COPERNICUS (or KOPPERNIGK), NICOLAUS (1473-1543)  , Polish astronomer, was born on the 19th of February 1493, at Thorn in Prussian Poland, where his father, a native of Cracow, had settled as a wholesale trader . His mother, Barbara Watzelrode, belonged to a family of high mercantile and civic standing . After the death of his father in 1483, Nicolaus was virtually adopted by his uncle Lucas Watzelrode, later (in 1489) bishop of Ermeland . Placed at the university of Cracow in 1491, he devoted himself, during three years, to mathematical science under Albert Brudzewski (1445-1497), and incidentally acquired some skill in painting . At the age of twenty-three he repaired to Bologna, and there varied his studies of canon law by attending the astronomical lectures of Domenico Maria Novara (1454-1504) . At Rome, in the Jubilee year 1500, he himself lectured with applause; but having been nominated in 1497 canon. of the cathedral of Frauenburg, he recrossed the Alps in 1501 with the purpose of obtaining further leave of absence for the completion of his academic career . Late in the same year, accordingly, he entered the medical school of Padua, where he remained until 1505, having taken meanwhile a doctor's degree in- canon law at Ferrara on the 31st of May 1503 . After his return to his native country he resided at the episcopal palace of Heilsberg as his uncle's physician until the latter's death on the 29th of March 1512 . He then retired to Frauenburg, and vigorously attended to his capitular duties . He never took orders, but acted continually as the representative of the chapter under harassing conditions, administrative and political; he was besides commissary of the diocese of Ermeland; his medical skill, always at the service of the poor, was frequently in demand by the rich; and he laid a scheme for the reform of the currency before the Diet of Graudenz in 1522 . Yet he found time, amid these multifarious occupations, to elaborate an entirely new system of astronomy, by the adoption of which man's outlook on the universe was fundamentally changed . The main lines of his great work were laid down at Heilsberg; at Frauenburg, from 1513, he sought, with scanty instrumental means, to test by observation the truth of the views it embodied (see ASTRONOMY: History) .

His dissatisfaction with Ptolemaic doctrines was of

early date; and he returned from Italy, where so-called Pythagorean opinions were then freely discussed, in strong and irrevocable possession of the heliocentric theory . The epoch-making treatise in which it was set forth, virtually finished in 1530, began to be known through the circulation in manuscript of a Commentariolus, or brief popular account of its purport written by Copernicus in that year . Johann Albrecht Widmanstadt lectured upon it in Rome; Clement VII. approved, and Cardinal Schonberg transmitted to the author a formal demand for full publication . But his assent to this was only extracted from him in 1540 by the importunities of his friends, especially of his enthusiastic disciple George Joachim Rheticus (1514-1576), who printed, in the Narratio prima (Danzig, 1540), a preliminary account of the Copernican theory, and simultaneously sent to the press at Nuremberg his master's complete exposition of it in the treatise entitled De revolutionibus orbium coelestium (1543) . But the first printed copy reached Frauenburg barely in time to be laid on the writer's death-bed . Copernicus was seized with apoplexy and paralysis towards the close of 1542, and died on the 24th of May 1543, happily unconscious that the fine Epistle, in which he had dedicated his life's work to Paul III., was marred of its effect by an anonymous -preface, slipt in by Andreas Osiander (1498-1552), with a view to disarming prejudice by insisting upon the purely hypothetical character of the reasonings it introduced . The trigonometrical section of the book had been issued as a separate treatise (Witten-berg, 1542) under the care of Rheticus . The only work published by Copernicus on his own initiative was a Latin version of the Greek Epistles of Theophylact (Cracow, 1509) . His treatise De monetae cudendae ratione, 1526 (first printed in 1816), written by order of King Sigismund I., is an exposition of the principles on which it was proposed to reform the currency of the Prussian provinces of Poland . It advocates unity of the monetary system throughout the entire state, with strict integrity in the quality yof the coin, and the charge of a seigniorage sufficient to cover the expenses of mintage . AuTH0RITIEs.—Rheticus was the only contemporary biographer of Copernicus, and his narrative perished irretrievably . Gassendi's jejune Life (Paris, 1654) is thus the earliest extant of any note .

It was supplemented, during the 19th

century, by the various publications of J . Sniadecki (Warsaw, 18o3—1818); of J . H . W . Westphal, J . Czynski, M . Curtze, H . A . Wolynski, F . Hipler, and others, but their efforts were overshadowed by Dr Leopold Prowe's exhaustive Nicolaus Coppernicus (Berlin, 1883—1884), embodying the outcome of researches indefatigably prosecuted for over thirty years . The first volume (in two parts) is a detailed biography of the great astronomer; the second includes some of his minor writings and correspondence, family records, and historical documents of local interest . The effects of his Italian sojourn upon the nascent ideas of Copernicus may be profitably studied in Domenico Berti's Copernico e le vicende del sistema Copernicano in Italia (Roma, 1876), and in G .

V .

Schiaparelli's I Precursori del Copernico nell' antichild (Milano, 1873) . A centenary edition of De revolutionibus orbium coelestium was issued at Thorn in 1873, and a German translation by C . L . Menzzer in 1879 . (A . M . C.) COPIAPb, a city of northern Chile, capital of the province of Atacama, about 35 M. from the coast on the Copiapo river, in lat . 27° 36' S., long . 70° 23' W . Pop . (1895) 9301 .

The Caldera & Copiapo railway (built 1848—1851 and one of the first in

South America) extends beyond Copiapo to the Chanarcillo mines (5o m.) and other mining districts . Copiapo stands 1300 ft. above sea-level and has a mean temperature of about 67° in summer and 51° in winter . Its port, Caldera, 50 M. distant by rail, is situated on a well-sheltered bay with good shipping facilities about 6 m . N. of the mouth of the Copiapo river . Copiapo is perhaps the best built and most attractive of the desert region cities . The river brings down from the mountains enough water to supply the town and irrigate a considerable area in its vicinity . Beyond the small fertile valley in which it stands is the barren desert, on which rain rarely falls and which has no economic value apart from its minerals (especially saline compounds) . Copiapo was founded in 1742 by Jose de Manso (afterwards Conde, de Superunda, viceroy of Peru) and took its name from the Copayapu Indians who occupied that region . It was primarily a military station and transport post on the road to Peru, but after the discovery of the rich silver deposits near Chanarcillo by Juan Godoy in 1832 it became an important mining centre . It has a good mining school and reduction works, and is the supply station for an extensive mining district . For many years the Famatina mines of Argentina received supplies from this point by way of the Come-Caballo pass .