The Engineering of the Drinking Bird

I would make a Darkman reference, but I'm guessing nobody would get it.

Maybe a Simpsons reference would be better.

This video goes through the liquid evaporating on the head of the bird...causing cooling in the head...causing a decrease in pressure in the head...causing the lower bulb's greater pressure to push the liquid into the head...causing the center of gravity of the bird to shift slightly forward...causing the liquid in the base to drop below the level of the inner tube...causing the vapor from the bottom bulb to flow through the tube and equalize pressure between the two bulbs and liquid to shift back down...the process repeats as long as the bird'd beak can 'drink' to stay wet and - as Bill points out - the humidity is low enough to allow evaporation.

This is also how hand boilers work.

I'd never heard the temperature difference's connection to heat engines (referenced previously on the blog). That's a nice connection there, Bill.