Wind Powered Prayer Wheels

With all the current talk about "alternative" energy sources, it is amusing to recall that "spiritual engines" have been with us for a very long time. Above, are some wind powered prayer wheels worth noting. It would appear they have gearing which permits spinning in the correct direction, which is always an issue. The two examples below seem to rely on the shape of the vanes (is that the correct term?) to provide correct direction. I am always interested in wind powered prayer wheels, so if anybody has any examples, please bring them to my attention.