The Ties That Bound

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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 (gerard@research.att.com) 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).

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