36 Optical Phenomena of the Atmosphere. {January, 
was visible from the Mersey, at Liverpool, from about 11.50 
till 12.15 at noon, on Wednesday, April roth. (See sketch on 
next page.) It seems to me to bea very unusual form. The 
wind was nearly N. at the time, and the weather cold. As I 
have ventured to maintain that halos and kindred optical 
phenomena generally indicate a transitional state of the 
temperature or of the weather, and not, as is popularly 
supposed, an approaching storm, I draw attention to this 
case aS an important, though by no means isolated, con- 
firmation of the theory. it followed many days of wet, 
and preceded about a week’s dry weather. On referring to 
the sketch it will be seen that an arc of a halo attended the 
mock suns (which were not very brilliant), and that the 
chief peculiarity of the case lay in this—that the mock 
suns were clearly external to the halo, and at a distance of 
1° 30. or 2. The halo showed chiefly a red colour, and the 
parhelia were entirely of a light prismatic blue, very distinct 
from that of the surrounding sky. 
Exactly a week after the last mentioned phenomena were 
seen, a solar halo again occurred about I p.m., Wednesday, 
April 17, and after this the weather grew warmer and the 
sky still clearer. We shall probably not be justified in 
expecting a decided change after every appearance of these 
phenomena, for I have often observed that, in showery and 
changeable weather, two or three solar halos of varying 
degrees of definition will occur on successive days; but for 
several years I have found that, when there is anything very 
singular in the form or combinations of the circles, changes 
of a decided character often follow. 
Upon examining the recorded notices of these appearances, 
we find that there are usually more accounts of lunar than 
of solar halos, yet I have no doubt, from my own observa- 
_ tions, that more solar halos really occur, and that most of 
them are overlooked on account of the dazzling effect of 
the sun’s rays, rendering their observations somewhat 
troublesome to those who have not a strong eyesight. I 
can safely say that in the neighbourhood of Liverpool they 
greatly preponderate in number. Scarcely any change, 
indeed, from wet to fair, as well as from fair to wet, occurs 
without their appearance. Two more years’ observations 
enable me to endorse the statement concerning their 
prognostic value, which I published in spring, 1871.* I 
desire now, however, to draw attention to two peculiarities 
connected with the lunar halo which appear to be of very 
* Nature, March 23, 1871. 
