Historical Telegraph Key Diagram - Labeled Mechanical Sending Device #3523312 (License: Personal Use)

This black-and-white technical illustration depicts a mechanical telegraph key, likely from the late 19th or early 20th century, featuring labeled parts such as the lever (L), spring (e), contact screw (s), base mounting (m), and tension adjusters (α, n). The device operates by pressing the lever to close an electrical circuit, generating pulses for Morse code transmission. Fine hatching indicates metal construction and precise engineering typical of period telegraphy equipment.

Used in educational articles, museum exhibits, or historical tech blogs about early telecommunications; targets users researching Morse code, telegraph history, or antique communication devices.