This 1955 cover depicts a supersonic wind tunnel being built at the Ames Aeronautical Laboratory in Mountain View, Calif. Now known as the Ames Research Center, it has been a major NASA research center since the agency’s founding in 1958. The Unitary Plan Wind Tunnel at Ames was designed for aerodynamics research, with air speeds in the transonic and supersonic ranges—up to 3.5 times the speed of sound. The wind tunnel circuits are huge steel conduits that follow rectangular plans. Diameters vary from 20 ft to 70 ft, and steel thickness ranges from 0.5 in. to 4.5 in. It was made of 15,000 tons of heavy plates of low-carbon steel that had good weld characteristics. Cylindrical sections of steel plate were joined by automatic welding while they were slowly rotated, but much of the welding was done by hand. Welds were inspected by x-ray and magna flux, and the completed shells were subjected to vacuum tests.…