Aeronautical education and research at the Swiss Institute of Technology in Zurich
This is a NACA technical memorandum, number 616, issued by the National Advisory Committee for Aeronautics, and catalogued under a 1931 Zurich aeronautics title. The two pictures are engineering line drawings of wind tunnels, one a closed-circuit tunnel with a test chamber, compressors and motor, the other a free-jet tunnel shown in longitudinal section and plan with a honeycomb, nozzle and fan. A designer might take the clean technical diagram style, with thin dimension lines, hatched ground and numbered scale bars, as a model for schematic or infographic layouts.
