An Accompt of the Improvement of Optick Glasses

of the progress of the Studies, Labours, and attempts of the Curious and learned in things of this kind, as of their compleat Discoveries and performances: To the end, that such Productions being clearly and truly communicated, desires after solid and usefull knowledge may be further entertained, ingenious Endeavours and Undertakings cherished, and those, addicted to and conversant in such matters, may be invited and encouraged to search, try, and find out new things, impart their knowledge to one another, and contribute what they can to the Grand design of improving Natural knowledge, and perfecting all Philosophical Arts, and Sciences. All for the Glory of God, the Honour and Advantage of these Kingdoms, and the Universal Good of Mankind. An Accomp of the improvement of Optick Glasses. There came lately from Paris a Relation, concerning the Improvement of Optick Glasses, not long since attempted at Rome by Signor Giuseppe Campani, and by him discoursed of, in a Book, Entituled, Ragguaglio di nuove Osservazioni, lately printed in the said City, but not yet transmitted into these parts; wherein these following particulars, according to the Intelligence, which was sent hither, are contained. The first regardeth the excellency of the long Telescopes, made by the said Campani, who pretends to have found a way to work great Optick Glasses with a Turne-tool, without any Mould: And whereas hitherto it hath been found by Experience, that small Glasses are in proportion better to see upon the Earth, than the great ones; that Author affirms, that his are equally good for the Earth, and for making Observations in the Heavens. Besides, he useth three Eye-Glasses for his great Telescopes, without finding any Iris, or such Rain-bow colours, as do usually appear in ordinary Glasses, and prove an impediment to Observations. The Second, concerns the Circle of Saturn, in which he hath observed nothing, but what confirms Monsieur Christian Huygens de Zulichem his Systeme of that Planet, published by that worthy Gentleman in the year, 1659. The Third, respects Jupiter, wherein Campani affirms he hath observed by the goodness of his Glasses, certain protuberancies and inequalities, much greater than those that have been seen therein hitherto. He addeth, that he is now observing, whether those fallies in the said Planet do not change their situation, which if they should be found to do, he judgeth, that Jupiter might then be said to turn upon his Axes; which, in his opinion, would serve much to confirm the opinion of Copernicus. Besides this, he affirms, he hath remarked in the Belts of Jupiter, the shadows of his satellites, and followed them, and at length seen them emerge out of his Disk. A Spot in one of the Belts of Jupiter. The Ingenious Mr. Hook did, some months since, intimate to a friend of his, that he had, with an excellent twelve foot Telescope, observed, some days before, he than spoke of it, (videl. on the ninth of May, 1664. about 9 of the clock at night) a small Spot in the biggest of the 3 obscurest Belts of Jupiter, and that, observing it from time to time, he found, that within 2 hours after, the said Spot had moved from East to West, about half the length of the Diameter of Jupiter. The Motion of the late Comet predicted. There was lately sent to one of the Secretaries of the Royal Society a Packet, containing some Copies of a Printed Paper, Entituled, The Ephemerides of the Comet, made by the same Person, that sent it, called Monsieur Auxout, a French Gentleman of no ordinary Merit and Learning, who desired, that a couple of them might be recommended to the said Society, and one to their President, and another to his Highness Prince Rupert, and the rest to some other Persons, nominated by him in a Letter that accompanied this present, and known abroad for their singular abilities and knowledge in Philosophical Matters. The end of the Communication of this Paper was, That, the motion of the Comet, that hath lately appeared, having been predicted by the said Monsieur Aux-