Compass Confusion

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Physics Puzzler

Compass Confusion

Out of luck in the Outback


Donald Simanek Emeritus Professor of Physics, Lock Haven University of Pennsylvania

University of Pennsylvania

Using a magnetic compass. Photo courtesy of the United States government printing office.A Colorado outdoorsman vacationing in Australia wished to explore the outback on foot. He packed his gear, which included a fine magnetic compass passed down to him from his great-great-grandfather, who had been an explorer of the American West. The compass was an expensive one, made by the prestigious Tait Instrument Company of Philadelphia.

While hiking in the outback, he found that his compass wasn't functioning well at all. Its needle was sluggish, dragging on the base of the compass, so he was unwilling to trust it. Thanks to some helpful and savvy Aborigines, who never used compasses, he found his way back to civilization. He related his sad story to his Australian friends. They examined his compass and saw the finely engraved lettering "Tait's Compass" on the case. "We've seen this before when you blokes from the states bring along one of these old compasses. We have a saying 'He who has a Tait's is lost.'"

What was the problem with the compass, and how might our intrepid explorer have overcome it?

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