From the website:
The ChronArte Canna is a spectacular wall clock with real liquid display. A unique design feature for generous and timeless rooms. The twelve crystalclear tubes fill like a cascade with colored water. Minute by minute, hour by hour. When all are filled, the system empties and the cycle begins anew. Continuously flowing water as a symbol for time and its passing. Time as an endless river. Realized with modern means.
http://en.wikipedia.org/wiki/Water_clock