Optical Telegraphy 

The Edelcrantz Telegraph Systems

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Abraham Niclas Clewberg-Edelcrantz (1754-1821) (Source)

Edelcrantz wisely wrote in his Treatise on Telegraphs (1796)

It often happens, with regard to new inventions, that one part of the general public finds them useless and another part considers them to be impossible.

When it becomes clear that the possibility and the usefulness can no longer be denied, most agree that the whole thing was fairly easy to discover and that they knew was significant."

References:

• The Early History of Data Networks see also a online copy here
  
  
• Proceedings of a Symposium on "The Optical Telegraph" (Stockholm, June 21-23 1994) - the URL for this resource seems to be no longer available from Stockholm's Tekniska Museet.
  
  
• Word Made Visible: The Optical Telegraph System in Sweden 1794-1881
  
  
• A biography of Abraham N. Edelcrantz is included in The Early History of Data Networks
  
  
• A Treatise on Telegraphs: the first English translation of a document written in 1796 by Abraham Niclas Edelcrantz is also included in The Early History of Data Networks
  
  
• Optical Telegraphs in Denmark (1794 - 1862) gives lots of detail about the operation of many different kinds of optical telegraphs - the URL for this resource seems to be no longer available from Stockholm's Tekniska Museet.

Initially, Edelcrantz Experimented with a Semaphore Telegraph System

From Edelcrantz's A Treatise on Telegraphs

"...In September 1794 I began experiments in this area which led me to several telegraphic devices, some of which were similar and some of which were completely different from the French system, a description of which had still not been made available.  Since then I have continued these experiments, in order to perfect the design and operation of a telegraph that, after weighing all factors, I believed would combine most benefits.

"The first design I used was similar to the one in Paris. AB, in Figure 10, is a vertical rod, to which two others are attached, CD and EF, movable on axles at G and H in such a manner that GA, GC, GH, EH are all equal. ...Thereby 4 × 4 = 16 combinations can be produced, Figure 11, ..."

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Edelcrantz's Shutter Telegraph Systems

"The invention of the telescope in the 17th century paved the way for the development of the optical telegraph. The Frenchman Claude Chappe was in 1793 the first to build a functioning optical telegraph. In the wake of the French Revolution, the optical telegraph acquired great military importance.

At the same time as Chappe, the Swede A. N. Edelcrantz experimented with the optical telegraph in Sweden. In 1794 he inaugurated his telegraph with a poem dedicated to the Swedish King on his birthday. The message went from the Palace in Stockholm to the King at Drottningholm .

Edelcrantz eventually developed his own system which was quite different from its French counterpart and nearly twice as fast. The system was based on ten collapsible iron shutters. The various positions of the shutters formed combinations of numbers which were translated into letters , words or phrases via codebooks. The telegraph network consisted of telegraph stations positioned at about 10 kilometres from one another.

The Swedish optical telegraph network was restricted to the archipelagoes of Stockholm, Gothenburg and Karlskrona. Like its French counterpart, it was mainly used for military purposes.

After the Finnish War, the optical telegraph network was allowed to fall into disuse but some 20 years later it was rebuilt and simultaneously opened to the public. The traffic, however, was quite insignificant which was partly due to the fact that the optical telegraph could only be employed when the weather permitted. When the last telegraph station at Vinga was closed in 1881, the optical telegraph had become obsolete and was replaced by its electrical counterpart. " (Source)
 
 
 

Edelcrantz Models of Shutter Telegraph Systems
(Coll. Telemuseum, Stockholm)

Model of a Nine-Shutter Telegraph ca. 1808 (Source)

Model of a Ten-Shutter Telegraph ca 1794  (Source)

 

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"...Along with the usual ways of communication a special, telegraphic system existed in Sweden from 1794 - the optical telegraph. It was invented by the Swedish poet and scientist Abraham Niclas Edelcrantz, a Royal Counsellor, and consisted of ten shutters, arranged in a pattern that could be easily read off at a distance. The arrangement of the shutters formed what today is called a binary system with 10 signal elements - a predecessor of moden data signal systems. The optical telegraph envisaged a network of linking stations. A signal was successively repeated from one station to the next until the office of destination was reached.

 

Soon telegraph circuits linking castles and fortresses in the neighbourhood of Stockholm were set up and the system was extended to Grisslehamn and Åland.  Subsequently telegraph circuits were introduced between Gothenburg and Marstrand, at Helsingborg and between Karlskrona and its fortresses. Sweden was the second country in the world, after France, to introduce an optical telegraph network.

 

At the outbreak of war against Russia in 1808, optical telegraph lines were rapidly extended to important places on the east coast. After the peace in 1809, the optical telegraph network in Sweden fell into decay, except for the stations in the Gothenburg area. In the 1830s, however, the political situation in Europe became tense and the Swedish Government considered it necessary to strengthen coastal defences. The telegraph network was rebuilt and the lines from Stockholm, Gothenburg and Karlskrona were restored to their formerInteriör från den optiska telegrafstugan i Furusund utanför Norrtälje. Telegrafen rekonstruerades 1962 och är den enda i Sverige som fungerar. state and extended." (Source)

Early (1794) Model of Lord George Murray's Six-Shutter Design.  (Coll. Victory Museum, England)                                 (Source)	Interior of an optical telegraph station reconstructed in 1962  at Furusund (Source)
"Working the Ropes" in a telegraph station on the line from London to Deal that was designed by Lord George Murray.  Although not credited, the design is undeniably based on Edelcrantz's.  (Source)