ALMAMON, a celebrated astronomer, and one of the caliphs of Bagdad, was the second son of the caliph Ilarun-al-Raschid, and was born in the year 786. who died in S09, endeavoured to provide for the tranquillity of his subjects, by appointing his children to reign in succession ; but the wise views of the caliph were soon fru,trated by the vices and incapacity of his eldest son. No sooner had Al Amin assumed the reins of government, than he began to display that villainy of haracter which embittered his short and turbulent reign. From motives which neither ambition nor in terest could inspire, he cherished the most unnatural resentment against Almamon, and formed the design of excluding him from the succession. His first ag gression was to order the forces of his brother, who v. as governor of Khorasan, to repair to Bagdad ; but this insult did not shake the fidelity of Almamon, who continued to support the government of his brother, and even commanded the inhabitants of Khorasan to swear allegiance to Al Amin. This act of generosity, how ever, did not disarm the hostility of the caliph : De voted to gaming, and stupilied by intoxication, he aban doned the direction of his government to an unprinci pled vizier, who persuaded him to proclaim war against his brother. A force of 60,000 men were instantly despatched to the frontiers of Khorasan; but Almamon was prepared to oppose them with a powerful army, under the command of 'I'hahen-ebn-llosein, one of the most skilful generals of the age. After a few engage ments justice triumphed over oppression; the army of Al Amin was dispersed ; the provinces of Syria, Egypt, Yemen, and Hejaz, submitted to the conqueror, and Al mamon was proclaimed caliph throughout the depen dencies of Bagdad. This successful campaign paved the way for a complete revolution, in which Al Amin was deposed and assassinated, and the full possession of the caliphate conveyed to Almamon, (A. D. 213.) But this illustrious prince was not permitted to scat himself quietly on his throne. While he wielded the sceptre in one hand, he was obliged to brandish his sword in the other. At the instigation of his vizier F'adel, he publicly avowed his attachment to the sect of Ali, and obliged his courtiers and soldiers to assume the green turban, was the badge of this Mahometan party. The house of Abbas and the orthodox Mussulmans, alarmed at the preference which was thus publicly shown to their enemies, excited an insurrection in the metropolis, and proclaimed Ibrahim, Almamon's uncle, caliph of Bag dad. These commotions would have overturned the throne of any other sovereign than Almamon ; but by the vigour of his efforts, and the prudence of his ad ministration, he succeeded in extinguishing the flame o was about to involve his subjects in all the hor rors of a civil war. The assassination of his vizier by
the insurgents contributed to allay the popular discon tent. Ili, death was regarded as an atonement for the injuries of the people : Their rebellious spirits fell : Ib rahim was deposed ; and the inhabitants of Bagdad again submitted to the government of Almarnon. During these commotions, Thalen revolted against his mas ter; and havMg usurped the government ol Khora san, lie established a dynasty which continued for sixty y ears.
No sooner was tranquillity restored at Bagdad, than Almamon began to mature those great and liberal plans, vi hich, even in early life, he had formed for the civili zation of his subjects. During the reign ol his father, when he had scarcely arrived at the age of manhood, he had established a society at Khorasan, directed by Dleshe, a celebrated Christian physician from Damascus. and composed of the most eminent men of various na tions, whom lie had invited into his territories. The appointment of a Christian to a high office in a Maho metan country, did not fail to excite the pious alarms of the faithful. The caliph Harun remonstrated against the imprudence of his son ; but Almamon reminded him, that the learning of the times was confined to Jews and Christians, and that Mesne was not a teacher of religion, but of learning. When Almamon succeeded to the throne, his eflbrts for the diffusion of knowledge among his subjects increased with his power. Be formed an academy at Bagdad, and invited to his me tropolis, from every quarter, the most distinguished scholars and philosophers of the age. He visited in person the schools which he established throughout his dominions. The respect which lie felt due to ta lents, he willingly paid to the professors and teachers of youth ; and by his influence, as well as his example, he gave encouragement to every plan which had the re motest tendency to advance the interests of science, or form the minds of his people. A proficient in the sci ence of astronomy, he knew the value of that sublime and interesting study, and laboured to expand the minds of his countrymen with the grand and elevating views which it unfolds. By the command of Almamon, the miyi it, or Almagest of Ptolemy, a complete body of astronomical science, was translated into the Arabic language ; and a new work, which still exists in MS. was composed upon the same subject, entitled "astronomic elaborate a Compluribus, D. D. jussu Regis Maimon." 1Vith the rude instruments of his time, he observed the obliquity of the ecliptic, and employed the ablest geometers to measure a degree of the meridian upon the extensive plains of Mesopotamia.