Resistance of Transparent Plastics to Impact
A 1939 NACA technical note from the National Advisory Committee for Aeronautics, issued as a government research report on impact resistance of transparent plastics for aircraft windshields and enclosures, written for engineers and test laboratories. Its plates are black-and-white photographs of test apparatus: metal and wooden specimen frames, a falling-cart and Charpy impact rig, and a compressed-air gun, each captioned with a figure number. A designer might take from them the plain industrial look of laboratory fixtures, with bolted steel rings, clamped frames and gauge-equipped machinery.
