Measurements of vertical air currents in the atmosphere
This is a 1931 NACA technical memorandum on measuring vertical air currents, issued by the National Advisory Committee for Aeronautics for aviation researchers and meteorologists. The pictures are plain black-and-white line charts: vertical profiles of balloon paths and temperature layers, plotted over grids with contour lines and annotated altitude scales, plus one photograph of a wave cloud. A designer could take their dense technical linework, grid rules and hand-lettered labels as a model for scientific diagrams.
