322 
Proceedings of Royal Society of Edinburgh, [june 20 , 
A and arc B. Two points, P and Q (see fig. 6), were taken, and 
tlieir distances measured from the sun (S) and the mock sun (Z). 
S to Z 
P to Q 
S to Q 
S to P 
Z to Q 
Z to P 
23° 42' 
13° 22' 
24° 8' 
29° 52' 
28° 56' 
19° 34' 
The wings were not arcs of one circle; judging by the use of ring 
of stephanome, their centres of curvature lay about midway between 
the sun and the mock suns on either side. 
One mock sun was seen again at 17 h . 
Radius of red, 22° 0' ; of yellow, 22° 36' ; of blue, 23° 17'. 
March 16, 1887. — At ll 11 two mock suns, with faint trace of white, 
horizontal circle outside of them, seen on apparently perfectly clear 
sky. No trace of 22° halo. Radius of eastern mock sun = 25° 13'. 
April 5, 1887. — At 3 h , double lunar 
corona seen; colours and radii as on 
Colour. Radii. 
Red 2 . . . 4° 13' 
Yellow 2 . . 3° 58' 
Blue 
mar § m * Red* . 
Fog-bow (faint) seen at the same Yellow 1 . 
& x 7 Bluish White 
time. ]) 
May 13, 1887. — At ll h pink-coloured cloud seen with upper 
part under sun, coloured blue, green, and red. Length of cloud 
10 ' 
38' 
= 103°. Breadth = 6° 30'. 
Radius of green (only distinct line of colour) = 12° 36'. 
This cloud vanished suddenly, showing a halo on cirrus much 
higher up. Shortly afterwards the halo got more distinct ; it had 
inside it another ring, as in fig. 7. The outer ring was a distinct 
halo, with red inside and blue outside; radius of red = 22° 12'. 
The inner ring had only a faint tinge of red inside ; radius of this 
red = 17° 54'. By ll h 15 m all had disappeared. 
Coloured clouds were seen again several times during the day, 
and at 1 7 h a solar halo was again observed. The folloAving measure- 
ments were got : — 
Radius of red, 
yellowish green, . 
blue, . 
. 21° 54' and 22° 12' 
. 23° 17' „ 23° 17' 
. 24° 28' „ 24° 13'. 
y> 
