Foy–Breguet Telegraph
   HOME

TheInfoList



OR:

The Foy–Breguet telegraph, also called the French telegraph, was an
electrical telegraph Electrical telegraphy is point-to-point distance communicating via sending electric signals over wire, a system primarily used from the 1840s until the late 20th century. It was the first electrical telecommunications system and the most wid ...
of the needle telegraph type developed by Louis-François-Clement Breguet and Alphonse Foy in the 1840s for use in
France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...
. The system used two-needle instruments that presented a display using the same code as that on the
optical telegraph An optical telegraph is a line of stations, typically towers, for the purpose of conveying textual information by means of visual signals (a form of optical communication). There are two main types of such systems; the semaphore telegraph whic ...
of
Claude Chappe Claude Chappe (; 25 December 1763 – 23 January 1805) was a French inventor who in 1792 demonstrated a practical semaphore line, semaphore system that eventually spanned all of France. His system consisted of a series of towers, each within l ...
. The Chappe telegraph was extensively used in France by the government, so this arrangement was appealing to them as it meant there was no need to retrain operators. Most needle telegraph systems moved the needles by means of an
electromagnet An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire (likely copper) wound into a electromagnetic coil, coil. A current through the wire creates a magnetic ...
driven by battery power applied to the line at the sending end. In contrast, the Foy-Breguet telegraph used electromagnets but they did not directly drive the needle. Instead, they operated the
detent A detent is a mechanical or magnetic means to resist or arrest the movement of a mechanical device. Such a device can be anything ranging from a simple metal pin to a machine. The term is also used for the method involved. Magnetic detents are ...
of a clockwork mechanism which released the needle to move on one position at a time. The Chappe telegraph existed in some other countries, but no country besides France tried to duplicate the Chappe telegraph, or any other optical telegraph, as an electrical telegraph. Generally, each electrical telegraph system had a new code developed specifically to suit it. This was problematic for international communications, and in 1855 France abandoned the Foy–Breguet telegraph in favour of the Morse telegraph to bring them into line with the German–Austrian Telegraph Union. Many central European countries were members of this union and they had adopted the Morse system for better interoperability.


Development

The first attempt to bring the
electrical telegraph Electrical telegraphy is point-to-point distance communicating via sending electric signals over wire, a system primarily used from the 1840s until the late 20th century. It was the first electrical telecommunications system and the most wid ...
to France was made by
Samuel Morse Samuel Finley Breese Morse (April 27, 1791 – April 2, 1872) was an American inventor and painter. After establishing his reputation as a portrait painter, Morse, in his middle age, contributed to the invention of a Electrical telegraph#Morse ...
in 1838. He demonstrated his system to the
French Academy of Sciences The French Academy of Sciences (, ) is a learned society, founded in 1666 by Louis XIV at the suggestion of Jean-Baptiste Colbert, to encourage and protect the spirit of French Scientific method, scientific research. It was at the forefron ...
and made a bid for the contract to install a telegraph along the line of the
Paris Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, largest city of France. With an estimated population of 2,048,472 residents in January 2025 in an area of more than , Paris is the List of ci ...
to Saint-Germain railway. However, the French government decided that they did not want to entrust the construction of telegraph lines to private companies. Private operation of telegraph systems had been illegal in France since 1837 and all telegraph infrastructure was owned and operated by the state. Electrical telegraph could only start in France if the government sponsored it. France had the most extensive
optical telegraph An optical telegraph is a line of stations, typically towers, for the purpose of conveying textual information by means of visual signals (a form of optical communication). There are two main types of such systems; the semaphore telegraph whic ...
system of any country, developed for military purposes by
Claude Chappe Claude Chappe (; 25 December 1763 – 23 January 1805) was a French inventor who in 1792 demonstrated a practical semaphore line, semaphore system that eventually spanned all of France. His system consisted of a series of towers, each within l ...
in the
revolutionary A revolutionary is a person who either participates in, or advocates for, a revolution. The term ''revolutionary'' can also be used as an adjective to describe something producing a major and sudden impact on society. Definition The term—bot ...
and Napoleonic periods. There were strong arguments put forward for the superiority of optical telegraphs over electrical telegraphs. Chief amongst these reasons was that electrical systems were vulnerable to attack by
saboteurs Sabotage is a deliberate action aimed at weakening a polity, government, effort, or organization through subversion, obstruction, demoralization, destabilization, division, disruption, or destruction. One who engages in sabotage is a ''sab ...
. In an optical system, only the telegraph stations needed to be defended. An electrical system was impossible to defend over its many hundreds of miles of exposed wires. Alphonse Foy, the chief administrator of the French telegraphs, had a further objection to the Morse system. He believed that his illiterate telegraph operators would not easily be able to learn the Morse code. He did not, however, entirely reject the electrical telegraph. After the Morse system was rejected in 1839, Foy investigated the Cooke–Wheatstone telegraph in use in
England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...
. Foy realised that the needle telegraph displays used by the Cooke–Wheatstone system could be adapted to display the symbols of the French optical telegraph. He asked Louis-François-Clement Breguet to design such a system. It was first tested on the Paris Saint-Cloud to
Versailles The Palace of Versailles ( ; ) is a former royal residence commissioned by King Louis XIV located in Versailles, Yvelines, Versailles, about west of Paris, in the Yvelines, Yvelines Department of Île-de-France, Île-de-France region in Franc ...
line in 1842. Funding for an electrical telegraph was approved in 1844. Foy specified that the new telegraph must show the same display as the Chappe telegraph so that there was no need for operator retraining. This required the display to have three moving parts; the Chappe telegraph had a pivoted crossbar (the regulator) with two moveable arms (the indicators), one at each end of the regulator. A design meeting this requirement was submitted by Pierre-Antoine Joseph Dujardin. Implemented as a needle telegraph, the arrangement required three moving needles, which in turn required three signal wires. The wires were a significant part of the cost of installation; the Morse system, for instance, required only one wire. In May 1845, Foy ran a comparative test between the Dujardin, Breguet, and Cooke-Wheatstone systems on the Paris, Saint Germain to
Rouen Rouen (, ; or ) is a city on the River Seine, in northwestern France. It is in the prefecture of Regions of France, region of Normandy (administrative region), Normandy and the Departments of France, department of Seine-Maritime. Formerly one ...
line. Foy rejected the Dujardin system in favour of the one by Breguet, even though the Dujardin system more fully mimicked the Chappe system than Breguet's. The Breguet design required only two signal wires, but at the expense of having only two moveable needles. These represented the indicators of the Chappe system. The regulator was simply a marking on the face of the instrument, not a moving part—it was permanently in the horizontal position. The disadvantage of doing this is that it drastically reduced the available codespace which in turn impacted the speed a message could be transmitted. The rejection was perhaps due to the economic reason, or perhaps because Breguet was better acquainted with Foy. Breguet had a long history of working with the French telegraph. His grandfather,
Abraham-Louis Breguet Abraham-Louis Breguet (; 10 January 1747 – 17 September 1823), born in Neuchâtel, then a Prussian principality, was a Swiss-French horologist who made many innovations in the course of a career in watchmaking industry, including the tour ...
, a
watchmaker A watchmaker is an artisan who makes and repairs watches. Since a majority of watches are now factory-made, most modern watchmakers only repair watches. However, originally they were master craftsmen who built watches, including all their par ...
, had worked with Chappe on the design of the optical telegraph and Louis inherited the business. The Chappe system used a large
codebook A codebook is a type of document used for gathering and storing cryptography codes. Originally, codebooks were often literally , but today "codebook" is a byword for the complete record of a series of codes, regardless of physical format. Cr ...
with thousands of predetermined phrases and sentences. 92
codepoint A code point, codepoint or code position is a particular position in a table, where the position has been assigned a meaning. The table may be one dimensional (a column), two dimensional (like cells in a spreadsheet), three dimensional (sheets in ...
s were used to specify the line and page of the codebook (see ). There were some early attempts to use a reduced codebook on the Foy–Breguet system, but this was soon dropped in favour of a purely alphabetic code.


France compared to other countries

Many other
Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...
an countries installed optical telegraphs.
Napoleon Napoleon Bonaparte (born Napoleone di Buonaparte; 15 August 1769 – 5 May 1821), later known by his regnal name Napoleon I, was a French general and statesman who rose to prominence during the French Revolution and led Military career ...
extended the Chappe system into conquered territories. Other countries developed their own systems, but none of them were as extensive as that in France. Only the system of
Abraham Niclas Edelcrantz Abraham Niclas Edelcrantz (born Clewberg; 28 July 1754 – 15 March 1821) was a Finnish-born Swedish poet and inventor. He was a member of the Swedish Academy, chair 2, from 1786 to 1821. Edelcrantz was the librarian at The Royal Academy of Turk ...
in Sweden even came close. Consequently, other nations did not have such a strong desire for
backward compatibility In telecommunications and computing, backward compatibility (or backwards compatibility) is a property of an operating system, software, real-world product, or technology that allows for interoperability with an older legacy system, or with Input ...
as France and were able to move to the electrical telegraph sooner. France was unique in requiring the electrical telegraph to mimic the optical telegraph.


Operation

The display of Foy–Breguet telegraph instruments consists of two needles each pivoted at its centre. One half of each needle is coloured black and the other half white. The black part of the needles is meant to represent the indicators of the Chappe telegraph. The white part of the needles is ignored. A bar is marked on the faceplate of the instrument between the pivot points of the needles. This is meant to represent the regulator of the Chappe telegraph, but in the Foy–Breguet system it is purely decorative – it does not move. Each needle can take on any one of eight positions, moving in steps of 45°, resulting in a codespace of 8×8=64 codepoints. Unlike other needle telegraphs, the motive force that rotates the needles is not provided by the electric current on the telegraph line. Instead, it is provided by a
clockwork Clockwork refers to the inner workings of either mechanical devices called clocks and watches (where it is also called the movement (clockwork), movement) or other mechanisms that work similarly, using a series of gears driven by a spring or wei ...
mechanism that has to be kept wound. The winding keys can be seen in the image of the instrument hanging on chains either side of the instrument face. There is a separate key and a separate mechanism for each needle. When it is desired to wind the mechanism, the key is attached to a square winder situated directly below each needle. When current is applied to one of the telegraph lines, the
detent A detent is a mechanical or magnetic means to resist or arrest the movement of a mechanical device. Such a device can be anything ranging from a simple metal pin to a machine. The term is also used for the method involved. Magnetic detents are ...
of the corresponding clockwork mechanism is released by means of the armature of an
electromagnet An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. Electromagnets usually consist of wire (likely copper) wound into a electromagnetic coil, coil. A current through the wire creates a magnetic ...
and the needle advances by 45°. When the current is cut off, the detent is again released and the needle advances a further 45°. The current is applied to both the sending and receiving instrument so that the sending operator can view the resulting transmission. The operator controls the transmission by means of two ''manipulators''. Each of these manipulators has a crank handle which can be set in any one of eight notched positions corresponding to the eight possible positions of one of the needles. As the crank handle is turned through the notches, the battery is alternately connected and disconnected from the line and the local instrument. Thus, current is alternately applied and removed from the mechanism turning the needles. A drawback of the Foy–Breguet system was that it did not use
repeater In telecommunications, a repeater is an electronic device that receives a signal and retransmits it. Repeaters are used to extend transmissions so that the signal can cover longer distances or be received on the other side of an obstruction. Some ...
s over long distances. Other major telegraph systems used
relay A relay Electromechanical relay schematic showing a control coil, four pairs of normally open and one pair of normally closed contacts An automotive-style miniature relay with the dust cover taken off A relay is an electrically operated switc ...
s for this purpose and there were efforts to apply this technology to the French system. This was unsuccessful, which meant that the French system had to employ operators to retransmit messages in some places. The requirement to provide two lines could not be met, or was not economic to meet, on some routes. A single-needle instrument was developed to fill this need. This instrument was mechanically identical to one half of the two-needle version. In fact, it was possible to use one side only of a two-needle instrument with a single line if desired. The coding was the same on the one-needle device except that the positions of the two indicators of each character were sent sequentially instead of in parallel. This reduced the transmission speed to 16–18 wpm.


Connection to England

A
submarine telegraph cable A submarine communications cable is a cable laid on the seabed between land-based stations to carry telecommunication signals across stretches of ocean and sea. The first submarine communications cables were laid beginning in the 1850s and car ...
was laid from England to France by the
Submarine Telegraph Company The Submarine Telegraph Company was a British company which laid and operated submarine telegraph cables. Jacob and John Watkins Brett formed the English Channel Submarine Telegraph Company to lay the first cable across the English Channel. An un ...
in 1851. In the UK, the
Cooke and Wheatstone telegraph The Cooke and Wheatstone telegraph was an early electrical telegraph system dating from the 1830s invented by English inventor William Fothergill Cooke and English scientist Charles Wheatstone. It was a form of needle telegraph, and the first ...
was in use, which used a different code. This meant that at the English end, both a Foy–Breguet operator and a Cooke–Wheatstone operator were required so that messages could be recoded between the two systems. The Foy–Breguet system was faster to send and read (between 24 and 46 wpm) than the Cooke–Wheatstone. A Foy–Breguet operator could instantly see the letter being transmitted from the visual pattern, whereas the Cooke–Wheatstone operator had to count the left and right deviations of the single needle.


Withdrawal

For a decade France maintained a mixture of optical telegraph and electrical telegraph systems on its network. The Foy-Breguet system ensured that operators could easily be transferred from the optical to the electric systems, although many optical operators (semaphorists) declined to become
telegraphist A telegraphist (British English), telegrapher (American English), or telegraph operator is a person who uses a telegraph key to send and receive Morse code messages in a telegraphy system. These messages, also called telegrams, can be transmitte ...
s when their lines were updated. The semaphorists were largely rural workers on isolated stations used to taking on the responsibilities of carrying out mechanical repairs by themselves. After all, if the equipment broke down, they no longer had the means to call for assistance. Telegraphists were located in offices with management and service personnel on hand. They were forbidden from attempting any kind of repair and had a more paperwork intensive job. Despite its advantages in the French context, the uniqueness of the French system eventually led to its decline. During the 1850s, as international telegraph traffic grew, having different telegraph systems in different countries became increasingly problematic. Direct connections were not possible and operators had to be employed to recode messages crossing borders. The code that was later to become known as
International Morse Code Morse code is a telecommunications method which Character encoding, encodes Written language, text characters as standardized sequences of two different signal durations, called ''dots'' and ''dashes'', or ''dits'' and ''dahs''. Morse code i ...
was adopted in several countries. It was first used on Hamburg railways and was devised by Friedrich Clemens Gerke. This code was a heavily modified version of the original American Morse code and was known as the Hamburg code or Gerke code. Gerke's code was adopted in 1851 by the German-Austrian Telegraph Union which represented many central European countries. In 1855, France also adopted the code and replaced the Foy–Breguet telegraph equipment with the Morse system.Holzmann & Pehrson, p. 94


References


Bibliography

* Aitken, Frédéric; Foulc, Jean-Numa, ''From Deep Sea to Laboratory 1'', John Wiley & Sons, 2019 . * * Coe, Lewis, ''The Telegraph: A History of Morse's Invention and Its Predecessors in the United States'', McFarland, 2003 . * Haigh, Kenneth Richardson, ''Cableships and Submarine Cables'', Adlard Coles, 1968 . * Huurdeman, Anton A., ''The Worldwide History of Telecommunications'', Wiley, 2003 . * Holzmann, Gerard J.; Pehrson, Björn, ''The Early History of Data Networks'', Wiley, 1995 . * Roberts, Steven, ''Distant Writing: A History of the Telegraph Companies in Britain between 1838 and 1868''
ch. 13 "The companies abroad"
accessed 4 March 2020. * Shaffner, Taliaferro Preston
''The Telegraph Manual''
Pudney & Russell, 1859 . * Turnbull, Laurence
''The Electro-magnetic Telegraph''
A. Hart, 1853 .


External links

* Berghen, Fons Vanden
"Louis Breguet et ses appareils télégraphiques"
''Les Cahiers de la FNARH'', pp. 14–25, no. 111, Fédération Nationale des Associations de personnel de La Poste et d'Orange pour la Recherche Historique, 2009 (in French). Includes many photographs of French telegraph instruments. {{DEFAULTSORT:Foy-Breguet telegraph Telegraphy History of telecommunications in France