on the Planet Venus. 
*55 
which were both wanting in my topographical charts ; and 
about which, therefore, the question might arise, whether they 
were not newly produced ? — I had seen nothing of them with 
my more powerful instruments. Again, on the 6th, I examined 
the part of the surface which he had exactly pointed out, with 
powers 136 and 300 of the 13-feet reflector, and found no- 
thing. The 17th, I looked for them with the 7-feet, in vain. 
I did the same on the 3d February, with 179 of the 25-feet, 
and likewise on the 6th, but found not these craters. Hence 
I might have concluded, with probability, that the learned 
observer had been exposed to some deception ; and perhaps I 
should have been believed. And yet Dr. Olbers was perfectly 
in the right. On the 6th of March, I readily found the largest 
of these two craters, without seeking for it long, and saw it 
uncommonly sharp and clear , with 160 and 280 of the 7-feet 
Schr. It is very nearly as big as a crater which I discovered 
last year, lying also in the plain, between the eastern bounding 
mountains, where they break down ; it is surrounded with a 
broad, and proportionably flatter, annular elevation, of little 
brightness ; it appears to be uncommonly deep, in proportion 
to its breadth ; and if a straight line be conceived, running 
from Picard* towards the middle of the southern boundary 
mountain, which projects inward in the shape of a wedge, it 
lies on this line about ~ distant from Picard. As I have exa- 
mined this tract of the Mare Crisium very often, and under the 
most favourable angles of illumination/)*' in searching for the 
veins of mountains, or the flat mountainous layers to be found 
there, but never perceived the slightest trace of these craters, the 
* See Tab. VI. of the Selenotop. Fragmente. 
t See Tab. XXXIII. XXXIV. and XXXV. of the same work; and § 355 to 3 97. 
X 2 
