Strange Attraction Civity)
HISTORICAL NOTE and then quenched to freeze in the nec essary hardness and magnetic traits (such as improved retentivity and coer Strange Attraction civity). After 1855 it was known that adding tungsten or manganese Each year, several million tOns of Petrus Peregrinus de Maricourt (Peter improved carbon steel as a permanent metal are produced for use as magnetic the Pilgrim) described in detail the use magnet. materials in many everyday devices and of a compass for navigation. He processes common to all of us-from believed that the lodestone derived its Many different families of magnetic radio communication, information stor power from the sky. Apparently on one alloys have come into use since the age, telephone receivers, and stereo of his long voyages, Peter the Pilgrim beginning of this century. At the turn of speakers to electric motors, transform played with a sphere of magnetite, the 20th century Sir Robert Hadfield ers, and generators. All these things exploring its surface with bits of iron. invented iron-silicon alloys, which have would have completely baffled the He discovered that lines of magnetic especially high permeabilities in the ori shepherd Magnes 2500 years ago when, force circled the sphere and seemed to entation in which the alloy passes according to legend, he stepped on a intersect at two opposite places on the through the rolling press. Chrome-steel lodestone (magnetite). Pliny the Elder globe, which he named "poles" in anal alloys were developed in 1917, and until wrote of Magnes, "the nails of whose ogy to the Earth's poles. It wasn't until 1930 the only commercially available shoes and the [iron] tip of whose staff more than three centuries later in 1600, permanent magnets were made of car stuck fast in a magnetick field while he though, that William Gilbert, physician bon-steel, chrome-steel, or tungsten pastured his flocks." to Queen Elizabeth I, proposed that the steel.
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