Page:Philosophical Transactions - Volume 001.djvu/181

 which we see in swimming, &c.) And I have never found it lower than in high Winds.*

I have divers times, upon discerning my Quicksilver to fall without any visible cause at home, looked abroads and found (by the appearance of broken Clouds, or otherwise) that it had rained not far off though not with us: Whereupon, the Air being then lightened, our heavier Air (where it rained not) may have, in part, discharged itself on that lighter.

Since the publishing of of these Transactions, where, among other particulars, some short Observations were set down touching both the shadow of one of Jupiter's Satellits, passing over his Body, and that Permanent Spot, which manifests the Conversion of that Planet about his own Axis; there is come to hand an Extract of that Letter, which was written from Rome, about those Discoveries, containing an ample and particular Relation of them, as they were made by the Learned Cassini, Professor of Astronomy in the University of Bononia. That Extract, as it is found in the French Journal de Scavans of Febr. 22. 1666. we thus English.

Monsieur Cassini, after he had discovered (by the means of those Excellent Glasses of 50 palmes, or 35. feet, made by M. Campani) the Shadows, cast by the 4 Moons or Satellits of Jupiter upon his Diske, when they happen to be between the Sun and Him; after he had also distinguished their Bodies upon the Diske of Jupiter; made the last year some Prædictions for the Months of August and September, noting the dayes and hours, when the Bodies of the said Satellits and their shadows should appear upon Jupiter, to the end that the Curious might be convinced of this matter by their own Observations.

Some of these Prædictions have been verified not only at Rome, and in other places of Italy, but also at Paris by M. Auzout, the most Celebrated and the most Exact of our Astronomers; and in Holland, by M. Hugens. And we can now doubt no longer, of the rotation of the Satellits about Jupiter, as the Moon turns about the Earth; nor believe, that Jupiter or his Attendants have any other Light, than that, which they receive from the Sun; as some did Rh