164 
VOYAGE FOR THE DISCOVERY. 
1820. 
April. 
Sun. 9, 
to-day, had much of that tendency to arch, which has before been described 
on one or two occasions. Two distinct arches were thus formed this mornino- 
one in the northern, the other in the southern hemisphere of the heavens, 
their altitude in the centre being from 20° to 45°, and joining at each end in 
the E.N.E. and W.S.W. points of the horizon. 
From half-past six till eight A.M., on the 9th, a halo, with parhelia, was 
observed about the sun, similar in every respect to those described on the 
5th. At one P.M. these phenomena re-appeared, together with several others 
of the same nature, which, with Captain Sabine’s assistance, I have endea- 
voured to delineate in the annexed figure. 
t, u, a complete horizontal circle of white light passing through the sun. 
a, a very bright and dazzling parhelion, not prismatic. 
b, c, prismatic parhelia at the intersection of a circle a, b, d, c, whose radius 
was 22|° with the horizontal circle ^, u. 
X, d, V, an arch of an inverted circle, having its centre apparently about 
the zenith. This arch was very strongly tinted with the prismatic colours. 
k, e, 1 . an arch apparently elliptical rather than circular, e being distant 
from the sun 26° ; the part included between x and x was prismatic, the rest 
white. The space included between the two prismatic arches, x 6 v d was 
