National Defense: Swimming Tractor

One day last week seven tons of Duralumin "tractor," driven by a twelve-cylinder automobile engine, chugged into the surf of Guantanamo Bay and set out to sea. Instead of sinking, the Buck Rogersian vehicle paddled to & fro at ten miles an hour, turned, charged the beach and landed a party of U. S. Marines.*

The occasion marked the latest tests of the Marines' newest fighting machine, no screwball toy but the result of seven years of trial & error by 325-pound Sportsman-Inventor Donald Roebling. Originally conceived by Wire Ropeman John A. Roebling as...

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