267
- r. — y -W>— .- -
Ptolemy also gives us from Hipparchus , several observations oflunar eclipses made at Babylon above 720 years 15. C. and Aris-totle informs us, that they had many occultations of the planetsand lixed stars by the moon ; a circumstance which led them toconceive that eclipses of the sun were to be attributed to tire samecause. They had also no inconsiderable share in arranging thestars into constellations, and the comets did not escape their ob-servation. Dialing was also practised among them long before theGreeks were acquainted with that science. The Egyptians weremuch of the same standing in Astronomy with the Chaldeans.Herodotus ascribes their knowledge in the science to Sesostris;but probably not the same whom Newton makes contemporarywith Solomon, as they were acouainted with astronomy at leastmany hundred years before that acra. We learn, from the testi-mony of some ancient authors, that they believed the figure of theearth was spherical; that the moon was eclipsed by passing throughthe earth’s shadow, though it does not certainly appear that theyhad any knowledge of the true system of the universe : that theyattempted to measure, the magnitude of the earth ami smi,though their methods of ascertaining the latter were very erro-neous; and that they even pretended to forctel the appearance ofcomets, as well as earthquakes and inundations. r I his science,however, gradually decayed, and in the time of. Augustus it wasentirely extinct among them.
(6.) Astronomy passed from Chaldea and Egypt to thePhoenicians , and was applied by that commercial people, tothe purposes of navigation, steering their course by the northpolar star ; whence they became masters of the sea, and of al-most all the commerce in the world. The Greeks, it is pro-bable, derived their astronomical knowledge chiefly from theEgyptians and Phoenicians . The fable of Allas supporting theheavens upon his shoulders, shews that some Mauritanian monarchof that name had made considerable advances in astronomicalknowledge; and Iris discoveries had probably been communicatedto the Greeks. Several of the constellations are mentioned by Ifesiodand Homer , who lived about B. C. 870. Thales the Milesian,and other Greeks, who travelled into Egypt , brought from thencethe chief principles of the science. Thales was born about B. C.640, and he was the first among the Greeks, who observed thestars, the solstices, and predicted the eclipses of the sun and moon,
(7.) The science was farther cultivated and extended by hissuccessors Anaximander, Anaximenes, and Anaxagoras ; but es-pecially by Pythagoras , who about B. C. 577, brought fromEgypt the learning of these people, taught it in Greece and Italy ,and founded the sect of the Pythagoreans , who taught that the sunwas in the centre- of the universe; that the earth was round ; thatthere were antipodes; that the moon reflected the rays of the sun.and was inhabited like the earth ; that comets were a kind ofwandering stars, disappearing in the further parts of their orbits;that the white colour of the milky way was owing to the unitedbrightness of a great multitude of small stars, and that the distancesof the moon and planets from the earth, were in certain harmonicproportions to one another.
(8.) Philolaus, a Pythagorean , who flourished about B. C. 450,and asserted the diurnal motion of the earth on her own axis, wastaught by Hicetas, a Syracusan. About the same time Meton invented the cycle of nineteen years, which still bears his name.Eudoxus, of Cnidos , lived about B. C. 370, and was one of themost skilful astronomers and geometricians of antiquity. He in-troduced geometry into the science of astronomy. Calippusflourished soon after Eudoxus . lie invented a period of 76 years,containing four corrected Metonic periods, it commenced at thesummer solstice, B. C. 330.
(9.) Vitruvius , however, represents the introduction of astrono-my into Greece , in a manner somewhat different. He maintains,that Berosus , a Babylonian, brought it immediately from Babylon,and opened an astronomical school in the isle of Cos. And Pliny says, that in consideration of his wonderful predictions, the Athe-nians erected a statue to him in the gymnasium, with a gildedtongue. But if this Berosus be the same with the author of theChaldaic histories, he must have lived before Alexander. Aboutthis time, or rather earlier, the Greeks, having begun to plantcolonies in Italy, Gaul, and Egypt , these became acquainted withthe Pythagorean system, and the notions of the ancient Druids concerning astronomy. Julius C.wsar informs us that the latterwere skilled in this science; and that the Gauls in general were
able sailors, which at that time they could not be without a com'petent knowledge of astronomy: ami ills related of Pythoas, wholived at Marseilles in the time of Alexander the Great , that be ob-served the altitude of the sun at the summw-yolstice by ipeans of1 a gnomon. He is also said to have travelled as far as r l lmle to| settle the climates.
(10.) After Alexander’s death, the sciences flourished chieflyin Egypt , under thfe auspices of Ptolemy Philadelphia:, and hissuccessors. lie founded a school there, which continued till theinvasion of the Saracens, A. D. 650. Aristarchus , about 15. C.270, strenuously asserted the Pythagorean system, and gave amethod of determining the sun’s distance.by the dichotomy of themoon. Eratosthenes , who was born at Cv.rene, B. C. 271,mca-ured the circumference of the earth by a gnomon, lie also'"determined the distance between the tropics to be (4 oi the wholemeridian circle, which makes the obliquity of the ecliptic in histime to be 23" 5 1'4,
(11.) The celebrated Archimedes , too, cultivated, astronomy,as well as geometry and mechanics; determined the distances ofthe planets from one another; and constructed a kind of plane-,tariiun or orrery. Hipparchus who flourished about B. C. 140,was the first who applied himself to the study of every branch of .astronomy. Ptolemy says, he made great improvements in it; •he discovered that the orbits of the planets are eccentric, that the,t?.oon moves slower in her apogee than in her perigee, and that.there wash motion of anticipation of the moon’s nodes: he con-structed tables of the motions of the sun and moon, collected ac-counts of such eclipses, &c. as had been made by the Egyptiansand Chaldeans, and calculated all‘that were to happen for 600years: he discovered that the lixed stars changed their places,having a slow motion of their own from west to east. Most of hisobservations, are preserved by Ptolemy in his Almagest.
(12.) in the first century Ptolemy was .born at Pelusium i»Egypt, and profiting by the works of Hipparchus and oilier an-cient astronomers, lie formed a system or his own, which, thougherroneous, was implicitly followed for many ages by all nations.He compiled a great work, called the Almagest , which containedthe observations and collections of his predecessors in astronomy.'Phis work was preserved from the conflagration of the Alexan-drian library by the Saracens, aud translated into Arabic , A. 1).827, and info Latin in 1230. The Greek original was not knownin Europe till the beginning of the 15th century, when it wasbrought from Constantinople , then taken by the Turks, by George,a monk ofTrapezond, by whom it was translated into Latin ) andvarious other editions have been since made.
(13.) From A. D. 800, till the beginning of the 14th century,the western parts of Europe were immersed in gross ignorance,while the Arabians, profiting by the booksthey had preserved fromthe wreck of the Alexandrian library, cultivated and improvedall the sciences, and particularly that of astronomy, in which theyhad many able professors and authors. The caliph A1 Mansur firstintroduced a taste for the sciences into his empire. His grandsonAl.Mamun, who ascended the throne in 814, was a great en-courager and improver of the sciences, especially of astronomy.Having constructed proper instruments, he made many observa-tions; determined the obliquity of the ecliptic to be 23'* 35'; andunder his auspices a degree of the circle of the earth was measureda second time in the plain of Singar, on the border of the Bed Sea.
(14.) About this time Alfcrganus wrote elements of astronomy ;and Albategnius , who flourished about the year 880, greatly re-formed it, by comparing his own observations with those ofPtolemy. Hence he computed the motion of the sun’s apogeefrom Ptolemy’s time to his own ; settled the precession of theequinoxes at one degree in 70 years; and lixed the obliquity ofthe ecliptic at 23° 35'.
(15.) Ulug Beg, grandson of the celebrated Tamerlane , theTartarian prince , a great proficient in practical astronomy, hadvery large instruments, particularly a quadrant of about 180 feethigh, with which he made good observations. From these lie de-formined. ( the latitude of Samarcand, his capital, to be 39° 37' 23";and composed astronomical tables for the meridian of the same soexact, that they differ very little from those constructed after-wards by Tycho Brahe.
(16.) At this period, science began to dawn in Europe bythe settlement oi the Moors in Spain . The emperor Fre-deric 11, about 1230, also bewail to encourage learning; restor
i»*