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      Knowledge is Power

      Scientific American July 21, 1917

      Protecting our Timber Resources

      Using the Heliograph to Fight Forest Fires

      • By Arthur L. Dahl on July 21, 1917

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      More in the July 21, 1917 issue of Scientific American
      • An Inexpensive Dialyser for Class use
      • Eliminating Blue Monday from the Navy
      • Science Not Responsible for War
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