GEOGRAPHICAL LATITUDE. 763 



own to act as a fouudatiou of future development, tliey drew from a 

 rich fouutaiu ready at hand — Greek literature aud science — which 

 through the medium of transhitions they soon made their own. Not 

 only did the extent of their possessions and trade demand considerable 

 geographical knowledge, and at the snrne time provide much of the 

 material for it, but a stringent rule of their religion, requiring all 

 prayers to be said with the worshiper's face turned toward Mecca, 

 made necessary the determinatiou in every part of the realm of the 

 exact direction toward the holj'^ city. Although they were at first 

 guilty of the same fundamental errors as other Oriental nations in 

 conceiving the earth as a great plane or as having the form of a shield 

 or a drum,' they came Into possession of Ptolemy's work, probably as 

 early as the beginning of the ninth century,^ and from that time the 

 rotundity of the earth was among them an ahuost universally accepted 

 fact. That geography received a large share of attention is shown by 

 the considerable number of works on the subject written by them, 

 which have come down to us. One author, citing the Koran as au- 

 thority, calls geography "a science j^leasing to God."^ They not only 

 established by observation with the gnomon the latitude of a consider- 

 able number of places, but discovered also the error of one-fourth of a 

 degree inherent in all observations with that instrument, because the 

 shadow measures the angle to the uppermost edge of the sun instead 

 of its center.'' Having a passion for astrologj^ and a climate favorable 

 for observing the heavens, they made rai)id progress in astronomy, 

 aud accordingly in the theoretical part of geography connected with 

 it; but the geographers seem to have been unable both to value this 

 knowledge rightly and to use it in the preparation of their maps. To 

 read the praises of their work by one^ who has made a specialty of it 

 and constructed maps on nineteenth century lines as an illustration of 

 their production, must give a false idea of their true position in the 

 history of geographical development. He names Ptolemy's great work 

 a ^^ monument monsirueu.v,^^ and finds the purported translation, known 

 as '■'■rasm,^'' much better than the original, the translators having 

 adopted its principles without its errors of detail.*^ Though not a 

 single Arabic map now known has a net representing latitude and 



' Giinther, Rundschau, 4, 345. 



2Pe8chcl, Enlkunde, V.\2. 



» Hid., 10.^>. 



*IUd., 134. 



'^Lelewel, Gdog. du moyen-&ge. 



'^■Ibid,, I, 24. Contradictiiifj himself he speaks of it as " I'onvrage g^^ographique 

 d'uu anonyiue intituld 6pi6/.ioi, preferable a la g6<)graphie de Ptolciuee." D'Avezac, 

 293,294,1s decidedly of another opinion: "Mais les 6chantil]ons de cartographie 

 arabe qni sont parvenu jusqo'a nous se bornent en g<^n<^ral a de bien grossifercs 

 esquisses, sans exactitude en proportions d'ancune esp(^ce." Again: "II fa ut bien 

 recounaltre que leur role [des cartes arabes] est absolument nul dans I'histoire des 

 projections terrestrea," p. 295. 



