How to Make a Perpetual Motion Water Drinking Toy Bird

How to Make a Perpetual Motion Water Drinking Toy Bird
••• tam_odin/iStock/GettyImages

A perpetual motion drinking bird is powered by the heat differential between its head and tail. In an upright position, the felt bill of the bird is wetted, cooling it by evaporation. The contraction of the gas in the head leads to pressure reduction, which leads to methyline chloride in the tail bulb being sucked up. After becoming top-heavy, the bird drops forward. Its head dunked in cold water, the methylene chloride from the tail (both gas and liquid) cools and withdraws back into the tail, the two bulbs now in equilibrium.

Dunking Bird

    Fill one of the two glass bulbs with methylene chloride.

    Insert a glass tube into the filled bulb, almost to the bottom, then seal the bulb opening around the tube.

    Seal the second bulb onto the top of the tube, except for a small opening for evacuation.

    The tube should not extend into the top bulb, since the liquid should be able to evacuate from the top bulb easily.

    Evacuate the air and seal the top bulb entirely.

    Attach an external clamp to the middle of the tube, with small arms.

    Set the arms in a stand. The stand should be designed so the bird is never fully erect, but leaning forward at least a little. This way, any top-heaviness turns into its dropping forward to be cooled in a cup of water.

    Cover the top bulb with felt hood, preferably with a felt tip for a bill.

    When “dunking,” the liquid level will drop enough in the tail bulb that warmer gas from the tail will escape to the head bulb to be cooled by the wet felt. The liquid will then drain into the tail bulb, and the bird will right itself again.

    Things You'll Need

    • Glass tube
    • Two glass bulbs
    • Methylene chloride
    • Glassware experience
    • Evacuation equipment


    • Some trial and error may be required to see how much methylene chloride makes the dunking work the best for your size of bulbs and the distance you insert the tube.

Related Articles

How Does the Perfume Atomizer Work?
How to Make an Eyedropper Syringe
How to Make a Sodium Silicate Solution
How to Calculate Static Head
How to Extract Water From Ink, Milk, and Vinegar
Taking Care of Bobwhite Quail Chicks
How to Make a Copper Sulfate Solution
How to Read a Weather Swan Barometer
How to Rubberize an Egg
How to Fill a Water Barometer or Storm Glass
Jet Propulsion Science Projects
How to Sterilize Petri Dishes
Types of Mixing Valves for an Oil Furnace Boiler
How to Test Oil Viscosity
The Migration of Hummingbirds to South Florida
How Does the Condenser in a Fluorescent Lamp Work?
How to Concentrate a Solution
How to Calculate Load Current
How Do Electric Hot Water Heater Check Valves Work?