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on the Atmosphere of Venus. 
nature seems, however, to have raised on the former such great 
inequalities, and mountains of such enormous height, as to ex- 
ceed 4,5, and even 6 times the perpendicular elevation of Cim- 
boraco, the highest of our mountains. Thus are we, by these 
observations, led to a farther contemplation of the immense, 
and yet analogical variety with which the great Author of na- 
ture has dignified his works, as well in the greater objects, 
as in the smallest microscopic atoms ; and the incessant no- 
velty of combinations with which he has adorned them. 
On the Atmosphere of the Moon. 
Referring to my Selenotopographic Fragments for the proofs 
I there adduced of the real existence of a lunar atmosphere, 
which had been so frequently doubted ; I shall also appeal to 
the same work for the observations I formerly made on several 
of its relative properties, compared with the same in our at- 
mosphere, such as its greater dryness, rarity, and clearness, 
which, however, do not prevent its refracting the solar rays, 
having pointed out the circumstance, that the mountains in 
the dark hemisphere of the moon, near its luminous border, 
which are of sufficient height to receive the light of the sun, 
are the more feebly illuminated the more distant they are from 
that border : from which proofs of a refracting atmosphere, I 
also deduced the probability of the existence of a faint twilight, 
which, however, my long series of observations had not yet 
fully evinced. 
As one fortunate discovery often leads to another, I had no 
sooner succeeded in my observations on the twilight of Venus, 
than 1 directed my attention to that of the moon, and applied 
