The hydraulic telegraph of Aeneas

The hydraulic telegraph of Aeneas – long-distance communication of antiquity


Advances in technology have drastically changed the way we live today compared to those of our ancient past. One type of technology that many of us may take for granted is the ability to communicate with others over long distances, or to large groups of people. A look back at ancient civilizations can give us insight today into the very first methods of long-distance communications. In 350 BC, a Greek named Aeneas invented the hydraulic telegraph, which was a means of communicating important, fairly detailed information, quickly over long distances.

Aeneas was a Greek writer who focused on military history, strategy, communications. He was one of the first authors to provide a guide on military communications, which were important for ensuring that any society had the ability to anticipate possible invasions, and to communicate strategy and tactics back and forth between groups. Aeneas was frustrated by the limitations placed on communications via torches and beacons. Torches allowed some messages to be conveyed, for example, they could indicate danger, or communicate that an objective had been accomplished, but they could not send messages with any level of detail or description. Essentially, they could communicate that something had occurred, but there was no way to communicate what had occurred.

Information transmission through beacons

Information transmission through beacons. Image source: Nature

Aeneas therefore developed the hydraulic telegraph in an attempt to overcome these obstacles. The telegraph involved a system of water-filled vessels containing rods that contained agreed-upon messages (such as “horsemen entering the country”, or “ships”). The two groups who wished to communicate would both have an identical set of supplies, and would be positioned far away from one another, but still within a line of sight, usually upon a hill. When one party wanted to send a message to the other, they would raise a torch. Upon seeing the torch raised, the second party would raise their torch to confirm they were prepared to receive the message. When the initial sender lowered his torch, both sides would simultaneously pull the plug from the bottom of the water-containing vessel. As the water drained, different messages on the rod would be revealed. When the intended message reached the top, the initial sender would again light his torch, signaling that the receiver should re-plug the vessel and read the message on the rod. For this to work properly, both parties had to have vessels of the same size, filled with the same volume of water, and rods containing the same messages. They also had to be very precise, starting and stopping drainage at the correct moment.

A replica of the hydraulic telegraph of Aeneas

A replica of the hydraulic telegraph of Aeneas. Credit: Augusta Stylianou

While the technology of the hydraulic telegraph seems very simple, its creation was marveled as a significant advancement in communication technology by allowing pre-determined messages to be sent long distances. In the event of an intrusion or an enemy approaching, they would only see the brief torch flashes, and would not be able to intercept the message in any way. This advancement in communication was also a great advancement in military communication and strategy.  Messages were sent from Sicily to Carthage during the First Punic War (264-241 BC) using the hydraulic telegraph, also known as a Semaphore line.

A stamp depicting the hydraulic telegraph in use

A stamp depicting the hydraulic telegraph in use. Image source:

Through the hydraulic telegraph, the military now had the ability to communicate specific messages that allowed other groups of military personnel, as well as civilians, to better prepare for potential invasions by land or sea. This early form of long-distance communication was advanced for its time, and it paved the way for future forms of communications, which have led to the many methods we have available today.

Featured image: Greek Hydraulic Telegraph of Aeneas relief. Image source: Wikipedia


The ''hydraulic telegraph'' of Aeneas – Museum of Ancient Greek Technology. Available from:

The Telegraph – Connected Earth. Available from:

The Hydraulic Telegraph – History of Information. Available from:

The Hydraulic Telegraph – Wikipedia. Available from:

By M R Reese


It's simply amazing that whinging Brits continue to pretend that their country matters to anyone more than 100 miles from London.

It is simply amazing that the Americans have tried to take credit for electric traffic lights when the Londoners had gas lit ones; simply shocking.

The key part is that others couldn't intercept the message like your ships at sea flashes. Any code book handed out to the military would get copied in short order. Of course people knew about signals before the lightbulb, Americans pretend they invented traffic signal lights when London had gaslight ones before cars where invented.

I wonder if anyone ever thought about developing different torch signals to represent different letters in their alphabet? And just spell words in the air similar to the way we used to do with flashing electric lights between ships at sea in Morse Code? Did they think it would be too complex and take too long? How long did it take to drain that water from the cannisters to get to the correct pre-written message you needed? And what if none of the pre-written notes fit what you needed to relay? They could have developed signals--maybe patterns drawn with one or more torches in the air--to represent 20 to 30 different letters and other symbols, and then had an additional set of patterns which represented entire thoughts, ideas or sentences to save time (similar to the pre-determined messages in the hydraulic system). Or heck, they could have simply held a dark cloth between the flame and the receiver, took it away, put it back over and over in pre-determined patterns, and sent signals exactly like our Navy did with flickering lights between ships. You can't tell me, what with Pythagoreas and all those other amazing mathematicians roaming the forests and deserts in ancient times, no one thought of this until the lightbulb was invented!

rbflooringinstall's picture

That's actually pretty inovative for the time. Probably blew everybody's mind back then.

Peace and Love,



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