Robert Fludd's design to build a perpetual motion machine that would keep water flowing without end was certainly an interesting idea. It was a great attempt at "beating the system" to keep motion going without an end. The idea was to design wheels in a way to allow water to flow down, causing a wheel to turn. As the wheel turns, it turns a screw type of tube which would make the water to flow back upward.
This is a great idea and the concept looks great. But the problem is that friction causes the entire process to lose energy. It may work for a while, but as the energy is lost, the machine would come to a halt. But if you were to add some energy, that would allow it to continue forever.