Frequency measurements in wireless telegraphy
A 1911 engineering thesis by William Henry Hyslop, submitted at the University of Illinois, on measuring frequency in early wireless telegraphy circuits, written for examiners and fellow radio researchers. The plates are plain line schematics printed on toned paper: hand-drawn helical coils, paired dots for spark gaps, capacitor plates, aerial and ground symbols, and italic letter labels, useful as early electrical diagram vocabulary or sparse linear ornament.
