Properties and preparation of ceramic insulators for spark plugs
A 1920 technical report from the NASA Technical Reports Server, a historical engineering document about electrical insulators and spark plugs, prepared for engineers and researchers studying ceramic materials. The pictures are scientific charts and a test apparatus diagram: a labelled furnace setup with thermocouple and wiring, plotted curves of log resistance against temperature, current-over-time polarization traces, and conductance graphs. A designer could draw on their clean, grid-based line plotting, dense annotation and monochrome technical drawing style.
