Novelty items, in particular novelty toys, can provide mere seconds or endless
hours of enjoyment, depending upon the level of enlightenment already achieved by
their owners. An important factor in the success of novelty items is their
ingenuity. Here, in the amusement of the inane and bored masses, science has a vital
part to play. While drinking straw glasses can make one look silly for a few minutes,
a toy that can dumbfound those unaware of the principles behind it can make one
look silly for an entire lifetime. The drinking bird is one such toy.

The drinking bird, as its name suggests, is a fascinating albeit not very life like toy that perpetually 'drinks' from any glass of water you care to put in front of it. Its ingenuity lies in the fact that, aside from looking rather wet and
bedraggled at its head, it does not appear to take on any of the water. So where does it all go and what on earth is it that can make an inanimate object so thirsty?

Anatomy Of A Drinking Bird

The bird is made of four essential parts¹: armature (body), pivot (hips and legs), wick
(head) and guts (inner liquid). The armature consists of a glass tube attached to two
glass bulbs, one at either end. The tube opens out into the upper bulb, while extending
to near the bottom of the lower bulb like a straw in a drink. The very bottom of the
tube is for the most part immersed in the liquid.

The pivot consists of a horizontal bar clamped about the middle of the armature by a piece of metal tubing
and two upright stands (legs) with holes drilled at the same height, into which the bar
can fit loosely. The bar is bent backwards slightly (or are concave
dorsally²) at the points where it makes contact with the legs so that
it is inclined to lean forwards.

The wick consists of a fuzzy material that coats the upper bulb and beak of the
bird. The liquid inside must be suitably dense and viscous (i.e. not very either) and
have a low latent heat of evaporation (ld). The ld of water is 2250
kJ/kg (kilojoules per kilogram), the ld of ethanol is 880 kJ/kg, while that of
methylene chloride is 406, making it more efficient and a preferred choice. The
ld of mercury is only 281, however it is dangerous and expensive, though it
would look rather pretty. Most modern drinking birds contain Freon-11. Freon is a
chemical used to cool fridges and freezers.

How It Works

The bird is an example of a 'heat engine' where a difference in temperature is
converted into cyclical motion. To start the bird in motion, the head must first be
soaked in water. As the water evaporates, it draws heat from inside the head, forcing
the vapour within it to condense. The loss of heat and contraction of vapour results in
an imbalance of pressures between the head and the lower bulb (which for the sake of
consistency we shall call the abdomen). The vapour in the abdomen pushes down to
compensate, forcing liquid up the tube and reducing the volume of vapour in the head
in the process. Meanwhile, as the pressure in the abdomen decreases, more
evaporation occurs, creating more vapour, therefore more pressure, forcing more
liquid upwards.

The rising liquid raises the centre of mass of the bird to the point where it can no
longer stay upright and tips forwards into the glass. The level of liquid in the bulbs
has been set so that when the bird 'dips' the bottom of the tube is exposed. The angle
of dip allowed by the pivot has also been calculated so that a bubble of vapour can
rise through the tube and allow the liquid to drain back into the abdomen, tilting the
bird back. The head, charged with more water from the glass, continues the seemingly
never-ending cycle of bird-thirst.

The visual effect of the dipping cycle is thus, beginning at the dip. The force from
the liquid draining back into the abdomen tips the bird back and creates a
pendulum-like rocking motion. As the liquid rises through the tube, the swinging
motion slows and the magnitude of each swing decreases. This is because the liquid
mass has become more evenly distributed throughout the armature (rather than
pooling at the bottom, which would allow the rocking to continue for a while longer).
As the liquid level nears the point of overbalance, the rocking has all but stopped. The
liquid continues to rise, almost unbidden. Slowly but surely the head tips into the
water, and stays there until most of the liquid has drained back into the lower bulb (a
few seconds at most). It is this pause that gives the appearance of drinking, rather than
simple ducking.

The length of a dipping cycle depends upon the heat and humidity of the
surrounding air, and the amount of time a bird can continue drinking is dependent on
these same factors (remember, no water in the glass means no dipping, and the water
is used up by evaporation). Many minutes of research have brought the researcher to conclude that Britain has a
fairly good climate for drinking birds. Studies carried out on drinking birds in many
parts of America tend to be stifled by heat and humidity. The average cycle of the researcher's
drinking bird (from dip to dip) lasts approximately 50 seconds.

The Many Guises Of The Bird

The drinking bird has no one patent on it, and so has been produced numerous
times by several manufacturers with varying quality. It has acquired several different
identities in the process. The instructions for the researcher's model refer to it as a 'Miracle Toy'.
Other aliases include 'Dippy Bird', 'Happy Dippy Bird' and 'Magic Bird'. Whatever its
called, the characteristic 'look' of the bird is one that, for reasons unknown to this
researcher, most manufacturers adhere to. This consists of large feet (usually booted,
for stability), a single, brightly coloured tail feather (anything that insulates the lower
bulb could effect the bird's performance) and a hat that falls somewhere between
early twentieth century gentleman and hideously dressed tap dancer. In spite of this
clear transgression in fashion sense, 'Dippy' has attracted quite a following, both
among the learned and the psychtropified. Type 'drinking bird' into a search engine
and be astonished by the amount of curiosity it generates in physics teachers and
complete numskulls alike.

Another topic that remains in question is the species of the bird. While many have
suggested that they are ducks³, it is this researchers belief that this is not the case. Several facts
point to this. Firstly, the lack of plumage (i.e. a singular feather) means that the bird
would fail to be recognised by other ducks, as well as being unsuitable for life in
water⁴. Secondly, the abundance of fuzz on the beak, essential to its
survival (or at least its drinking habits), has not yet been reproduced by
nature⁵. This researcher
believes that the drinking bird is of an entirely separate species, temporarily named
infinidippicus thirstae⁶.

How To Stop The Madness

You now know who it is, what it is, how it works and why it is so compulsive.
But what if you just can't stand it? If a friend or a loved one owns a drinking bird that
drives you crazy, here's how to stop it in its fuzzy, wobbling tracks.

• Empty The Glass: After a while the bird will stop. However, the threat
  still remains.
• Insulate the Abdomen: Drinking birds are quite sensitive, so much so
  that natural human skin oil can affect their performance. Insulating the lower bulb
  may reduce its motion, thereby reducing damage to your sanity.
• De-fuzz The Head: Removing the absorbent properties of the head may
  drastically reduce the bird's thirst.
• Just Get Rid Of The Damn Thing: This verges on the criminal and may
  cause grief or argument within the family. The researcher accepts no responsibility
  for this. You have been warned.

Some Final Words Of Warning

If you have or intend to purchase a drinking bird, always read the instructions
carefully and handle with care. Remember, more than simply a toy, it is also a
drinking companion.

The following precautions were advised by the makers of 'Miracle Toy'

1. Beware of cat. ⁷
2. Do not keep in sunlight.
3. Be careful to assemble. ⁸
4. Don't disturb the place. ⁹

If you wish to purchase a drinking bird, visit your local novelty toy store or
contact a general scientific wares supplier. Alternatively, get a life.