Elementary telegraphy : a manual for students; written specially to meet the requirements of the ordinary grade of the subject as published in the syllabus of the city and guilds of London Institute
A students' manual of telegraphy by Henry Walter Pendry, published in London and New York by Whittaker & Co. in 1910 for candidates preparing the City and Guilds ordinary grade examination. Line diagrams show batteries, relays, keys, switchboards and up- and down-line instruments joined by thin wire paths, plus hatched earth returns — usable as circuit motifs, schematic symbols and sparse technical linework.
