As I was reading chapter three, the author mentioned previous methods of telling time, by ways of sundials, hourglasses and clepsydras. I was aware of the former two methods but had never heard of the latter. Most likely because it is the most ancient man made method of telling time. I was interested in seeing what these clocks looked like and as I began researching them I realized that there are many, many designs of water clocks from all over the world. The earliest known water clocks came from Egypt, China and India, predating 4000 BC ! Water clocks essentially all worked with the same method, by way of either an outflow or later an inflow of water and a measuring device on the inside of the water basin.
Image 1: ancient outflow water clock from 16th century Egypt.
Water drips out of a hole in the bottom of the basin at a consistent speed and 12 markings on the inside of the other basin marked the passing of ‘hours’.
Image 2: Inflow water clock from 19th century Greece
The hour indicator ascends as the water flows in, and a series of gears rotate a cylinder to correspond to the temporal hours. This device is also one of the earliest controlled systems and possibly one of the first ancestors of today’s industrial robot devices.