Beautiful Simplicity (part 2)

Don't you think, that there is a beauty in simple solutions? Do you know some beautiful-simple devices?

(pictures from Wikipedia if not stated otherwise.)

1) Hydraulic Ram (Water Ram) -- a device pumping the water up, using kinetic energy of flowing water.

2) Valveless pulse jet motor, -- it is working, even though there are no moving parts: (also look here: http://www.home.no/andreas.sunnhordvik/English/mechanical/valveless_e.htm )

3) Thermoacoustic heat engine / Stirling Motor -- only moving parts are piston, crank and flywheel (Wikipedia has a bit poor pictures, but Youtube has better films: Thermoacoustic Heat Engine)

4) Solar cooker (solar oven)

5) Pot-in-Pot refrigerator (Zeer)

6) Thermoelectric generator -- converting heat into electricity

7) Air Well -- device that collects water vapour from air and converts into liquid water.

8) Crystal Radio -- powered by energy of radio waves: