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Telegraph Key - E. A. Machin, Reversing, circa1911 Object Reg. No: ST 043254

Summary:
Reversing telegraph key used for the transmission of signals in the electric telegraph system.

This type of key was used in conjunction with long submarine telegraph cables which distorted electrical signals so that the normal on-off pulses used in land telegraphy to mark the dots and dashes of Morse code would not work. Instead, the direction of flow of signal current was changed so that current flowing in one direction signalled a dot and in the other direction a dash. The reversing key used two separate keys, one for each direction of current flow.

At the receiving end the sequence of current pulses were displayed as a wavy line on a moving paper tape which could be interpreted by the operator .

Manufactured in Melbourne by E. A. Machin & Co. sometime in the period 1907-1915. Similar to keys made by Elliott Bros., London.
Description:
Reversing telegraph key, with two brass contact spring blades with ebonite knobs. Mounted on a wooden base. Brass screw terminals.
Acquisition Information:
Unknown from Unknown
Discipline: Technology
Dimensions: 54 mm (Height), 101 mm (Width), 125 mm (Length)

More information

Tagged with: electrical apparatus instruments, electrical switches, morse keys, physical apparatus instruments, telegraph equipment, telegraphy
Themes this item is part of: Australia and the global telegraph network 1854-1902, The Australian telegraph network 1854-1877, Telegraphy Collection, Information & Communication Collection, Science & Measurement Collection
Primary Classification: COMMUNICATIONS
Secondary Classification: Telegraphy
Tertiary Classification: components
Inscriptions: Base engraved:
"E.A. MACHIN & CO.
MAKERS
377 ELIZABETH STREET"
Maker: E. A. Machin & Co., Melbourne, Victoria, Australia, circa 1910

Sands & McDougall's Melbourne Directories list Machin, Ernest A. & Co., scientific instrument makers, at 377 Elizabeth Street, Melbourne for the years 1907-1915. From 1916, the address changed to 413-415 Elizabeth Street. Thus seems likely that this object was manufactured in Melbourne by E.A. Machin & Co during the period 1907-1915.
Bibliography:
  1. [Catalogue] 1895. Elliott Brothers (London) Catalogue., E4, 1895, Page 86, item 809 Pages

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