Balloon flight and atmospheric electricity
A 1924 NACA technical memorandum on balloon flight and atmospheric electricity, issued by the National Advisory Committee for Aeronautics for aeronautical engineers and researchers. Its pictures are plain line diagrams of equipotential lines, with labelled cloud, balloon and terrain cross-sections in black on white. A designer could take their clean, schematic contour-line style for abstract patterns, scientific layouts or vintage technical diagram treatments.
