40 Dr. Herschei/s Account of the 
time of their beginning to appear, when I saw them first, 
might be one or two seconds past. 
9 h 5'- 7-feet reflector; power 287. The internal, luminous 
angle made on the sun, by the intersection of the limb of the 
moon, which is now but little more than a rectangle, is per- 
fectly sharp up to the very point. It is not in the least disfi- 
gured by the refraction of the lunar atmosphere. The present 
shape of the angle, however, is not favourable for shewing the 
effects of that atmosphere. 
9 h if. The luminous angles of the sun J s preceding and fol- 
lowing limbs, which are now acute, remain perfectly sharp. 
One of them, indeed, was disfigured, a little while ago, by the 
entrance of a mountain of the moon, but is now restored to its 
sharpness. 
io h 5'. I delineated the appearance of the limb of the moon 
upon the sun, and found its mountains as in fig. 2. At a was a 
large table mountain, as it may be called, from its flat appear- 
ance ; at b and c were elevated, pointed rocks. Their ap- 
pearance changing pretty fast, no great accuracy can be ex- 
pected in their expressed relative situation. 
I suppose the height of the most elevated of these moun- 
tains not to exceed a mile and an half ; for, on drawing seve- 
ral of them upon the segment of a large circle, so as to look 
like what they appeared when projected upon the sun, I found 
them to be from the ^oodth to the 200odth part of the dia- 
meter of that circle. Then, putting the moon s diameter, as 
M. de la Lanoe states it, at 782 French leagues, or 2151 
English miles, we find the i^oodth part of this to be less than 
one mile and an half for the highest ; and the 200odth part, 
not quite one mile £Uid a tenth for the lowest,, 
