Barus & Holley 190
170-180 Hope Street
Georeferencing the Yujitu and its implications for Chinese cartography"
Prof. David Mumford
The Yujitu is a stone map of greater China carved in 1136. Remarkably it also has NS and EW grid lines described as spaced 100 li apart. With A. Akin, we identified 40 points on the map which can be located on modern maps and applied a non-linear morphing algorithm developed for medical imaging applications. When superimposed with a modern map, the EW grid lines turn out to be quite accurate but the NS lines deviate from true meridians by as much as 18 degrees. We will describe the map and the algorithm and give some background on Chinese measurement of latitude. We speculated on the possible role Shen Kuo might have played and whether its creators were aware of its inaccuracies.
"Absence of geometric models in medieval Chinese astronomy"
Prof. Jayant Shah
Professor of Mathematics
Department of Mathematics
Buddhists brought Indian astronomy of the 7th and 8th century to China which was based on the geometric astronomy of the Greeks. Under Kubilai Khan, geometric Islamic astronomy arrived in China in the 13th century. An analysis of the solar equation of the centerand the lunar parallax in two important official Chinese astronomy texts show how little impactforeign imports had on the Chinese astronomy until the arrival of the Jesuits in the 17th century.