9 
1 877.] Physical Changes upon the Moon's Surface. 
relied on as proving that the subsequent maps and drawings 
of Lohrmann, Beer and Madler, and Schmidt must be en- 
tirely wrong in this point. It is a remarkable circumstance 
that in every other case of a discrepancy between the draw- 
ings of Schroter and Beer and Madler, one alone of the 
above authorities, the drawings of Schroter, have been 
rejected as entirely unworthy of comparison with those of 
Beer and Madler. In this particular instance, however, one 
of the earliest drawings of Schroter, made with his most 
imperfect and least powerful instruments, on an occasion 
when the definition from his own account must have been 
very inferior, has been brought forward to prove the incor- 
rectness of the drawings and micrometric measures of his 
great successors. Now, no selenographer acquainted with 
Schroter’s works will allow that this is permissible. Schro- 
ter’s early drawings are never to be trusted when they differ 
from his successors in the more minute features. Whenever 
a discrepancy exists, it will be found that Lohrmann or Beer 
and Madler are correct, and Schroter wrong. It is true the 
same does not hold with Schroter’s later drawings, and espe- 
cially when he was in possession of his great reflectors of 
13 feet and 26 feet focus respectively ; but this particular 
drawing of Schroter’s is one of his very first. It must also 
be remembered that Schroter did not draw the portion con- 
taining Linne with the same fulness or accuracy as the rest, 
but that, while the western portion is fairly correctly drawn, 
the eastern portion, where Linne should be, is misplaced and 
imperfect. Mr. Birt, our best English selenographer, doubts 
in fact whether this white spot, v, really is meant for Linne, 
and has made out a very strong case for supposing that the 
dark grey spot, g, farther south, really represents Linne as 
seen by Schroter. If this is really the case it entirely 
upsets the view commonly held by astronomers that 
Schroter’s drawing proves no change to have occurred in 
Linne. For Schroter describes this spot g, which was only 
faintly illuminated, from its being near the dark portion 
of the moon, as being very similar to, and probably of 
the same nature as, another smaller formation a little to 
the west of it. Now this smaller formation, r, is really a 
fine distinct crater, Bessel in, about 3 to 3 j miles in diameter 
and 600 or 700 feet in depth. If, then, the spot g is Linne, 
as seen by Schroter, it would have been a large crater, in 
tolerable accordance with the description of Lohrmann and 
Beer and Madler. Further, as Mr. Birt points out in rela- 
tion to the western and best shown portion of the 
drawing of Schroter, g falls exactly into the position which 
Linne should occupy. 
