We stopped at a little tourist attraction on the equator. It had the usual features—bathrooms (not necessarily to First World standards), lots of handicrafts, and a snack bar—but also it had a sign for the equator, sold certificates that you had been there, and did a little scam in the form of a physics demonstration (see below).

(The pictures on this page aren't clickable.)

The red pail has a hole punched in the bottom. The demonstrator carefully filled it with water from the blue pitcher and floated the match in it, letting the water drain back back into the pitcher. When he did this 5 or 6 meters north of the equator, the match circled clockwise; 5 or 6 meters south of the equator, counterclockwise; close to the equator, the water drained straight down, so the match didn't circle.

This is supposed to demonstrate the Coriolis effect, which really is the reason for hurricanes' rotation. However, the effect is strong only over long distances, and in something as small as a bathtub, let alone a toy pail, it's too weak to see except under laboratory conditions. (The water in my bathtub sometimes swirls clockwise and sometimes counterclockwise.) Also, the effect is particularly tiny near the equator, which is natural as it's zero at the equator.

I tried the demonstration myself. If I poured the water in with my right hand, it drained counterclockwise; with my left hand, clockwise. That's because I was pouring it in slightly behind the center. The demonstrators must have been doing something similar.

Also, the Coriolis effect on draining water has the same direction as on a hurricane, since in both the flow is toward the center. I couldn't quite remember this at the time (shame on me), but hurricanes in the northern hemisphere are counterclockwise. The people at the tourist stop demonstrated the wrong direction!

To their credit, the demonstration was free, though it might have helped induce people to spend $5 on a certificate. (We did.)