Share 'Explorer II Dowmetal Commemorative Coin'

3/16 of an inch; this was the total thickness of Dowmetal that protected the balloonist from the uncertainties of the stratosphere during the the 1934 and 1935 National Geographic Society - U. S. Army Air Corps Stratosphere Balloon Flights.  The Dow Chemical Company in Midland, MI touted their magnesium alloy as the "World's Strongest Light Metal" (it was only two-thirds the weight of aluminum an…