While present-day Chinese have replaced coal-burning stoves with geothermal heaters to minimize pollution, their ancestors over 200 years ago had learned to build fireplaces underground to keep their home clean and tidy.

Workers at the former residence of a Qing Dynasty (1644 -- 1911) general in Hohhot city, capital of the Inner Mongolia Autonomous Region, recently found a complex underground heating system during their repair work in the compound, which has been listed as a cultural heritage site for special protection by the local government.

The heating system consists of a zigzagging tunnel some 33 centimeters underground that still has trails of flames and ashes inside and interconnects the living room with the two wing-rooms on the east and west.

At the end of the tunnel are two burners by the main entrance of the western room, which "could have been the bedroom of the general himself or his daughter", said Tong Jingren, a specialist on the history of the Manchu, the dominant ethnic group of the Qing Dynasty.

"The heater is a prototype of the geothermal heaters we use today, and is the first fireplace ever found underground," he said.

Throughout China's history, people in the north used to warm themselves by fireplaces built inches above the floor to survive severe winters, said Tong.

The general's residence was built in 1737 -- the second year of Emperor Qianlong's reign, and the construction took two years. Like residences of other high-ranking officials of the time, the architecture boasts quality material and fine craftsmanship.
 
(Xinhua News Agency December 16, 2003)