section_path: Society/Science
section_name: Science
paragraph_text: Science
  
  The Mongol Empire saw some significant developments in science due to the patronage of the Khans. Roger Bacon attributed the success of the Mongols as world conquerors principally to their devotion to mathematics. Astronomy was one branch of science that the Khans took a personal interest in. According to the Yuanshi, Ögedei Khan twice ordered the armillary sphere of Zhongdu to be repaired (in 1233 and 1236) and also ordered in 1234 the revision and adoption of the Damingli calendar. He built a Confucian temple for Yelü Chucai in Karakorum around 1236 where Yelü Chucai created and regulated a calendar on the Chinese model. Möngke Khan was noted by Rashid al-Din as having solved some of the difficult problems of Euclidean geometry on his own and written to his brother Hulagu Khan to send him the astronomer Tusi. Möngke Khan's desire to have Tusi build him an observatory in Karakorum did not reach fruition as the Khan died on campaign in southern China. Hulagu Khan instead gave Tusi a grant to build the Maragheh Observatory in Persia in 1259 and ordered him to prepare astronomical tables for him in 12 years, despite Tusi asking for 30 years. Tusi successfully produced the Ilkhanic Tables in 12 years, produced a revised edition of Euclid's elements and taught the innovative mathematical device called the Tusi couple. The Maragheh observatory held around 400,000 books salvaged by Tusi from the siege of Baghdad and other cities. Chinese astronomers brought by Hulagu Khan worked there as well.
  
  Kublai Khan built a number of large observatories in China and his libraries included the Wu-hu-lie-ti (Euclid) brought by Muslim mathematicians. Zhu Shijie and Guo Shoujing were notable mathematicians in Yuan China. The Mongol physician Hu Sihui described the importance of a healthy diet in a 1330 medical treatise.
  
  Ghazan Khan, able to understand four languages including Latin, built the Tabriz Observatory in 1295. The Byzantine Greek astronomer Gregory Chioniades studied there under Ajall Shams al-Din Omar who had worked at Maragheh under Tusi. Chioniades played an important role in transmitting several innovations from the Islamic world to Europe. These include the introduction of the universal latitude-independent astrolabe to Europe and a Greek description of the Tusi-couple, which would later have an influence on Copernican heliocentrism. Choniades also translated several Zij treatises into Greek, including the Persian Zij-i Ilkhani by al-Tusi and the Maragheh observatory. The Byzantine-Mongol alliance and the fact that the Empire of Trebizond was an Ilkhanate vassal facilitated Choniades' movements between Constantinople, Trebizond and Tabriz. Prince Radna, the Mongol viceroy of Tibet based in Gansu province, patronized the Samarkandi astronomer al-Sanjufini. The Arabic astronomical handbook dedicated by al-Sanjufini to Prince Radna, a descendant of Kublai Khan, was completed in 1363. It is notable for having Middle Mongolian glosses on its margins.