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During my last summer in New Jersey, I audited an astronomy course at Rutgers. While explaining the Coriolis force, the professor told a great story. He said that there was a WW I naval battle in the Southern Hemisphere in which the Germans beat the British because their engineers were more farsighted. The Brits’ gunsights were designed to correct for the Coriolis force in the Northern Hemisphere only — in the Southern Hemisphere it put their shots even further off the mark. The Germans’ gunsights, on the other hand, could be switched to compensate for the reversed effects of the Coriolis force in the Southern Hemisphere.

If you search the web, you’ll find several references to this anecdote, with variations.

The Goddard Space Flight Center Question of the Week:

In World War I, during a naval battle near the Falkland Islands (off the east coast of South America, about 52 degrees south latitude) between the German and British Navy, British gunners were surprised to see their salvos falling 100 yards to the left of the German ships. The engineers who designed the sighting mechanisms were well aware of the Coriolis deflection and had carefully considered it, however, they neglected the fact that not all sea battles occur in the Northern Hemisphere. Thus, during the engagement, the initial British shots fell at a distance from the targets equal to twice the Coriolis deflection.

The Weather Notebook:

During an embarrassing battle in World War I, British battle cruisers engaged two German warships, at a range of nearly ten miles, near the Falkland Islands, but forgot to reverse their Coriolis correction. The British gunners at first couldn’t figure out why their artillery was falling astray. They had adjusted the guns. But instead of setting them off to the right to account for the left turn of the Coriolis force in the southern hemisphere, they set them off target to the left, like they did in the northern hemisphere. So, the missiles ended up missing two times more than had they not made any adjustments.. Ultimately, the British eventually won the battle with about sixty direct hits, but not before more than a thousand shells had fallen into the ocean.

PBS TeacherSource:

This discussion all seems very dry and academic. It was all too real and deadly in the World War I naval battle near the Falkland Islands. This engagement between British and German fleets occurred at about 50 degrees, southern latitude. The guns were calibrated for northern latitudes. It would seem that the great powers at that time never expected a large-scale naval engagement to occur outside of European waters.

And more. This site cites Classical Dynamics of Particles and Systems as a source for this story. This one credits The Flying Circus of Physics.

Today, at the San Francisco Public Library, I looked at Geoffrey Bennett’s Coronel and the Falklands and Naval Battles of the First World War. There were two important Southern Hemisphere naval battles in WW I — the Germans won near Coronel, Chile on November 1, 1914. The British dispatched more ships, and beat the Germans near the Falklands on December 8.

There are myriad references to these battles on the web.

Not one of them mentions the Coriolis force, or shells mysteriously missing their targets. Neither do Bennett’s books. All of them agree that in both battles, both sides were doing damage to each other as soon as they were in range. In fact, the only references to the Brits’ failing to correct for the Coriolis force I can find are in physics lessons by Americans.

I suppose someone asserted it at some point and it was such a great story that it stuck with people (as it did with me.) And it’s been propagated without anyone bothering to check it.

These lessons consistently go to pains to debunk the myth that water flushes in opposite directions on opposite sides of the equator due to the Coriolis force. And in accord with some sort of conservation of myth principle, they substitute another.