third page from your link, and thanks again:
http://www.travelchinaguide.com/attraction/shaanxi/xian/terra_cotta_army/mausoleum_3.htm
"Sima Qian, a great historian who wrote in early Han dynasty, offered archeologists great insight on the mausoleum's construction. We learned from him that the tomb is huge. The coffin of Emperor Qin Shihuang was cast in bronze. Underground Palace was gem-studded replica of imperial housing above ground. Moreover, booby traps with automatic-shooting arrows were installed to deter would-be tomb robbers. Heaven and earth were represented in the central chamber of the tomb. Ceiling shaped into sun, moon and stars by inlaying pearls and gems symbolizes the sky and the ground was an accumulation point of rivers, lakes and seas, like Yellow River and Yangtze River, which stands for the earth. It is said that the underground palace was brightly lit by whale oil lamps for eternity. Nowadays, the records in this book have been definitely proved right by archaeological findings and the underground palace of the tomb is presumably well preserved."