HEVELIUS, or HOEVELKE, JOHN, a celebrated Polish astronomer, was born at Dantzic on the 28th January 1611, and was the son of a brewer of that city. After studying mathematics under Peter Cruger, he travelled through Ilolland, Germany, England, and France, between the years 1630 and 1634 ; and upon his return to his native place, he was principally employed in the affairs of the republic of Dantzic, of which he was made consul in 1651. About the year 1660, by the advice of his former master, he devoted himself wholly to the study of astronomy. In the year 1641, he built an observatory at his own expense, and fur nished it with excellent telescopes and graduated instru ments, which he constructed with his own hands. With these instruments, which consisted of a sexant, a quadrant 6i feet radius, and very large telescopes, he made numer ous observations, the result of which appeared at Dantzic in the year 1647, in his work entitled 44 Selenographia, sive Lunge descriptio, atque accurata, tam maculorum ejus, quam motuum diversorum, aliarumque omnium vicissitudi num pliasiumque telescopii ope deprehensarum, delineatio: in qua simul cxterortim omnium planetarum nativa facies, varixque observationes, presertint autem macularum so larium et jovialium tubo specillo acquisitx, figuris sub aspecturn ponuntur ; necnon quail plurimae astronomicx, optica2, physi..xque quxstiones resolvuntur. Addita est nova ratio lentes expoliendi, telescopia construendi, et ho rum adminiculo varias observationes exquisite histituendi." In 1650, he published an epistle to his friend Eichsiad, on the eclipse of the sun, on Nov. 4th, 1649 ; and in 1652, appeared another epistle on the solar eclipse, addressed to Gassendi and Bullialdus.
About this time, Hevelius made the important discovery of the moon's libration, of which he gave an account in a letter to Riccioli, which was published in 1654, and entitled De niotu Lunx libratorio in certas tabulas redact°. Li 1656 he published his Dissertatio de Native Saturizifacie,ejusque variis phasibvs, certa period° redeuntibus cui addita est _Eclipsis Solis anni 1656, observatio et diametri solus appa• rentis accurate diozensio.
In 1661, Hevelius had the good fortune to observe the transit of Mercury on the sun's disc : and in 1662, he pub lished his observations, entitled ‘, Alercurius in sole virus :Irmo 1661, cum aliis quibusdant rcrum ccelestium observa tionibus, rarisque phenomenis ; cui annexa est Venus in sole pariter visa 1639, Liverpolix a Jeremia Ho•roxio, nuns primurn edita, notisquc illustrata. Accedit succincta
historiola nova; ac mii stellie in collo Ceti certis anni temporibus Clare achnodum effulgentis, rarsus oinnine eva nescentis ; necnon genuina clelineatio paraselenarum et par heliorunt* quorundam rarissimorum." The reputation of Hevelius was now so great, that the illustrious Colbert recommended him to the notice of Louis XIV. who granted him a pension. A copy of the letter, in which Colbert announced this act of liberality to Heveli us, is preserved in the Royal Library at Paris. Hevelius chewed his gratitude by dedicating to Colbert his " Prodro mus Cometicus, quo Historia Cometx anno 1664 exorti cursum, faciesque diversas capitis ac caudx accurate de lineatas complectens, necnon dissertatio de cometarurn om nium motu, generatione variisque phcnomenis exhibetur," -Dant:. 1665. A supplement to this work appeared in 1666, entitled " Descriptio Comets anno 1665, exorti cum genuinis obserrationibus tam nudis quail enodatis mense Aprili habitis ; cui addita est mantissa Prodromi Cometici, observationes (mines prioris Cometx 1664, ex iisque ge nuinum motum accurate deductum, cum notis ct animad versionibus, exhibens." In the year 1668, he published in folio, his great work on comets, under the title of 44 Cometographia, totam na turam Cometarum, utpote sedem, parallaxes, distantias, orttnn et interitum, capitum caudarumque diversas facies, affectionesque, necnon motum cornm summe admirandurn, beneficio unius, ejusque fixre et convenientis hypotheseos, exhibens ; in qua universa insuper phenomena, question esque de cometis omnes rationibus evidentibus deducuntur, demonstrantur, ac iconibus a ri incisis plurimus illustran tur ; cumprimis vero Cometx annorum 1652, 1661, 1664, 1665, ab ipso auctore stunmo studio observati.—Accessit omnium Cometarum, a mundo condito hue usque, ab his toricis philosophis et astronomis annotatorum, historia, no tis et annotationibus locupletata, cum peculiari tabula Co metarum Universali." When this work was completed, Hevelius sent a copy of it to Dr Hooke, and to other distinguished members of the Royal Society. In return for this work, Dr Hooke presented Hevelius with a Description of the Dioptric Telescope, and the method of using it ; and recommended it as preferable to the use of plain sights in astronomical instruments. In this way commenced the celebrated con troversy respecting the use of plain and telescopic sights.