Although its origins are uncertain, the new studies of the inscriptions suggest it would have been constructed around 100-150 BC…

Writing in Nature, the team says that the mechanism was “technically more complex than any known device for at least a millennium afterwards”.
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the Moon sometimes moves slightly faster in the sky than at others because of the satellite’s elliptic orbit. To overcome this, the designer of the calculator used a “pin-and-slot” mechanism to connect two gear-wheels that introduced the necessary variations.

“When you see it your jaw just drops and you think: ‘bloody hell, that’s clever’. It’s a brilliant technical design,” said Professor Mike Edmunds.