The Motion of the Second Comet Predicted, by the Same Gentleman, Who Predicted That of the Former

relation to the Dew, but after finding the Gnats to be multiplied and the little watry Animals to be much lessened in quantity, and finding great numbers of their empty skins floating on the face of his Dew, He thought he had just reason to persuade himself, the Gnats were by a second Birth produced of those little Animals. That vapouring away great quantities of his putrefied Dew in Glass Basons, and other Earthen glazed Vessels, He did at last obtain, as he remembers, above two pound of Grayish Earth, which when he had washed with more of the same Dew out of all his Basons into one, and vapoured to fiscity, lay in leaves one above another, not unlike to some kind of brown Paper, but very friable. That taking this Earth out, and after he had well ground it on a Marble, and given it a smart Fire, in a coated Retort of Glass, it soon melted and became a Cake in the bottom, when it was cold, and looked as if it had been Salt and Brimstone in a certain proportion melted together; but, as he remembers, was not at all inflammable. This ground again on a Marble, he faith, did turn Spring water of a reddish purple Colour. That by often calcining and filtering this Earth, He did at last extract about two ounces of a fine small white Salt, which, look'd on through a good Microscope, seemed to have Sides and Angles in the same number and figure, as Rochpeeter. The Motion of the Second Comet predicted, by the same Gentleman, who predicted that of the former. Monsieur Auzout, the same Person, that not long since communicated to the World his Ephemerides touching the course of the former Comet, and recommended several Copies of them to the Royal Society, to compare their Observations with his Account, and thereby, either to verify his Predictions, or to shew, wherein they differ, hath lately sent another Ephemerides concerning the Motion of the Second Comet, to the same end, that invited him to send the other. In that Tract he observes, first in General, that this second Comet is contrary to the precedent, almost in all particulars: seeing that the former moved very swift, this, pretty slow; that, against the Order of the signs from East to West, this, following them, from West to East: that, from South to North, this, from North to South, as far as it hath been hitherto, that we hear off, observed: that, on the side opposite to the Sun, this, on the same side: that, having been in its Perigee at the time of its Opposition, this, having been there, out of the time of its Conjunction: where he taketh also notice, that this Comet differs in brightness from the other, as well in its Body, which is far more vivid and distinct, as in its Train, whose splendor is much greater, since it may be seen even with great Telescopes, which were useless in the former, by reason of its dimness. After this he descends to particulars, and informs us, that he began to observe this Comet April the second, and continued for some days following, and that as soon as he had made three or four Observations, he resolved to try again an Ephemerides; but that, having no instruments exact enough, and the Comet being in a place, destitute of Stars, and subject to Refractions, he feared to venture too much upon Observations so near one another, since in such matters a perfect exactness is necessary, and wished to see some precedent Observations to direct him: which having obtained, he thereby verified what he had begun, and resolved to carry on his intended Ephemerides, especially being urged by his Friends, and engaged by his former undertaking, that so it might not be thought a meer hazard, that made him hit in the former; as also, that he might try, whether his Method would succeed as well in slower, as in swifter Comets, and in those, that are near the Sun; as in such as are opposite thereunto, to the end, that men might be advertised of the determination of its use, if it could not serve but in certain particular Cases. He relateth therefore, that he had finish'd this New Ephemerides April the sixth, and put it presently to the Press; in doing of which, he hopes, he hath not disobliged the Publick: seeing that, though we should loose the sight of this Star within a few days, by reason of its approach to the Sun, yet having found, that that it is always to rise before the Sun, and that we may again see it better, when it shall rise betimes, towards the end of May, and in the beginning of June, if the clearness of the Day-break hinder us not; he thought it worth the while to try, whether the truth of this Ephemerides could be proved. He affirms then, that the Line described by this Star resembles hitherto a Great Circle, as it is found in all other Comets in the midst of their Course. He finds the said Circle inclined to the Ecliptique about 26. d. 30', and the Nodes, where it cuts it, towards the beginning of Gemini and Sagittary: that it declines from the Equator about 26. d. and cuts it towards the 11. d. and consequently, that its greatest Latitude hath been towards Pisces, where it must have been March 24. and its greatest Declination, towards the 25. d. of the Equator, where it was to have been April 11. He puts it in its Perigee March 27. about three of the Clock in the Afternoon, when it was about the 15. degrees of Pisces, a little more Westerly than Marchab, or the Wing of Pegasus, and that it was to be in Conjunction with the Sun, April 9. Where yet he noteth, that according to another Calculation, the Perigee was March 27. more towards Night, so that the Comet advances a little more towards the East, and retards towards the West; which not being very sensible in the first days, differs more about the end, and in the beginning; which he leaves to Observation. He calculateth, that the greatest Motion it could make in one day, hath been 4. d. and 8'. or 9'; in one hour, about 10'. and 25". so that its Diurnal Motion is to its least distance from the Earth a little more than as 1. to 14. and its Hourly Motion, as 1. to 330. He wonders, that it hath not been seen sooner; the first Observations that he hath seen, but made by others, being of March 17. Whereas he finds, that it might have been seen since January, at least in the Months of February and March, when it rose at 2 of the Clock and before: because it is very likely, that, considering its bigness and brightness, when it was towards its Perigee, it was visible, since that towards the end of February it was not three times as much remote from the Earth, than when it was in its Perigee, and that towards the end of January it was not five times as much. In the interim, faith he, the other Comet could be seen with the naked eye until January 31, when it was more than ten times further remote, than in its Perigee, although it was not by far so bright, nor its streamer shining as this hath appeared. He wishes, that all the changes that shall fall out in this Comet, might be exactly observ'd; because of its not being swift, and the Motion of the Earth very sensible, unless the Comet be extremely remote, we should find much more light from this, than the former Star, about the Grand Question, whether the Earth moves or not: this Author having all along entertained himself with the hopes, that the Motion of Comets would evince, whether the Earth did move or not; and this very Comet seemed to him to have by design appeared for that end, if it had had more Latitude, and that consequently we might have seen it before Day-break. He wishes also, that, if possible, it may be accurately observed, whether it will not a little decline from its great Circle towards the South; Judging, that some important truth may be thence deduced, as well as if its motion retarded more, than the place of its Perigee (which will be more exactly known when all the passed Observations shall have been obtained) and its greatest Motion doe require. He fears only, that it being then to rise at Break of Day, exact Observations cannot be made of it: but he would, at least have it sought with Telescopes, his Ephemerides directing whereabout it is to be. April 10. it was to be over against the point of the Triangle, and from thence more Southerly by more than two degrees; and April 11. over against the bright Star of Aries: April 17. over against the Stars of the Fly, a little more Southerly, and May 4. it is to be over against the Pleiades, and about the fourth or fifth of the same Month, it is to be once more in Conjunction with the Sun; after which time, the Sun will move from it Eastward, and leave it towards the West; which will enable us to see it again at a better hour, provided the clearness of the Day-break be no impediment to us. He addeth, that this Star must have been the third time in Conjunction with the Sun, about the time when it first began to appear: and foresees, that from all these particulars many considerable consequences may be deduced. It will cut the Ecliptick about the end of July, new Style, a little more Eastwards than the Eye of Taurus: at which time there will be no seeing of it, except it be with a Telescope. It will be towards the End of April, new Style, twice as far distant as it was in its Perigee, thrice as far, May the fourth, four times, May the eighteenth, and five times, June the first, &c. He would not have Men surprized, that there have been two Comets within so short a time; seeing, faith be, there were four, at least, three, in the Year 1618. and in other Years there have been two and more at the same time. What he adds about their signification, we leave to Astrologers to dispute it with him. He concludeth with asking pardon, if he have committed mistakes, which he hopeth he shall obtain the sooner, because of the small time he hath had for these calculations: and he wishes that he could have made all the Observations himself, seeing that it is easy to fail, when one must trust to the Observations of others, whereof we know not the exactness: where he instances, that, according to his Observations, the way of the Comet should go nearer the Ecliptick than he hath marked it, even without having any great regard to the Refractions: but since he would subject himself to others, he hath made it pass a little higher, which, he saith, was almost insensibly so, in those few days that he was observing and writing, but that this may perhaps become sensible hereafter: which if it be so, he affirms that it will cut the Ecliptick and Equator sooner, than he hath marked it, &c. However, he thinks it convenient, to have given beforehand a common Notion of what will become of a Comet, to prepare men for all the Changes that may fall out concerning it: which he affirms he hath endeavoured to do; the rest being easy to correct, as soon as any good Observations, somewhat distant, have been obtained, considering, that there need but two very exact ones, a little distant when the Star is not swift, to trace its Way; although there must be at least three, to find out all the rest. But, then would he have it considered, that although his Method should be very exact, if there be not at hand Instruments big enough, and Globes good enough to trust to, nothing can be done perfectly in these kind of Predictions. A Relation