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Sketch and diagram for Delco cut-out relay.

Delco

Sketch and diagram for Delco cut-out relay.

Method of "Crowning" the spring, Delco Ignition Relay.

Ignition Relay

Method of "Crowning" the spring, Delco Ignition Relay.

"Diagram illustrating one type of time-limit relay." —Croft 1920

Time-limit Relay

"Diagram illustrating one type of time-limit relay." —Croft 1920

"With a long main-line and many instruments in circuit, the resistance may be so great as to render the main-battery current so feeble that it cannot operate the sounder with sufficient energy to render the signals distinctly audible. This difficulty is met by introducing a 'local battery,' and a 'relay' at each station on the line." -Avery 1895

Telegraph Relay

"With a long main-line and many instruments in circuit, the resistance may be so great as to render…

"A complete telegraph system, displaying batteries, keys, receivers, relays and local batteries on both ends." -Avery 1895

Complete Telegraph System

"A complete telegraph system, displaying batteries, keys, receivers, relays and local batteries on both…

"...two stations...each being furnished with a neutral relay, connected as [shown] and also each with a sounder and key, at each of which an operator is seated..." -Atkinson 1903

Telegraph with Neutral Relay

"...two stations...each being furnished with a neutral relay, connected as [shown] and also each with…