I did found my Hypothesis upon three Observations only, viz. those of the 22, 26, and 31. of December. Nor have I done, as some have fancied of me, who having been able to observe the Comet, the 27, 28, 29, 30, and 31. of December, and to see the diminution of its motion, have judged, that I had only determined that diminution for the time to come, conform to the augmentation thereof in time passed until the 29. of December. For January 1. (on which day I composed my Ephemerides) I knew not (nor any person here) that the motion of the Comet did diminish; but on the contrary, most men believed, it was not the same Comet. But Signior Cassini knows very well, that that was not necessary, seeing that two portions of a Tangent being given, and the Angles answering thereunto, 'tis easie to find the position and magnitude of its Circle. The reason, which I think the true one, of the diminution of its Motion in Longitude, and of its Retrogradation, by me conjectured in my Ephemerides, I began to be assured of, Febr. 10. For until the sixth, the Comet had alwaies advanced, as Signior Cassini also hath very well noted: but after that day, I found that it returned in augmenting alwaies its Latitude. And I have constantly observed it, until March 8. between many Stars, which must be the same with these mentioned by Cassini, whereof the number was so great, that I think, I saw of them March 6. with one Aperture of my Glass, more than 40. or 50. and especially, above the head of Aries; but I did not particularly note the scituation of more than 12. or 15; amongst which I have observed the position of the Comet since January 28. every day, when the weather did permit, viz. January 29. February 3, 6, 10, 17, 19, 24, 26, 27. and March 6,
7, 8. I left it on March 8. at the 18. of the Horn of Aries, almost in the same latitude: and I am apt to believe, it will be Eclipsed, which I wish I may be able to observe this evening, if it be not already passed.
If Signior Cassini hath observed it on those daies that I have, he will be glad to find the conformity of our Observations. I shall only add, that on February 3. we were surprized, to see the Comet again much brighter than ordinary, and with a considerable Train. Some did believe, that it approach'd again to us. But having beheld it with a Telescope, I soon said, that it was joyned with two small Stars, whereof one was pretty bright, which I had already seen, on February 28. and 29. And this conjunction gave the Comet that brightness, as it happens to most of the Stars of the fifth and sixth magnitude, where 2. or 3. or more are conjoyned, which perhaps would shew but faintly single, though by reason of their proximity to one another, they appear but one Star. Hence it was, that I assured my friends here, that the following daies we should no more see it so bright, because I knew, that there were none such small bright Stars in the way, which by my former observations I conjectured it was to move.
An Observation imparted to the Noble Mr. Boyle, by Mr. David Thomas, touching some particulars further considerable in the Monster mentioned in the first Papers of these Philosophical Transactions.
Upon the strictest inquiry, I find by one, that saw the Monstrous Calf and stone, within four hours after it was cut out of the Cows belly, that the Breast of the Calf was not stony (as I wrote) but that the skin of the Breast and between the Legs and of the Neck (which parts lay on the smaller end of the stone) was very much thicker, than on any other part, and that the Feet of the Calf were so parted as to be like the Claws of a Dog. The stone I have since seen; it is bigger at one end
than the other; of no plain Superficies, but full of little cavities. The stone, when broken, is full of small peble stones of an Ovall figure: its colour is gray like free-stone, but intermixt with veins of yellow and black. A part of it I have begg'd of Dr. Haughten for you, which I have sent to Oxford, whither a more exact account will be conveyed by the same person.
Extract of a Letter, lately written from Venice by the Learned Doctor Walter Pope, to the Reverend Dean of Rippon, Doctor John Wilkins, concerning the Mines of Mercury in Friuli; and a way of producing Wind by the fall of Water.
The mines of Mercury in Friuli, a Territory belonging to the Venetians, are about a days Journey and a half distant from Goritia Northwards, at a place call'd Idria, scituated in a Valley of the Julian Alps. They have been, as I am inform'd, these 160. years in the possession of the Emperor, and all the Inhabitants speak the Sclavonian Tongue. In going thither, we travell'd several hours in the best Wood I ever saw before or since, being very full of Firrs, Oakes, and Beeches, of an extraordinary thickness, straitness, and height. The Town is built, as usually Towns in the Alps are, all of wood, the Church only excepted, and another House wherein the Overseer liveth. When I was there, in August last, the Valley, and the Mountains too, out of which the Mercury was dug, were of as pleasant a verdure, as if it had been in the midst of Spring, which they there attribute to the moistness of the Mercury; how truly, I dispute not. That Mine, which we went into, the best and greatest of them all, was dedicated to Saint Barbara, as the other Mines are to other Saints, the depth of it was 125. paces, every pace of that Country being, as they inform'd us, more than 5 of our Feet. There are two ways down to it; the shortest perpendicular way is that, whereby they bring up the Mineral in great Buckets, and