320 
Mr. Schroeter's Observations 
1. That the faint streak at the northern cusp, as represented 
in its projection, fig. 3. extended at least 8" of a degree along 
the limb of the dark hemisphere. 
2. That the prolongation of the southern cusp measured 
likewise full 8", its inflected hooked form appearing now very 
distinctly : and, 
3. That the apparent diameter of Venus subtended an angle 
of between 59 and 60". 
Had it not been for these very favourable observations from 
the 9th to the 12th of March, 1790, which evinced, beyond a 
possibility of doubt, that the illuminated limb of Venus actually 
exceeds the semicircle, I should, perhaps, never have arrived 
at the important cosmological discovery it led to ; the days 
preceding them being too hazy, and those following, though 
somewhat clearer, yet too near the inferior conjunction of the , 
planet to admit of fair observations. On the 17th, and on the 
18th, when the conjunction took place at 4 P. M. the sky was 
cloudy. From the 21st to the 25th, as also on the 30th of 
March, the 1st, 7th, 8th, and 21st of April, the mornings about 
five o'clock were indeed sufficiently clear, and it may easily be 
imagined, that, considering the importance of the discovery, I 
did not fail to avail myself of them ; but the northern decli- 
nation of the planet had now decreased too much, and on the 
other hand, the twilight in our latitude was become too great 
i' 
to see distinctly and with certainty what I had observed before. 
I had no doubt, at times, of the prolongation of either cusp 
into the dark hemisphere ; but circumstanced as the objects 
were, I was much upon my guard against visual deceptions. 
My journal, however, supplies me with the following ap- 
pearances : 
