Tools of Telegraphy Page 3
Page 1- Leg Key, Legless Key, Local Sounder, Mainline Sounder
Page 2- Morse Relay, Bug, KOB, Box Relay
Page 3- Barclay Box Relay, Candlestick Resonator, Swing-arm Resonator, Cordless Jackbox
Page 4- Sideswiper, Repeater, Polar Sounder, Register, Gravity Battery, Insulators
Barclay Box Relay
The "Barclay" set is another form of box relay. It has a resonant 5 sided box made of brass. The sixth side is made of thin wood. The fixed contact is attached to the thin wood. This makes the Barclay design very efficient at amplifying the sound. The Barclay design is significantly smaller than the conventional box relay, making it more desireable for portable use. This set was wound to 150 ohms. It was made by the Western Electric Company. The key was also made by Western Electric.
The resonator focuses the sound from the receiving device (the sounder) so that the operator can receive Morse messages in noisy environments. A resonator is nothing more than a wooden box in which a sounder is mounted. Telegraph offices were often located in busy train stations. Central telegraph offices sometimes contained dozens of sounders in a a single room. This must have been incredibly noisy ! When copying Morse using a typewriter (commonly called a "mill" by telegraphers), the clicking sound of the typewriter is practically indistinguishable from the clicks of a sounder. Without a resonator to focus the sound on the telegrapher's ear, it would have been almost impossible to copy using a mill. This example is a "Mascot" candlestick style resonator by Bunnell. The sounder is is a 4 ohm local sounder also by Bunnell.
Swing Arm Resonator
This is the so-called "swing arm" resonator. Swing arm resonators can have one, two, or three arms. The multi-jointed arm allows the resonator to be moved very close to the operators ear. This is especially convenient for copying with a mill. The swing arm's base can be mounted to the rear of the desk, which means it takes little usable desk space. It can be moved out the way when not in use, which is extremely convenient for a busy operating desk. The swing arm was manufactured by the White Company of Worcester, Massachusetts. The wood resonator was made by Bunnell.
Most telegraph offices were connected to more than one wire. Each wire was connected to a mainline sounder. The mainline "calling" sounder was used to monitor the traffic on the wire. If the office call was heard on the calling sounder, the "cordless jackbox" was used to switch that circuit to the relay and local sounder. The desired circuit was selected by inserting the plug into the appropriate jack. Contacts inside the jackbox transferred the circuit from the mainline sounder to the relay and local sounder. The plug was nothing more than a brass rod. No wires or cords had to be connected to the plug thus the name "cordless jackbox". This rather beaten up example is labelled "W.U.T. CO. CORDLESS TABLE JACK UNIT 2-A". It will handle 3 telegraph circuits.
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