Atmospherié Phenomena. 315 
Possibly some light may be thrown upon the subject by the so- 
lutions, which may this year be expected, of a problem regarding: 
corone, which was proposed two years ago by a distinguished 
institution on the continent; supported as the arguments pro- 
bably will be, by the recent improvements in the theory of light. 
The inquiry ts doubtless rendered still more perplexing on ac- 
count of the great halo being accompanied, much more frequently 
(according to the observations of Dr. Burney) than is generally 
supposed, by the appearance of parhelia or mock-suns. These 
are most usually situated in the circumference of the great halo, 
at the same height above the horizon as the real sun, and are 
connected with a horizontal beam of white light extending to a 
greater or smaller distance in a direction opposite to the sun. In 
fact, two classes of coincident phenomena are to be accounted. 
for; viz. corone having the sun, or moon, for their common 
centre, and luminous circles or arches parallel to the horizon. 
The former, when observed by reflection from still water, appear 
sometimes very numerous. ‘The latter are of rare occurrence, if 
we may judge from the small number of recorded observations. 
These reflections were elicited by the appearance of a very in- 
teresting combination of such phenomena, which I had the plea- 
sure of witnessing yesterday in the vicinity of this city. The halo 
was very perfect, increasing in brightness towards the summit. 
The sun shone with dazzling brightness through a light stratum 
of vapours. Both parhelia were very bright, coloured on the side 
next the sun, and attended by horizonal trains of ten degrees or 
more in length. But the most beautiful object was a brilliant 
reverted rainbow, about a quarter of a circle in extent, whose 
centre seemed to coincide with the zenith, and its vertex was on 
the sun’s azimuth. ‘The time was about 4 p. m. the barometer 
standing at 304, and the thermometer in a north room at 57°. 
A similar rainbow, in the same position with regard to the 
zenith and the sun, | happened to see at sun-set about eighteen 
months ago, I am Sir, &e. 
Grosvenor-Place, Bath; March 30. W. G. H. 
April \.—Last evening, a little before nine o’clock, I had an 
-opportunity of observing a similar combination of circles about 
the moon, viz. the great halo and a complete horizontal circle of 
white light passing through the apparent place of the moon. 
Both this and the former phenomenon occurred in strata of va- 
pour rapidly passing into the cirrostratus form; and taken in 
connection with the change of weather, from S.W. winds and 
mildness, to N.E, stormy and frost, certainly seem to favour the 
notion alluded to above, which ascribes these appearances to the 
refleeting and refracting powers of frozen vapour. 
Rr2 BIOGRAPHY, 
