274 



SIR DAVID BREWSTER ON THE 



1842, December 22.— Barom. 29-38, falling. Rain. 



Apparent Time. 

 2 h 43 m 



2 46 



R = 29° maximum polarisation in zenith plane. 



1842, December 23.— Barom. 29-01, after rain. 



Apparent Time. 

 3 h m 



R=30° maximum polarisation in zenith plane. 



1842, December 24.— Barom. 2933. 



Apparent Time. 

 12 h 3 m R = 26^° maximum polarisation in zenith plane. 



E = 28 0- 

 R=27 

 R=29 

 R=27i° 

 R = 29i 



12 



44 



1 



32 



2 



24 



3 



8 



3 



37 



2 



27 



3 



5 



3 



39 



f The point of maximum polarisation rising as the "1 

 \ sun's altitude diminishes. J 



1842, December 26. — Barom. 2888. 



Apparent Time. 



l h 3 m R=26i° maximum polarisation, alt. 30°. 



3 27 



3 30 



R = 28° maximum polarisation in zenith plane. 



Arago. 



17° 50' 



Babinet. 

 16° 10' 



Arago. 

 18° 16' 



Babinet. 

 19° 4' 



Arago. 



15° 28' 



15 



5 



17 



30 



18 



40 



17 



52 



19 



14 



Babinet. 



18° 



28' 



20 



6 



17 



55! 



Arago. 

 16° 25' 



17 



15 



Babinet. 

 17° 40' 



1842, December 27— Barom. 29*35. Sun shining through a dry haze : which 

 continued all day. The lines in the sun's spectrum singularly sharp. 



Apparent Time. 

 Hh 48 m 



12 4 



1 45 



2 35 



3 15 



12 9 



1 50 



2 38 



Arago. 

 R=26J° maximum polarisation in zenith plane. 15° 50' 



{R=23^ maximum polarisation in zenith plane, "1 .._ . 

 141° in horizon. j 17 15 



R=24° maximum polarisation in zenith plane. 20 25 



R=27J° „ „ 21 30 



19 

 Babinet. 

 12° 25' 

 14 40 

 16 5 



R=29| 



1842. December 28.— See " Edinburgh Transactions," vol. xxiii. pp. 219, 226. 

 1842, December 29.— Barom. 2950. Clear in north. 



Apparent Time. 

 11^40™ 

 12 



11 44 



R=26|° maximum polarisation in zenith plane. 1 



Slight clouds. 



R=28J° alt. 50°. Sky clearer. 



J 



Arago. 

 15° 25' 

 15 29 



Babinet. 



17° 49' 



