1818.] and their Effects. 371 



8. — Heavy dew and hoar-frost as the preceding' morning : at 

 six, a. m. a dense Cirrostratus formed a fog-bank on Portsdown- 

 hill, about four miles distant ; and on its arriving here at eight 

 o'clock, the hygrometer, which before stood at 75°, went to 80°, 

 notwithstanding a brisk northerly wind : a clear atmosphere the 

 remainder of the morning. P. M. Fleecy and dusky Cumuli, 

 which, being to the westward, at sun-set passed through orange, 

 dark blue, lake, and crimson tints, while the eastern sky exhi- 

 bited a rose colour ; the arched part of it was about 35° in height, 

 with a purple base : this magnificent appearance of the evening 

 Crepusculum, which remained in view an hour after sun-set, was 

 evidently produced by reflection from haze descending rapidly 

 in that quarter, the dew having fallen here copiously soon after- 

 wards : an apparent clear sky through the night. 



9. — Very heavy dew and hoar-frost as the preceding morning ; 

 also a dense Stratus resting on the ground, and large Cirri and 

 Cirrociimuli descending into the lower atmosphere. At 10 

 minutes before eight, a. m. another parhelion appeared 23° 30' to 

 the east of, and parallel with, the sun, on an attenuated Cirro- 

 stratus that was passing slowly in an easterly direction : the 

 south end of this modification did not extend more than 10° 

 beyond the real sun, nor was there any solar halo to be seen ; 

 but a faint one appeared at noon. Hence a parhelion with its 

 natural colours may appear without a solar halo when a cloud is 

 thus situated between the sun and the observer, or when there 

 is not enough vesicular vapour on either side of the sun to create 

 a mock-sun ; and on the other hand, a solar halo 45°, 46°, or 47° 

 in diameter may frequently be seen in a vaporous atmosphere 

 without a parhelion, or parhelia. 



Faint sunshine through attenuated and undulated Cirrostratus, 

 and some distant Cumuli near the horizon till five, p. m. when 

 the wind veered from N.W. to S.W., and the night turned 

 out wet. 



The two subsequent days and nights were very wet, mostly 

 drizzling, till the evening of the latter day (the 11th), when a 

 strong gale with heavy rain came on from the S.W. and closed 

 this change of weather ; and the barometer is now rising to its 

 former level. 



Errata. 



In the middle of p. 235, the article a before beautifully 

 coloured parhelia is superfluous ; and in the second line below, 

 for equidistant from, read equidistant 23° 30' from. 



2a2 



