on the Atmosphere of the Moon. 34,1 
power magnifying 161 times; and had full leisure, and the 
means to examine every thing carefully and repeatedly, and to 
take very accurate measurements. 
Although a just idea of so delicate a phenomenon as this 
crepuscular light cannot possibly be conveyed by a drawing, 
but must be gathered from actual inspection, I have never- 
theless attempted a delineation of it, and of the southern 
and eastern cusps fig. 1 and 2, Tab. VIII. as deduced from 
my measurements, especially at the southern cusp, in hopes 
thereby to render what I have farther to say concerning this 
observation the more intelligible. 
The southern cusp, fig. 1. extended from a to c, with a 
gradually fading but still resplendent solar light, of its usual 
pale yellow colour, and terminated at c with a mountain. 
That this was really the point of the cusp, appears not only 
from the general construction of the falcated segment, which 
was sufficiently narrow even at its beginning a, near which 
it was somewhat disfigured at b by a high mountain ; but also 
from the narrowness of its luminous curve at d e and f, the 
breadth of which seldom exceeded 1", and had a sensible inter- 
ruption so near as d. This curve was throughout, from a to 
c, except where the glare of the solar rays spread some degree 
of light, bordered with the pale ash-colour of the dark hemi- 
sphere, glimmering with the faint light reflected from our earth, 
out of which, however, rose the higher mountains g, h, i, c, 
which were now already illuminated by the sun; and farther 
on, not less than thirty lines, or, according to my usual pro- 
jection, two minutes, distant from the point c, was seen another 
mountain /, which belonged to the high ridge Leibnitz, and 
also received its light immediately from the sun. 
mdccxcii. Y y 
