Page:Encyclopædia Britannica, Ninth Edition, v. 10.djvu/189

Rh ~;'.)',‘3.1‘- -53- fected in principle by Hipparchus, who ﬂourished from 160 while Alexandria continued to be the emporium whence to 135 13.0. He was the ﬁrst astronomer who undertook were imported the commodities of the East. The em the arduous task of making a catalogue of the stars and peror Justinian sent two Nestorian monks to China, who ﬁxing their relative positions. His object was to transmit returned with eggs of the silkworm concealed in a hollow to posterity a knowledge of the state of the heavens at the cane, and thus silk manufactures were established in the period of his observations. The extremities of the in1agi- | Peloponnesus and the Greek Islands. It was also in the nary axis round which the heavens perform their diurnal reign of Justinian that Cosmas Indicopleustes, an Egyptian cosmas, revolutions suggest two ﬁxed points by which the position I merchant, made several voyages, and afterwards composed of the great circle of the celestial sphere, called the celestial his Topogrup/u'a (J/n'istz'cmu, containing a particular descrip- equator, is determined. If a great circle be supposed to tion of India. The great outburst of Mahometan conquest pass through these points and any star, the position of the was followed by an Arabian civilization, having its centres star will be ascertained if we measure in degrees and parts at Cordova and Baghdad, in connexion with which geo- of a degree the arc of the meridian circle intercepted be- graphy again received a share of attention. tween th‘ star and the equator, and also the arc of the From the 9th to the 13th century intelligent Mahometan Mahome- equator intercepted between a given point in it and the travellers wrote accounts of what they had seen and heard tan tra- meridian circle passing through the star. Upon this prin- in distant lands, which have been handed down to t1s;""“e‘"s' ciple Ilipparchus arranged the stars according to their while the caliphs of Baghdad encouraged the study of places in the heavens; and the great improvement which geographical science. he introduced into geography consisted in this, that he The caliph Al-Manifm, the worthy son and successor of applied to the determining of the position of any point on Harﬁn er—llashid, caused an Arabic version of Ptolemy’s the surface of the earth the same rule which he had intro- great astronomical work (ELTV-raft; ,-tcyfo-n7) to be 111ade, dueed in the arrangement of the constellations. Thus he which is known as the illmagcst, the word being nothing furnished the means of ascertaining the relative positions of 111ore than the Greek psyforvy with the Arabic article at places with far greater accuracy than could be obtained from preﬁxed. The geography of Ptolemy is also constantly itinerary measurements. He made a considerable number referred to by Arab writers. The learned men under of observations for latitude, and pointed out how longitudes Al-.Iam1‘.u1 began to apply themselves to astronomy in 813 might be determined by observing the eclipses of the sun ..D., following the system of Ptolemy; and the ﬁrst obser- and moon. vations that are properly their own were made by El-Bzithany Islemy. The most ancient maps that have reached modern times in Mesopotamia, of the vernal and autumnal eqninoxes, in are those which illustrate Ptolemy’s geography, but an earlier 882 A.D. The Arab astronomers also measured a degree map made for Aristagoras, king of Miletus (500 13.0.), is on the plains of )Iesopotan1ia, and Ibn Yﬁnus observed minutely described by Herodotus. Ptolemy composed his three eclipses at Cairo. The calipl1’s librarian, Abu J afar system of geography in the reign of Antoninus Pius, about Muhammad Ben Musa, wrote a geographical work, now 150 A.D. Ilis materials consisted of all the itineraries unfortunately lost, entitled Iiasm el Arsi (“ A Description of prepared by the Romans, proportions of the height of the the World”), which is often referred to by subsequent gnomon and its shadow at the time of the equinoxes and writers as having been composed on the model of that of solstices taken by different astronomers, calculations founded Ptolemy. on the length of the longest days, and various reports of The earliest Arabian traveller whose observations have travellers and navigators. Ptolemy undertook the task of come dow11 to us is the merchant Sulaiman, who embarked comparing and reducing this mass of crude material into in the Persian Gulf and made several voyages to India and 0119 system. following the principles laid down by Hippar— China, in the middle of the 9th century. Sulaiman’s infor- chus, but which had been neglected during the two centuries Ination was supplemented by that collected by another and a half since his time, even by such men as Strabo and writer named Abu Zaid ; and, so far as India is concerned, Pliny. In Ptolemy’s work we ﬁnd for the ﬁrst time the this work is the most important that we possess before the mathematical principle of the construction of maps, as well grand epoch of the discoveries of Marco Polo. Next to as of several projections of the sphere. Sulaiman followed the voyages of Sindbad the Sailor, whose The errors of Ptolemy arose from defective information, narrative, though inserted in the Arabian fl"z'[//zts, also forms and the want in many instances, and especially as regards a distinct and separate work, which was translated into the remote parts of the then known world, of astronomical French by M. Langles in 1814. Baron Valckenaer ascribes observations. He adopted the measure of a degree at 500 to the voyages of Sindbad a date about coincident with stadia ; and the latitudes along the chief parallel of Rhodes, those of Sulaiman. Ibn Khurdadra, a ﬁre-worshipper con- as ﬁrst laid down by Eratosthenes, are tolerably correct. verted to Islam, who died in 912 A.D., also wrote an account But the elements for determining the longitudes were still of India. Al Masudi, a great traveller who knew all the derived from itineraries, and errors in latitude accumulated countries between Spain and China, described the plains, to the north and south of the central parallel. mountains, and seas, the dynasties and peoples, in his Ezbo. Although Ptolemy was the ﬁrst scientific geographer .l[zmZju—l Zahab (“Meadows of Gold”). He died in 956. whose work l1as come down to us in a complete form, the His contemporaries were Al Istakhri, who travelled through earlier labours of Strabo, who lived in the reigns of Augustus all the Mahometan countries, and wrote his Book of Cl {mates and Tiberius, are of equal value, and we fortunately possess in 950, and Ibn Haukal, whose Book of I3oacls and Ii'2'ng- Iuy. the whole of his 17 books. Pliny also devoted two books dams was written in 976. Al Idrisi was born at Ceuta, and of his extensive work to geography; and the scattered after travelling far and wide, settled in Sicily, where he was geographical notices of other ancient writers were collected induced by Roger II., the Norman king, to write his book EARLY D1scovEP.rEs.] alian at the sacred promontory of Iberia, and their longitu- dinal error increased rapidly as they advanced eastwards. This is no doubt due to their longitudes being based en- tirely on distances calculated in the itineraries of travellers. Such data of course produced very great distortions iii the representations given of the countries on the surface of the globe. The improvements introduced by Eratosthenes were per- GEOGRAPHY 1 17 into one work of four volumes by Iludson, and published between 1693 and 1712, with notes by Dodwell. From the days of Ptolemy to the revival of letters in Europe, little was done towards the scientiﬁc improvement of geographical science, though military and commercial enterprise led to a. great extension of knowlege of the earth’s surface. After the dissolution of the Ptoman empire, Constan- tinople became the last refuge of arts, taste, and elegance ; X.—23