IDRISI or Edrisi (Abu Abdallah Mohammed Ibn Moham med Ibn Abdallah Ibn Idrisi, c. A.D. 1099-1154), Arabic geog rapher. His great-grandfather, Idrisi II., "Biamrillah," a mem ber of the princely house which had reigned as caliphs in north west Africa, was prince of Malaga. After his death in Malaga was seized by Granada, and the Idrisi family then prob ably migrated to Ceuta, where a freedman of theirs held power. Here the geographer was born in A.H. 493 (A.D. 1099). He stud ied at Cordova and visited before A.D. I I 54, both Lisbon and the mines of Andalusia. He had also resided near Morocco city, and once was at (Algerian) Constantine. In A.D. 1117 he visited the cave of the Seven Sleepers at Ephesus; he probably travelled extensively in Asia Minor. Some have inferred that he had seen part of the coasts of France and England. Roger II. of (1101-54) invited him to his court between 1 125 and 1150. Idrisi made for the Norman king a celestial sphere and a disk represent ing the known world of his day—both in silver. Roger bestowed on him rich presents, and employed him in the compilation of a fresh description of the "inhabited earth" from observation. The king and his geographer sent emissaries to various countries to observe, record and design ; and Idrisi inserted in the new geography the information they brought. Thus was gradually completed (by the month of Shawwal, A.H. 548 =mid-January, A.D. 11S4), the fa mous work, best known, from its patron and originator, as Al Rojari, but whose fullest title seems to have been, The going out of a Curious Man to explore the Regions of the Globe, its Prov inces, Islands, Cities and their Dimensions and Situation. This has been abbreviated to The Amusement of him who desires to traverse the Earth, or The Relaxation of a Curious Mind. The title of Nubian Geography, based upon Sionita and Hezronita's misreading of a passage relating to Nubia and the Nile, is mis leading. The Rogerian Treatise contains a full description of the world as far as it was known to the author. The "inhabited earth" is divided into seven "climates," beginning at the equinoctial line, and extending northwards to the limit at which the earth was supposed to be rendered uninhabitable by cold. Each climate is then divided by perpendicular lines into eleven equal parts, beginning with the western coast of Africa and ending with the eastern coast of Asia. The whole world is thus formed into 77 equal square compartments. The inconveniences of the arrange ment (ignoring all divisions, physical, political, linguistic or re ligious, which did not coincide with those of his "climates") are obvious.
We find few traces of his influence on European thought and knowledge. The chief exception is perhaps in the delineation of Africa in the world-maps of Marino Sanuto (q.v.) and Pietro Vesconte. His account of the voyage of the Maghrurin or "De ceived Men" of Lisbon in the Atlantic (a voyage on which they seem to have visited Madeira and one of the Canaries) may have had some effect in stimulating the later ocean enterprise of Chris tian mariners; but we have no direct evidence. In spite of the record of the Lisbon Wanderers, he shares the common Muslim dread of the black, viscous, stormy and wind-swept waters of the western ocean, whose limits no one knew, and over which thick and perpetual darkness brooded. But his breadth of view, his recognition of scientific truths (such as the roundness of the world) and his wide knowledge and intelligent application of preceding work (such as that of Ptolemy, Masudi and Al Jayhani) must not be forgotten. He also preserves and embodies a con siderable amount of private and special information—especially as to Scandinavia, portions of the African coast, the river Niger (whose name is perhaps first to be found, after Ptolemy's doubt ful Nigeir, in Idrisi), portions of the African coast, Egypt, Syria, Italy, France, the Adriatic shore-lands, Germany and the Atlan tic islands. Unfortunately the place-names are often illegible or hopelessly corrupted in the manuscripts. Idrisi's world-map, with all its shortcomings, is perhaps the best product of the Mohammedan cartography of the middle ages.
Besides the Rojari, Idrisi wrote another geographical work cited by Abulfida as The Book of Kingdoms, but apparently entitled by its author The Gardens of Humanity and the Amusement of the Soul. This was composed for William the Bad (1154-66), son and successor of Roger II., but is now lost.
Two manuscripts of Idrisi exist in the Bibliotheque Nationale, Paris, and two others in the Bodleian Library, Oxford. One of the English mss., brought from Egypt by Greaves, is illustrated by a map of the known world, and by 33 sectional maps (for each part of the first three climates) . The second manuscript, brought by Pococke from Syria, is dated A.H. 906, or A.D. 1500. It consists of 32o leaves, and is illus trated by one general and 77 particular maps. The general map was published by Dr. Vincent in his Periplus of the Erythraean Sea. A copy of Idrisi's work in the Escorial was destroyed by the fire of 1671.
A French translation of the whole of Idrisi's geography. based on one of the mss. of the Bibliotheque Nationale, Paris, was published by Amedee Jaubert in 1836-40, and forms volumes v. and vi. of the Recueil de voyages issued by the Paris Societe de Geographie. Part of a contemplated critical edition was prepared by de Goeje—Description de l'Afrique et de l'Espagne par Edrisi, texte arabe, public avec une traduction, des notes et un glossaire par R. Dozy et M. J. de Goeje (Leiden, E. J. Brill, i866) . Other parts of Idrisi's work have been separately edited; e.g., "Spain" (Descripcion de Espana de . . . Aled ris), by J. A. Conde, in Arabic and Spanish (Madrid, 1799) ; "Sicily" (Descripzione della Sicilia ... di Elidris) , by P. D. Magri and F. Tardia (Palermo, 5764) ; "Italy" (Italia d scritta nel "libro del Re Ruggero," compilato da Edrisi), by M. Amari and C. Schiaparelli, in Arabic and Italian (Rome, 1883) ; "Syria" (Syria descripta a . .. El Edrisio . .. ), by E. F. C. Rosenmuller, in Arabic and Latin, 1825, and (Idrisii ... Syria), by J. Gildemeister (Bonn, i885) (the last a Beilage to vol. viii. of the Zeitschrift d. deutsch. Palastina-Vereins). See also M. Casiri, Bibliotheca Arabico-Hispana Escurialensis (2 vols., Madrid, 1760-7o) ; V. Lagus, "Idrisii notitiam terrarum Balticarum ex commerciis Scandinavorum et Italorum . ortam esse" in Atti del IV ° Congresso internaz. degli orientalisti in Firenze, p. 395 (Florence, 1880) ; R. A. Brandel, "Om och ur den arabiske geografen Idrisi," Akad. afhand. (Upsala, 1894) . (C. R. B.)