The drinking bird novelty item has been around for decades, but it's seemingly simple design is deceptive. Carefully calculated physics principles have gone into the creation of this toy. Mostly, it utilizes energy conversion, operating as a heat engine that changes heat energy from water into mechanical work.
The drinking bird design is made up of several important components:
-two glass bulbs of equal size attached on either end of a glass tube
-a fuzzy, absorbent material to cover the bird's head
-two plastic legs connected to the body with a pivot
-a small amount of methylene chloide (industrial paint stripper and solvent) liquid in the bottom glass bulb
-either a red or a blue hat, depending on the model
For the toy to work, the felt tip on the bird's beak must be dipped into a cup of water, which then allows it to absorb a small amount of that water. As the water in its beak evaporates, the temperature in it goes down, which causes the methylene chloride vapor to condense. When this happens, liquid from the bottom bulb is forced upward, toward the head and beak portion. Then, as liquid enters the head, the bird becomes top-heavy and slowly begins to tip forward once again. As the drinking bird does tip, the rest of the liquid goes to the bird's head and the bottom portion of the tube isn't submerged any more. Vapor then travels back up the tube which will then cause the head to drain of liquid again. As the bottom glass bulb is filled with liquid again, the bird becomes more bottom heavy and the entire process begins again.