88 Mr H. Blackadder on Unusual Atmospherical Refraction. 
came more and more obscured, and regained its previous trans- 
parency, as the line bounding its upper surface became elevated. 
At other times, another line gradually receded downwards from 
the former, during which the image of the Isle of May became 
first confused, then gradually divided transversely, and ulti- 
mately double, and very distinct, one of the images being in- 
verted. 
The appearance of the coast of East Lothian underwent in- 
cessant and almost endless transformations ; so that, at this par- 
ticular part, the variations in the density of the lower atmo- 
sphere must have undergone changes not less great than rapid. 
When sailing at some little distance from this part of the coast, 
in the hot season of the year, and early in the morning, when 
the lower atmosphere is occupied by dense mist of milky white- 
ness, this looming of these rocks forms a very beautiful and in- 
teresting spectacle ; their dark colour appearing remarkably 
contrasted with the smooth whiteness of the mist, and serene 
blueness of the cloudless sky, which may sometimes be seen 
when the mist has but a moderate elevation. These rocks then 
appear immensely magnified, while the variety of forms which 
they assume bids defiance to all description ; the most common, 
however, being the double inverted cone variously modified. It 
seems almost unnecessary to remark, that this appearance is ob- 
viously produced by an inverted image, being so formed as to 
give the object and its image the appearance of one continuous 
solid body. 
One cannot but suspect, on seeing appearances similar to those 
described, that the common way of accounting for objects ap- 
pearing magnified through a fog, by referring it to a mental 
deception, is not altogether correct For objects whose height 
or magnitude, and distance, are exactly known, are not only 
seen variously magnified, but their forms often as variously mo- 
dified ; which cannot on such occasions be supposed to proceed 
from any mental deception, or defect of the visual organ. It is 
certain that objects do not always appear magnified when seen 
through a fog, though sometimes a living object, such as a man 
or a horse, appears surrounded by a sort of dark-looking, but 
transparent halo, caused probably by a rarefaction of the con- 
tiguous air by the heat emitted from the central object. The 
