172 Mr. Schroeter's new Observations 
not lying in the shade, to assume the appearance of dark 
spots. This accident, however, of which indeed I have no 
sufficiently certain experience, must occur but seldom, be- 
cause 1 have hitherto perceived the mixture of shade and in- 
dentation only at the boundary of light; and it would not be 
easily explained, why those dark places should not be perceived 
further in upon the enlightened parts , unless they were true sha- 
dows of mountains, and not barely atmospherical appearances. 
Thus at least is every thing to be explained very naturally ; 
and if the phasnomena themselves are put out of all doubt by 
me and others, they confirm the propositions delivered above. 
And equally insignificant appears to me also, the doubt which 
6 . A phenomenon might raise, that occurred to my oppo- 
nent only or chiefly in April of last year: the same, as may 
easily be supposed, was seen by me many years ago, but es- 
pecially in 1790, and frequently since ; though, not thinking 
it particularly instructive or remarkable, I forgot to deliver it 
separately in my paper “ on the atmospheres of Venus and the 
moon.” 
The phenomenon in question, according to my older obser- 
vations, consists in this ; that the external edge, for a very 
small breadth, appears incomparably brighter than the rest of 
the enlightened part, nearer to the boundary of^ light; and 
forms a much brighter small border, which is sharply termi- 
nated at its outer edge, but on its inner side appears without 
any sharp boundary, losing itself in the weak light of the rest 
of the illuminated part ; so that in general, the falling off, or 
gradual diminution, of the light toward the line bounding the 
illumination, is perceived according to the photometrical laws, but 
particularly becomes chiefly striking nearer to the boundary of light . 
