History Weblecture for Unit 31
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At the same time that Newton was crafting a new vision of the world as a kind of machine, with the motions of objects precisely defined by the external forces operating on them, William Gilbert provided a different view, in which a kind of internal "life" force created attraction and repulsion through magnetism. Like William Harvey and Andreas Vesalius, he was physician to royalty, in this case, to Elizabeth I of England. His position made him financially secure, and his light duties when the Queen was healthy left him time to work on various scientific investigations.
Gilbert was fascinated by the operation of compasses. The discovery that lodestone, rocks embedded with highly magnetized iron, could cause wires to move lies so far back in human history that we do not know the discoverer or even the first culture to play with the phenomena. By the fourteenth century, however, sailors were using simple compasses to sail out of sight of shore and still navigate their way when the pole star was not available to identify one's course.
It was widely known that two lodestones or two "charged" pieces of iron would repel or attract one another, depending on how the stones were positioned. Gilbert concluded that since a magnetized compass needle responded to its surroundings by reorienting itself, regardless of where on earth it was, the earth itself must be a magnet.
Read the biography of William Gilbert, archived from the University of Jerusalem's Institute of Chemistry site.
Look through David Stern's article on De Magnete.
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