272 SIR DAVID BREWSTER ON THE 



1842, September 17. — Barom. 29 - 45, after a rainy day. 



Apparent Time. 

 6 h 48 m p m. 



6 53 



R = 28|° maximum polarisation in zenith. 



Arago. 



17° 20' 



Babinet. 

 16° 25' 



1842, September 18 — Fine blue sky. Barom. 29*57. 



Apparent Time. 



3 h m R=21|° in zenith plane to 19£° in horizon. 



R=22£ in zenith plane to 20|- in horizon. 

 R=25° in zenith plane to 23° in horizon. 

 Fringes all + opposite sun and in horizon. 



3 45 



4 20 

 4 46 



4 47 



5 6 

 5 36 

 5 56 

 5 21 



R = 27|° max. polarisation in zenith to 24J 3 in hor. 



1842, September 28.— Fine day. 



Apparent Time. 



4 h 32 m R = 28° maximum polarisation in zenith plane. 



4 58 



1842, September 29.— Fine day ; cold ; wind east. 



Apparent Time. 



4 h 37 m R=30^° maximum polarisation in zenith. 



5 11 



1842, September 30.— Fine day. 



Arago. 

 15° 28' 

 16 36 

 20 16 

 19 40 



Arago. 



18° 36' 



Arago. 

 17° 34' 



Apparent Time. 

 4 h 18 m 

 4 24 



4 55 



5 47 



4 58 



5 44 



R=29*° max. polarisation in zenith to 26^ c in hor. 

 Neutral point not risen. Bands + . 



R=:29 1 f maximum polarisation in zenith plane. 



1842, October 15— Fine day. Barom. 30'0, rising. 



Apparent Time. 



4 h 32 m R = 29|° maximum polarisation in zen. to 26|° in hor. 



5 



11 



5 



42 



4 



34 



5 



9 



5 



46 



Arago. 



16° 



11' 



18 



18 



Babinet. 



15° 



23' 



17 



28 



Arago. 



18° 



0' 



18 



11 



25 



30! 



Babinet. 



15° 



23' 



17 



26 



20 







1842, October 19.— Barom. 29 3. Cold. 



Apparent Time. 



4 h 56 m 

 5 5 



R = 27-2° maximum polarisation in zenith plane. 



19° 11' 

 20 9 



Babinet. 

 16° 39' 





