In the famous fairytale by the Brothers Grimm a donkey, a dog, a cat and a cock decide to become musicians in Bremen, a Hanseatic town in Northern Germany. Here we see the donkey hammering tirelessly at the keyboard - as long as sand is running, while his colleagues are looking from behind.

The mecanical sculpture is powered by a sand motor. From a hopper in the upper part of the model. Sand trickles onto a lever like in an hour glass. Under the weight of the sand the lever comes down lifting up the forelegs. Forelegs and lever are connected by a toothpick as an axle. The sand gllides down from the sloping lever and it raises up again - the donkey's hooves fall down onto the keys.