POLARISATION OF THE ATMOSPHERE. 285 



1844, June 3.— Barom. 2986. Wind west. 



Apparent Time. Arago. 



8 h 46 m 20° 58' 



Babinet. 

 8 52 20° 35' 



1844, June 10.— See " Edinburgh Transactions," vol. xxiii, pp. 220, 227. 



1844, June 13.— 



1844, August 20. — Barom. 29*77, rising. Fine day. 



Apparent Time. ■ Arago. 



6 h 57 m R=23° maximum polarisation, 27° in horizon. 17° 1' 



7 38 R = 27J „ „ 20 40 



8 8 21 25 

 8 46 19 



Babinet. 



8 50 R=29° 17° 15 



1844, August 26. — Barom. 2977, rising. Fine day. 



Apparent Time. Arago. 



6 h 18 m Neutral point among small mottled clouds. 29° 0' ! 



1844, August 29.— Barom. 29-92, falling. Fine day. A China-ink sky. 

 Brewster's neutral point distinctly seen. 



Apparent Time. * 



2 h 20 m R = 19£° maximum polarisation in zenith plane. 



1844, September 21. — Barom. 30-1; cold and clear sky. 



Apparent Time. Arago. 



6 h 16 ra R= 28|° maximum polarisation in zenith, 251° in hor. 18° 55' 



Babinet. 

 6 18 Polarisation of moon 17 J°. 17° LI' 



1845, January 11. — Fine day, cold ; wind west. 



Apparent Time. Arago. 



2 h 10 m Rzz28J° maximum polarisation in zenith. 8° 15' 



1845, January 20. — Barom. 2948. Fine day ; frosty. 



Mean Time. 



3 h 10 m R = 29° maximum polarisation in zenith. Above Horizon. 



3 15 Alt. of Arago's neutral point, 12" 56' 



3 17 Alt. of Babinet's neutral point ; clouds came on, 22 



1845, January 24. — Barom. 29 -55, rising. 



Mean Time. Above Horizon. 



3 h 37 m Alt. of Arago's neutral point, 11° 0' 



3 59 Alt. of Arago's neutral point, 17 30 



4 4 Alt. of Babinet's neutral point, 19 35 

 4 39 Alt. of Arago's neutral point, 13 35 

 4 41 Alt. of Babinet's neutral point, 24 



