The Ties That Bound
Networking over vast distances isn't a novel concept. Even the ancient Greeks knew how to reach out and touch someone
The preoccupation with information is not peculiar to the information age. People have always explored new ways to carry information farther, faster. The ancient empires of the Egyptians, the Babylonians, the Romans, the Mongols, and the Incas all reached a geographic size that competes easily with the largest independent states today. How did the rulers of those empires stay abreast of developments in the remote corners of their territory, such as attacks from neighbors? They developed long-distance communication networks as innovative for their time as our networks are for ours.
One of the earliest recorded forms of long-distance communication made use of pigeons. As early as 2900 B.C. in Egypt, a ship returning from an extended trip would announce its arrival well in advance by releasing carrier pigeons it had on board. Around 2350 B.C., during the reign of King Sargon of Akkad in Mesopotamia, royal messengers carried not just mail and goods but also at least one pigeon. If attacked, a messenger would release a pigeon. The return of the pigeon to the palace was taken as a warning that the original messenger had been intercepted and that a new messenger should be sent, presumably by another route.
It has been speculated that the ancient oracles, such as the one at Delphi, could have received early notification of events by the use of pigeons, thus enabling the oracles to know breaking news before their visitors did.
Another ancient method of communication, probably as old as civilization itself, was the relay system -- a network of specially trained long-distance runners or runners and horses that carried information and even goods. Relay systems are mentioned in many ancient sources, including the biblical book of Jeremiah, written about 588 B.C. The Greek historian Xenophon (430-355 B.C.) credited the Persian king Cyrus (599-530 B.C.) with the introduction of the relay system, and Herodotus described Persia's relay runners under Xerxes, between 486 and 465 B.C., with these famous words: "And him neither snow nor rain nor heat nor night holds back for the accomplishment of the course that has been assigned to him, as quickly as he may."
Virtually the same system seems to have been adopted in almost every ancient empire. Marco Polo, for instance, described the system adopted by Genghis Khan and used by his descendant Kublai Khan around 1280. That system carried more than information, he notes: "Fruit gathered in the morning in the city of Khan-balik [Beijing] is delivered on the evening of the next day to the Great Khan in the city of Shang-tu, ten days' journey away." The historian Pedro de Cieza de Leon (1518-1554) similarly described the system that was used by the Incas in South America: "Almost all early chroniclers agree that the chasquis [Inca couriers] could run in relays between Quito and Cuzco, a distance of 1,250 miles, in five days -- and this at an altitude ranging from 6,000 to 17,000 feet! This means the runners had to run an average of some 250 miles a day."
A system that more closely resembles a communication network as we understand it today, however, is mentioned in the following passage from Homer's epic The Iliad, which was written about 700 B.C.: "Thus, from some far-away beleaguered island, where all day long the men have fought a desperate battle from their city walls, the smoke goes up to heaven; but no sooner has the sun gone down than the light from the line of beacons blazes up and shoots into the sky to warn the neighbouring islanders and bring them to the rescue in their ships."
That passage is not the only ancient reference to fire beacons. Explicit references were found in the library of King Ashurbanipal, who ruled Assyria from 668 to 626 B.C. And in the opening of the play Agamemnon, the Greek dramatist Aeschylus (525-456 B.C.) describes how beacons relayed news of the fall of Troy from Asia Minor -- across a distance of 600 kilometers -- to Agamemnon's palace in Greece, in approximately 1200 B.C.
Of course, a beacon system had limitations, as the historian Polybius (circa 200-118 B.C.) described in Book X of his work The Histories: "Now in former times, as fire signals were simple beacons, they were for the most part of little use to those who used them. . . . It was possible for those who had agreed on this to convey information that a fleet had arrived at Oreus, Peparethus, or Chalcis, but when it came to some of the citizens having changed sides or having been guilty of treachery or a massacre having taken place in the town, or anything of the kind, things that often happen, but cannot all be foreseen -- and it is chiefly unexpected occurrences which require instant consideration and help -- all such matters defied communication by fire signal."
To overcome the problem, Polybius developed a code in which the characters of the Greek alphabet (24 characters at that time) were divided into five groups. The "telegraph" consisted of two large screens hiding five torches apiece. Torches would be raised to indicate a pair of numbers. The pair 4 and 3, for instance, corresponded to character 4 on table 3. It was sent by raising four torches behind the left-hand screen and three torches behind the right-hand screen.
No one improved significantly on the fire-beacon system for many centuries. It took the invention of the telescope during the first decade of the 17th century to spark renewed interest in building communication systems. An optical telegraph system became practical because each station in the network could be linked visually with the next.
By the late 18th century, many improvements had been made in telescope design. French clergyman and physicist Claude Chappe went on a mission to persuade the French revolutionary government to construct the world's first nationwide data network, using telescopes. In 1793 he obtained an assignment from the National Convention to establish a telegraphic connection between Paris and the besieged city of Lille, a distance of 190 kilometers (120 miles). Chappe's French state telegraph organization is the oldest organization of its kind in the world. The line of 15 stations between Paris and Lille began operating in August 1794 and proved to be a success. Over the next few decades, the network of optical telegraphs in France grew to 556 stations, covering roughly 3,000 miles and connecting 29 of France's largest cities to Paris.
Chappe's system relied on a series of semaphores -- signaling devices much like those used by railroads. The position of the arms (picture a windmill) represented letters, words, or common phrases. The semaphores could be set in 256 different positions, 94 of which were used to create a code of some 8,930 entries. Each semaphore station had two operators on duty -- one at a telescope watching the semaphores at the neighboring stations and the other manipulating the semaphore at that station. The system employed more than 1,000 people.
Similar optical-telegraph networks sprang up in Sweden, England, Germany, Spain, Australia, and the United States. A line of about 65 miles, connecting Boston to Martha's Vineyard, was in operation from 1801 to 1807. Another line, connecting Boston to Nantucket, was built in the 1820s. An optical-telegraph line was also used in San Francisco from 1849 to 1853 to announce the arrival of ships. The famous Telegraph Hill in downtown San Francisco served as one of three stations; the other two were at the Presidio House and Point Lobos.
Drawings of Staten Island, dating from 1838 to 1850, show the optical-telegraph station that connected Staten Island with Manhattan and Sandy Hook. From 1840 to 1845 another optical-telegraph line operated between Philadelphia and New York. Running it was a Philadelphia stockbroker who wanted to be notified immediately about fluctuations in the stock market. The information didn't make him rich, but he profited from the attention it brought him.
Around that time the electrical telegraph of Morse and Vail in the United States and the independently developed telegraph of Cooke and Wheatstone in England started to draw attention. However, optical telegraphs already had had a track record in Europe of almost half a century. Many resisted the dangerous electrical novelties that required seemingly whimsical investments in large quantities of expensive copper wire strung over miles of roads, which was vulnerable to any vandal with no more than a pair of snippers.
However, that resistance -- even if reasonable -- could not obscure the improvements electric telegraphy represented, nor could it delay progress toward the limitless communication networks we rely on today.* * *
Researcher and author Gerard J. Holzmann (firstname.lastname@example.org) is a member of the technical staff at AT&T Bell Laboratories, in Murray Hill, N.J. His latest book (with Björn Pehrson) is The Early History of Data Networks (IEEEComputer Society Press, 1995).