1 6 o Mr . cock i n’s Account of an 
and the other by Dr. macfait as feen in Scotland (iL A 
third, however, may be met with as obferved at Pamba- 
marca^, in ulloa’s Voyage to South America. 
It is the pleafure of philofophy to attempt fomething 
by way of folution concerning every extraordinary fadt 
which falls under its cognizance : and though it be not 
always fo happy as to produce fatisfadtion, it may at leaft 
fucceed in the way of amufement. Under the influence 
of thefe notions, let us fee what offers refpe<ffing the phi- 
lofophy of the curious appearance before us. 
With regard to the elliptical form of the curve fpaces, 
as it cannot be accounted for from refradtion, I appre- 
hend it is owing to the oblong figure of the obferver’s 
fir ado w, which is very evidently the dark part in the 
middle, and to which* the coloured marginal rings are in 
Tome fort obliged to conform. The bright places aa 
correfpond to an appearance once obferved by Dr. 
smith (d \ and which he very plaufibly attributes to a 
confufed mixture of the principal refiedted beams 
(b) This was feen in an extremely thick fog or mift. The interval cor- 
refpond ing to bb was obferved to confift of colours Similar to, though fainter 
than, thole of dd, 
(c) The apparent diftance is here, placed at. about ten toifes. The vapours 
are faid .to be of a tenuity cognizable by the fight. The gradual change of the 
diameter of the rings is mentioned j as alfo, that they appeared at hrft to be of 
an elliptical figure. 
( d ) See Art. 502. of the remarks at the end of his Optics. 
5 
that 
