The light pulses were amplified and used to modulate a carrier current.”

Pardon me if this comes off as pedantic, but I’m pretty certain detection, amplification, and modulation were all invented after the telephone, so I am sure these things would not have been employed in an optical light telegraph invented in the time period 1837 – 1877 between the invention of the telegraph and the telephone.

Furthermore, even if you could determine that a message was delayed, how do you determine which station is at fault? (Given that each signaler has a strong incentive to blame someone else.)

King Squid to Mobby:
“Go! Go and bring my message to Ahab. That is the only way our Worlds can meet and cooperate for the salvation of this planet.”

Mobby:
“Oooohh shit!”

BTW, There was a line of Chappe telegraph between Moscow and then occupied Warsaw. With more than 1200 km it had about 200 stations and about 1,3 k-man to operate :-)
So Tsars also invested in it !

The history of the remote communication is fascinating. The revolution the electric telegraph made a bit later, was more dramatic than initial web revolution of early 90s….

French Optical Telegraphy, 1793-1855: Hardware, Software, Administration
http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1109255
Alexander J. Field
Santa Clara University – Leavey School of Business – Economics Department

Technology and Culture, Vol. 35, pp. 315-347, April 1994

Abstract:
French optical telegraph represented a highly refined blend of software and hardware generating performance levels in long distance communication which were, given the limitations of the hardware, quite remarkable. Had the electromagnetic telegraph not become available, French optical telegraphy, or a variant, would have served increasingly as an imperfect substitute, particularly in the transmission of price data on commodity, stock, and bond exchanges. This affirmation of the commercial viability of optical telegraphy does not, however, significantly reduce our estimate of the contribution of electromagnetic telegraphy to economic growth. The more substantial economic payoff to the electromagnetic device came from its use by firms to reduce inventory holdings and raise fixed capital utilization rates in sectors with large minimum efficient scales. Here optical telegraphy’s vulnerability to disruption by the weather, limited channel capacity, and restriction to daylight use would have made it a very imperfect substitute in an age of rail speed communication.

I live near one of these remaining towers, wich has been restored by the legion, near the toswn of Catelnaudary, because it is a military relic.

For those who say those towers are restricted to daylight use only, it’s false, they can light up at night, with a gas torch on each branch.

Dang, you called me on my poor memory. Now I’ll have to look it up, but I know it was quite obscure.

As for modulation, I’d point out that the telegraph itself was modulated, though by hand. This line-of-site optical beam telegraph I remember reading about in my optoelectronics textbooks years ago was the same: Basically, a human hand caused a light to flash in morse-code fashion (I can’t remember if it was a lightbulb or candles behind a shutter). The “receiver” through some clever mechanism I can’t remember initiated a nonzero current to translate the light flashes back into morse code on a line.

No “modulation” in the modern sense, though.

Perhaps it never caught on because it only existed right as telephones were coming into common occurrence. It’s application was also quite “niche” in that where a wire was available that would be preferable due to atmospheric conditions, etc…(ie, no LIDAR yet!).

Look here:

http://www.electronics.dit.ie/staff/tfreir/optical_1/Unit_1.1.pdf

They’ve got some pictures of a “heliograph” as well as a Bell “photophone” from 1880 that actually encodes voice!

http://www.polity.co.uk/book.asp?ref=9780745640907

A must read! (Though hardly nicely translateable, for his ironic post-heidegger style of word play and play with different registers of language, as his mimicry of German public official’s style ((Deutscher Beamter)) which he is, of course, as most of Germany’s Professors.

http://chappe.ec-lyon.fr/

One of the remaining Chappe towers is quite near where I live, so I wandered by and took a few photos this afternoon (I’d been meaning to do so for a while anyway; thanks, BB). I stuck ‘em up on my blog– not great pictures but a better look at the mechanism, anyway:

http://thefrogmarch.blogspot.com/2009/06/chappe-optical-telegraph-tower-ste-foy.html

Oh well, here goes anyway:

Are you sure about that 9,999 words figure? This article sounds more realistic:
“This regulator, as it was known, had a 1.8 metre indicator at each end and had four basic positions – horizontal, vertical or at 45-degree angles.

When not in operation the indicators were left as horizontal extensions of the regulator and these would then be moved in seven combinations of angles at 45-degree tilts.

All up the Chappe semaphore tower had 196 combinations known as signs and would be worked by a series of pulleys and levers. ”

Of course if it really was 9,999 words out of 196 signs, does anyone have more info on the coding scheme?

@Tak: http://en.wikipedia.org/wiki/Semaphore_line#Sweden:

“At the same time as Chappe, the Swedish inventor Abraham Niclas Edelcrantz experimented with the optical telegraph in Sweden.”

“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.”

And in the UK:

“Lord George Murray, stimulated by reports of the Chappe semaphore, proposed a system of visual telegraphy to the British Admiralty. He employed large wooden boards on his towers with six large holes which could be closed by shutters.”

I’m reasonably certain that presence or absence of an object is easier to perceive than angle.

The Chappe brothers determined by experiment that it was easier to see the angle of a rod than to see the presence or absence of a panel. Their semaphore was composed of black movable wooden arms, the position of which indicated alphabetic letters. With counterweights (named forks) on the arms, the Chappe system was controlled by only two handles and was mechanically simple and reasonably rugged. Each of the two 2m-long arms showed seven positions, and the 4.6m-long cross bar connecting the two arms had four different angles, for a total of 196 symbols (7x7x4). Night operation with lamps on the arms was unsuccessful.

To speed up transmission and to provide some semblance of security a code book was developed for use with semaphore lines. The Chappes’ corporation used a code that took 92 of the basic symbols two at a time to yield 8,464 coded words and phrases.

This must have been the most boring job in history