IN the study Of history, the attention Of the observer is drawn by a peculiar charm towards those epochs, at which nations, after having secured their independence externally, strive to obtain an inward guarantee for their power, by acquiring eminence as great in science and in every art of peace as they have already at tained in the field of war. Such an epoch was, in the history of the Arabs, that of the Caliphs AL mansur, harun AL rashid, and AL mamun, the illustrious contemporaries of charlemagne; to the glory of which era, in the volume now offered to the public, a new monument is endeavoured to be raised.