From the May 16, 1931, issue

FOUR-MILE-PER-MINUTE WIND POSSIBLE IN NEW TUNNEL

An artificial windstorm blowing 240 miles per hour has been found possible in the remarkable wind tunnel recently constructed at Pasadena for the California Institute of Technology. The outfit is a feature of the new Guggenheim Aeronautical Laboratory. This velocity exceeds the original hopes of the designers.

A wind tunnel enables airplane investigators to reverse the conditions of normal flying with obvious experimental convenience.