For some reason I was thinking about that theory of how water goes down a plug hole in different parts of the world - I believed in the Northern hemisphere it went in a different way to the southern hemisphere.NOT SO .. BBC1's "Bang goes the theory" says:So your sink is too small and drains too quickly for the Earth's spin to control how the water flows. But the effect could possibly happen, in a big enough bath. How big?Research done by Ascher Shapiro in the early 1960s in Boston, USA did report a tendency for water to swirl anti-clockwise (viewed from above). Scientists in Sydney, Australia copied his method and described seeing clockwise swirling.The experimental baths were perfectly circular and nearly 2m in diameter. The water was 15cm deep and Shapiro allowed it to stand for 24 hours so that any currents from filling would die down. The plug was on the outside and could be removed without disturbing the water. A small outlet meant the water took about half an hour to drain away.By eliminating all the other disturbances that they could, the two research teams at 42°N and 33°S of the Equator did find an apparent influence from the Coriolis effect.Something to try at home ?

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