This time keeper, erected on the top story of the North Worshipping Tower, in the Han dynasty (BC 206), was the invention of a well-known General, named Chin Tau, who was proclaimed "King of the South". It consists of four large brass pots, named after the Sun, the Moon, the Star and the Planet. At the bottom of each pot, there is a little whole, through which the water trickles in drops one after the other, and to a well said to be hidden underneath the Planet, from which the ooze ends. It was so designed that there need no supply of water by any human hand but by a natural source of another well leading to the Sun. - The reading gauge, which bears letters of the 12 hours, (each divided into 8 parts of quarters), begins to pop up from inside "The Planet"at the fourth hour of Mau (i.e. at dawn of day), according to the proportion of water that the latter receives, and it drops down again when the water has finished a days trickling. The North Worshipping Tower was built by Chin Tau, for the prupose of paying respect to the Emperor in the North every morning.