400 Proceedings of Royal Society of Edinburgh. [sess. 
with visible light, than the parts nearer to the sun. I think, how- 
ever, that further efforts should be made with the most suitable 
instruments available, before photography has to confess itself 
unable to do for the whole of the Corona what it has already done 
for the greater part of it. 
Plates I., II., III., and IY. have been reproduced from the 
photographs, and show fairly well the general appearance of the 
Corona, though the details are necessarily not so distinct as they 
are in the negatives. 
Plate Y. is a reproduction of a drawing made from the negatives, 
and is intended to show the details of the Corona in stronger 
contrast than they present in the originals. Proofs of this 
drawing have been compared with the negatives, and no detail 
has been discovered which is not found on more than one of them, 
with the exception of a very faint wisp of light which appears to 
emanate obliquely from the south edge of the great west streamer. 
This is to be seen only on the longest exposed negative. The 
outmost extensions of the Corona have also been drawn, as shown 
in this negative. 
