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      Knowledge is Power

      Scientific American July 07, 1917

      A Telephone Instrument that is Designed after the Human Ear, Providing the Bolt with a Nut that Stays in Place

      • By E. A. Dime on July 7, 1917

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      More in the July 07, 1917 issue of Scientific American
      • Re-introducing the Concrete-and-Steel Fortification, Morality at Newport, and more
      • Electricity- July 7, 1917
      • Recently Patented Inventions- July 7, 1917
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