ON THE POLARISATION OF THE ATMOSPHERE. 



219 



1842, November 20.— Barom. 2974. Cold and clear. 



Apparent 



Time. 



lOh 



8m 



A.M. 



10 



15 



)) 



10 



27 



5> 



10 



39 



JJ 



10 



55 



)J 



R=iMaximum Polarisation. Height of Neutral Point above 



In Zeiiithi, In Horizon. the Antisolar Point. 



2ir 



11 



Neutral point lingering in the horizon. 



18° 



5' 



17 



30 



16 



25 



45 



15 



15 



5 



1842, November 21. — Barom. 2977 ; therm. 31°. Frosty morning. 



R=Maximum Polarisation 



Apparent Time. 





IX iVlKlAlUlUlU r 



In Zenith. 



jittiiaaLiuu. 

 In Horizon. 



the Antisolar Point. 



9^ 1™ A.M. 





... 



... 



21° 10' 



9 13 „ 





26r 



i9r 



20 25 



11 4 „ 





• • • 



... 



15 45 



12 22 P.M. 



Neutral 



point below land horizon ; bands 



scarcely visible in horizon. 



12 43 „ 



Neutral 



point in horizon. 







1 40 „ 









16 30 



The decrease in these numbers as the sun's altitude increased is very interest- 

 ing. The light of the sky was increasing till noon, whereas, when the numbers 

 increase, the light of the sky diminishes. 



The observations on the 14th, 20th, and 21st Nov. were the only morning 

 ones I made. 



1842, December 28.— Barom. 29 56. Sky very fine at 11"^ 38'°. 



K=Maximum Polarisation. 

 In Zenith. In Horizon. 



App 



arent Time 



11"^ 



SS'" 



P.M. 



11 



68 



)> 



1 







A.M. 



1 



28 



)) 



2 



33 



n 



29° 

 27 



IH 



18* 



ight of Neutral Point above 



the Antisolar Point. 



17° 



20' 



17 



21 



18 



25 



22 



16 



22 



15 



See in p. 237 the state of Babinet's neutral point at this date, when a halo of 

 45" encircled the sun. 



1843, February 2. — Barom. 29*05. Snow storm with wind. 



Apparent Time. 



9^ 55™ A.M. 



R^Maximura Polarisation. 

 In Zenith. In Horizon. 



24r 17i° 



Height of Neutral Point above 

 the Antisolar Point. 



Polarisation of the sun's light by the snow hardly perceptible, whether we 

 look towards or from the sun. 

 2 5 P.M. Neutral point in sea horizon. ... 12° 5' 



2 47 „ 26-h 19J 14 35 



1843, February 14. — Barom. 29-45. Bitter cold day ; frost in the morning. 



Apparent Time. t rz -.i, t tt • 



"^^ In Zenith. In Horizon. 



2** 48™ A.M. Neutral point below horizon. 



2 53 „ |^?*-.PM.28i 23^ 



|^^,"*-.P^-l28j 

 [ m horizon j 



the Antisolar Point. 



12° 5' 

 11 45 



VOL. XXIII. PART II. 



3p 



