Foy–Breguet telegraph
The system used two-needle instruments that presented a display using the same code as that on the optical telegraph of Claude Chappe.
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.
Instead, they operated the detent of a clockwork mechanism which released the needle to move on one position at a time.
He demonstrated his system to the French Academy of Sciences and made a bid for the contract to install a telegraph along the line of the Paris to Saint-Germain railway.
France had the most extensive optical telegraph system of any country, developed for military purposes by Claude Chappe in the revolutionary and Napoleonic periods.
[2] Alphonse Foy, the chief administrator of the French telegraphs, had a further objection to the Morse system.
[4] In May 1845, Foy ran a comparative test between the Dujardin, Breguet, and Cooke-Wheatstone systems on the Paris, Saint Germain to Rouen line.
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.
His grandfather, Abraham-Louis Breguet, a watchmaker, had worked with Chappe on the design of the optical telegraph and Louis inherited the business.
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.
[11] Consequently, other nations did not have such a strong desire for backward compatibility as France and were able to move to the electrical telegraph sooner.
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.
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 of the corresponding clockwork mechanism is released by means of the armature of an electromagnet and the needle advances by 45°.
As the crank handle is turned through the notches, the battery is alternately connected and disconnected from the line and the local instrument.
This was unsuccessful, which meant that the French system had to employ operators to retransmit messages in some places.
The semaphorists were largely rural workers on isolated stations used to taking on the responsibilities of carrying out mechanical repairs by themselves.
[25] Gerke's code was adopted in 1851 by the German-Austrian Telegraph Union which represented many central European countries.
