170 Mr. Schroeter/s new Observations 
such indistinctness, that we never can distinguish , as we do in the 
moon, a projection of the land on the surface of the planet , nor even 
the shadows cast by its mountainous inequalities, unless it be under a 
combination of every favourable circumstance, a?id even then only 
in a faint undefined manner. This will be more readily appre- 
hended, when we consider, that the shadows on Verms must 
appear, from the density of her atmosphere, and its reflection 
and refraction of light, only dark-grey, like those on the earth, 
and not black, as they are on the moon. 
4. Yet, in the same manner as in the moon, we discern in 
Venus, even under the most favourable circumstances, only 
those parts of her surface, which lie nearest to the boundary 
of illumination, at the time when we see her half enlightened, 
because then we look, in a shorter line, perpendicularly through 
her atmosphere, and moreover the reflection and refraction are 
much less injurious, and the shadows are longest. Only at 
such times, and when the atmosphere is likewise clear over 
such parts of her surface, can we see these shadows, which do 
not appear sharply terminated, but like a faint mixture of 
greyish shade and light, sensible enough, but not clear. 
5. Granting this rational theory, so conformable at least 
to our experience on this earth, and to analogy, all the phe- 
nomena I have pointed out are very easily and clearly ex- 
plained by it ; and this experience shews at the same time 
the justness of the theory, and that it cannot well be other- 
wise. 
Thus we can naturally account for, 
( a ) The soft mixture of light and shade, to be seen only 
near the time of the greatest elongations, yet not always, but 
only sometimes , and at those moments alone when the atmo- 
