294 Sir David Brewster on the Polarization 



1841, April 30. 



Mean time, 

 h m 



2 5 Polarization a maximum in plane of zenith and sun, 



and at 78° 25' from sun. 

 1841, May 6. 



3 30 Polarization, when a maximum, greater in plane of 



zenith and sun than in any other plane. At sunset 

 the difference small. The polarization was greater 

 in the S. horizon than at the same point in the N. 

 horizon, prohably from the sky being there freer 

 from haze. 

 1841, May 8. 



10 10 Polarization, or R, =25|°, and a maximum in plane of 



zenith and sun. In the N.E., at an altitude of 40°, 

 R=14^°, and also much less in S.W. horizon. 

 1841, May 9. 



12 noon. Sky greenish blue. In plane of zenith and sun 

 R= 13f°. At 4 h R = 24f and 22^° in different places, 

 and always greatest where the sky was bluest. 



1841, May 11. 



3 45 p.m. R = 24.}°, and a maximum in plane of zenith and sun. 



In other planes R=22|°. 



L841, May 12. 



10 15 a.m. The sky blue and unusually clear throughout the day. 



Barom. 30*1 in.; therm., 9 h p.m. 48°. 

 R=26y° in plane of zenith and sun and a maximum. 

 In other planes 22^°. 



11 40 „ R= 28^° in plane of zenith and sun. 



21|° in lower planes. 



White clouds; cumuli in motion. 



o 



12 „ R=27| in plane of zenith and sun. 



R=20| near horizon. 

 R=25i? at intermediate points. 

 1 20 p.m. R= 



R=21^ near E. horizon. 



Near the large white cumuli R diminishes. 



o 



4 30 R=30^ in plane of zenith and sun. 



R=25^ in horizon. 



6 R=27| in plane of zenith and sun. 



R=24| in horizon. 



7 10 R=30^ in plane of zenith and sun. 



R=28| in horizon. 

 7 35 R=30| in plane of zenith and sun. 



R=29| in horizon. 

 7 45 R=28| in plane of zenith and sun* 



R=28^ in horizon. 

 See Phil. Mag. vol. xxx. pp. 120, 162 for the places of the 

 neutral points on this day.^ 



