Telegraph engineering : a manual for practicing telegraph engineers and engineering students
A 1922 instructional manual on telegraph engineering by Erich Hausmann, published in New York by D. Van Nostrand for working telegraph engineers and engineering students. The plates are line-drawn circuit schematics — keys, relays, sounders, battery stacks, coils, ground symbols and long horizontal line wires, with lettered labels and perforated-tape detail — a vocabulary of electrical symbols and flat wiring layouts.
