The Clepsydra or water clock of Canton, China. This water clock was first made in about 1324, and was destroyed and restored many times. It was housed in the Double Gateway in the old city, Canton (Guangzhou). Water dripped from one copper bucket to another, over a twelve hour period. A float on the lowest bucket indicated the approximate time of day and this time was exhibited on a board outside the building. From The Wonders of the World, published c.1920.