Hydraulic telegraph

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An ancient hydraulic telegraph being used by Aeneas to send a message. Greek Hydraulic Telegraph of Aeneas relief.jpg
An ancient hydraulic telegraph being used by Aeneas to send a message.

A hydraulic telegraph (Greek : υδραυλικός τηλέγραφος) is either of two different hydraulic-telegraph telecommunication systems. The earliest one was developed in 4th-century BC Greece, while the other was developed in 19th-century AD Britain. The Greek system was deployed in combination with semaphoric fires, while the latter British system was operated purely by hydraulic fluid pressure.

Greek language Language spoken in Greece, Cyprus and Southern Albania

Greek is an independent branch of the Indo-European family of languages, native to Greece, Cyprus and other parts of the Eastern Mediterranean and the Black Sea. It has the longest documented history of any living Indo-European language, spanning more than 3000 years of written records. Its writing system has been the Greek alphabet for the major part of its history; other systems, such as Linear B and the Cypriot syllabary, were used previously. The alphabet arose from the Phoenician script and was in turn the basis of the Latin, Cyrillic, Armenian, Coptic, Gothic, and many other writing systems.

Telecommunication Transmission of information between locations using electromagnetics

Telecommunication is the transmission of signs, signals, messages, words, writings, images and sounds or information of any nature by wire, radio, optical or other electromagnetic systems. Telecommunication occurs when the exchange of information between communication participants includes the use of technology. It is transmitted through a transmission media, such as over physical media, for example, over electrical cable, or via electromagnetic radiation through space such as radio or light. Such transmission paths are often divided into communication channels which afford the advantages of multiplexing. Since the Latin term communicatio is considered the social process of information exchange, the term telecommunications is often used in its plural form because it involves many different technologies.

Ancient Greece Civilization belonging to an early period of Greek history

Ancient Greece was a civilization belonging to a period of Greek history from the Greek Dark Ages of the 12th–9th centuries BC to the end of antiquity. Immediately following this period was the beginning of the Early Middle Ages and the Byzantine era. Roughly three centuries after the Late Bronze Age collapse of Mycenaean Greece, Greek urban poleis began to form in the 8th century BC, ushering in the Archaic period and colonization of the Mediterranean Basin. This was followed by the period of Classical Greece, an era that began with the Greco-Persian Wars, lasting from the 5th to 4th centuries BC. Due to the conquests by Alexander the Great of Macedon, Hellenistic civilization flourished from Central Asia to the western end of the Mediterranean Sea. The Hellenistic period came to an end with the conquests and annexations of the eastern Mediterranean world by the Roman Republic, which established the Roman province of Macedonia in Roman Greece, and later the province of Achaea during the Roman Empire.


Although both systems employed water in their sending and receiver devices, their transmission media were completely different. The ancient Greek system transmitted its semaphoric information to the receiver visually, which limited its use to line-of-sight distances in good visibility weather conditions only. The 19th-century British system used water-filled pipes to effect changes to the water level in the receiver unit (similar to a transparent water-filled flexible tube used as a level indicator), thus limiting its range to the hydraulic pressure that could be generated at the transmitter's device. [1]

While the Greek device was extremely limited in the codes (and hence the information) it could convey, the British device was never deployed in operation other than for very short-distance demonstrations. [1] The British device could, however, be used in any visibility within its range of operation so long as its conduits, if unheated, did not freeze in sub-zero temperatures —which contributed to its impracticality.

Greek hydraulic semaphore system

Reconstruction, Thessaloniki Science Center and Technology Museum Hydraulic telegraph, 4th century BC (reconstruction).jpg
Reconstruction, Thessaloniki Science Center and Technology Museum
Reconstructed model, messages attached to rod, Thessaloniki Science Center and Technology Museum Hydraulic telegraph messages, 4th century BC (reconstruction).jpg
Reconstructed model, messages attached to rod, Thessaloniki Science Center and Technology Museum

The ancient Greek design was described in the 4th century BC by Aeneas Tacticus and the 3rd century BC by the historian Polybius. According to Polybius, it was used during the First Punic War to send messages between Sicily and Carthage.

Aeneas Tacticus was one of the earliest Greek writers on the art of war and is credited as the first author to provide a complete guide to securing military communications. Polybius described his design for a hydraulic semaphore system.

Polybius Ancient Greek historian

Polybius was a Greek historian of the Hellenistic period noted for his work The Histories, which covered the period of 264–146 BC in detail. The work describes the rise of the Roman Republic to the status of dominance in the ancient Mediterranean world and includes his eyewitness account of the Sack of Carthage and Corinth in 146 BC, and the Roman annexation of the mainland Greece after the Achaean War.

First Punic War First war between the Roman Republic and Carthage, fought between 264 and 241 BCE

The First Punic War was the first of three wars fought between Ancient Carthage and the Roman Republic, the two great powers of the Western Mediterranean. For 23 years, in the longest continuous conflict and greatest naval war of antiquity, the two powers struggled for supremacy, primarily on the Mediterranean island of Sicily and its surrounding waters, and also in North Africa.

The system involved identical containers on separate hills, which are not connected to each other; each container would be filled with water, and a vertical rod floated within it. The rods were inscribed with various predetermined codes at various points along its height.

Code method to represent information for various purposes (storage, transmission, protection against unauthorized access, ...)

In communications and information processing, code is a system of rules to convert information—such as a letter, word, sound, image, or gesture—into another form or representation, sometimes shortened or secret, for communication through a communication channel or storage in a storage medium. An early example is the invention of language, which enabled a person, through speech, to communicate what they saw, heard, felt, or thought to others. But speech limits the range of communication to the distance a voice can carry, and limits the audience to those present when the speech is uttered. The invention of writing, which converted spoken language into visual symbols, extended the range of communication across space and time.

To send a message, the sending operator would use a torch to signal the receiving operator; once the two were synchronized, they would simultaneously open the spigots at the bottom of their containers. Water would drain out until the water level reached the desired code, at which point the sender would lower his torch, and the operators would simultaneously close their spigots. Thus the length of time the sender's torch was visible could be correlated with specific predetermined codes and messages.

A contemporary description of the ancient telegraphic method was provided by Polybius. In The Histories, Polybius wrote: [2]

British hydraulic semaphore system

The British civil engineer Francis Whishaw, who later became a principal in the General Telegraph Company, publicized a hydraulic telegraph in 1838 but was unable to deploy it commercially. [3] By applying pressure at a transmitter device connected to a water-filled pipe which travelled all the way to a similar receiver device, he was able to effect a change in the water level which would then indicate coded information to the receiver's operator. [1] [4]

The system was estimated to cost £200 per mile (1.6 km) and could convey a vocabulary of 12,000 words. [5] The U.K.'s Mechanics Magazine in March 1838 described it as follows: [6]

The article concluded speculatively that the "... hydraulic telegraph may supersede the semaphore and the galvanic telegraph". [1]

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  1. 1 2 3 4 Distant Writing: A History of the Telegraph Companies in Britain between 1838 and 1868 - Non-Competitors, Distantwriting.co.uk website. Retrieved 2009-07-14
  2. Lahanas, Michael, Ancient Greek Communication Methods Archived 2014-11-02 at the Wayback Machine , Mlahanas.de website. Retrieved 2009-07-14.
  3. Herapath, John. The Railway Magazine and Annals of Science, Vol. V.: Hydraulic Telegraph (section), London, Charing-Cross East: Wyld and Son, 1839, pp. 9–11.
  4. Whishaw, Francis. "Report of the Annual Meeting of the British Association for the Advancement of Science, Volume 18, Parts 1848–1849: On The Uniformity Of Time And Other Telegraphs", British Association for the Advancement of Science London: John Murray, 1849, p. 123.
  5. The Civil Engineer and Architect's Journal, Volume 1: Oct. 1837 to Dec. 1838: Miscellany, London: William Laxton, 1838, p. 88.
  6. Roberts, Steven. A History of Telegraph Companies In Britain Between 1838 And 1868: Whishaw's Hydraulic Telegraph, retrieved from DistantWriting.co.uk website January 8, 2013.