A BIRD'S-EYE VIEW OF THE HISTORY OF ASTRONOMY 



W". ALI-Ri;i) I'AKK. 



toK it is in\' o])iiiion that the occasions h\' whicli 

 men liave acquired a knowledge of celestial 

 phenomena are no less admirable than the discoveries 

 themselves." Thus wrote Kepler in niemi)ral)le 

 words at the beginning of the seventeenth centurw 

 and few will deny that the history of the oldest and 

 grandest of the sciences possesses a fascination far 

 transcending that of many another record of human 

 acti\ity. In no other sphere of knowledge is the 

 gradual unfolding of human genius so palpahh' 

 shown as in this slow endeavour throughout the 

 centuries to unravel the m\steries of the stars, for 

 the movement of the mind has been constantK' 

 onward, and the problems of astronomv ha\e e\er 

 called its highest energies into requisition. 



To chronicle, as conciseh' as mav be, the salient 

 features in the more modern aspect of this upward 



struggle, is the object of the folk 



Ta 



which purports to present in its \ertical columns a 



chronometrical. and in its horizontal columns a 



contemporar\- miniature histor\' of astronom\-. 



embracin 



instrumental details of an\ 



the chief biographical, theoretical, and 

 •en period. In order 

 to bring the whole within reasonable dimensions the 

 vertical spaces have been arranged in periods of 

 fifty years, beginning with A.D. 1500. the ejioch 

 immediately succeeding the Re\i\al of Science in 

 Europe, thus the various landmarks in the evolution 

 of modern astronomy appear in close perspective, 

 showing, in a more graphic manner than is otherwise 

 jjossible. how completeh' each stage in the progress 

 of the science has depended on those that preceded, 

 besides affording a comprehensive mental picture 

 of this later development as a whole. The method 

 adopted not only imparts a sense of proportion to 

 the conception of history which can never be gained 

 from a mere perusal of abstract dates or a studv of 

 isolated periods, but also jjermits of the sejiarate 

 study of the contained matter in a specific way, for 

 the descending columns give a compressed histor\- of 

 an\- particular siihjecf. while the horizontal columns 

 treat of any particular />t7/o(/. 



Before, howe\er. entering upon a detailed stud\- 

 of the Table itself, it w ill be well to premise, in as 

 brief a manner as possible, an e[)itomized account 

 of the leading discoveries which were made during 

 the whole of the pre-Copernican period. 

 PRIMITIVE .ASTRONOMY. 



.Astronomy was cultivated from the earliest times in Egvi'T, 

 India, and China. The path of the sun and moon amongst 

 the stars forming the Zodiac and the primary divisions of 

 the year and month were determined, the motions of the five 

 planets, Mercury. Venus, Mars, Jupiter, and Saturn 

 studied, and the Obliquity of the Ecliptic measured by 

 the nations of antiquity, the most systematic astronomical 

 observations being those of 



THE CH.ALDEANS 

 who map out the Constellations about 2000 B.C., and who 

 discover that the Phenomena of Eclipses repeat themselves 

 in the Saros Period, or cycle of eighteen years. The next 

 great advance is made by 



TH1-: GRICEKS. 



B.C. 635 Thalks of Mii.i;tus holds the earth to be a sphere, 

 and predicts a solar eclipse. (The Gnomon is in 

 use, and Sundials are constructed.) 



., 5S2 Pythagoras, according to his disciple Phii.oi.aus 

 (B.C. 4001, speculates upon the motion of the 

 earth. 



.. 40') EUDOXUS OF Cnidus expressesthe planetary motions 

 by the aid of geometry, and sets up the hypothesis 

 of Moving Spheres, afterwards extended by 

 Callippus (B.C. 3301. 



.. 395 Hkraclidfs OF Pontus is the first to teach the 

 doctrine of the Earth's Diurnal Rotation. 



., 300 Aris tillus and TniocHARis deteruiine the relative 

 positions of the principal stars of the Zodiac, thus 

 preparing the way for Hipparchus. 



.. 2S0 .Aristarchus OF Samos is the first to propound 

 the Heliocentric System, lEmployinent of the 

 .Armillary Sphere.) 



.. 2.50 .Al'ol.l.ONlus OF Pkrca devises the system of 

 Eccentrics and Epicycles. 

 IfiO Hii'i'ARCHUS. the greatest astronomer of antiquity, 

 establishes the science on a firm footing by his 

 catalogue of 1,080 stars, and his discovery of the 

 Precession of the Eqnino.xes, as well as by his 

 precise observational methods ensuring accurate 

 results. (Employment of the Astrolabe}. 

 .\.I). 130 Ptolemy of Alexandria elaborates in his 

 " .Almagest " the Epicycles and Deferents of 

 his predecessors, thus discarding the juster helio- 

 centric views of .Aristarchns. The Ptolemaic. 

 or Geocentric. System is doiniuant for fourteen 

 centuries. 



.After this time the .Alexandrian school of 

 astronomy declines until after the Moham- 

 medan Conquest in 642. the next advances 

 being made by 



TH1-: AKABS. 



iS13 -Almamon founds a school of astronomy at B(r;i;(/(;(/. 

 and has Ptolemy's ".Alma'^est " translated into 

 Arabic. 



., cS50 .Alba tegnius. the most celebrated astronomer of 

 the .Arabs, makes accurate observations, and 

 compiles valuable .Astronomical Tables. 



.. 903 .Al-Sufi revises the .Alexandrian list of stars. 



.. 1000 .Abui. Wefa discovers the Moon's Variation. 



.. 1433 L'lugh Begh establishes a well-equipped Observa- 

 tory at Samarcand, and compiles a \ahiable 

 Star Catalogue. 



-After this time Eastern astronomy comes to an 

 end, but Western Europe continues the cultivation 

 of the science introduced liy the .Arabs into Spain, 

 the first advances being made b\- 



THI-: MOORS. 



., 103S .Alhazen discovers the Laxc of Refraction. 

 .. lOSO .Arzachel. of Toledo, publishes his Toletan 

 Tables, and repeats the observations of .Albategnius 



with greater accuracy. 

 ., 1230 The .Arabic version of Ptolemx's ".Almagest " is 



translated into Latin, and about 

 .. 1270 .A(j()Nso X. of Castile produces at Toledo the 



.Alphonsine Tables, compiled by the best 



mathematicians of the Moorish universities. 



The impulse thus given to a.stronomy by the two latter 

 events draws the attention of Western learning to the science, 

 and John HfJi.vwooD's (Sacrobosco) publication of a 

 Treatise on the Sphere about 1230, and Nicolaus von 

 Cusa's speculations on the Planetary System about 1440. 

 prepare the way for the advent of CoPERNICUS. 



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