Drinking Bird - a novel heat engine





This is a classic toy. The Drinking bird swings, taking regular sips of water until it runs out of water. The toy often runs for days at a time despite just using evaporation of water to power the device. A great demonstration of thermodynamics.

When drinking bird’s head gets wet and it will bob back up, the water on the head starts to evaporate which lowers the temperature of the glass head. The lowered causes some of the red vapour in the head to condense which in turn creates a drop in pressure in the head. The base of the drinking bird’s body is warmer and at a higher pressure, so the liquid in the body pushes up toward the head. As the liquid rises, the drinking bird’s head becomes top heavy and so tips over. The bottom end of the neck tube rises above the surface of the liquid in the drinking bird’s body. A bubble of warm vapour rises up the tube through this gap, displacing liquid as it goes. Liquid flows back to the bottom bulb and the pressure equalizes. The weight of the liquid in the bottom bulb restores the bird to its vertical position. And, so a thermodynamic cycle is created that keeps the drinking tipping over and over again.

For more infomation about the drinking bird click here
  • Demonstrates of thermodynamics
  • Only requires water to work
  • Classic toy
  • Super quick/easy to assemble/adjust
  • Made from glass
  • Often runs for days


video play button


Price: £5.99 in



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Ideal for ages 8+.
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