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Navy's Super-Airship Nears Completion

Incandescent Refrigerators

By Henry Norris Russell


By Albert A. Hopkins

Salt Domes

By M. F. Knoy

Which Races Are Best?

Why Science Can Not Admit Racial Differences in Intelligence

By G. H. Estabrooks

More About the Great Siberian Meteorite

By J. G. Crowther

The Ultimate in Skyscrapers?

By Andrew J . Eken

From the Archeologist's Note book

An Industry That Was Made-To-Order

By A. E. Buchanan

A Twenty-Four Hour Automatic Market

Electricity Runs this Typewriter

How Big is a Quantum?

By Paul R. Heyl

Clemenceau and Foch

A Biographical Study of Two Fearless Frenchmen

By W. D. Puleston

Wanted: A Wild Rice Harvester

By Lawrence W. Pedrose


  • Departments

    Across the Editor's Desk, May 1931

  • Back of Frontispiece, May 1931

  • Millions of Hand Stitches on Acres of Cloth

  • Our Point of View, May 1931

  • Lightning, Benefactor of Mankind, New Paint Resists Corrosion and more

  • Current Bulletin Briefs, May 1931

  • Foreign Telephone Patent Suit Settled, Glass Trademark Upheld and more

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