Wankel Rotary Island

At your country estate construct a pond in the shape of a peritrochoid (see link). It doesn’t need to be very deep, but the walls should be smooth and vertical, perhaps lined with brick or concrete. Fill with water, fish, etc.

In this pond build an equilaterally-triangular floating platform or “island”. It should be big enough that all three corners touch the walls of the pond. Put wheels or rollers at the corners so that they can easily roll along the walls. Place soil, plants, and park benches on the platform to make it look like a real island.

Next, divert some water from the nearest brook. Make the water flow into the pond through inlets located on the “sides” or short axis of the pond. Allow water to drain out through outlets on the “ends” or long axis of the pond.

Voila! Because of water’s natural tendency to seek the lowest level, your island will rotate and revolve in a majestic fashion as the water babbles around.