by Megan Gannon
June 23, 2016
from LiveScience Website
 

This ancient Greek "computer"

called the Antikythera mechanism

continues to puzzle scientists

as to what it was used for.
Credit: Wikipedia Commons

Thanks to high-tech scanning, 2,000-year-old inscriptions on the Antikythera Mechanism, an ancient Greek "computer," can be read more clearly than ever before, revealing more information about the device and its possible uses.

Ever since the first fragments of the device were pulled from a shipwreck off the coast of the Greek island Antikythera in 1901, scientists and historians have been trying to learn more about its purpose.

The bronze astronomical calculator was about the size of a shoebox, with dials on its exterior and an intricate system of 30 bronze gear wheels inside.

With the turn of a hand crank, the ancient Greeks could track the positions of the sun and the moon, the lunar phases, and even cycles of Greek athletic competitions.

The 82 corroded metal fragments of the Antikythera mechanism contain ancient Greek text, much of which is unreadable to the naked eye.

But over the past 10 years, new imaging techniques, such as 3D X-ray scanning, have revealed hidden letters and words in the text.

"Before, we could make out isolated words, but there was a lot of noise - letters that were being misread or gaps in the text," said Alexander Jones, a professor of the history of science at New York University.

 

"Now, we have something that you can actually read as ancient Greek. We can tell what these texts were saying to an ancient observer."

Fragment 19,

which is a piece of the device's back cover,

is much more clear in a PTM visualization.

With PTM, different lighting conditions can be simulated

to reveal surface details on artifacts that might otherwise be hidden.
Credit: Antikythera Mechanism Research Project

Alexander Jones and his colleagues recently published a set of papers on the inscriptions (The Inscriptions on the Antikythera Device) in a special issue of the journal Almagest.

The Inscriptions of the Antikythera Mechanism

Table of Contents and Abstracts

Almagest 7-1, May 2016
 

1. General Preface to the Publication of the Inscriptions
M. Allen, W. Ambrisco, M. Anastasiou, D. Bate, Y. Bitsakis, A. Crawley, M.G.Edmunds, D. Gelb, R. Hadland, P. Hockley, A. Jones , T. Malzbender, H. Mangou, X. Moussas, A. Ramsey , J.H. Seiradakis, J. M. Steele, A.Tselikas, M. Zafeiropoulou

This is the prefatory paper to a series which presents the surviving text inscriptions on the Antikythera Mechanism.

 

The structure of the mechanism and the history of the reading of the inscriptions are briefly reviewed.

 

The methods used by the Antikythera Mechanism Research Project to image the inscriptions  - computed tomography and polynomial textual mapping - are outlined.

 

The layout of the inscriptions is described, and the dimensions of the mechanism deduced to allow the space available for inscriptions to be estimated.

 

General conventions and notations are provided for the presentation of the inscriptions.
 

2. Historical Background and General Observations
A. Jones

This paper presents a detailed account of the history of the fragments of the Antikythera Mechanism preserved in the National Archeological Museum, Athens, with particular attention to previous transcriptions and paleographical appraisals of the inscriptions in the fragments.

 

The paper concludes with general observations about the technique and paleography of the inscriptions.
 

3. The Front Dial and Parapegma Inscriptions
Y. Bitsakis, A. Jones

The dial at the center of the front face of the Antikythera Mechanism was surrounded by two scales, one representing the zodiac, the other the Egyptian calendar year.

 

The Zodiac Scale was inscribed with the names of the zodiacal signs as well as series of index letters in alphabetic order, while the Egyptian Calendar Scale was inscribed with the Greek names of the Egyptian months.

 

In addition, two rectangular plates, the remains of which survived displaced from their original positions, bore an inscription, called the Parapegma Inscription, comprising an alphabetically indexed list of annually repeating astronomical events relating to the Sun and to fixed stars.

 

This paper gives transcriptions and translations of the inscriptions on the dial scales and the Parapegma Inscription, and deduces the original structure, layout, and location of the Parapegma Inscription.

 

A provisional astronomical analysis of the data in the Parapegma Inscription and tentative restorations of some of its damaged and missing lines are also provided.
 

4. The Back Dial and Back Plate Inscriptions
M. Anastasiou, Y. Bitsakis, A. Jones , J. M. Steele, M. Zafeiropoulou

The rear face of the Mechanism consisted of a rectangular "Back Plate" dominated by two large spiral dials.

 

The upper five-turn Metonic Dial represented a 235-lunar-month calendrical cycle while the lower four-turn Saros Dial represented a 223-lunar-month eclipse prediction cycle.

 

A subsidiary quadrant "Games" dial was situated inside the Metonic Dial, and a subsidiary three-sector Exeligmos Dial inside the Saros Dial.

 

Preserved text inscribed around the dials (from the lower right quarter of the plate), probably representing about a quarter of the original inscription, provided further information associated with the predictions of eclipses.

 

This paper describes the reconstruction from the Mechanism's fragments of the surviving parts of the text on the plate and its dials, giving transcriptions and translations.

 

The Metonic Dial inscriptions imply a calendrical scheme similar to that described by Geminos. It was intended to be a version of the calendar of Corinth as it was practiced either at Corinth itself or in some locality of Epirus.

 

The Games dial shows six competitions, four Panhellenic (Olympics, Pythian, Isthmian, and Nemean) plus Naa (Dodona) and very probably Halieia (Rhodes).

 

On the Saros dial there were probably originally about 50 or 51 month cells with a lunar and/or solar eclipse prediction, each carrying a "glyph" and an index letter.

 

Predicted eclipse times (in equinoctial hours) on the glyphs were calculated as times of true syzygy according to solar and lunar models that both involved anomaly, with the simple Exeligmos dial extending the predictions over three or more Saros cycles.

 

We are reluctant to base a firm construction date on interpretation of the eclipse cycles.

 

The additional information referred to by index letters from the Saros dial was grouped into paragraphs; that for lunar eclipse prediction probably ran down one side of the plate, and that for solar eclipse prediction down the other.

 

Statements about direction may imply a meteorological aspect by referring to predictions of winds attending the eclipses.

 

Five references to color and size at eclipse are the only Greco-Roman source known to us that suggests prediction of eclipse colors, and might conceivably be linked with astrology.
 

5. The Back Cover Inscription
Y. Bitsakis, A. Jones

This paper presents an edition with translation and commentary of an extended text that was inscribed on a plate (or conceivably a pair of plates) that lay against the rear face of the Antikythera Mechanism while it was under the sea.

 

This plate, which may have functioned as a protective cover, is extant only in small fragments, but more of its text was preserved as offsets on a layer of accreted matter that built up against it.

 

The text was a systematic description of the dials, pointers, and other external features of the Mechanism, beginning with the front face and continuing with the rear face.

 

The best preserved passages include descriptions of features on lost parts of the Mechanism: a display of pointers bearing small spheres representing the Sun and planets on the front dial, and a dial on the upper back face representing a 76-year "Kallippic" calendrical cycle.
 

6. The Front Cover Inscription
M. Anastasiou, Y. Bitsakis, A. Jones , X. Moussas, A.Tselikas, M. Zafeiropoulou

The bronze plate known as the "Front Cover" of the Antikythera Mechanism had inscriptions on its outside face.

 

This paper describes the reconstruction of the surviving parts of this text from the Mechanism's fragments, giving transcriptions and translations.

 

The texts give data on synodic cycles for the five planets, and it may be conjectured that lost lines described the behavior of the Sun and Moon.

 

The data strongly support the idea that planetary motions were displayed on the front face of the Mechanism using simple epicyclic or eccentric models.

 

Previously unattested long and accurate period relations are given for Venus and Saturn, which are favorable for geared representation and probably of Greek, rather than Babylonian, origin.

The newly filled-in bits of text have allowed Jones and his colleagues to get a better idea of what the machine might have looked like in antiquity.

Inscriptions on the cover of the back face of the device, for instance, contain an inventory of all of the dials and what they mean.

"That's where we get the key information that there was a full-blown display of planets moving through the zodiac on the front," Jones said.

This display, which is now lost, had pointers with small spheres representing the sun, moon and planets known at the time (Mars, Jupiter and Saturn) arranged in a geocentric system with circular orbits around Earth, according to the inscription on the back cover.

Researchers had proposed the existence of this feature before, but they never had any physical evidence for it, Jones said.

Sponge divers discovered the device in the wreckage of an ancient Greek vessel that seems to have been headed to the western Mediterranean carrying commercial goods, including high-end luxury objects, when it sank around 65 B.C.

American and Greek marine archaeologists are continuing to excavate the Antikythera wreck site.

In their latest expedition, which ended on June 11, the team found ceramic vessels, bits of wooden furniture, marble statue fragments and gold jewelry, according to the Greek Ministry of Culture.

The researchers did not report finding any more pieces of the Antikythera mechanism.

"There's always the hope that more will come out of new dives," Jones said.

For him, the biggest unanswered question about the device is, what was it used for?

"We know what it did now pretty well, but why would someone want to have something like this made?" Jones said.

 

"For my part, I think this is something that is very likely to have been made as an educational device, something that was not for research but for teaching people about cosmology and all sorts of time-related things about our world."

Perhaps the operator would have understood how the wheels inside the device worked, but to casual observers, the gear work would have been a mystery.

"Most people would have seen it as a closed box," Jones said. "For them, it must have been a wonderful device."