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      Memorial Day Sale

      Scientific American March 20, 1920

      Finger Signals for the Motorist, Breaking Away from the Conventional in Mail Airplanes and more

      • By Robert G. Skerrett on March 20, 1920

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      More in the March 20, 1920 issue of Scientific American
      • Strange Things to Eat
      • Iron Castings from Steel Scrap, Using Brick and Wood in Reinforced Concrete and more
      • The Future of the Cotton Industry
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