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      The Sciences

      Shadow-Testing of Gear Teeth, The Radio Typewriter for Airplanes

      • By Allen P. Child, George H. Dacy on March 1, 1923
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      ABOUT THE AUTHOR(S)

        Recent Articles by Allen P. Child

        • Clay Needles for the Talking Machine, The Rocking of a Tall Chimney and more

          Recent Articles by George H. Dacy

          • Our Agricultural Ellis Island
          • Why Headlight Glare?
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