318 Dr. Herschel's Observations to investigate , &c. 
conclude, by adding, that this prediction ought not to be relied 
on by any one, with more confidence than the arguments which 
have been brought forwards in this Paper may appear to deserve. 
EXPLANATION OF THE ISt, 2d, llth and l£th FIGURES. 
See Plates XVIII. and XIX. 
Plate XVIII. Fig. i, represents an opening in the luminous 
solar clouds, with its surrounding shallow, in a situation much 
past the centre, towards the preceding limb of the sun. The 
lines marked with the letters a> b, c, d, e,f, answer to those which 
are marked with the same letters in Fig. 2. 
Figure 2, is a section of the same opening. The lines a, b, c , 
d, e,f, are supposed to be drawn from the eye of the observer. 
a and b point out the elevation of the corrugations g, h, on the 
preceding side P, above the surface of the shallow i, k. c and d 
shew the thickness of the shallow ; and the line d goes through 
the opening, down into the clear atmospheric space P F, till it 
meets with the opaque surface of the sun A B. On the following 
side F, the thickness of the shallow and elevation of the corru- 
gations cannot be seen ; since the line e goes abruptly into the 
opening; and / goes, as abruptly, from the top of the corruga- 
tions, down to the shallow. 
Plate XIX. Fig. 11, shews a section of the corrugations, shal- 
low, and opening, of Fig. 10, in the same manner as Fig. 2 
represents those of Fig. 1. There is a hanging cloud a , in 
Fig. 11, over the preceding part of the opening ; and the same 
cloud is represented at b, in Fig. 12, to which place it was seen 
to move from its former situation, in 58 minutes of time. 
The rest of the figures are sufficiently explained in the places 
of the text which refer to them. 
