How Does the M.C. Escher Waterfall Machine Work?

I think it may actually be one continuous apparatus, just with a bit of slight-of-hand. The water could very well be flowing up the trough. This is how I think it works:

a) There is a piece or plastic/plexiglass just above the wood’s surface.

b) The bottom “ramp” is actually stepped or sloped down from where the water is poured in front of the wheel.

c) The water enters the plastic/wood channel via gravity and then moves up the other slopes by capillary action. The pressure at the entry point by the wheel is greater than the pull of gravity on the water. It would readily flow up and out of the “top” where the pressure is lower.

d) The structure is a bit of an optical illusion as I don’t believe the slopes are as steep as they appear, and it is shot from a very particular angle.

At least that’s my guess.