Bad Astronomy: Misconceptions and Misuses Revealed, from ...

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PPPPPP
Flushed with Embarrassment:
The Coriolis Effect and
Your Bathroom
I t’s
a pretty scene. Nanyuki is a small town situated just north
of the equator where it cuts across Kenya in Africa. The town
was founded early in the twentieth century, and still has something
of a frontier feel to it.
It’s a frequent stop for tour buses on their way to nearby Mount
Kenya. It has the seemingly mandatory gift and curio shops, but it
also features a local man named Peter McLeary. As tourists gather
around, McLeary shows them a demonstration they are not likely
to forget. More’s the pity.
McLeary takes the tourists to a line drawn on the floor of an
old burned-out hotel, and tells them that it’s the actual location of
the equator. A glib speaker, he explains that water swirls down a
drain clockwise north of this line and counterclockwise south of it,
an effect caused by the rotation of the Earth.
He then goes on to prove it. He takes a small, roughly square
pan about 30 centimeters across and fills it with water. He places
some matchsticks in it so that his audience can see the rotation
more easily. Walking to one side of the line and turning to face his
audience, he pulls out a stopper, letting the water drain out. Sure
enough, when he does this demonstration north of the equatorial
line the water drains clockwise, and when he repeats the experiment
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