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seemed to be new, for it had never been seen by any previous 
observer, whereas it was still far too conspicuous to be overlooked. 
The moon quickly setting put an end to his observations. 
On the next evening Dr. Klein again turned his telescope on 
this region, but to his surprise the crater-like spot had com- 
pletely disappeared. 
Dr. Klein awaited with impatience an opportunity of ob- 
taining further observations with the view of elucidating this 
mystery. The Fates were unpropitious. A spell of bad weather 
set in, and lunation after lunation went by, and no chances 
were afforded of obtaining additional observations. At last, on 
November 13, a short observation was obtained of this region 
on the second day after sunrise, and an ill-defined dark spot was 
seen in the place of the strange formation, which had looked 
like a deep crater when seen at sunrise. The next day came, 
and the spot had again disappeared. It was evident that it was 
only to be seen for a short time after sunrise, and disappeared 
when the rays of the sun fell more perpendicularly on the sur- 
face. It was again visible on December 13, but only as a dark 
spot, the sun having then risen some 15° above the horizon of 
this part of the moon. 
These observations threw a good deal of additional light on 
the nature of this mysterious strange formation. Dr. Klein 
came to the conclusion that it was a great deep black crater, 
surrounded by a very low wall and sinking deep into the surface. 
It appeared to be elliptical in form, and to be over three miles 
in diameter. At sunrise it seemed to be so conspicuous, that 
Dr. Klein felt certain that had it then existed it could not have 
been overlooked by Schroter, Lohrmann, G-ruithuisen, Madler, 
or Neison, when they had so repeatedly drawn the region. 
Moreover, he was sure from his own observation that it did not 
exist prior to 1876. It was then a new formation. 
To an experienced observer the features presented by this 
crater were not new. They instantly recalled to his mind the 
peculiar crater- like depressions of the far south-west. Far away 
on the south-west quadrant of the moon, in the wild regions 
aroimd Fraunhofer, and near Stihorius, there are known to exist 
a number of deep crater-like formations, with low walls, or even 
without walls, and penetrating with steep sides deep into the lunar 
surface. When seen just after sunrise, when the solar rays fall 
very obliquely on the surface, these formations are seen in the 
form of deep black craters. As the solar altitude slowly in- 
creases and the rays fall less obliquely on the surface, these 
craters grow more indistinct, and take the appearance of dark 
grey or blackish spots with ill-defined borders. Gradually, as 
the solar altitude increases, these spots grow more and more 
indistinct, and two or three days after sunrise they completely 
