SUMMARY OF THE CONTENTS. XV 



fractiofl of rays. Indian planetary tables. The disturbance in the 

 moon's longitude recognized by Abul Wefa. Astronomical Congress 

 of Toledo, to which Alfonso of Castille invited Rabbis and Arabs. Ob 

 servatory at Meragha, of Ulugh Beig, the descendant of Timur, at Sam- 

 arcand, and its influence. Measurement of a degree in the plain be- 

 tween Tadmor and Rakka. The Algebra of the Arabs has originatecJ 

 from two currents, Indian and Greek, which long flowed independent 

 ly of one another. Mohammed Ben Musa, the Chowarezmier. Dio- 

 phantus, first translated into Arabic at the close of the tenth century, 

 by Abul Wefa Buzjani. By the same path vvhich brought to the Arabs 

 the knowledge of Indian Algebra, they likewise obtained in Persia and 

 on the Euphrates the Indian numerals and the knowledge of the ingen- 

 ious device of Position, or the employment of the value of position. 

 They transmitted this custom to the revenue officers in Northern Afri- 

 ca, opposite to the coasts of Sicily. The probability that the Christians 

 of the West were acquainted with Indian numerals earlier than the 

 Arabs, and that they were acquainted, under the name of the system 

 of the Abacus, with the employment of nine ciphers, according to their 

 position-value. The value of position was known in the Suanpan, de- 

 rived from the intei'ior of Asia, as well as in the Tuscan Abacus. Would 

 a permanent dominion of the Arabs, taking into account their almost 

 exclusive predilection for the scientific (natural, descriptive, physical, 

 and astronomical) results of Greek investigation, have been beneficial 

 to a general and free mental cultivation, and to the creative power of 

 art?— p. 219-228. 



VI. Period of the great Oceanic Discoveries. — America and the Pa- 

 cific. Events and extension of scientific knowledge which prepared 

 the way for great geographical discoveries. As the acquaintance of the 

 nations of Europe with the western portion of the globe constitutes the 

 main object of this section, it is absolutely necessary to divide in an in- 

 contestable manner the first discovery of America in its northern and 

 temperate zone by the Northmen, from the rediscovery of the same con- 

 tinent in its tropical regions. While the Califate of Bagdad flourished 

 under the Abbassides, America was discovered and investigated to the 

 41^° north latitude by Leif, the son of Erik the Red. The Faro6 Islands 

 and Iceland, accidentally discovered by Naddod, must be regarded as 

 intermediate stations, and as starting points for the expeditions to the 

 Scandinavian portions of America. The eastern coasts of Greenland in 

 Scoresby's Land (Svalbord), the eastern coasts of Baffin's Bay to 72° 

 55', and the entrance of Lancaster Sound and Barrow's Straits, were 

 all visited — Earlier (?^ Irish discoveries. The W^hite Men's Land be 

 tween Virginia and Florida. Whether, previously to Naddod and In- 

 golf's colonization of Iceland, this island was inhabited by Irish (West- 

 men from American Great Ireland), or by Irish missionaries (Papar, 

 the Clerici of Dicuil), driven by the Northmen from the Faro6 Islands? 

 The national treasures of the most ancient records of Northern Europe, 

 endangered by disturbances at home, were transferred to Iceland, which 

 three and a half centuries earlier enjoyed a free social.Constitution, and 

 were there preserved to future ages. We are acquainted with the com- 

 mercial relations existing between Greenland and New Scotland (the 

 American Markland) up to 1347 ; but as Greenland had lost its repub- 

 lican Constitution as early as 1261, and, as a crown fief of Norway, had 

 been interdicted from holding intercourse with strangers, and there- 

 fore also with Iceland, it is not surprising that Columbus, when he vi&r 

 ited Iceland in 1477, should have obtained no tidings of the new conti- 



