Three hundred and fifty years ago, long before Newton was born, at a time when the motions of freely falling bodies were first being carefully observed and analyzed, William Gilbert, the physician of Queen Elizabeth I, was collecting facts about magnets. These he published in his famous book De Magnete. Magnets were, at the time, thought of as curios having occult and magical properties. These Gilbert reviewed, but in addition he performed a most extraordinary feat of synthesis. He collected data on the orientation of compass needles carried around the surface of the earth earth by mariners and showed that the enormously varied observations could all be described by means of one basic assumption, that the earth itself was a magnet.

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