If you are old enough you will remember "television lamps" from the day that people thought watching tv was bad for your eyes if you didn't have another light in the room. They were dim - maybe 40 watt bulb and decorative, usually the light passed through a plastic "shade" that had some landscape scene on it. Really popular were ones that had ocean waves or waterfalls. The effect of moving/falling water was created by having a moving cylinder INSIDE the lamp that rotated. In the case of the waterfall, there were diagonal slots cut in the cylinder so light the light would seem to move down the vertical, giving the effect of falling water. The cylinder would turn as heat from the light bulb passed through vents at the top. I have thought of using this effect behind a waterfall on a layout. Add a little sparkly dust to the clear "water" and it would also give the effect of spray. A test had showed potential but I haven't developed a workable prototype yet.