The Efficiency of Small Bearings in Instruments of the Type Used in Aircraft
A 1921 technical report from the NASA Technical Reports Server, a government aeronautics research document on small bearings for aircraft instruments, written for engineers and testers. Its pictures are plain black-and-white line drawings of bearing mechanisms with labelled screws and a photograph of a bench-mounted test rig, useful to a designer for their clean mechanical diagram style and stripped-down industrial look.

