Ever since people began using phonographs for pleasure they have found their pleasure marred by the continual necessity of changing needles. Sound engineers have long sought the solution to this annoyance: a needle that would last indefinitely without wearing out phonograph records. Seeking the ideal substance for such a permanent needle, the late Thomas Alva Edison hit upon sapphire,† used it for the needles of his oldfashioned wax-cylinder talking machines as early as 1888. But when modern hard-surfaced records were developed, the sapphire needle fell into discard for musical purposes: it could...
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