Drinking Bird Perpetual Motion (2 Pack) The Original Vintage Retro Magic Sippy Dipping Bird A Science Wonder Wholesale Bulk Set of 2. This incredible scientific toy is a childhood favorite. Call it a game, Science experiment, educational, an office desk toy, call it what you like. This novelty is great for all ages. A great physics thermodynamic gadget and perpetual motion desk, school or office toy. Just dip the birds head into a glass of water and soak his head. Adjust the middle metal piece to sit just below the center of his body. Place a glass of water in front of him so when he dips down he will be able to wet his beak and head. The Thermodynamics should kick into action. It is really cool to see the Happy Bird in motion rocking, bobbing and dipping up and back to get his fill of drink. To operate the Dippy Bird, you get its head wet. As the water evaporates, fluid moves up into the head, causing the bird to become top-heavy and dip forward. Once the bird dips forward, fluid moves back into the abdomen, causing the bird to become bottom-heavy and tip up. Here is how a Dippy Bird works: When water evaporates from the fuzz on the Dippy Bird's head, the head is cooled. The temperature decrease in the head condenses the methylene chloride vapor, decreasing the vapor pressure in the head relative to the vapor pressure in the abdomen. The greater vapor pressure in the abdomen forces fluid up through the neck and into the head. As fluid enters the head, it makes the Dippy Bird top-heavy. The bird tips. Liquid travels to the head. The bottom of the tube is no longer submerged in liquid. Vapor bubbles travel through the tube and into the head. Liquid drains from the head, displaced by the bubbles. Fluid drains back into the abdomen, making the bird bottom-heavy. The bird tips back up. If the bird dips into a cup of water, the fuzzy material absorbs water again and the cycle starts over.