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RVFM Drinking Bird

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Brand: Rapid  MPN: PH20065 
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A classic toy that is really a heat engine!

The bird demonstrates the cooling effect caused by evaporation of water on its beak. The cooling causes a volatile liquid in the bird's body to condense, then evaporate again as it warms up, constantly changing the balance of the bird's body.

  • Push the bird's head into water to begin the bobbing motion
  • Continues to 'drink' as long as there is water in the container

The bird works best in warmer areas as it relies on there being a sufficient temperature difference between the bird's beak and its surroundings. Should the bird fail to bob, gently heating the glass bulb in the bird's tail with a hair-dryer on a low setting should suffice.
Type Drinking bird


*Question functionality currently disabled

31 January 2019 Question by: Rapid Customer | Product code: 06-6838
Q. How long does each complete cycle take, roughly, eg between drinks?
A. Hi Jonathan, thank you for your question. Approximately 1-2 seconds once at room temperature.

04 November 2011 Question by: Rapid Customer | Product code: 06-6838
Q. I cant get mine to work, I dip the birds beak into the water and it bob's back an forth then it gets slower and slower then stops, the red liquid gets just up the tube just into the head but not enough for it to over balance and dip into the water, help
A. It sounds like the ambient temperature in the room is slightly too low to get liquid in the bird to evaporate. The differential in temperature is what is important. If the liquid is rising most of the way up, the room is probably only a couple of degrees too cool for it to work properly. You should get much better results in a warmer room with cool water.


Still a source of fascination

Reviewed by: Pippa - 06 December 2011
I remeber being enthralled by this as a child when my grandfather had one (it was yellow then and the tubes were opaque, so you could not see how it worked). Now my grandchildren are equally fascinated - I have to make sure his drinking bowl is filled up when they come to see me. My 4 year old grandson provides a running commentary of what is happening - and is starting to understand why! A great example of 'Science is fun'...

Reviewed by: Natalie Winter - 24 June 2009
Lovely! I remember these from 40-odd years ago, and now theyre back! Even my mum-in-law has one and loves it :)

Reviewed by: ATB - 14 March 2009
One of the best toys I have ever owned