What are some advantages to the water clock?

* Accuracy: Water clocks are very accurate, as the flow of water is constant and can be easily measured.

* Simplicity: Water clocks are relatively simple to construct and maintain.

* Reliability: Water clocks are very reliable, as they do not require any complex machinery.

* Low cost: Water clocks are relatively inexpensive to build and operate.

* Environmental friendliness: Water clocks do not produce any pollution.