104 
South West. The illuminated line from the western mock 
moon was not traceable to any distance, nor did a mock moon 
appear in the North, opposite to the moon. The red rays were 
next the moon. The phenomenon was faint and ill-defined ; 
the eastern and upper moons scarcely discernible. It dis- 
appeared in about half an hour after it was first observed. 
‘‘ No observation being taken at these hours at the Mag- 
netic Observatory, there is no record of the phenomenon as 
observed there. But the observer at ten, P.M. has noted as 
follows :—Sky all covered with very fine long cirrostrati, ex- 
tending across the entire sky from North to South. Haze 
visible about the moon. ‘The barometer, at this hour, stood 
at 29.978; the thermometer at 48.4; wet thermometer, 47.1. 
Professor Allman made the following observations on the 
same phenomenon. 
Observed between the hours of 10 and 11 o’clock, P. M., 
on the 21st May, 1845, a thin haze spreading over the sky. 
The arm of the cross which approached more nearly to the 
horizontal was slightly inclined to the horizon, at an angle 
which, as far as the unassisted eye could determine, might 
have been about 15°. The other arm was perpendicular to 
this. The diameter of the circle included within the halo was 
equal to about forty diameters of the moon. At the points 
where the cross, if produced, would have intersected the halo, 
were paraselene. ‘The two lateral paraselene were more con- 
stant in their appearance than the superior, which was visible 
only two or three times during the observation. ‘The lower 
part of the halo was not visible. The moon itself was imme- 
diately surrounded by an ordinary blur-like halo, which was 
more intensely luminous than the cross, and within the mar- 
gins of which it was wholly confined. The extremities of the 
paraselene, which were placed upon the halo, were obscurely 
prismatic ; but I could determine nothing satisfactory as to 
the order of the colours. The arms of the cross were inter- 
