Chappe Semaphore
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Chappe’s Semaphore
History of Claude Chappe
Claude Chappe was born in 1763. He was the grandson of a French Baron, and went on to train for the church. When he lost his religious compassion in 1783 during the French Revolution, he went to work with his four brothers. Together they worked on the troubles surrounding the optical telegraph.
History of Semaphores
Before Claude Chappe and his brothers invented the optical telegraph that became termed Chappe’s Semaphore, there were records of other optical telegraphs. According to the Talmud, to let everyone know of a new month, the Temple of Jerusalem would light bonfires on the tops of hills and mountains in Ancient Israel. Also, the Chinese used smoke signals in times of war.
History of Chappe’s Semaphore
Chappe and his brothers spent 10 years and many experiments on finally inventing the Chappe’s Semaphore. The earliest experiments of the Synchronized System, invented in 1791, started out with the use of pendulum clocks. The clocks had 16 numerals on the face, as opposed to the 12 we have today. The clocks would use the synchronization of the numerals and the loud sounds that numeral made to send messages to the receivers. Financial support could not be found for the Synchronized System because electrical insulation did not exist at the time.
The second phase of experiments led to the invention of the Panel Telegraph in 1792. This wooden structure used five sliding panels to communicate with a sort of binary code with 32 combinations. Not long after the final invention, the mob destroyed it. They believed that the invention was not used for France’s benefit, but rather to work against it by communicating with France’s enemies.
The third and final wave of experiments in 1793 ended with the completion of Chappe’s Semaphore. The Chappe brothers realized that it was easier to see the angle of a rod so they took that realization and came up with the semaphore. The semaphore had a horizontal beam called the regulator and two smaller beams called the indicators that were moved in 45 degree advancements. This invention also sparked the term “telegraph” which means “far writing.”
After much deliberation, many improvements were made to the semaphore before it became a full blown network. First, secondary locations were made for use when weather made the visibility of the semaphores bad. Secondly, the size and height of the machines were multiplied to be almost six times larger than the original. Finally, a new coding system was invented for faster, more efficient communication.
Functionality
After 15 stations were built between Paris and Lille in France, the line was declared open in 1794 with the first official message letting everyone know about the “recapture of the city of LeQuesoy from the Austrians and Prussians.” The way to relay messages was by, as previously stated, using the many different angles of the rods to indicate a letter or short phrase.
The reason this mechanism became the better known invention than the other two was because of the visibility. It was hard to hear the noises of the Synchronized System, and hard to see the panels moving on the Panel Telegraph, but was easy to see the different angles of the rods on the Semaphore. The position of the arms could be translated into alphabetical letters and even short phrases in times of emergencies.
The mechanism was moved by two handles which made it fairly simple to use, although the use of the mechanism at night made it impossible to see even if lamps were used to make it more visible. The arms had seven positions and the connecting cross bar of the arms had four positions. This made a total of 196 positions (7x7x4). In times of emergencies though, a secret code book was invented. It consisted of 92 symbols used two at a time to make 8,464 secret words and phrases.
Advantages
The semaphore was highly superior to the postal system because they could travel farther and faster than the post. Also, the posts could be farther apart because, with the use of a telescope, they could be seen from farther away and without having to send someone to take the message, especially in bad weather and rough terrain. Finally, many cities could benefit from one semaphore, rather than having one per town, which in turn saves a town money, and makes it less expensive for each town in the region. The semaphore also had great military advantages as found by Napoleon Bonaparte. He even carried a portable semaphore so he could send crucial messages about the French Revolution to each camp he led. He was able to keep his whole army bettered informed faster, and spread out farther than any other army that he was battling against.
Disadvantages
The only disadvantages documented for the semaphore deal with bad weather and visibility. The visibility of the semaphores became bad when the weather was rainy or foggy. Also, anyone that has a knowledge of the symbols and what they mean could interpret the messages. This is the main reason for the secret code book for military purposes.
Relative Costs
Although the semaphore made France highly innovative, the cost of the semaphores was very inefficient; nearly 30 times more expensive than the electric telegraph that soon replaced the semaphore.
To break this down a little bit more, if both the semaphore and the electric telegraph were covering an area of 120 miles, or Paris to Lille the cost of the semaphore would be immense. First 15 towers would be needed at a cost of $1,500,000. Fifteen full time operators would be $450,000 per year.
The semaphore would be in use at least 10 hours a day. Also, two words a minute would be sent. Finally, the cost of sending one word per mile with a 10% interest rate would be $0.0114.
To show how financially inefficient this is here is the equivalent data for the electric telegraph. Six full time operators would be needed at $180,000 per year. The equipment needed to connect the span of the 120 miles would be $1,800,000. The electric telegraph would be operating 24 hours a day. Also, the telegraph can send up to 15 words per minute. The cost of one word per mile at an interest rate of 10% would be $0.000380.
The Semaphore Replaced
In the early 1800s, the arms of the semaphore were replaced by the arms of men in the nautical world. The arms were replaced by men who held flags in their hands in order to send signals to ships. This method was first used at the Battle of Trafalgar. When the electric telegraph came around, Samuel Morse could not get the French to invest in it since they were still enjoying the immense success of the semaphore. The French finally gave in and replaced the semaphores with electric telegraphs in 1846 because they succumbed to the many advantages the telegraph had over the semaphore. The last semaphore station was taken out of service in 1880 in Sweden. The mainland would communicate with an island using this final semaphore.
- French Semaphore Telegraph (http://www.napoleonguide.com/semaphore.htm)
- Chappe Telegraph System (http://people.deas.harvard.edu/~jones/cscie129/images/history/chappe.html)
- Semaphore Communication (http://en.wikipedia.org/wiki/Semaphore)
- Semaphore (http://www.answers.com/topic/semaphore-communication)
- Napoleon's Secret Weapon (http://bnrg.eecs.berkeley.edu/~randy/Courses/CS39C.S97/optical/optical.html)
John Hillis--Jdive5 15:52, 6 Dec 2005 (EST) Senior in Liberal Arts. Majoring in Telecommunications and Film Studies. Diver for Purdue Men's Varsity Swimming and Diving Team.
