 29-58, rising after rain. 



Apparent Time. Arago. " 



3 h 16™ 18° 5' 



Babinet. 



3 19 R = 29° maximum polarisation in zenith. 17° 50' 



1842, December 18. — Barom. 29-79. Raining occasionally. 



Apparent Time. Arago. 



ll h 13 m 13° 45' 



12 23 14 42 



