Another Accompt of the Same Subject, Englished Out of the French Journal Des Scavans, Printed at Paris the 22th of June 1671

cum ferè in ea fuerim opinione, illam vel nunquam, ut plerumque factum fuit, vel tam citè non redituram, ad locum illum haud sapius oculos direxi; nec fieri id quidem poterat, cum hac hyeme, nocturno tempore, circa & infra Horizontem Caput Cygni perpetuo haeret. Cerius interim sum, ad menem Decemb. Januar. imo Februarii haud conspicuam fuisse. Etenim post 14. Octobris, quo visideri desit, memini me eam sapius quaestivisse eo in loco, sed nunquam apparuisse. Idcirco, quantum colligere datur, vix ante initium Martij, quin sine dubio, adhuc tardius iterum prodit. Pridie eam à reliquis quibusdam Fixis sum dimensus. Distat à Cauda Cygni, 20 gr. 55°. 20"; ab ancone Alæ superioris Cygni, 17 gr. 47°. 50"; à Capite vero Serpentarii, 34 gr. 19°. 40"; sic ut eodem planè loco adhuc persit, ubi antea fuerat. De reliquo, mihi persuadeo, cum semel, & quidem intra adeò breve temporis spatium redierit, illam sapius fore invisibilem rursusque conspicuam, cum incremento & decremento, illas, quae in Collo Ceti est, adinflar. Proinde operæ pretium fuerit, cum Philosophiae plurimum intersit scire. An dentur evidentes ejusmodi alterationes in Cælo plures, ut diligentius imposterum ad eam attendamus; possitne certa quaedam Hypothesis de ejus occasu & ortu, decremente item & incremento, à nobis excogitari? Et an singulis annis, ut Stella in Collo Ceti, sub aspectum veniat? An certo anni & omni tempore sub aspectum veniat, pariratione; an vero cum retardatione vel anticipatione aliqua certa? Et denique, an semper æquali magnitudine, simili colore & lumine prodeat, permaneatque? Ego, dante Deo, meam operam hac in parte polliceor; reliqui Uraniae cultores quin idem facturi sint, nullus dubito. Another Accomp of the same Subject. Englished out of the French Journal des Scavans, printed at Paris the 22nd of June 1671. The New Star, which Don Anthelme, a Carthusian of Dyon, hath lately discover'd *, is one of the rarest Appearances observed this good while. As this person contemplated the Heavens at night, June 20th of the last year, desirous to discover that admirable Star, which hath appear'd and disappear'd twice since the beginning of this Century in the Constellation of the the Swan*, he perceived near the same Constellation * which is that in a Star of the Third Magnitude, which he had never yet observed. He presently signified it to the Company which assembleth in the Library of the King: And divers of that Assembly having beheld the Heavens about the end of June and the beginning of July, took notice, that there was indeed about the Beak of the Swan a New Star of the third magnitude, not to be met with in any Catalogue of Astronomers, although many other neighbouring Stars, that are much smaller, be exactly marked by them. It was situate as appears in the following figure*. *See Fig. 2. The Obliquity of the Ecliptick supposed to be $23\frac{1}{2}$ degrees, the Longitude of this Star, according to the Observation of Mr. Picard, was $1^\circ 55'$ of Aquarius. - The right Ascension ———— 293° 33'. - The Boreal Latitude ———— 47° 28'. - And the Declination ———— 26° 33'. It came to the Meridian after the Star in the Beak of the Swan ———— 16' 44"': And before the lucid Star of the Eagle ———— 0° 27'. It was distant from the great Star of the Constellation of Lyra ———— 18° 39' 40". From the Beak of the Swan ———— 3° 47' 30". And from the Tail of the Swan ———— 20° 54' 30". But that which is further remarkable, is, that in the beginning of July this Star was observed to decrease. In the night of July 3d, it appear'd yet of the Third magnitude, but her Light was sensibly fainter. In the night of the 11th of the same month, she scarce appear'd of the Fourth magnitude. In the night of August 10th, she was but of the Fifth. And she hath ever since decreased still, so that at last she became so small that she was seen no more. And so she hath remained for six months without shewing her self, and we could not discover her again till the night of March 17th last, when Don Anthelme spied her in the very same place, where she was the year before, and found, that she was of the Fourth magnitude. The Assembly that meets in the Kings Library, having notice thereof, several of them did observe this Star in the night of the 2d of April last, finding her in the self same place where they had seen her the precedent year. The 3d of the same month M. Cassini found her greater than the two Stars of the Third magnitude that are below in the Constellation of Lyra, but a little smaller than that in the Beak of Cygnus. The 4th of the same month, she appear'd to him almost as great and much more radiant than that of the Beak of the Swan. The 9th of the same, he found her a little diminish't; and almost equal to the greatest of the two Stars that are below in Lyra. The 12th, she was equal to the least of these two Stars. The 15th, he perceived that she encreased, and he found her equal, the second time, to the greatest of these two Stars. From the 16th unto the 27th, she appear'd of different magnitudes, being sometimes equal to the biggest of these two Stars, sometimes equal to the least, and now and then between both. But the 27th and 28th, she was become as big as the Star in the Swan's beak. The 30th, she appear'd a little clearer. And the first six days in May, she was greater. The 15th of May she was seen smaller than the same Star. The 16th, she was in bigness between the two Stars that are below in Lyra: And ever since she hath still diminished. Thus this Star hath been twice in her greatest splendour, first on the 4th of April; and the second time, in the beginning of May: Which we read not to have ever happen'd to any other Star. As far as can be judged from the few Observations made of this Star, 'tis likely she is returning about Ten months unto the same appearance; whereas that in the Whale's Neck maketh its revolution in Eleven months. As for the Star in the Swans Breast, we have as yet no certain knowledge of the period of her revolution; yet yet one may assure, that she taketh no less than Fourteen years to finish it. The Discoveries, that have been made in the Heavens this last age, do evince, that Changes are not so rare there, as formerly was believed. If that was true, what Pliny saith, that Hipparchus, on the occasion of a New Star he perceived, made an Enumeration of all those which appear'd at that time, there would not be any one Constellation, in which some change were not found since that time, in regard there are few, wherein there be not found more Stars now than that Astronomer hath noted in them. But as the little assurance we have of the exactness of Hipparchus his Catalogue giveth us cause to believe, that many Stars, which were not in that Catalogue, were yet in the Heavens; so we may well grant, that some of those, that have been observed since, have not appear'd always. For, not to speak of the Stars, that have been seen in the Constellation of Cassiopea, in the Neck of the Whale, in the Breast of the Swan, and in Serpentarius; Monsieur Cassini hath discover'd many other little ones*, which may very well be presumed to be New. For example, he hath observ'd one of the Fourth magnitude, and two of the Fifth in Cassiopea, where 'tis certain they were not seen before, many Astronomers having exactly reckon'd up the very smallest Stars of that Constellation, and yet not one of them mention'd those three. He hath discover'd Two others, towards the Beginning of the Constellation of Eridanus, where we were sure they were not yet about the end of the Year 1664, considering that this place of the Heavens, where passed the then appearing Comet, was diligently beheld by many, who perceived divers other small Stars, without observing those two. The same hath also observed, towards the Arctic Pole Four of the Fifth or Sixth magnitude, which Astronomers, that always have their Eyes upon that place, would not have failed to note, if they had there appear'd before. Nor are we to wonder at it, that we see now more Stars in the Heavens than there appear'd formerly, seeing there appear'd those formerly, which are seen no more now. For M. Cassini hath observ'd, that the Star, which Bayerus puts near that which he marketh in the Figure of Ursa minor, appears no more; that that, which is marked A in the Figure of Andromeda, is also disappear'd; that in lieu of that, which is marked v, at the knee of the same figure, there are two others more Norward; and that that, which is noted ξ, is very much diminished. The Star, which Tycho placeth at the extremity of Andromeda's Chain, and calls it of the Fourth magnitude, is now so small that one can scarce see it: And that which is in his Catalogue the 20th of the Constellation of Pisces, is now no more seen; unless you will say, that it is gone down lower than four degrees, degrees, to the place marked o in the Figure of Bayerus *. * We cannot omit taking notice here of what was communicated to the R. Society, about the same subject, in a Letter of April 30. 1670. by Signor Montanari, the Learn'd Professor of the Mathematicks in Bologna, in these words: *Malia possem certe novae de Calo Vobis tradere, qua ad multos annos observo, atque Firmamento meo Inflabili ex- armando ad propediem evulgando supposita- vero; sed unum, quod catenis admirabilibus est, proferam. Deunt in Calo duo Stella Secundae Magnitudinis in Puppi Navis e- jus ad Tauritis, Bayero & Co., prope Canem majorem, &c. aliis, occasione praestim Cometa A. 1664. observata & recognita. Earum Dispositionem cui Anno debeam, non movi; hoc indubitum, quod die 10. April. 1668. ne velegium quidem illarum adeisse amplius observo; catenis circa eas, etiam quarta & quinta magnitudinis, immotis Plura de aliarum Stellarum mutationibus, plus quam centenis, at non tanti ponderis annotatis, &c.* New ones: And it is very probable, that with that in the Neck of the Whale, which was not observed at first, but when it was already of the third magnitude; although it hath been since found, that it is not really so great when it begins to appear, but that, being very small in the beginning, it increaseth insensibly until it come to that greatness. However, these Phenomena deserve always to be carefully observed by all Astronomers. An Answer of Dr. Wallis to Mr. Hobbes's Rosetum Geometricum in a Letter to a friend in London, dated July 16. 1671. Clarissime vir, Perlegi Hobbij fave Rosetum, fave Finetum, (nam utrumque olet;) in quo antiquum obtinet: Mirumque est, ut nec sibi in animum inducere posse nec ab amicis suaderi, ne sic delirando persisset se contemptui exponere. Notata quadam hic tibi mitto: non quasi metuerim, te talibus ratiociniis faciui posse, sed ut tu, aliique, quibuscum hæc forte communicaveris, sine anxia consideratione dennò instituendâ, statim videatis ubi potissimum peccatur. Prima Propositionis, five Problematis, constructio (ut ut in re facili) falsa est. Rectam extremâ & mediâ ratione fecare; docuerat Euclides, & demonstraverat, prop. 30. El. 6. (qui & alii haec tenus consenserunt.) Secun- dum quem, postâ rectâ secundâ 1R, erit majus segmentum $\frac{1}{2}R$; adeoque segmentum