Ikigai Daily
Menu
WonderCommunications engineering fact

In the 1790s Claude Chappe built a chain of towers across France whose movable wooden arms signalled coded messages. Operators watched the neighbouring tower through a telescope and copied each signal, so one symbol could cross the 230 kilometres between Paris and Lille in about nine minutes.

Optical telegraph

TechnologyEngineeringLanguageHistory

The story behind the card

Chappe worked on the system with his brothers, and in 1792 the revolutionary government asked him to build the first line, between Paris and Lille. In 1794 it brought news that French troops had taken the town of Condé-sur-l'Escaut from the Austrians to Paris less than an hour after it happened. A beam and two smaller arms on top of each tower could form many different positions, standing for letters, numbers or entries in a codebook, and the operators copied them without knowing what they meant. The word “telegraph”, Greek for “far writer”, was coined for the system by the French statesman Miot de Mélito. At its height the network had 556 stations covering about 4,800 kilometres. Darkness and fog stopped it, and in 1846 France decided to replace it with the electric telegraph.

Türkçe oku
Claude Chappe, 1790'larda Fransa'da, tepelerindeki hareketli tahta kollarla şifreli mesaj gönderen bir kule zinciri kurdu. Her kuledeki görevli komşu kuleyi dürbünle izler, gördüğü işareti aynen tekrarlardı; böylece tek bir işaret Paris ile Lille arasındaki 230 kilometreyi yaklaşık dokuz dakikada aşabiliyordu.

Chappe sistemi kardeşleriyle birlikte geliştirdi; devrim hükûmeti de 1792'de ondan ilk hattı, Paris ile Lille arasında kurmasını istedi. 1794'te bu hat, Fransız askerlerinin Condé-sur-l'Escaut kasabasını Avusturyalılardan aldığı haberini, olaydan bir saat bile geçmeden Paris'e ulaştırdı. Her kulenin tepesindeki bir kiriş ve iki küçük kol pek çok farklı konum alabiliyordu; bu konumlar harflere, sayılara ya da bir kod kitabındaki ifadelere karşılık geliyordu. Görevliler işaretleri anlamlarını bilmeden aktarırdı. Yunancada “uzağa yazan” anlamına gelen “telgraf” sözcüğü, bu sistem için Fransız devlet adamı Miot de Mélito tarafından türetildi. Ağ en geniş hâlinde 556 istasyona ve yaklaşık 4.800 kilometreye ulaştı. Karanlık ve sis iletişimi durduruyordu; Fransa 1846'da sistemi elektrikli telgrafla değiştirme kararı aldı.

Sources and further reading

Background reading: Optical telegraph
Get the mobile appAbout our cards

Related cards

These cards share a subject or reading mode with the card above.

WonderLanguage

Morse code spells each letter as a pattern of short and long signals, so a message can travel as clicks, tones, flashes of light or electrical pulses. From the 1840s it let the electric telegraph carry messages over long distances.

Samuel Morse's first telegraph code, around 1837, used only numbers, which stood for words in a codebook. His collaborator Alfred Vail expanded it in 1840 to letters, giving the most common letters the shortest signals; he judged which were most common by counting the metal type in a local newspaper's print shop. In 1848 the German telegraph pioneer Friedrich Gerke simplified the code, and his version became the basis of the International Morse code agreed in Paris in 1865. Ships sent distress calls, including the famous SOS, in Morse until satellite-based systems replaced it in 1999, but radio amateurs still use it and navigation beacons still identify themselves in Morse.

Library of Congress / Smithsonian InstitutionRead card
WonderEngineering

A qanat is an underground channel, developed in ancient Persia, that brings groundwater from the foot of hills to fields and towns using gravity alone. From above, a qanat shows as a line of shaft openings across dry land.

Builders start with a 'mother well' dug down to the water table, then cut a tunnel back towards the surface on a very gentle slope, so the water flows without wearing away the channel. Vertical shafts along the route let workers lift out soil, bring in air and later clean the tunnel. The Qasabeh qanat at Gonabad in eastern Iran, dated to between 700 and 500 BCE, has a mother well more than 360 metres deep and about 33 kilometres of channels, and still carries water. In 2016 UNESCO listed eleven Iranian qanats together as a World Heritage site, recognising both the engineering and the old customs for sharing the water fairly.

Qanat water systemsRead card
WonderEngineering

The Archimedes screw lifts water with a spiral blade turning inside a tilted tube: each turn traps a pocket of water and carries it upwards. Described more than 2,200 years ago, it is still used to irrigate fields, drain land and pump sewage.

Tradition credits the Greek mathematician Archimedes of Syracuse with the invention in the third century BC, but the credit is uncertain. Similar screws may already have been used in Egypt, and the historian Stephanie Dalley has argued that the Assyrian king Sennacherib watered his gardens at Nineveh with bronze screws in the seventh century BC. A famous early use comes from the Syracusia, a giant ship built for King Hiero II of Syracuse: according to an ancient account, one man could pump out the water that collected in its hull with a screw. Run in reverse, with falling water turning it, the same device now drives small hydroelectric plants.

Archimedes' screwRead card
WonderMigration

Over several thousand years, Bantu-speaking farming peoples spread from the highlands between today's Cameroon and Nigeria across most of central, eastern and southern Africa. Hundreds of related Bantu languages, including Swahili, Zulu, Shona and Kikuyu, are spoken there today.

Historians once pictured a single great 'Bantu migration'. Linguistic, archaeological and genetic evidence now points to a slower spread along many routes, roughly between 4000 BC and AD 500, with Bantu speakers reaching what is now South Africa by about AD 300. The German linguist Wilhelm Bleek coined the name Bantu in 1862 from the word for 'people' shared by many of these languages. Farming, herding and iron-working spread in different mixes from region to region, and everywhere the newcomers mixed with the people already living there. The click sounds of Zulu and Xhosa, for example, were borrowed from the Khoisan languages spoken earlier in southern Africa.

Bantu migrationsRead card
WonderArchitecture

Angkor, capital of the Khmer Empire in today's Cambodia from the ninth to the fifteenth century, was ringed by giant reservoirs, moats and canals that stored monsoon rain and moved water across an urban area of about 1,000 square kilometres.

The largest reservoirs, called barays, are vast rectangles banked with earth: the West Baray, built in the eleventh century, measures about eight kilometres by two and still holds water. Moats such as the one around Angkor Wat framed temples modelled on the sacred mountain and surrounding oceans of Hindu and Buddhist cosmology. Radar and aerial surveys published in 2007, and airborne laser scanning (lidar) that saw through the forest in 2012, revealed roads, canals and house mounds across at least 1,000 square kilometres, the largest known pre-industrial settlement. Researchers still debate how much the barays watered rice fields. Tree rings show long droughts broken by intense monsoons in the fourteenth and fifteenth centuries, which damaged the network and probably contributed to Angkor's decline.

Angkor hydraulic systemRead card
Next card in the archiveThe Plimsoll line, a circle with a line through it painted on a ship's hull, marks how deep a loaded ship may safely sit in the water. Extra lines beside it allow for fresh water, tropical water and winter seas, where the safe limit is different.Read next →