Leave a comment


Louis Starr said on June 22nd, 2011 at 8:23 am :

I’m a student of graphic design and had an assignment on early visual communications. I was looking for a image of early Scotland semaphore that I found while doing another report that I ended up not completing because of assignment restrictions and lost the subject material, or web site that I had visited. While trying to find it I stumbled upon your site, as I see we kind of think alike. Pleased to meet your acquaintance.
Cordially, Louis Starr

Dec 24, 2007 | The True Origins and History of the Telegraph

The Chappe Telegraph

Man has sought to communicate between large distances for a long time now, and with the advent of the Internet, email and chat it seems ridiculous to imagine a time when a message of any level of urgency would take four days to travel a distance of 500km. The late 18th century saw the rise of one of the more fascinating technologies of the day called the telegraph, one that predates Joseph Henry and Samuel B. Morses’ electric devices. It is now more commonly referred to as the Chappe telegraph or the optical semaphore/telegraph.

A bit of history

Lithograph of Claude Chappe

Its invention is attributed to Frenchman Claude Chappe and his brothers, who unveiled their device on the 3rd of March, 1791 between the towns of Brûlon and Parcé, a total distance of 14 kilometers. Claude was only 26 at the time. It wouldn’t be for another two more years, however, before he and his brothers could perfect their contraption and convince the government that it would be successful, but the construction of his telegraphs was approved by the Convention Nationale (the Assembly) on the 4th of August, 1793. The Paris-Lille line opened a year later, on the 16th of July, 1794.

By the mid 19th century, an expansive network of 534 relay stations connecting 29 major French cities across some 5000 kilometers was in place.

Network across France

Now a communiqué from Paris to Strasbourg would take approximately two hours, comparable to the fastest connections by train connecting the two cities by modern day TGVs.

How does it work?

Marine semaphore

The Chappe telegraph is a semaphore not unlike the ones used at sea in by flagmen in order to communicate from ship to ship. In order to send signals over larger distances, however, the Chappe telegraph used a stationary tower upon which stood a wooden stand approximately 7 meters in height. A 4.6m x 0.35m long black regulator wooden beam was pivoted upon this stand, and two indicator ‘wings’ were affixed to the ends of this. The different positions of the wooden beams would thus communicate a particular signal and were ultimately controlled by a system of pulleys and ropes developed by the famous watchmaker Abraham Louis Breguet. Each tower would be positioned approximately 10-15 kilometers from each other in order to guarantee visibility, though fog or night would halt communication altogether.

Chappe tower

While the beams would be kept completely vertical in the absence of a message to transmit, once a code signal is displayed by an operator at a tower, he would wait for the following tower to copy the same signal. As a result, if a transmission was not being recieved correctly a relay station would continue sending the same signal, backing up the whole process back to the origin of transmission if something wrong should occur.

Chappe telegraph stage 1 No message to transmit
Chappe telegraph stage 2 Message on its way
Chappe telegraph stage 3 First code indicates page of code book
Chappe telegraph stage 4 Neutral between first and second code
Chappe telegraph stage 5 Second code indicating line from page

98 unique signals could be made, of which 6 were reserved for particular communications such as “error in transmission” or “priority”. The two signalmen stationed at each post knew the significance of only these six, and recorded the 92 others by number only, to be deciphered by superior officers. In order to include more sophisticated messages, each transmission would be divided into two numbers: the first would indicate a page number for a particular reference manual that each station had, and the second would indicate a particular number line on that page. All told this allowed for 92 x 92 signals or 8464 unique words or phrases. For example, the phrase “I respond to your last dispatch” (Je réponds à votre dernière dépêche) was located on page 53, line 21.

Chappe tower

Napoleon Bonaparte immediately saw its military potential and had the network vastly expanded under the urgency of the tense situation during the French Revolution. After its peak success, Napoleon Bonaparte, then First Consul of France, decided in 1800 to reduce the appropriation of funds to the construction of the telegraphs and, in dispair, Claude Chappe committed suicide by throwing himself into a well. Interestingly enough, however, once he was crowned Emperor, he made an effort to re-expand the network as a means of keeping control- indeed it was during this time that the system of telegraphs expanded across borders and into Italy, Belgium, and Holland. The true demise of the technology was not until 1856, when it was replaced by its electric counterpart.

The Chappe telegraph is truly remarkable in allowing for reliable and rapid transmission of words across long distances, something we grapple with even today in its digital form. A message could travel 500 kilometers in just about two hours, remarkable speed in a time of messengers on horses. Some might even venture to say that it is the predecessor of the modern day Internet and, ultimately, email, but something inside of me says it just is a lot more cooler.

Sources: Top image, Portrait (middle), Map (Bottom)
Le télégraphe Chappe from the Ecole Centrale de Lyon.
Le Telegraphe Optique Chappe
Telegraphe Chappe from the Association Mont Saint-Quentin Télégraphe de Chappe

This entry was posted on Monday, December 24th, 2007 at 6:27 pm, EST under the category of Articles. Both comments and pings are currently closed.