$i6 Mr. Schroeter's Observations 
been able to devise any new mode of observing) on the 9th, 
10th, 11th, and 12th of March, upon an observation, which I 
repeatedly confirmed, and which, on account of its singularity, 
and the light it will probably throw on the physical constitu- 
tion of this planet, will certainly be ever thought important ; 
especially as it may not in many years be repeated under so 
favourable a combination of incidents. 
On the 9th of March, 1790, immediately after sun-set, and 
till 6 h 45', I saw Venus with a seven-feet reflector, magnifying 
74,95, and 161 times, very distinctly, and uncommonly splen- 
did. The southern cusp did not appear precisely of its usual 
circular form, but rather as is represented at a, fig. 5, inflected 
in the shape of a hook beyond the luminous semicircle into 
the dark hemisphere of the planet. This, however, after my 
former observations,* w 7 as not new to me : but a far more 
striking phcenomenon, which I had never seen before, excited 
my admiration, and particular attention. The northern cusp 
was terminated at b, in the same narrow tapering manner as 
the southern, but did not extend in its bright luminous state 
into the dark hemisphere. From its point, however, the light 
of which, though gradually fading, was yet of sufficient bright- 
ness, a streak of glimmering bluish light proceeded into the 
dark hemisphere, from b to c, which though intermittent as 
to intensity, was yet permanent as to duration, and although 
very faint, could yet be plainly seen with both the abovemen- 
tioned magnifying powers. Like the luminous line then seen 
on Saturn, its light seemed to twinkle in various detached 
points, and appeared throughout not only very faint, when 
compared with the light at the point of the cusp, but also of 
* See Selen. Fragm. §.523. 
