When visiting the Forbidden City, you can see the big tanks for storing water in front of many temples. Since most of the buildings in the Forbidden City are made of brick and wood, which is easy to catch fire, the purpose of placing large tanks in each courtyard is to "control fire and eliminate disaster".
In the imperial palace of the Forbidden City, there are copper tanks and iron tanks. The original intention is to prevent fire. These tanks are usually filled with clear water. Once there is a fire in the palace, you can take water nearby to put out the fire. Therefore, the big tank is also known as "auspicious tank" and "Taiping tank". It is said that these VATS also have a common name of "Menhai". They take the meaning of the sea in front of the gate and pray that the "sea" in front of the gate can overcome the fire with water. There will be no more fire in the palace.
In winter, what should we do if the VAT is frozen? In order to prevent the water in the big tank from freezing in winter, a cotton sleeve should be put on the outer cover of the tank every October to February of the next year, and the tank should be capped. When the temperature is particularly low, carbon should be burned under the tank to heat up. According to the book of the Great Qing Dynasty, there are 308 large tanks in the palace. But as time goes by, there are only 231 left. These VATS can be divided into three types: Copper gilded vats, copper vats and iron vats. The early VATS were cast in the reign of Hongzhi of Ming Dynasty (1488-1505). In the Ming Dynasty, the shape of the iron cylinder was extravagant and restrained, simple and generous, and the two ears of the cylinder were added with iron rings. Most of the bronze jars were cast in Qing Dynasty. The two ears of the big jars were equipped with copper rings with animal faces, and the belly was closed with large mouth. The bronze water jars were exquisite in workmanship.