Yeah, this one was a crackup. Apparently because there was so much wood used in the construction of the Forbidden City the emperor was panicked constantly about fire. So much so that they kept dozens of huge copper and iron vats around filled with water to make sure that they could put the fire out should one ever get started. Unfortunately, it gets cold there (yeah, like today) and freezes. How do they make sure that the water doesn't freeze? Yep, you guessed it. They light a fire.