14,0 Mr. Schroeter’s new Observations 
a careless observer. Did not Cassini, Bianchini, and other 
observers, surely not deficient in caution, perceive similar phe- 
nomena, and draw the same conclusion ? 
At 8 h 35', Venus presented not a clear image. She had al- 
ready passed the pleiades about half a degree, and my hope 
of seeing perhaps an occulta tion was frustrated. 
io h 15'. A very instructive observation, by comparison with 
the preceding. Notwithstanding Venus was got near the ho- 
rizon, and had some tremulous motion from the fine vapours, 
the sky being otherwise clear, yet her image was free from 
false light, and sufficiently distinct, with power 160 of the 
7-feet Schr. a reflector which almost never fails me. I was 
quite surprised to perceive most evidently , at the first sight, that 
the abovementioned remarkable phase had changed as remarkably 
within 2 hours 1 5 minutes ; and that , even whilst the instru- 
ment was screwing to its focus, in all parts of the field, the north- 
ern horn a, fig. 12, constantly appeared pointed ; whereas the 
more slender point of the southern horn, b, had vanished, and this 
horn had become rounded, as it was on the 2,6th, 27th, and 28 th 
of February, and the 13th of March. 
Comparing this observation with those I have here named, 
it becomes very remarkable and decisive, by confirming my 
former approximated estimate of the period of rotation. On 
the days just mentioned I had, at the hours noted down, ob- 
served a somewhat similar change in the southern horn, con- 
formably to such a period of rotation ; but had never seen it 
again in all the numerous observations I made since the 13th 
of March, at hours when, according to t ie rotation, it should 
not appear. But now it was seen again at io h 15' in the 
evening. From n b in the forenoon of the 13th of March, to the 
