Off the Beaten Track
in Vol. 18 - July Issue - Year 2017
The Antikythera Mechanism
The Largest Fragment
A Schematic Diagram of the Gearing
The sudden storm had blown their boat off course and the men were lucky to find shelter on a small, uninhabited island. They were sponge divers, and the next morning they decided to explore the waters surrounding the unknown islet. Imagine their surprise when, instead of sponges, the men found jewelry, coins, fine glassware, marble and bronze statues in an ancient shipwreck lying on the seabed.
The valuables were brought to the surface over the following months, but a lump of corroded bronze and wood went totally unnoticed...
It is thought that a Roman ship taking home booty from military campaigns along the Aegean coast sank off the Greek island of Antikythera in about the year 60 BC. The wreck was discovered in April 1900 and all artifacts were taken to the National Museum of Archaeology in Athens, where researchers began the painstaking task of cleaning and restoring. While sifting through the recovered objects in May 1902, an archeologist noticed that one of the rocks had a gear wheel embedded in it, but scholars quickly dismissed its importance because they decided that it was something much more recent that must have fallen into the sea in the same location.
And so, this strange object lay in a dark corner of the museum warehouse until it came to the attention of the British scientist Derek John de Solla Price in 1951. In the course of the following two decades of study, Price and the Greek nuclear physicist Charalampos Karakalos made some X-ray and gamma-ray images and published their work in 1974. Scientists were astonished when they realized that what appeared to be an indistinguishable mass of bronze components was actually a sophisticated mechanism, similar to clockwork, unlike anything known in the ancient world. It was dubbed the Antikythera Mechanism and remains one of the most intriguing objects in the history of technology.
Corrosion has fused the pieces, but thanks to computer tomography and high-resolution surface scanning technology, it has been possible to achieve greater in-depth analysis of the mechanism, which in the meantime has broken into several fragments due to cleaning and handling. The device must have been similar in size to a mantel clock, housed in a wooden case of approximately 34 x 18 x 9 cm. It had up to thirty-seven gears of different sizes, all neatly meshing with precisely-cut teeth and with a ring divided into degrees. It has been estimated that the mechanism was built in the first century BC, probably between the years 80 and 90 BC, in an unspecified location in Greece. An additional significant discovery was made when it became possible to read numerous inscriptions on the faces of the gears. These writings were a sort of instruction manual, describing the functions of the mechanism and how to obtain various kinds of information.
The Antikythera Mechanism must have had a large circular face with at least seven hands. By turning a hand crank on the side, the user could move the hands forward or backward. As the crank turned, the gears would move the hands at various speeds. The hands displayed different types of celestial time: one hand for the Sun, one for the Moon and one for each of the five known planets – Mercury, Venus, Mars, Jupiter and Saturn. There was also a rotating black and silver ball showing the phases of the Moon and two dials on the back of the case, one being a calendar and the other showing the timing of lunar and solar eclipses. Another dial gave the dates of major athletic events, such as the Olympics. Inscriptions explained when certain stars would appear in the sky on any particular date.
Further research is providing valid theories on who made the mechanism and where. Cicero had described a bronze device made by Archimedes in the third century BC, although it has not been possible to connect his invention to the mechanism built two centuries later. Hipparchus, an astronomer born around 190 BC who taught most of his life on the island of Rhodes, was one of the first philosophers to speculate that the Earth revolved around the Sun. He created the first trigonometric tables while studying problems related to spheres. Cicero also mentioned a planetary device built by Posidonius, a Greek astronomer, philosopher and historian who died in 51 BC and who was a disciple of Hipparchus. Since Posidonius took over his school on Rhodes when Hipparchus died, it can be stated that Hipparchus is the theoretical father of the Antikythera Mechanism.
By Giovanni Gregorat, Contributing Editor MFN
Author: Giovanni Gregorat