Fenlandphil's Blog A blog from the low country

The Antikythera mechanism as found in the sea (picture from Wikipedia)

A friend of mine is a member of the Cambridge Astronomical Association, from time to time he invites me to accompany him to their lectures. The latest outing was to watch a very interesting presentation about an ancient (180-70BC) machine discovered on a shipwreck in the Aegean Sea. This mechanism has been described as the worlds oldest analogue computer.

The excellent and interesting presentation was given by John Lancashire. Mr Lancashire has built his own working reconstruction of the machine using the original design to produce 3d printed plastic reproductions of those components to use in his machine. He did, however, change the tooth profiles of the gears to involute from the straight cut original form.

John Lancashires reproduction of the Antikythera mechanism

The machine was recovered from the sea in 1901 and identified as containing gears by the Greek archaeologist Valerois Stais in 1902. Only recently with the aid of modern X-ray and scanning techniques was its purpose discerned.  This enabled the true extent of its complexity and sophistication to be established.

John outlined the timeline of key steps in the development of astronomical theories in the Hellenistic period from 500BC through to the time when it was thought the mechanism was lost. At that time the earth was still considered to be at the centre of the universe with the sun and planets orbiting it.

This side of the machine shows the pointers representing the position of the sun and the known planets. The ball in the centre in black rotates to show the phases of the moon.

He completed his presentation by demonstrating his model of the mechanism and how he had calibrated it for the present day, the lecture was so interesting that it continued well past its scheduled slot and we departed much later than usual.

A view of the gearing and on the right the pointers for each planet and the sun. The complexity of such an ancient machine is astounding.

On the trip home my friend and I discussed the machine and concluded that there could have been earlier less complex versions of this mechanism, that someone must have sat down and designed it possibly recording their design. It is possible that these designs and the underpinning theories were lost in the burning of the library at Alexandria. For me, the interest was not only in the machine itself but how it was constructed with such accuracy and the history of the machines that well may have preceded it. We can only speculate about those people who had the intellect to have designed this and possibly other similar machines unless we can design a time machine to travel back in time we will never know their identity.