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Indicator - Wheatstone Alphabetical Telegraph System, circa 1858 Object Reg. No: ST 008476

Indicator from a Wheatstone ABC telegraph system.

This indicator is a component of one of the first electric telegraph systems which could be used easily by non-skilled operators. It did not require the operator to learn morse or any other code.

The Wheatstone ABC telegraph system allowed the transmission of telegraph messages without requiring an operator skilled in the use of morse code. The system consisted of a generator, a communicator and an indicator, all mounted on a common base. The communicator had a circular dial with the letters of the alphabet marked around its periphery. Opposite each letter on the communicator dial was a key. The generator was a magneto device which produced a series of current pulses when the operator turned a handle projecting from the base of the unit. The indicator had a circular dial with the letters of the alphabet marked around its periphery and a needlle pivoted at the centre of the dial.

To transmit a letter, the appropriate key on the communicator was depressed and the handle of the generator was turned. A number of pulses corresponding to the selected letter was transmitted over the telegraph wire to the indicator of the receiving station and the needle rotated to indicate the received letter.

The Wheatstone ABC telegraph system was patented in 1858.

Wheatstone ABC telegraphs were used in Victoria in areas where the amount of telegraph traffic did not justify the employment of an operator. They were also used on private lines such as that between the Melbourne 'Argus' newspaper office and the reporters' gallery in Victorian Parliament House.
Circular instrument with a brass case and a white dial. Dial is marked with the letters of the alphabet around its periphery. Inside the ring of letters is ring of numbers. A pointer pivoted in the centre of the dial can move to indicate a particular letter or number. The pointer is mounted on a wire coil which can rotate between the poles of a magnet mounted on the back of the instrument.

The instrument is mounted on the sloping front of a hollow wooden rectangular case. Four brass screw terminals are located on the vertical back of the case, together with a pivoted vertical brass strip which can be moved to make or break connections between two of the terminals.
Discipline: Technology
Dimensions: 150 mm (Height), 173 mm (Width), 150 mm (Length)

More information

Tagged with: telegraphy
Themes this item is part of: Sir Charles Wheatstone - a biography, Copy of text for label for Wheatstone's Alphabetical Telegraph, 1916, The Wheatstone ABC Telegraph, Telegraphy Collection, Information & Communication Collection
Primary Classification: COMMUNICATIONS
Secondary Classification: Telegraphy
Tertiary Classification: input/output
Inscriptions: The dial is marked above the needle pivot with the words:
"C. Wheatstone"
and below the needle pivot with the word:

A small circular metal plate, about 12 mm diameter, on the front of the case, below the dial, is embossed with the number:

Two small circular metal plates, each about 14 mm in diameter, on top of the case are inscribed "A" and"T" respectively.
Inventor: Sir Charles Wheatstone, England, Great Britain, circa 1858
References: http://en.wikipedia.org/wiki/Charles_Wheatstone - accessed 3 December 2008

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