POLARISATION OF THE ATMOSPHERE. 



253 



Sun set. Haze in S.E. 



R = 28J° through zenith, and 26£° 



R=28£ through zenith, and in 



horizon. 

 Haze continued. 



in horizon. 



S. and N. 



Arago. 



17° 20' 



21 39 



22 12 



1841, June 8.— Barom. 30. Fine day. 



Mean Time. 

 ll h 40 m 



5 

 10 

 30 

 45 



50* 



K = 21i c 

 Rr=29j- 

 R=26i 

 = 28J 



R 



through zenith, 

 through zenith, 

 through zenith. 



R=19°in W. horizon. 



R = 27° 30' from N.E. horizon. 

 45° above N.E. horizon. 

 Babinet's neutral point and the neutral hyperbolic line clearly seen. 

 R=20° to 24° as the sky was more or less clear. 



At this hour the curious phenomenon shown in the annexed figure was 

 seen, two hyperbolic neutral lines meet- 

 ing in the sun. 



Mean Time. 



6 h 



7 

 8 

 9 

 9 



42m 



50 



28 



10 



30 



Babinet's N. Point 

 above sun. 

 13° 24' 



m.+ 



26 

 15 

 20 

 15 



37 



16 



24 









+ 



Fig. 2. 



Mean Time. 

 6 h 45™ 



Arago. 



30 

 35 

 20 

 23 

 10 

 30 



R = 27J° maximum polarisation. 

 R=24i° in S.W. horizon. 



Faint clouds near. 



19° 

 20 



21 

 22 

 23 



50' 

 25 



10 



6 



41 



1841, June 9— Barom. 209. Fine day ; mackerel-sky occasionally. 



Fine pure sky. R=25£° in N. horizon. 



Mean Time. 

 3 h 55"i 



Babinet. 

 5° 0' 



R = 26J° + in zenith and horizon. 



Fine cirri above the sun. 

 R=28|° in zenith and horizon. 



Antisolar point below horizon. 



At 8 h 40 m clouds suddenly covered the whole horizon. 



* See Edin. Trans, vol. xxiii. p. 221. 



f During the preceding quarter of an hour a stratum of cirri surrounded the neutral point, 



and was just absorbed, when the observation was made. 



