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 lodestone held in the hand. This arrangement was perhaps copied from the compass of the Phoenician sailors, who buoyed a lodestone and observed it set towards the north. There is reason to believe that the magnet was employed by the priests of the Oracle in answering questions. We are told that the Emperor ValeriusValens [sic], while at Antioch in 370, was shown a floating needle which pointed to the letters of the alphabet when guided by the directive force of a lodestone. It was also believed that this effect might be produced although a stone wall intervened, so that a person outside a house or prison might convey intelligence to another inside.

This idea was perhaps the basis of the sympathetic telegraph of the Middle Ages, which is first described in the Magi Naturalis of John Baptista Porta, published at Naples in 1558. It was supposed by Porta and others after him that two similar needles touched by the same lodestone were sympathetic, so that, although far apart, if both were freely balanced, a movement of one was imitated by the other. By encircling each balanced needle with an alphabet, the sympathetic telegraph was obtained. Although based on error, and opposed by Cabeus and others, this fascinating notion continued to crop up even to the days of Addison. It was a prophetic shadow of the coming invention. In the Scepsis Scientifica, published in 1665, Joseph Glanvil wrote, 'to confer at the distance of the Indies by sympathetic conveyances may be as usual to future times as to us in literary correspondence.'

Dr. Gilbert, physician to Queen Elizabeth, by his