"He goes on to state, that years passed by, and both his old school-friends found him out, and came and claimed a share in his good fortune, according to the school-day vow. The Vizier was generous and kept his word. Hasan demanded a place in the government, which the Sultan granted at the Vizier's request; but discontented with a gradual rise, he plunged into the maze of intrigue of an oriental court, and, failing in a base attempt to supplant his benefactor, he was disgraced and fell. After many mishaps and wanderings, Hasan became the head of the Persian sect of the _Ismailians_,--a party of fanatics who had long murmured in obscurity, but rose to an evil eminence under the guidance of his strong and evil will. In A.D. 1090, he seized the castle of Alamút, in the province of Rúdbar, which lies in the mountainous tract south of the Caspian Sea; and it was from this mountain home he obtained that evil celebrity among the Crusaders as the OLD MAN OF THE MOUNTAINS, and spread terror through the Mohammedan world; and it is yet disputed whether the word _Assassin_, which they have left in the language of modern Europe as their dark memorial, is derived from the _hashish_, or opiate of hemp-leaves (the Indian _bhang_), with which they maddened themselves to the sullen pitch of oriental desperation, or from the name of the founder of the dynasty, whom we have seen in his quiet collegiate days, at Naishápúr. One of the countless victims of the Assassin's dagger was Nizám-ul-Mulk himself, the old schoolboy friend. "Omar Khayyám also came to the Vizier to claim his share; but not to ask for title or office. 'The greatest boon you can confer on me,' he said, 'is to let me live in a corner under the shadow of your fortune, to spread wide the advantages of Science, and pray for your long life and prosperity.' The Vizier tells us, that when he found Omar was really sincere in his refusal, he pressed him no further, but granted him a yearly pension of 1200 _mithkáls_ of gold from the treasury of Naishápúr. "At Naishápúr thus lived and died Omar Khayyám, 'busied,' adds the Vizier, 'in winning knowledge of every kind, and especially in Astronomy, wherein he attained to a very high pre-eminence. Under the Sultanate of Malik Shah, he came to Merv, and obtained great praise for his proficiency in science, and the Sultan showered favors upon him.' "When the Malik Shah determined to reform the calendar, Omar was one of the eight learned men employed to do it; the result was the _Jaláli_ era (so called from _Jalál-ud-din_, one of the King's names)--'a computation of time,' says Gibbon, 'which surpasses the Julian, and approaches the accuracy of the Gregorian style.' He is also the author of some astronomical tables, entitled Zíji-Maliksháhí," and the French have lately republished and translated an Arabic Treatise of his on Algebra.