Prussian semaphore system
Encyclopedia
The Prussian Semaphore System was a telegraphic communications system
Telegraphy
Telegraphy is the long-distance transmission of messages via some form of signalling technology. Telegraphy requires messages to be converted to a code which is known to both sender and receiver...

 used between Berlin
Berlin
Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...

 and the Rhine Province
Rhine Province
The Rhine Province , also known as Rhenish Prussia or synonymous to the Rhineland , was the westernmost province of the Kingdom of Prussia and the Free State of Prussia, within the German Reich, from 1822-1946. It was created from the provinces of the Lower Rhine and Jülich-Cleves-Berg...

 from 1832 to 1849. It could transmit administrative and military messages by optical signal over a distance of nearly 550 kilometres (341.8 mi). The telegraph line comprised 62 stations each furnished with a signal mast with six cable-operated arms. The stations were equipped with telescopes that operators used to copy coded messages and forward them to the next station. Three dispatch departments (telegraphische Expeditionen) located in Berlin
Berlin
Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...

, Cologne
Cologne
Cologne is Germany's fourth-largest city , and is the largest city both in the Germany Federal State of North Rhine-Westphalia and within the Rhine-Ruhr Metropolitan Area, one of the major European metropolitan areas with more than ten million inhabitants.Cologne is located on both sides of the...

 and Koblenz
Koblenz
Koblenz is a German city situated on both banks of the Rhine at its confluence with the Moselle, where the Deutsches Eck and its monument are situated.As Koblenz was one of the military posts established by Drusus about 8 BC, the...

 handled the coding and decoding of official telegrams. Although electric telegraphy made the system obsolete for military use, simplified semaphore
Semaphore
A semaphore telegraph, optical telegraph, shutter telegraph chain, Chappe telegraph, or Napoleonic semaphore is a system of conveying information by means of visual signals, using towers with pivoting shutters, also known as blades or paddles. Information is encoded by the position of the...

s were still used for railway signals
Railway semaphore signal
One of the earliest forms of fixed railway signal is the semaphore. These signals display their different indications to train drivers by changing the angle of inclination of a pivoted 'arm'. Semaphore signals were patented in the early 1840s by Joseph James Stevens, and soon became the most...

.

Historical background

At the time of construction of the Prussia
Prussia
Prussia was a German kingdom and historic state originating out of the Duchy of Prussia and the Margraviate of Brandenburg. For centuries, the House of Hohenzollern ruled Prussia, successfully expanding its size by way of an unusually well-organized and effective army. Prussia shaped the history...

n semaphore system, the technology had already been known for thirty years. It was based on earlier designs by Claude Chappe and his brother which were in use in France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 on many telegraph lines from 1794.

Soon Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....

, Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...

, and England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

 also had working optical telegraph systems while couriers remained in use throughout Germany. The states that existed in German-speaking areas at the end of the 18th century were uninterested in a communications system that crossed multiple borders and the political conditions did not exist to put the necessary treaties and agreements in place among these states. Countries such as Sweden, England and France had the necessary centralized control for such a project, and they confronted political, military and economic challenges such as securing long coastlines, and controlling sea routes. They were therefore far more motivated to build an advanced communications network.

Prussia was at that time the second largest German state in terms of area and it saw no structural or political necessity for the introduction of telegraphy after the Congress of Vienna
Congress of Vienna
The Congress of Vienna was a conference of ambassadors of European states chaired by Klemens Wenzel von Metternich, and held in Vienna from September, 1814 to June, 1815. The objective of the Congress was to settle the many issues arising from the French Revolutionary Wars, the Napoleonic Wars,...

 of 1814-1815. Plans for the construction of a first telegraph line were delayed by resistance from the conservative Prussian military
Prussian Army
The Royal Prussian Army was the army of the Kingdom of Prussia. It was vital to the development of Brandenburg-Prussia as a European power.The Prussian Army had its roots in the meager mercenary forces of Brandenburg during the Thirty Years' War...

, even when the usefulness of mobile telegraphy in war is taken into account. It was exactly this technology that was used with success by Napoleon Bonaparte and this at least awakened the interest of the Prussian military.

However, Prussia was confronted with a fragile domestic political situation in its western provinces at the beginning of the 1830s. Nobles and liberals from the Rhine region were opposed to the administration in Berlin. They were strengthened in their movement for a national constitution by the July Revolution
July Revolution
The French Revolution of 1830, also known as the July Revolution or in French, saw the overthrow of King Charles X of France, the French Bourbon monarch, and the ascent of his cousin Louis-Philippe, Duke of Orléans, who himself, after 18 precarious years on the throne, would in turn be overthrown...

 in France and the revolution in Belgium
Belgian Revolution
The Belgian Revolution was the conflict which led to the secession of the Southern provinces from the United Kingdom of the Netherlands and established an independent Kingdom of Belgium....

 in 1830. In this time of turmoil, urgent official messages traveled slowly by courier on horseback. This was unsatisfactory to the Prussian military, therefore, the proponents of a telegraph network could finally execute a plan for a line from Berlin to Koblenz via Cologne.

The technical idea and the initiative to build the then longest telegraph line in central Europe came from the Geheime Postrat
Geheimrat
Geheimrat was the title of the highest advising officials at the Imperial, royal or principal courts of the Holy Roman Empire, who jointly formed the Geheimer Rat reporting to the ruler...

 Carl Philipp Heinrich Pistor. Pistor wrote a memorandum
Memorandum
A memorandum is from the Latin verbal phrase memorandum est, the gerundive form of the verb memoro, "to mention, call to mind, recount, relate", which means "It must be remembered ..."...

 to the Prussian General Staff in December 1830 which laid out a draft proposal for a telegraph line within the Royal Prussian States. Pistor’s ideas were inspired by the Englishman Bernard L. Watson whose designs were based on the “Second Polygrammatic Telegraph” of William Pasley. The design went back to 1810 and consisted of a mast with six telegraph arms. Pistor took the six-arm principle and thoroughly reworked the mechanics of the construction. Further, his workshop developed the optical telescopes which were a necessary component of the system. The order for the construction of the system was finally given by an order of the Prussian Cabinet
German Imperial Military Cabinet
The Prussian Military Cabinet or the German Military Cabinet was a military institution under the direct command authority of the Prussian king and German emperor for handling personnel matters of the army officer corps....

 on July 21, 1832.

The Prussian system remained the only state-run optical telegraph system within German territory. There were also a couple of examples of privately-run systems. The first existed between 1837 and 1850 and was created by the Altona
Altona, Hamburg
Altona is the westernmost urban borough of the German city state of Hamburg, on the right bank of the Elbe river. From 1640 to 1864 Altona was under the administration of the Danish monarchy. Altona was an independent city until 1937...

 businessman Johann Ludwig Schmidt who operated it as a signal system for ships between the mouth of the Elbe
Elbe
The Elbe is one of the major rivers of Central Europe. It rises in the Krkonoše Mountains of the northwestern Czech Republic before traversing much of Bohemia , then Germany and flowing into the North Sea at Cuxhaven, 110 km northwest of Hamburg...

 at Cuxhaven and Port of Hamburg. From 1841, this system was run by Friedrich Clemens Gerke
Friedrich Clemens Gerke
Friedrich Clemens Gerke was a German writer, journalist, musician and pioneer of telegraphy who revised the Morse code in 1848. It is Gerke's notation which is used today.-Life:...

, a pioneer in telegraphy for whom the modern telecommunications tower
Friedrich-Clemens-Gerke Tower
Friedrich Clemens Gerke Tower is a 230 metre tall telecommunication tower of reinforced concrete at Cuxhaven in Germany. Friedrich Clemens Gerke Tower, which is named after Friedrich Clemens Gerke, was completed in 1991 and is not accessible for tourists...

 in Cuxhaven is named. The second, also created by Schmidt was inaugurated in 1847. This system ran between Bremen
Bremen
The City Municipality of Bremen is a Hanseatic city in northwestern Germany. A commercial and industrial city with a major port on the river Weser, Bremen is part of the Bremen-Oldenburg metropolitan area . Bremen is the second most populous city in North Germany and tenth in Germany.Bremen is...

 and Bremerhaven
Bremerhaven
Bremerhaven is a city at the seaport of the free city-state of Bremen, a state of the Federal Republic of Germany. It forms an enclave in the state of Lower Saxony and is located at the mouth of the River Weser on its eastern bank, opposite the town of Nordenham...

, but this second system was taken out of service by 1852 because a competing electric telegraph line that was placed into service at almost the same time.

Construction and Function

As with later telegraph operations, the responsibility for the construction of the entire system fell to the Prussian Military. Major Franz August O'Etzel led the construction. O'Etzel studied in Berlin and Paris and trained as pharmacist. He knew the Rhineland
Rhineland
Historically, the Rhinelands refers to a loosely-defined region embracing the land on either bank of the River Rhine in central Europe....

 as he had previously done survey work in the region. Along with the construction, O'Etzel also concerned himself with the necessary codes for transmitting messages. He wrote the codebook
Codebook
A codebook is a type of document used for gathering and storing codes. Originally codebooks were often literally books, but today codebook is a byword for the complete record of a series of codes, regardless of physical format.-Cryptography:...

s for the line. Once construction was complete, he was given the title of “Director of the Royal Prussian Telegraph” and he oversaw the operations of the entire system.

Route

The line began with Station #1 at the old Berlin Observatory
Berlin Observatory
The Berlin Observatory is a series of observatories and related organizations in and around the city of Berlin in Germany, starting from the 18th century...

 in Dorotheenstrasse. The construction of the first section – with fourteen stations – was completed by November 1832. The route ran via the Telegraphenberg in Potsdam
Potsdam
Potsdam is the capital city of the German federal state of Brandenburg and part of the Berlin/Brandenburg Metropolitan Region. It is situated on the River Havel, southwest of Berlin city centre....

 across Brandenburg an der Havel to Magdeburg
Magdeburg
Magdeburg , is the largest city and the capital city of the Bundesland of Saxony-Anhalt, Germany. Magdeburg is situated on the Elbe River and was one of the most important medieval cities of Europe....

.

The locations of the stations were chosen by O'Etzel himself. In choosing, he took into consideration of existing structures - for example the village church in Dahlem
Dahlem
Dahlem can refer to:*Dahlem , a district of Berlin, part of the borough Steglitz-Zehlendorf.*Dahlem, North Rhine-Westphalia, a municipality in western Germany.*Dahlem, Rhineland-Palatinate, a municipality in south-western Germany....

. He also had his team construct towers on existing tall buildings.

In many places along the route, trees had to be felled or have their tops cut off in order to maintain the sight lines between stations. French telegraph operators had already recognized that signals were hard to recognize if they came from stations placed before certain backgrounds, while signals from stations against an open sky were much easier to recognize. For this reason, the Prussian stations were built on higher ground where necessary. Later, such places were often designated as “Telegrafenberg” as with Glidow (station #5) or station #13 southeast of Biederitz
Biederitz
Biederitz is a municipality in the Jerichower Land district, in Saxony-Anhalt, Germany....

. Because the receipt and distribution of messages was intended only for dispatch stations at the beginning and end of the line, no great value was placed on connecting smaller localities and cities. Frequently, stations were placed away from settled areas. The last station of the first section was constructed on the tower of the Johannis-Kirche in Magdeburg
Magdeburg
Magdeburg , is the largest city and the capital city of the Bundesland of Saxony-Anhalt, Germany. Magdeburg is situated on the Elbe River and was one of the most important medieval cities of Europe....

.

To hasten construction of the second and longer section between Magdeburg and Koblenz, the finance minister as well as the interior minister ordered all their subordinates to offer their total cooperation to the construction leadership. This was done to avoid time-consuming territorial conflicts between local authorities. If an agreement over the acquisition of a piece of land for the construction of a new station was not possible, expropriation of private lands could be undertaken in the worst case. The line ran north of Egeln
Egeln
Egeln is a town in the Salzlandkreis district, in Saxony-Anhalt, Germany. It is situated on the river Bode, approx. 15 km northwest of Staßfurt, and 25 km southwest of Magdeburg....

 (Schloss Ampfurth), through Halberstadt
Halberstadt
Halberstadt is a town in the German state of Saxony-Anhalt and the capital of the district of Harz. It is located on the German Half-Timbered House Road and the Magdeburg–Thale railway....

, Goslar
Goslar
Goslar is a historic town in Lower Saxony, Germany. It is the administrative centre of the district of Goslar and located on the northwestern slopes of the Harz mountain range. The Old Town of Goslar and the Mines of Rammelsberg are UNESCO World Heritage Sites.-Geography:Goslar is situated at the...

, Höxter
Höxter
Höxter is the seat of the Höxter district, and a town in eastern North Rhine-Westphalia on the left bank of the river Weser, 52 km north of Kassel in the centre of the Weser Uplands...

 to station #31 near Entrup where it turned in a southwesterly direction just before reaching Paderborn
Paderborn
Paderborn is a city in North Rhine-Westphalia, Germany, capital of the Paderborn district. The name of the city derives from the river Pader, which originates in more than 200 springs near Paderborn Cathedral, where St. Liborius is buried.-History:...

 after crossing the Weser Uplands. Subsequently, it ran along the southern side of a line connecting Salzkotten
Salzkotten
Salzkotten is a town in the district of Paderborn, in North Rhine-Westphalia, Germany. The name Salzkotten is based on the former salt production, which gave Salzkotten its raison d'être...

, Erwitte
Erwitte
Erwitte is a town in the district of Soest, in North Rhine-Westphalia, Germany.-Geography:Erwitte is situated approx. 8 km south of Lippstadt and 15 km east of Soest.- Neighbouring municipalities:* Lippstadt* Geseke* Rüthen* Anröchte...

, Soest
Soest
-Places:* Soest, Netherlands* Soest, Germany** Soest , a district around the location in Germany-Organizations:*SOEST, School of Ocean and Earth Science and Technology at the University of Hawaii at Manoa...

, Werl
Werl
Werl is a town located in the district of Soest in North Rhine-Westphalia, Germany.-Geography:Werl is easily accessible because it is located between the Sauerland, Münsterland, and the Ruhr Area...

, Iserlohn
Iserlohn
Iserlohn is a city in the Märkischer Kreis district, in North Rhine-Westphalia, Germany. It is the largest city by population and area within the district and the Sauerland region.-Geography:...

, Hagen
Hagen
Hagen is the 39th-largest city in Germany, located in the federal state of North Rhine-Westphalia. It is located on the eastern edge of the Ruhr area, 15 km south of Dortmund, where the rivers Lenne, Volme and Ennepe meet the river Ruhr...

, Schwelm
Schwelm
Schwelm is a town in the district of Ennepe-Ruhr-Kreis in the administrative region of Arnsberg within the state of North Rhine-Westphalia.It's a town that's noted for the famed basketball player Virgil Matthews.-Geography:...

 and Lennep it made its way finally to Cologne
Cologne
Cologne is Germany's fourth-largest city , and is the largest city both in the Germany Federal State of North Rhine-Westphalia and within the Rhine-Ruhr Metropolitan Area, one of the major European metropolitan areas with more than ten million inhabitants.Cologne is located on both sides of the...

 via the stations Schlebusch
Schlebusch
Schlebusch is a surname of German origin. It is derived from the German word for a thorn bush. The family name was originally "von Schlebusch" which may indicate a title. . The first recorded name bearer of the surname Schlebusch was, Arnoldus de Rode von Schlebuschrode tracing back to 1174...

 (station #49), and Flittard (#50). From there he route ran parallel to the east bank of the Rhine via Spich to Ehrenbreitstein
Ehrenbreitstein
Ehrenbreitstein may refer to:, a district of Koblenz* Ehrenbreitstein Fortress * Ehrenbreitstein , the hill on which the fortress stands on the east bank of the Rhine...

. The final station (#60) was built into the Fortress Ehrenbreitstein. After the completion of construction and the start of operations of the whole system in 1833, it quickly became clear that the Rhine ferry crossing to Koblenz presented a major hold up in telegraphic traffic. This could only be solved by expanding the line with an end station in Koblenz. In the same year, station #61 was put into service in the Electoral Palace in Koblenz, which was then used as a barracks. The palace also served as the administrative offices for the western section of the route.

The route traveled over Hanoverian domain at stations #22 and #23 in Schladen
Schladen
Schladen is a municipality in the district of Wolfenbüttel, in Lower Saxony, Germany. It is situated on the river Oker, approx. 15 km south of Wolfenbüttel, and 25 km south of Braunschweig....

 and Liebenburg
Liebenburg
Liebenburg is a village and a municipality in the district of Goslar, in Lower Saxony, Germany. It is situated within the eastern Innerste Uplands, approx...

. Likewise, stations #23 through #28 lay in the domain of the Duchy of Brunswick
Duchy of Brunswick
Brunswick was a historical state in Germany. Originally the territory of Brunswick-Wolfenbüttel in the Holy Roman Empire, it was established as an independent duchy by the Congress of Vienna in 1815...

. Negotiations with both governments for the acquisition of land and the construction of stations quickly met with success. Additionally, two stations were economized within the Brunswick domain by increasing the distance between stations #23, 24, and 25. After a year of service, it became clear that the wide interval between these stations led to frequent interruptions in visual contact during drizzly and grey weather. In 1842 this problem was solved with the construction of station #24a near Mechtshausen. The entire route now comprised 62 stations. They were on average 11 kilometres (6.8 mi) apart with the longest distance separating stations at 15 kilometres (9.3 mi) and the shortest at 7.5 kilometres (4.7 mi).

There were only two dispatch stations, one at each end of the line. Koblenz was the seat of the Oberpräsident of the Rhine Province and the western headquarters of the Prussian defense force. Messages could neither be sent nor received from the obviously larger and more important economic and transportation center of Cologne. Messages arriving in Cologne from England or Belgium
Belgium
Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...

 addressed to Berlin had to first be sent by courier to Koblenz and then from there telegraphed again through Cologne to Berlin. This whole process caused a day’s delay. Hence, in 1836, a third dispatch bureau was opened at the Cologne telegraph station of St. Pantleon.

Stations

The common functional element of all of the telegraph stations was the ca. 6.3 metre high softwood mast. The mast carried the six telegraph arms - also known as indicators - and it also held the control mechanism for the arms. A ring was fastened between the top two sets of signal arms to which was attached four cables that were secured to the four corners of the station roof. This provided additional stability to the mast during storms. The mast and control mechanism ran through the roof of the observation room. The roof was specially sealed against rain. The mast was secured to the floor beams and likewise the roof with cast iron
Cast iron
Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrous alloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due...

 hardware.

Indicators and their control

The moving signal arms were suspended with counterweights to enable easy adjustment. The indicators measured 1.74 m × 0.33 m. Only two of the original indicators still exist today; one is on display in the Boerdemuseum in Ummendorf
Ummendorf
Ummendorf is a town in the district of Biberach in Baden-Württemberg in Germany....

 and the other in the Museum for Communication in Berlin. These arms, as well as preserved construction drawings, suggest that the arms consisted of a wooden framework with a wood or sheet metal interior. This provided greater wind resistance.

The operating mechanism of the system was located at the bottom of the mast in the observation room of the station. The indicators were operated with six adjustable levers arranged above each other in pairs. The position of each lever corresponded to the three-level alignment of the signal arms on the mast above. The levers and signal arms were connected by hemp ropes and later by wire cables. The levers each were lockable in four different positions, that exactly corresponded to the position of signal arm: 0° (arm hanging downward parallel to the mast), 45°, 90° (perpendicular to the mast), and 135°. Each position was relative to the mast.


Scopes

Each station had two telescopes for observing the neighboring stations. The scopes were either of English construction or they came from Pistor’s workshop. The portion of the route between Cologne and Koblenz was outfitted chiefly with scopes from the Munich lens-maker Georg Merz. The scopes’ magnification is estimated at between 40 and 60x. As with the other technical aspects of the stations, very specific instructions existed at each for the storage, use, and care of the scopes. Twelve paragraphs of instruction were allotted to the scopes alone.

Station Clocks and Time Synchronization

"Berlin Time" was the authoritative time used along the entire telegraph line; with a time-synchronizing message coming from Berlin every three days at the latest. A Schwarzwald Clock
Cuckoo clock
A cuckoo clock is a clock, typically pendulum-regulated, that strikes the hours with a sound like a common cuckoo's call and typically has a mechanical cuckoo that emerges with each note...

 with a chime hung in each station as the official station clock. The synchronization process would be announced an hour in advance with a signal which prompted the station agents to continuously observe the neighboring station in the direction of Berlin. The signal had to then be sent to the next station without delay. Once the signal reached Koblenz, it was relayed back to Berlin as confirmation. In good weather conditions, the entire process from Berlin to Koblenz and back took less than two minutes. With such a synchronization process, the time difference amounted to less than one minute.

See also

  • Semaphore Flag Signaling System
    Semaphore Flag Signaling System
    In computer networking, Semaphore Flag Signaling System is a humorous proposal to carry Internet Protocol traffic by semaphores. Semaphore Flag Signaling System was initially described in RFC 4824, an April 1 RFC issued by the Internet Engineering Task Force edited by J. Hofmueller, et al. and...

  • Flag semaphore
    Flag semaphore
    Semaphore Flags is the system for conveying information at a distance by means of visual signals with hand-held flags, rods, disks, paddles, or occasionally bare or gloved hands. Information is encoded by the position of the flags; it is read when the flag is in a fixed position...

  • Heliograph
    Heliograph
    A heliograph is a wireless solar telegraph that signals by flashes of sunlight reflected by a mirror. The flashes are produced by momentarily pivoting the mirror, or by interrupting the beam with a shutter...

  • Railway signalling
    Railway signalling
    Railway signalling is a system used to control railway traffic safely, essentially to prevent trains from colliding. Being guided by fixed rails, trains are uniquely susceptible to collision; furthermore, trains cannot stop quickly, and frequently operate at speeds that do not enable them to stop...

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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