The Antikythera Mechanism is believed to be one of the world’s oldest known geared devices. It dates from around the 1st century BC and is the most sophisticated mechanism known from the ancient world.

X-Tek is a leading company with a reputation for high-resolution industrial X-ray systems. Founded by British X-ray entrepreneur Roger Hadland, the company was approached in 2000 by freelance film-maker Tony Freeth who had heard about X-Tek’s high-resolution X-ray radiography work and wanted to apply this to investigating the mechanism.

Over the next four years, Freeth brought together researchers from Cardiff University, the National and Kapodistrian University of Athens, the Aristotle University of Thessaloniki and the National Archaeological Museum of Athens to form the Antikythera Mechanism Research Project. The project is funded by the Leverhulme Trust and supported by the Cultural Foundation of the National Bank of Greece.

X-Tek was keen to take on the challenge. However, it soon became apparent that CT, Computed Tomography, would be necessary for the project to provide 3D imaging, similar to medical CAT scans. This process images an object from all angles and builds a 3D volume showing interior structure. X-Tek had already developed the high power BladeRunner CT system for internal inspection of safety-critical aircraft turbine blades.

At the time, no X-ray source existed that was capable of penetrating the thick sections of bronze whilst retaining a microfocal X-ray spot to show the fine detail hidden inside. Hadland’s team, motivated to take on the challenge put every effort into developing a new higher voltage, high resolution X-ray source. Software engineers also had to integrate a new highly sensitive X-ray detector, kindly lent to X-Tek by PerkinElmer for the inspection.

The National Archaeological Museum in Athens, home of the Antikythera Mechanism, set a tight deadline and X-Tek worked long into the evenings to complete the system.

Recovered in 1901, fragments of the bronze geared mechanism were found by Greek sponge divers on a Roman shipwreck near the island of Antikythera. From readings of the external inscriptions, the device dates from about 100BC and is technically more complex than any known device for a millennium afterwards, consisting of 80 bronze fragments containing approximately 30 gear wheels.

The challenge has been tremendous, for more than a hundred years the device has been a profound mystery, the subject of intense research and speculation. These factors really helped to fuel X-Teks desire to maximise the X-ray capability for the project. The corroded device was initially believed to be the remains of an astronomical clock by earlier researchers. However, the fragile condition of the fragments had prevented a close-up study until the arrival of new technologies.

Researchers took four years to persuade the National Archaeological Museum in Athens to allow them to examine fragments of the device and the Antikythera Mechanism Research Project was created to gather new data on the mechanism using the latest technologies, and to challenge the previous research assumptions.

Late in 2005 the Mechanism was investigated using advanced digital surface imaging by Hewlett-Packard (USA) and microfocus X-ray computed tomography by X-Tek. The BladeRunner CT X-ray system created by X-Tek, originally to acquire CT data on aircraft turbine blades, weighs nearly 8 tonnes and was shipped to Athens for installation in the Museum. Both companies used imaging techniques that allowed inscriptions that had previously been impossible to read to be deciphered.

Hadland and his team inspected the fragments over a two-and-a-half week timescale with tremendous success. The team delighted in their achievement having recently finished production of the new 450kV X-ray source, a dramatic advance over the previous 225kV source. By contrast the energy of medical X-rays is between 70 and 140kV. The new system’s ability to penetrate much more material led to far more detail being seen, and hidden inscriptions finally revealed the purpose of the Antikythera Mechanism, a Greek computer of remarkable sophistication constructed a century before the birth of Christ.

Tony Freeth, a chief driving force in the inspection, said: “It’s a very complex mechanism that has transformed our understanding of what the Greeks were capable of in terms of technology. It could follow the movements of the sun and moon, predict eclipses and recreate the irregular orbit of the moon as seen from the earth.”

X-Tek’s X-ray scanner revealed a complicated arrangement of more than 30 precision, hand-cut bronze gears, with up to 223 teeth. With these the mechanism could predict solar and lunar eclipses and planetary positions many decades into the future. The device may also have predicted the positions of some planets, in particular Mercury and Venus.

Following a study of its workings published in the journal Nature, the Antikythera Mechanism will transform the way we think about the technological capabilities of the ancient world.

“In terms of historic and scarcity value, I have to regard this mechanism as being more valuable than the Mona Lisa,” said Professor Edmunds of Cardiff University, and continued, “when you see it your jaw just drops and you think, ‘Wow, that’s clever – if they could that, what else could they do?’”

The first results of the Antikythera Mechanism Research Project were announced at a conference in Athens at the beginning of December last year and a new model of the device’s function was presented. The organisers discussed the mechanism’s structure, origins, purpose and wider significance for the state of technology in ancient Greece. n

X-Tek Group is based in Tring, Hertfordshire, UK. www.xtekxray.com