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THURSDAY, JULY 19, 1894. 



ANCIENT ASTRONOMY. 

 Recherches sttr I'histoire de V Astronomie Ancienne. Par 

 Paul Tannery. (Paris : Gauthier-Villars et Fils, 1S93.) 



THE author's previous work, " Pour I'Histoire de la 

 Science hellCne," in which early Greek scientific 

 ideas are treated of from the time of Thales to that of 

 Empedocles, and which first appeared in fragments in 

 the pages of the Reznte Philosophique, leads the reader 

 to open the present with high expectations, which its 

 perusal will assuredly not disappoint. It in no degree 

 trenches upon the ground occupied by the former ; but its 

 main object is to furnish an analysis of the Almagest, 

 more accurate and complete than those given by previous 

 writers, and also to discuss the views of those who may 

 fairly be called the precursors of Ptolemy, and especially 

 of Hipparchus. On this latter point M. Tannery's re- 

 searches have led him to conclusions somewhat different 

 from those which have been generally entertained. The 

 part played by Hipparchus in the progress of astronomy 

 he considers to have been singularly exaggerated, and 

 the ground to have been prepared rather by the earlier 

 writers of the Alexandrian school, particularly by Apollo- 

 n"ius of Perga, in the invention of geometrical and tri- 

 gonometrical methods, and the first systematic combina- 

 tion of recent with earlier Chaldean observations. To 

 illustrate clearly his meaning, he affirms that, without 

 these previous works, Hipparchus would have been 

 unable to accomplish the greater part of that which has 

 made his name immortal ; whereas without that of 

 Hipparchus, Ptolemy would have been able in great 

 measure to have composed his Almagest ; it would have 

 been undoubtedly much more imperfect and less accurate 

 in many numerical details, but "I'ensemble ne prJsen- 

 terait pas un caracti^re tr^s notablement different." 



The work begins with an etymological discussion (cer- 

 tainly conducted on historical principles) of the origin 

 of the words {i.e. of their Greek equivalents) " astronomy " 

 and " astrolo jy.'' The former is the older of the two, 

 and is found in Plato and in Aristophanes ; the substitu- 

 tion of " astrology " was made by Aristotle. Hipparchus 

 preferred the term mathematician to astronomer or 

 astrologer ; and following in his wake, Ptolemy called 

 his great work (for which we usually use the Arabic 

 designation "Almagest") the mathematical composition. 

 It may be interesting to remember that though in modern 

 times the expressions astronomy and astrology 

 returned into use (at first with the same meaning, 

 but the latter became degraded by exclusive appli- 

 cation to absurd and superstitious attempts, in the 

 manner of the Chaldeans and Egyptians, to predict 

 future events by supposed planetary influences), yet 

 Flamsteed's favourite way of designating himself was as 

 M.R., for " mathematicus regius." M. Tannery thinks 

 that the term dorpoi/ouos preceded that of dcrTpopoiiia, and 

 that it strictly signified one who distributed the stars into 

 groups, or, as we call them, constellations. With regard 

 to the well-known passage in Homer, speaking of the 

 Bear that alone has no part in the baths of the ocean, he 

 takes the poet to include under that name .all the stars 

 NO. 1290. VOL. 30I 



within the circle of perpetual apparition . The knowledge 

 of the distribution of the stars in the visible firmament 

 was obviously of use in navigation ; the extension of this 

 astronomy to reasoning on their motions, for which the 

 expression astrology was afterwards logically preferred 

 by Aristotle, was, we are told by Xenophon, discouraged 

 by Socrates ; but the language of the historian rather 

 points to the works of Eudoxus of Cnidus, which appe.ared 

 subsequently to the time of Socrates. 



M. Tannery takes occasion to allude to the famous 

 story or legend of the number of the year in the Metonic 

 Cycle taking its name from its being graven in golden 

 letters on a public square in Athens; whereas Boeckh has 

 proved that the cycle in question was not brought into 

 use there until the reform of Calippus, a century after the 

 time of Meton, and Aristophanes in more than one 

 passage ridicules the disorders of the calendar in his own 

 time. 



In his second chapter, M. Tannery treats of the pro- 

 gress made in the science which acquired the name of 

 astrology (but for which modern science prefers the more 

 ancient term astronomy, to avoid confusion with what 

 Kepler called its hair-brained sister, though we refuse to 

 recognise any relationship, and it was felt to be too much 

 trouble always to call the other judicial astrology) during 

 what may be considered the .Athenian period, for thither 

 came Eudoxus, who founded the school of Cyzicus and 

 introduced the use of the instrument called the dpiixyn, 

 identical in principle with the astrolabe, the invention 

 of which was long falsely attributed to the Arabs ; and 

 there also Calippus conferred with Aristotle. But 

 Alexandria was destined to take the place of Athens as 

 the principal seat of Greek learning. It was, however, 

 to the second period of its prosperity, under the Roman 

 domination, that the astronomical glory of Alexandria 

 culminated in the hands of Claudius Ptolemy, whose 

 work may be said to comprise all that was known of 

 astronomy until the era of Copernicus and Tycho, soon 

 to be followed by that of Kepler and Galileo. Mean- 

 while one of the islands on the coast of Asia Minor, on 

 which, according to the Greek proverb, the sun always 

 shone, so that it may be presumed that the stars also 

 frequently did at night, had been the scene of the scientific 

 labours of Hipparchus, probably the best known amongst 

 the ancient astronomers. Mr. Chambers calls him "the 

 Newton of Greece," but it is evident that iM. Tannery 

 does not share that view at any rate. The illustrious 

 Bithynian is usually considered, he says, " comme un 

 gdnie absolument hors de pair" ; but without desiring in 

 any way to depreciate his very important contributions 

 to science, he adds, " L'importance de son role est en 

 tout cas assez grande pour que ce ne soit pas lui faire 

 injure que d'essayer de le ramener a des proportions un 

 peu plus humaines. II a posscdc, sans contredit, les 

 qualitds essentielles i un astronome ; habile et patient 

 observateur, calculateur dmdrite, il fut dgalement doudde 

 la sagacitd qui conduit aux ddcouvertes capitales et dela 

 puissance de ddduction qui permet d'enchainer les 

 vdritcs nouvellement acquises dans un syst^me solidement 

 construit. Eut-il, au mcme degre, le giinie de I'invention 

 matht-matique .' C'est ce qui semble pouvoir etre mis 

 en doute." 



The author proceeds to show that in many of the 



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