HISTORY OF ASTRONOMY. 



313 



Among the Romans, astronomy was never much 

 esteemed ; and no astronomical discovery had 

 its origin with them ; though it must be observed, 

 that expressions occur in Seneca's Quastiones Nat., 

 vii. 13, respecting comets, which are worthy of a 

 riper age; and the service likewise deserves men- 

 tion, which Julius Caesar rendered, by his correction 

 of the calendar, the details of whicli may be found 

 in the article Calendar. But, with the irruption of 

 the barbarians on one side, and the destruction of the 

 Alexandrian library on the other, such a total stagna- 

 tion occurred in the case of astronomy, as in that of 

 the sciences in general, that we find no traces of 

 astronomical study and observation, till the ninth 

 century, among the Arabs, whose translation of 

 Ptolemy's works has already been mentioned. Of 

 their astronomers, the caliph Almamon, and the 

 princes Albategni and Thebith, deserve to be named. 

 Among the Moors who invaded Spain, there were 

 Arabic scholars, who transplanted the science to that 

 country With the Mohammedan faith, Arabic 

 learning was likewise introduced into Persia, the 

 reigning prince of which, Ulug-Beigh, in the begin- 

 ning of the 15th century, collected, at his capital, 

 Samarcand, an assemblage of the most famous living 

 astronomers. But we must not overrate the merits 

 of the Arabian astronomers, since they confined them- 

 selves entirely to the system of Ptolemy, and con- 

 founded the science with the dreams of astrology ; 

 though, on the other hand, the benefits which they 

 have rendered by valuable observations of the fixed 

 stars (many of which, it is well known, still bear 

 Arabic names), of eclipses, of the obliquity of the 

 ecliptic, (q. v.) &c., and by the preservation of an- 

 cient mathematical works, which have come to us in 

 their translations, are not to be forgotten. Among the 

 Christian nations, during this time, a deep ignorance 

 generally prevailed, but the cultivation of the astro- 

 nomical sciences was not entirely neglected. Thus 

 the emperor Frederic II., who died in 1250, caused 

 the Almagest (the Greek original being no longer 

 extant) to be translated from the Arabic into Latin ; 

 and king Alphonso of Castile, about the same time, 

 invited to his court several astronomers, and com- 

 missioned them to prepare a set of new astronomical 

 tables, which, under the name of Alphonsine tables, 

 have acquired much celebrity, but, in the 17th cen- 

 tury, differed a whole degree from the true situation 

 of the celestial bodies. We pass over several less 

 famous names, in order to introduce those of the 

 German astronomer and mathematician, George of 

 Peurbach or Purbach, born in the Austrian dominions, 

 in 1423, who published various valuable astronomical 

 tables, such as the table of sines, from 10 to 10', and 

 a still more famous scholar, John Muller, born at 

 Konigsberg, in Franconia, and thence called Regio- 

 montanus, from whom we possess the first good and 

 complete Ephemerides. After him, a brighter light 

 was shed over astronomy by Nicholas Copernicus 

 (q. v.), bom in 1473, who gave the science an entirely 

 different aspect, exploded the PtolemaRan hypothesis, 

 and, in its stead, substituted the Copernican system of 

 the world, which, with a few modifications, is still 

 prevalent, and universally acknowledged to be cor- 

 rect. He it was that gave the sun its place in the 

 centre of the planetary system ; or, as is magnifi- 

 cently expressed in his epitaph, " commanded the 



distance of the fixed stars is so great, that this circle can 

 only be considered as a point in comparison; but he seems 

 to bare come to this conclusion, not as an astronomer, but 

 as a fythapnrean. regarding fire (the aun) as the centre of 

 the universe. We take this occasion to correct the common 

 but erroneous opinion, that Copernicus was indebted, for 

 his system of the world, to this passape of Avenarius, as 

 this book was not printed till after his time. 



sun to stand still ;" who first conceived the bold 

 idea, that the earth is a planet, like Mercury, Ve- 

 nus, and the rest, and moves, in common with 

 them, in a circle around the sun ; and who main- 

 tained that these circles (or, in conformity with sub- 

 sequent corrections, these orbits, differing but little 

 from circles) were sufficient to explain the most 

 complicated motions of the other planets, and even 

 their apparent cessations of motion and retrograda- 

 tions, which had hitherto baffled all conjecture. (For 

 a view of the Copernican System, see the Plate en- 

 titled The Planetary System.) How much freedom of 

 spirit was required thus to rise superior to the preju- 

 dices of centuries, we are almost incompetent to 

 judge, now that the truth of the system is settled ; 

 but his great countryman, Kepler, has depicted the 

 spirit of the man, by a few energetic strokes, calling 

 him virum maximo ingenio et quod in hoc exercitio 

 magni momenti est, anhno libero. His system did not, 

 however, meet, immediately, with a general recep- 

 tion ; and, while Rheticus and others were its advo- 

 cates, some distinguished astronomers made objections 

 to it, among which the imperceptibleness ot any an- 

 nual parallax of the fixed stars, which it seemed must 

 necessarily result from the motion of the earth, was 

 the one of most weight. The most distinguished of 

 these opponents of the great Copernicus was Tycho 

 Brahe (q. v.), born in Denmark, in 1546. He main- 

 tained that the earth is immovable, in the centre of 

 the universe ; that the whole heavens turned around 

 it in twenty-four hours ; that the moon, and also the 

 sun, by virtue of their own motions, describe circles 

 around the earth, while Mercury, and the other 

 planets describe epicycles around the sun. (See 

 Epicycle.) This system, called after him the Ty- 

 ihonic Sysh-m, may be represented thus : 



The principal authority that Tycho adduced in sup- 

 port of his opinion was, the literal sense of various 

 passages of the Bible, where a total absence of 

 motion is ascribed to the earth ; but, although he 

 did much injury to science by supporting this erro- 

 neous opinion, we are under infinite obligation to him 

 for the great exactness of his observations, which 

 opened to his pupil and assistant, Kepler (q. v.) of 

 Wurtemburg (born 1571, died 1631), the way to the 

 more accurate discovery of the form of the celestial 

 orbits, and the true theory of the planets ; for onkj 

 eight minutes' difference between the position of the 

 planet Mars, as calculated on the hypothesis of the 

 circle, and its actual position, as observed by Tycho, 

 gave this sagacious astronomer occasion, as he ex- 

 presses himself, in p. 114 of his Astroiwmia? "ad 



The title of this immortal work, .containing the code of 

 theoretical astronomy, is, Astro nmniar nova, A.r.oXoy^.5, gf U 

 Pliysica Calestis traiiita Cinnmenta- is tie MotiUu.i Stella 

 Mortis, ex Obsrrvationibus Tyc/ionis Bralte, Jtiftu ft 



