278 SIR DAVID BREWSTER ON THE 



1843, April 19.— Nebulosity in zenith. Clouds round horizon. 



Apparent Time. Arago. 



7 h 30 R = 25|° maximum polarisation in zenith plane. 18° 35' 



Babinet. 

 7 33 19° 0' 



1843, April 28.— Barom. 29*44, after rain. Clear sky after clouds had cleared 

 away. 



Apparent Time. Arago. 



7 h 9 m 20° 23' 



7 40 19 37 



Babinet. 

 7 3 R = 29° maximum polarisation in zenith plane. 16° 46' 



7 44 R = 29 maximum polarisation in zenith, 20 -J ° in hor. 18 



1843, April 29.— See "Edinburgh Transactions," vol. xxiii. pp. 22G-27. 

 1843, April 30.— Barom. 30-07. Morning, and rising. Not a cloud. 



Apparent Time. 



l h m R = 26V maximum polarisation in zenith, 22£° in horizon. 



4 15 R = 26| 



5 43 Secondary neutral point forming. 



Arago. 



6 4 11° 20 



6 52 Rz=29°. maximum polarisation in zenith, 22^° in hor. 19 20 



7 33 R = 29| maximum polarisation in zenith, 22;V in hor. 19 35 

 7 58 19 3 



A brown haze rising up upon the blue sky. See " Edinburgh Transactions," 

 vol. xxiii. p. 231. 



1843, May 2.— Barom. 3007. Wind east; no sun. 



Babinet's neutral point near zenith, and polarised bands scarcely seen, except- 

 ing at 90° from sun. 



1843, May 3.— See " Edinburgh Transactions," vol. xxiii. p. 227. 



Apparent Time. Arago. 



6 h 49 m 18° 26' 



Babinet. 

 6 53 R=30° maximum polarisation in zenith, 27° in hor. 14° 20' 



Very clear in zenith, with a whitish sky. 



1843, May 6.— Wind east ; uniform China-ink clouds over the sky, through 

 which the sun shone brightly, but ill-defined. 



4 h 4 3 m .— Polarised bands distinct over the face of the sun and above him, but 

 exceedingly feeble opposite the sun. 



1843, May 11.— Barom. 30 0. Fine day. 



Apparent Time. Arago. 



2 h 30 m R = 20J° maximum polarisation in zenith plane. 



6 Neutral point not up. 14° 34' 



6 12 R=23|-° maximum polarisation in zenith. 18 15 



Whitish- blue sky. White clouds in horizon. 



