The real Archimedes Dial? The Antikythera mechanism explained

When was the world’s oldest-known computer built? Nearly 20 centuries before Charles Babbage sketched out plans for his Difference Engine, ancient Greek scientists had created a sophisticated orrery – a mechanical device to calculate the movements of the Sun and Moon through the zodiac over many years.

The importance of this long-lost object was recognised on 17 May 1902 by Greek archaeologist Valerios Stais. He was combing through ancient artefacts retrieved from a cargo ship discovered the previous year off the coast of the Greek island of Antikythera, where it had sunk in the first century BC.

While rummaging through the haul, his eye was caught by a bronze fragment that he realised contained a mechanical gear. Subsequent study revealed further wheels, dials and Greek inscriptions on various pieces of the device, which may have been designed in Rhodes around 150 BC.

As imaging techniques have improved, it’s become possible to piece together the structure and operation of the item now known as the Antikythera mechanism. Yet there’s much still to learn about this astonishing artefact and its place in the ancient Mediterranean world.

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This content first appeared in the May 2023 issue of BBC History Magazine