["Kubilai Khan established in Peking two astronomical boards and two observatories.  One of them was a Chinese Observatory (sze t’ien t’ai), the other a Mohammedan Observatory (hui hui sze t’ien t’ai), each with its particular astronomical and chronological systems, its particular astrology and instruments.  The first astronomical and calendar system was compiled for the Mongols by Ye-liu Ch’u-ts’ai, who was in Chingis Khan’s service, not only as a high counsellor, but also as an astronomer and astrologer.  After having been convinced of the obsoleteness and incorrectness of the astronomical calculations in the Ta ming li (the name of the calendar system of the Kin Dynasty), he thought out at the time he was at Samarcand a new system, valid not only for China, but also for the countries conquered by the Mongols in Western Asia, and named it in memory of Chingis Khan’s expedition Si ching keng wu yuean li, i.e., ’Astronomical Calendar beginning with the year Keng wu, compiled during the war in the west.’  Keng-wu was the year 1210 of our era.  Ye-liu Ch’u-ts’ai chose this year, and the moment of the winter solstice, for the beginning of his period; because, according to his calculations, it coincided with the beginning of a new astronomical or planetary period.  He took also into consideration, that since the year 1211 Chingis Khan’s glory had spread over the whole world.  Ye-liu Ch’u-ts’ai’s calendar was not adopted in China, but the system of it is explained in the Yuen-shi, in the section on Astronomy and the Calendar.

“In the year 1267, the Mohammedans presented to Kubilai their astronomical calendar (wan nien li, i.e.), the calendar of ten thousand years.  By taking this denomination in its literal sense, we may conclude that the Mahommedans brought to China the ancient Persian system, founded on the period of 10,000 years.  The compilers of the Yuen-shi seem not to have had access to documents relating to this system, for they give no details about it.  Finally by order of Kubilai the astronomers Hui-Heng and Ko Show-King composed a new calculation under the name of Shou-shi-li which came into use from the year 1280.  It is thoroughly explained in the Yuen-shi.  Notwithstanding the fame this system generally enjoyed, its blemishes came soon to light.  In the sixth month of 1302 an eclipse of the sun happened, and the calculation of the astronomer proved to be erroneous (it seems the calculation had anticipated the real time).  The astronomers of the Ming Dynasty explained the errors in the Shou-shi-li by the circumstance, that in that calculation the period for one degree of precession of the equinox was taken too long (eighty-one years).  But they were themselves hardly able to overcome these difficulties.” (Palladius, pp. 51-53.)—­H.  C.]

[1] Besides the works quoted in the text I have only been able to consult
    Gaubil’s notices, as abstracted in Lalande; and the Introductory
    Remarks to Mr. J. Williams’s Observations of Comets ... extracted
    from the Chinese Annals, London, 1871.