This is the Sasa Clock, by Þórunn Árnadóttir. It really is quite amazing, but time consuming. It's basically a large beated circle on a spinning wheel, but -
Each beat represents five minutes. One beat falls down every five minutes.
The white beats represent one hour.
Silver and gold beats represent midnight and noon.
To find out what time it is you have to find either the gold or silver beat and count from it the hours and then mintes.
I saw it here.