Page:Philosophical Transactions - Volume 002.djvu/215

 I was surprised at the same time to find, that the same Motion, which was made from South to North in the inferiour part of the Disk, was on the contrary made from North to South in the superiour part; whence the determination of the Motion may be better taken: For we have no Example of the like motion, except it be in that of the Libration of the Moon.

The next day, at the rising of the Sun, the said bright part was not far from the Section, and distant from the Southern Horn ¼ of the Diameter. When the Sun was 4 degrees high, the lame was scituated near the Section, and remote from the Southern Horn ⅖ of the Diameter. The Sun being high 6 deg. 10 min. it seem'd to have been passed the Center, and that the Section of the Disk did cut the same. The Sun being 7 deg. high, it appeared yet more advanced Northward, together with two obscure Spots seated between the Section and the Circumference, and equally distant from one another, and from each Horn on both sides. And the Sky being very clear, I observ'd the motion of the bright part for 1⅛ hour, which then seem'd to be exactly made from South to North, without any sensible inclination Eastward or Westward. Mean-time I perceiv'd in the motion of the dark Spots so great a Variation, that it cannot be adscribed to any reason in Opticks.

May 10. and 13. before Sun-rising, saw still the bright part near the Center Northward.

Lastly, June 5. and 6. before the rising of the Sun, I saw the same between the Northern Horn and the Center of this Planet, and I noted the same irregular Variation in the obscure Spots. But when Venus began to be further removed from the Earth, it was more difficult to observe these Phænomena.

I shall not presume to declare my sentiment touching these Apparences so boldly, as I did concerning the Spots formerly discover'd in Jupiter and Mars. For those Spots I could very well observe for a whole night together, during the opposition of those Planets to the Sun: I could consider their Motion for the space of several hours; and at last, seeing them return regularly to the same place, I could judge whether they were the same spots or not, and in how much time they