An isotherm is a line of equal or constant temperature on a graph, plot, or map; an isopleth of temperature. For example, isotherms are commonly seen on weather maps to show large-scale temperature distributions.
Drawing Contour Plots (http://avc.comm.nsdlib.org/cgi-bin/wiki_print.pl?Drawing_Contour_Plots). A lesson plan that deals with drawing various isopleths including isotherms.
... Qian[?] - spent 12 years starting in 138 BC exploring much of Central Asia for Emperor Han Wu Di[?]
Zheng He, (1371-1435), Chinese admiral who travelled widely over the ...