Never seen such a clock

What have this clock and the little (rubber) duck in common?

Both need water!

This clock is part of the "Pegelhaus" in Worms and this water level tower is located at the Rhine bank.
Pegel is German for water level. The water level is measured in the tower and the clock shows the current water level. (The back side of the tower has a digital water level display.)
The tower and the hence the clock are nearly 100 years old.

Well, the rubber duck makes most fun when it swims in a bath tob :)