The drinking bird, also known at the happy drinking bird, the dippy bird or the nodding bird, is a classic physics toy used to demonstrate a range of scientific principles, or just as a great desktop toy.
The drinking bird, when its beak is dipped in a beaker of water placed in front of it, will begin 'drinking' steadily. The bird will slowly tip forward, until the beak dips into water. It will then tip upright and then slowly begin to tip again. The 'drinking' motion will continue as long as there is a constant supply of water.
The drinking bird has been created in a number of different designs, but all have the same basic features. The drinking bird itself is made of two glass bulbs, one with an extruded 'beak', joined by a tube.
This glass structure is balanced via arms attached to the tubes on a stand, allowing the bird to pivot.
The bird contains a volatile liquid such as ethanol, which is coloured to make it easier to observe the movement of liquid within.
This one experiment manages to demonstrate a whole range of physical laws, including the combined gas law, the ideal gas law, the Maxwell-Boltzmann distribution, the heat of vaporisation, torque, centre of mass and capillary action.