The religious prejudices, as well as the interests of the Arabians, led them to exclude the Christians from every channel through which they had received the produce of India. That they were precluded from all commercial intercourse with Egypt, is evident, from a fact noticed by Macpherson, in his Annals of Commerce. Before Egypt was conquered by the Arabians, writings of importance in Europe were executed on the Egyptian papyrus; but after that period, at least till the beginning of the ninth century, they are upon parchment.--This, as Macpherson observes, amounts almost to a proof, that the trade with Egypt, the only country producing papyrus, was interrupted. In consequence of the supply of silks, spices, and other oriental luxuries which Constantinople derived from the fair at Jerusalem, (still allowed by the Arabians to be annually held,) not being sufficient for the demand of that dissipated capital, and their price in consequence having very much increased, some merchants were tempted to travel across Asia, beyond the northern boundary of the Arabian power, and to import, by means of caravans, the goods of China and India. Towards the beginning of the ninth century, as we have already remarked, the commercial relations of the Arabians and the Christians of Europe commenced, and Alexandria was no longer closed to the latter. The merchants of Lyons, Marseilles, and other maritime towns in the south of France, in consequence of the friendship and treaties subsisting between Charlemagne and the Caliph Haroun Al Rasched, traded with their ships twice a year to Alexandria; from this city they brought the produce of Arabia and India to the Rhone, and by means of it, and a land carriage to the Moselle and the Rhine, France and Germany were supplied with the luxuries of the east. The friendship between the emperor and the caliph seems in other cases to have been employed by the former to the advancement of the commercial intercourse between Asia and Europe; for we are expressly informed, that a Jewish merchant, a favourite of Charlemagne, made frequent voyages to Palestine, and returned with pictures,--merchandize before unknown in the west. Hitherto we have viewed the Arabians chiefly as fostering and encouraging commerce; but they also deserve our notice, for their attention to geographical science and discoveries. From the period of their first conquests, the caliphs had given orders to their generals to draw up geographical descriptions of the countries conquered; and we have already noticed some of these descriptions. In 833, A.D., the Caliph Almamon employed three brothers of the name of Ben Schaker, to measure a degree of latitude, first in the desert of Sangdaar, betweeen Racca and Palmyra, and afterwards near Cufa, for the purpose of ascertaining the circumference of the globe.