1

This animation shows slices through a false-colour X-ray volume of the main surviving fragment of the Antikythera Mechanism, going from the back to the front. You can see all the gears, plates, arbors, pins, bearings etc. It was made in ancient Greece and is one of the true wonders of the ancient world. It is also a work of genius. Thanks very much to Digital Humanities for asking me to give this presentation. Many thanks also to Lindsay MacDonald, who originally suggested it.

©2015 Tony Freeth. All rights in this presentation are reserved.

Please respect copyright.

2

Lindsay asked me how I had become so involved in the Antikythera Mechanism and I had replied that it was the product of a mis-spent middle age! So he suggested that I give a personal account of my life with the Mechanism. So that’s why I changed the title. I have never really looked at this history from a purely personal perspective before and I am somewhat apprehensive. In many ways, it goes against the grain for a scientist to give a personal account—particularly if they have worked with a research team. We normally say “we”, not “I”. But looking back on this history from a personal perspective has been very interesting. For me, it is an amazing, unlikely and almost surreal history. I hope that it doesn’t come across as being too egotistical but I thought that I should embrace the idea of a personal account. Lindsay isn’t here. He’s done a runner! He fled to France—no doubt to avoid the monster he had spawned! Anyway, if it all goes wrong, I shall blame it all on Lindsay, since he is conveniently not here!

3

I am not going to give an account of all the discoveries that I have been involved with, since there is nothing like enough time. I am going to concentrate on the most extraordinary discovery, which is how the Mechanism tracks the Moon—the so-called lunar anomaly. In the words of Douglas Adams, What is the answer to the Gears, the Moon and the Antikythera Mechanism? The answer will appear later!

4

First, the relevant background. I had a mis-spent childhood, playing with Meccano. I must have done other stuff—like eating and being hit by my elder brother—but I don’t remember much of it. This is a differential gear, which I must have made when I was around 12 years old. I was fascinated by it. It uses epicyclic gears, which are gears where the axle of the gear is mounted on the face of another gear and moves round with it. Epicyclic gearing is a subtle and extraordinary type of gearing system, with particular relevance to the Antikythera Mechanism.

5

It’s not really as difficult as Quantum Mechanics—but it is very surprising and hard to understand.

6

I had a mis-spent childhood and early adulthood studying mathematics. Mathematics was always my favorite subject at school. I became far too narrowly focused at much too early an age. First Cambridge: pure mathematics for my first degree and a postgraduate degree in mathematical logic and algebraic topology (Part III of the Maths Tripos, now MMath). Then Bristol: an MSc and PhD in mathematical logic, specializing in Set Theory. So what has all this advanced modern mathematics got to do with the Antikythera Mechanism? The answer is, nothing. So what has mathematics got to do with the Antikythera Mechanism, the answer is, everything. Every aspect of the design is informed by mathematics. The maths is simple, but it’s used in a way that amounts to genius. It is an astonishing design, which was clearly designed by a mathematician. I recognized the mathematical way of thinking that is embodied in every aspect of its design. A long immersion in mathematics gave me the background needed to understand it.

7

Then, being a perpetual student, I went to the National Film School and mis-spent my time training as a Director and Cameraman, followed by a 25-year mis-spent career in the film and television industry as a Director and Producer, making documentary films. So why is this background relevant? As regards filmmaking, the hugely difficult task of data gathering stretched all the skills that I had learned over 25 years producing and directing films. All the skills dealing with people and expensive projects. All the diplomatic skills needed to persuade people in institutions to do things they normally don’t do. So that’s the first 53 years dealt with! And 53 is a very significant number for the Antikythera Mechanism, as we shall see! If only I had realized the significance of my age at the time, I could have saved many years of research—as we shall see!

8

Now the jokes are over! It’s a serious account from now on. So, no laughing please! I first heard about the Antikythera Mechanism as a TV producer. I was approached one day in 2000 by someone I knew well, Professor Mike Edmunds, a distinguished astronomer at Cardiff University. He asked me if I had ever heard of the Antikythera Mechanism. He wanted to make a TV program about it. Little did I know the life-changing consequences of that conversation. I had never heard about the Antikythera Mechanism. So Mike told me the story of its discovery.

9

The story starts with a man called Fotis Lindiakos, seen here with his family in the 1890s.

10

He was a boat-owner running sponge fishers from the small island of Symi in the Eastern Mediterranean. This is the sort of equipment they used—large brass helmets and canvas suits, pumped air. It was very, very dangerous and many divers were killed or incapacitated.

11

The sponge divers set off from Symi. When they reached the small island of Antikythera, between Crete and mainland Greece, they were caught in a violent storm.

12

When the storm subsided, the captain, Demetrios Kondos...

13

... ...sent down one of the younger divers, Elias Stadiatis, to look for sponges. He soon emerged from the sea, trembling in fear and shouting that he had seen “a heap of dead naked people under the water”.

14

These turned out to be marble sculptures, lying on the seafloor along with many other ancient artefacts. He had discovered an ancient wreck, full of Greek treasure.

15

Then the captain went down and emerged from the sea carrying a larger-than-life bronze arm.

16

They continued with their sponge fishing expedition and returned to Symi. They debated what to do about their discovery, Should they return and plunder the site after their sponge-fishing trip? Or should they tell the authorities? To cut a long story short, they told the authorities.

17

The response some months later was the first major underwater archaeology in history. A navy gunboat, the Mykali, stood by to deter looters. The sponge divers (top right) were employed to carry out the dive. It was very dangerous—one diver died and two were permanently disabled. It took months to bring everything to the surface.

18

It was a stunning find. They had uncovered a treasure trove of ancient Greek objects: beautiful bronzes, jewellery, superb glassware, amphorae, tableware and many other objects.

19

No-one at the time was electrified by another object they found—a corroded lump, which almost certainly came out of the sea in one piece. Like all the other finds, it was taken to the National Archaeological Museum in Athens. It was left in an open-air cage to be examined at a later date. Then a former Minister, Valerios Staïs, visited the Museum and noticed that it had split apart. This changed everything!

20

Inside the object they discovered the remains of some gearwheels. These were not the crude mechanical gears you might find in a watermill or windmill, these were precision gearwheels—mathematical gearing as it is sometimes called—with teeth about a millimetre long. It was a truly shocking discovery for ancient Greece. Such gearwheels simply should not have been there. There was huge excitement and much controversy.

21

It is the most extraordinary artifact ever found from the ancient world. Finding out what it was has been an extraordinary voyage of discovery: for me personally, it has been an absolutely amazing journey. It has involved a 100-year trail of clues; mysteries; confusions; missed opportunities; and breakthroughs. At each stage of research, new generations of scientists have brought “new eyes” to this stunning object—not only new technology but new ideas and new ways of understanding the device.

22

To give an overview, I am going to sketch in the four major stages of research on the mechanical structure of the Mechanism. Albert Rehm was the first person to understand its essence as an astronomical calculating machine as well as crucial features of the inscriptions that cover its external plates. He got everything wrong mechanically but his ideas were extraordinarily prescient. Derek de Solla Price made major advances. He was the first to carry out X-rays, together with Charalambos Karakalos. This established the astonishing complexity of the gearing. He determined the basic architecture of the Mechanism. Crucially, he identified the 19-year Metonic Cycle in the gearing of the device. Michael Wright, initially with Professor Allan Bromley, carried out the second X-ray study— using stereo pairs and an early form of 3D tomography. He has made a sequence of major advances. Together with the Antikythera Mechanism Research Project, I organized new investigations of the Mechanism and determined a number of crucial features of its mechanical structure—including eclipse prediction. I am going to talk about the first lunar anomaly: it is the most important and astonishing feature of the Antikythera Mechanism, involving all four generations of research. First I am going to wind forwards to the results of this research to show you where we are going.

23

This is the back of the main surviving fragment of the Antikythera Mechanism. It is evidence for all of these gears at the back of the Mechanism. These fragments witness the back dials of the Mechanism, with an upper calendar and lower eclipse prediction dial. We now come round to the front of the Mechanism, which shows the Main Drive Wheel, with its mysterious pillars, which we believe are part of the evidence for planetary mechanisms, based on the epicyclic theories of Apollonios of Perga—though much of the evidence is missing. The basic architecture of this planetarium, mounted on this large four-spoked, wheel, was proposed by Michael Wright. These conjectural coaxial pointers indicate the positions of the Sun, Moon and planets in a display that portrayed the ancient Greek cosmos. This is Fragment C, part of which shows in the centre the Moon phase device discovered by Michael Wright. These fragments are evidence of the Parapegma—the star calendar discovered by Albert Rehm—on the front plate of the Mechanism. This extraordinary mechanism was contained in a wooden box, with an input at the side.

24

This is the final result. It is a wonder machine of genius, designed on mathematical principles. An astronomical compendium, incorporating the whole predictive power of ancient Greek astronomy. It is a “Theory of Nearly Everything in a Box”!

25

Mike Edmunds and I did not manage to set up a TV programme. The TV commissioners told us it was an old story. The main research had been published in 1974. So, at that stage, we failed to get the project off the ground. But we were still deeply interested and Mike started to set up an Anglo-Greek Academic team of interested people—with myself, Professor John Seiradakis, one of Greece’s leading astronomers, Professor Xenophon Moussas, an astrophysicist, who recruited physicist Yanis Bitsakis and later philologist Dr Agamemnon Tselikas.

26

I became completely fascinated with the Mechanism. Our main problem was that we had no good data—not even a good set of still photographs. I started to look at previous research.

27

In the early years after its discovery, there was much speculation. Some maintained that it was a navigation device (after all it had come from a ship); some that it was an astrolabe—a device for tracking the stars. This was closer, but neither hypothesis was right. There were fierce academic disputes, where both sides were wrong. (Nothing surprising there then!) There was much confusion but there was some significant progress.

28

The one person, who really understood it was a German philologist, Albert Rehm. He claimed that it was an astronomical calculating machine. Albert Rehm was an extraordinary man. Later in life in the early 1930s, he became Rector of Munich University. He was strongly anti-Nazi and this caused him to lose his job and he was forced into "internal exile". He was rehabilitated after the war and once again became Rector of the University.

29

Albert Rehm was an expert on ancient inscriptions and in 1905 he started by examining the text that was visible on the surfaces of the fragments. He is seen here with Fragment C.

30

On this fragment, he found many inscriptions, which you can see faintly in the pictures. Rehm identified an Egyptian calendar and he determined that the text on the face of Fragment C was a star calendar, called a Parapegma. He transcribed the text.

31

We owe the preservation of some of this text to Rehm, since the original material is now lost. Parapegmata were common in the ancient world. They were essentially star almanacs, which set out the risings and settings of prominent stars in the annual cycle. Often these were linked to weather predictions and sometimes medical advice. On the Antikythera Mechanism, it is purely astronomic. Rehm's published a couple of papers, but they are not of huge interest. It's his notebooks, where he expresses many speculative ideas, which are a goldmine.

32

Here is another page from Rehm’s notebooks. I’ve highlighted a note that he wrote in the margin. In this note we can see the numbers 76 and 19 and further down he mentions the Kallippic Cycle and the Metonic Cycle.

33

Here is another page from Rehm’s notebooks. I’ve highlighted the number 223. Where did Rehm get these numbers—76, 19 and 223? What are they all about?

34

This is Fragment 19. It is part of the Back Cover of the Mechanism, which is covered in inscriptions. It has been described as a sort of User Manual for the Mechanism. It describes the basic principles on which the Mechanism is based.

35

I want to look at this fragment, using a brilliant technique devised by Tom Malzbender of Hewlett-Packard, which I will come back to later. It highlights details on surfaces. It makes the text stand out very clearly.

36

Here we find exactly the numbers mentioned by Rehm. He must have seen this fragment and copied them. The 19-year Metonic cycle, named after a Greek astronomer, Meton of Athens, but known earlier in Babylonian astronomy. The Kallippic Cycle, an improvement on the Metonic Cycle, where Kallippos took four Metonic Cycles and removed a single day—making a 76-year cycle. And the 223-month Saros eclipse prediction cycle from 7th century BC Babylon. If you want to make a geared mechanism for tracking the astronomical bodies, these are the sorts of astronomical cycles that you need.

37

When the ancient astronomers looked at the night sky, they saw the great dome of stars rotating from East to West every night, centred on the Pole Star—as the Earth rotated in the opposite direction. But there is another movement of the astronomical bodies that are close to us—the Sun, Moon and planets. They move predominantly in the opposite direction, relative to the fixed stars, from West to East. And they all move in much the same plane, called the ecliptic, through the band of stars called the zodiac. These movements of the Sun, Moon and planets in the ecliptic plane were the primary subject matter of ancient astronomy. We call it the Solar System, but in ancient Greece their viewpoint was primarily geocentric—Earth-centred. The positions of the astronomical bodies were expressed in terms of their position in the zodiac—in other words their ecliptic longitude.

38

The Metonic Cycle is a 19-year cycle of the Moon. It comes in two parts. The first part identifies 19 years with 254 sidereal months: that’s the basic orbital cycle of the Moon from one star back to the same star. The second identifies 19 years with 235 lunar months: that’s the phase cycle of the Moon from New Moon back to New Moon. If we observe the Moon near a particular star at a particular phase and then we look at it 19 years later. It will be near the same star and at the same phase.

39

The Saros eclipse prediction cycle works like this. If you have an eclipse of the Moon or the Sun in one month and you look 223 lunar months later—just over 18 years—then you will get a very similar eclipse. And the repeat goes on for 12 – 15 centuries.

40

Rehm explored the basic architecture of the Mechanism, but he didn’t really understand how it was put together.

41

Rehm also started to explore possible mechanical arrangements. He got everything wrong. The thing about Rehm is that he got all the details of the mechanical structure wrong, but he had incredible insights. Rehm did publish some articles about the Antikythera Mechanism, but they are far less interesting than his unpublished research notes, which can now be found in the Bayerische Staatsbibliothek in Munich.

42

This is another remarkable page from Rehm’s notebooks.

43

Incredibly, he wrote about eccentrics and epicycles. Epicyclic gearing involves gears whose axes are mounted on other gears. It is a difficult and sophisticated concept and it is utterly astonishing to suggest this for ancient Greece. Again Rehm proved to be right—but in ways that he never dreamed of. Some of his notes are in an early German shorthand, called Gabelsberger. He is clearly struggling here to understand the mechanical structure, without enough data. Rehm was a genius. If his insights had been combined with our X-ray data, we could probably have saved a hundred years of research and I would have been deprived of my passionate journey of discovery! Rehm left a fascinating but unresolved legacy.

44

Half a century after Rehm had started on this Mechanism— a period in which nothing much happened—his legacy was taken up by the great Derek de Solla Price He was a British physicist, turned historian of science, originally at Cambridge, then at Yale. Like Rehm, he got much wrong, but what he got right was absolutely crucial. Price is the reason we are all here. 1959, Scientific American: brought the extraordinary device to a much wider audience. In his work, themes began to emerge: “At least 20 gear wheels… have been preserved... a sort of epicyclic or differential system.” Again epicyclic gears, probably following Rehm: a shockingly bold claim for ancient Greece. It has great significance for the history of technology. Price’s Differential became his most celebrated discovery. Price wrote, “…from all we know of science and technology in the Hellenistic Age we should have felt that such a device could not exist.” All of us, who have studied this Mechanism in depth, would heartily agree with Price.

45

In around 1970, Price teamed up with Greek radiologist, Charalambos Karakalos, to carry out the first X-ray study. It was a critical step. These X-rays showed the true complexity of the gearing. To their astonishment, they found 27 gears in Fragment A—all overlapping in a very confusing puzzle. In order to understand what a geared mechanism does, you need to count the numbers of teeth on the gears. This will tell you what astronomical cycles it embodies. In the right-hand picture, the teeth are marked for counting. This was done by Charalambos and his wife Emily. They would then estimate the total number of teeth on each gear—nearly all the gears are damaged and partial. They would then give these tooth counts to Price. By this time, Price was beginning to develop his own ideas about how the Mechanism worked and he began to argue with the Karakalos family about the tooth count—much to their annoyance apparently! They had done the scientific process of estimating tooth counts and Price was challenging them without any good evidence! Let me show you an example.

46

The gear here, which fills the square, was counted by the Karakalos family as having 128 teeth.

47

But Price said he thought that it has 127 teeth. Well, what’s a single tooth between friends!

48

Let me show you a modern X-ray CT of this same gear. You can see the huge advantage of modern X-ray technology. Nearly all the teeth are visible and we can with confidence say that it has 127 teeth. Price may not have been very scientific, but he was right! This was extremely significant...

49

...because 127 is the large prime factor in 254, which is the number of sidereal months in the 19-year Metonic cycle. Rehm had found the ancient Babylonian Metonic Cycle in the inscriptions; Price found it embedded in the gearing. It was a discovery of historic importance.

50

I want to show you how Price incorporated this gear into the Mechanism. It gives insights into how the whole Mechanism works.

51

At the back of the Main Drive Wheel is attached a small gear, b2, with 64 teeth. All the gearing behind the Main Drive Wheel is driven from this gear. I am going to build Price’s Metonic gear train from this. At the same time, I will show what is being calculated. The two gears on axis b rotate at 1 revolution per year.

52

Add another gear, c1, with 38 teeth. As you can see this brings the prime number 19 from the Metonic cycle into the calculation. The minus sign simply means that the gear rotates counter-clockwise when seen from the front.

53

c2, with 48 teeth, is riveted to c1 and they turn together on a fixed axle, attached to the Main Plate.

54

Adding d1, with 24 teeth means a simple doubling of the ratio.

55

Now we add a large gear d2 with 127 teeth, which you will recognize as Price’s gear.

56

This meshes with e2, with 32 teeth, to give the simple ratio 254/19. This represents the sidereal form of the Metonic cycle. This was a great discovery by Price: the Metonic cycle is embedded in the gearing of the Mechanism.

57

This is the output of this gear train. As you can see it is on an unusual axis with a small pentagonal section, which has a hole through it: it is the end of a tube. This output, which is the mean sidereal month, is a mystery that I will return to. Price thought wrongly that it went directly to the front of the Mechanism to show the mean position of the Moon in the zodiac on the large front dial. Why the axle had a pentagonal section is something I don’t completely understand—though I do have an idea. Later I will show you why there is a hole in the middle of the axle.

58

Price went on to examine the gears at the back of the Mechanism. Famously, he proposed that this system was a Differential, using epicyclic gears. It was a revolutionary idea—pre-empted by Rehm. The Differential subtracts (“differences”) the rotation of the Sun from the rotation of the Moon to give the phase cycle of the Moon. It was a brilliant and revolutionary idea for ancient Greece. It became his most celebrated discovery. But unfortunately, it was wrong. A beautiful idea that is wrong is hard to abandon and this in my view set back Price’s research significantly. He got stuck with his brilliant but wrong idea.

59

As it turned out, it was the right idea in the wrong place (again!) and it was far too complicated. And he could find no role for the largest gear in the system, E4. Gears from the Greeks includes much scientific presentation, with measurements to a tenth of a millimeter, complicated diagrams and confident assertions. At first, I didn’t question it. Then I started to get sceptical.

60

After 20 years work, Price put together all his ideas in what he believed was a complete model of the Mechanism. It’s complicated and hard to understand at first glance. I don’t want to explain it in detail. You can see his Metonic gear train in blue in the centre of the diagram.

61

I just want to say one thing: apart from his Metonic gear train, Price got everything else wrong! All of the rest of the gear trains are wrong! His “Sunwheel” was impossible. His “four-year dial” for the Upper Back Dial was wrong. His famous Differential was wrong.

62

This is where I came in terms of research. I wrote a paper called Challenging the Classic Research, which essentially said that Price’s model was very complicated but it did rather simple things. It was much too complicated for its outputs: a clear violation of the principle, often known as Occam’s Razor: that you should keep everything as simple as possible. I have spent the last fifteen years dismantling Price’s model.

63

But Price also got much of the Mechanism right. He was the first person to propose the basic architecture of the device, which we follow today. It is basically a box with an input handle and pointers that go round dials to show astronomical parameters, driven by complex gearwork inside.

64

Price did 20 years of research on the Mechanism. By 1974, Price was Avalon professor of the History of Science at Yale University and he wrote up all his results in his masterwork, Gears from the Greeks. Though much of the details are wrong, it is a truly great paper and we are all here because of Price. I revere Price: Gears from the Greeks is the ‘Bible’ for later researchers. But, just like the Bible, you do not have to literally believe all its details! In scientific research, you don’t have to get everything right to make very significant progress. And much of his work has not stood the test of time.

65

Gears from the Greeks drew me into a fascination with the Antikythera Mechanism. I became passionate about it—or obsessed as my wife describes it… But you don’t make any serious progress without total focus, total concentration. I studied every bit of literature that I could find. Having dismantled Price’s model, I wanted to find out how it actually worked. We had no good data—not even a good set of still photographs. None of our Greek colleagues could find the X-rays that Karakalos had done. So I started to look around for new techniques to gather new data.

66

Then I saw an article in New Scientist called Tricks of the Light about a technique for looking at surfaces, which enhanced detail. An example given was a Babylonian tablet, where the details of the carving and the text stood out with astonishing clarity. The external surfaces of the Antikythera Mechanism are covered in tiny inscriptions, literally thousands of text characters. Polynomial Texture Mapping (PTM) was invented by a brilliant scientist at Hewlett-Packard, called Tom Malzbender.

67

I met Tom at the National Gallery in London, where he was using his technique to study paintings—revealing such things as the fingerprints of the artists. We got on really well and Tom was keen to bring his equipment to Athens to study the Antikythera Mechanism.

68

So now we could add...

69

...the excellent Hewlett-Packard team to our growing research project.

70

I also wanted to look inside the fragments with 3D X-rays. One day I saw a false-colour X-ray image of a goldfish, with all the bones and fins visible. I wondered if this might work on the Antikythera Mechanism. I contacted the researcher, Steve Wilkins from Australia, who had made the X-ray images. I asked him if we could use his technique on the Antikythera Mechanism. He said, no: his technique of phase contrast X-rays needed thin slices of the sample. (I didn’t think that the Museum in Athens would be very keen on us slicing up the Mechanism into thin slices!) What I needed was Microfocus X-ray Computed tomography. To cut a long story short, via the Welding Institute...

71

...I found X-Tek Systems. They were world leaders in Microfocus X-ray Computed Tompgraphy (X-ray CT)—high-resolution 3D X-rays. In film-making, much of your time is spent persuading people to take part in your project—sometimes reluctantly. So my background in film-making kicked in and I managed to get the interest of the company. And then I had to keep them interested for four years, while we got all the necessary permissions from the Greek authorities. It was a nightmare. After a couple of years, they were going to ditch the project because they didn’t think that their equipment was powerful enough. So I wrote an email to the company founder, Roger Hadland and we arranged to meet.

72

I got on really well with Roger and I got his attention. Afterwards, he told me that he expected that the meeting would be a short one where he would say no. But he started to get interested in the Antikythera Mechanism—really interested! After the meeting, he decided that he would do the project. This would mean building a special prototype X-ray machine with much more power. It would be the most powerful X-ray CT machine in the world. It was an extraordinary decision. Later, I would learn that the company was failing at the time, with 60 employees and almost no orders for their machines. It was a huge risk and it cost Roger a furious row with his Finance Director. It was an incredibly courageous decision. But he was fascinated with the Mechanism and he had the instinct that, if he formed a team around making a uniquely powerful X-ray machine, it would have far-reaching commercial advantages.

73

So the X-Tek team joined the project. They were a superb team. But we didn’t have permission from the Greek authorities to carry out the new investigations. They had turned us down in 2001 because they said that the fragments are very fragile—a good reason—and that the previous set of X-rays had not yet been fully researched. This was a bad reason, since they had been done 12 years previously.

74

The previous set of X-rays had been taken by Michael Wright (on the right), a former curator of Mechanical Engineering at the Science Museum in London and Professor Alan Bromley, a professor of computer science at Sydney University and an expert on Babbage. You can see a reconstruction of one of Babbage’s engines in front of him.

75

They had wanted to get the 3D information that the Karakalos X-rays lacked and they had used an early form of tomography called linear tomography. It was a technique that delivered data, which was very hard to interpret. Sadly Bromley and Wright fell out and then Bromley died.

76

But Michael Wright was very persistent and made a series of important discoveries—some of which I will describe.

77

I am going to look now at one important part of Michael Wright’s work. I want to describe his work on the Metonic Calendar Dial.

78

Price had suggested that the Upper Back Dial might be a Metonic Calendar, with 47 months on each of its five rings—making a total of 235 months. But he threw the idea away in favour of his simplistic Four-Year Dial—again an idea that would find a role on one of the subsidiary dials (the Olympiad Dial). Right idea, wrong place... yet again! Wright revived Price’s idea of a Metonic Calendar and he showed how it could be turned by the surviving gears.

79

Let me strip off the plate to reveal the gearing. This is the Main Drive Wheel. On average it goes round once a year, driven by the small crown gear at the side. The gearing system that I am going to show you was proposed by Michael Wright. It is so bizarre that at first I thought that it was incomprehensible.

80

Fixed to this large wheel is a smaller wheel with 64 teeth. Much of the Mechanism is driven from this wheel.

81

I am going to build up the gear train that leads to the Upper Back dials. l1 meshes with b2 and brings the prime factor 19 into the ratio—the Metonic cycle. The minus sign simply means that l1 turns in the opposite direction. This is a gear train that was proposed by Michael Wright.

82

l2 is fixed to the same axle as l1 and they turn together. It brings the strange prime number 53 to the ratio...

83

And here is an X-ray of the actual gear. It really does have 53 teeth. I couldn’t understand what it was doing there when I first read Michael Wright’s paper.

84

And on axis m we get this ratio, with no apparent astronomical meaning, and with the bizarre prime number 53.

85

Now we can complete the gear train. We get exactly the ratio we need for a 19-year 5-turn Saros Dial. But notice, we have had to introduce another conjectural gear to get rid of the damn prime number, 53. It doesn’t seem to make sense. Why introduce 53 and then cancel it out like this? What on earth is going on?

86

I should say that I was so concerned about Wright’s 53-tooth gear that I changed 53...

87

...to 54 in my model. This turned out to be a big mistake!

88

This is Michael Wright with the version of his model, which he published in 2005.

89

It included a pioneering planetarium at the front, which is conjectural because the evidence is missing. At the back is the Metonic Calendar that Price had suggested and then thrown away, and which was then revived by Wright. Also he introduced a dial that showed the draconitic month, the latitude cycle of the Moon that is important for eclipses, over a scale of 218 half days. Immediately I read about it, I knew that it was wrong. This was the latest model that was published before our new investigations...

90

...which only happened because of the extraordinary persistence of one of our Greek professors, Xenophon Moussas, in getting the necessary permissions. Xenophon would not take “no” for an answer. He called the Ministry of Culture between 40 and 60 times and got the same negative answer each time, until one day they gave him an appointment with the Deputy Minister of Culture, Petros Tatoulis. Xenophon went to the meeting, expecting 15 minutes at best. Tatoulis was there with his wife who worked with him in his office. It turned out that they were both really keen on ancient Greek astronomy! After more than an hour, Tatoulis told Xenophon that he wanted to do the new investigations. He called the Director of the Museum, Dr Nikolaos Kaltsas. Kaltsas, who said no, he didn’t want to do it. But Tatoulis was very persuasive and finally persuaded Kaltsas to do the new investigations. Without Xenophon’s persistence, the project would not have happened.

91

At last we had the full team. At the National Archaeological Museum in Athens we would be looked after by senior archaeologist, Mary Zapheiropoulou, and Head of Chemistry, Eleni Mangou. Everything was set and then the Museum suddenly asked us how we proposed to insure the fragments! Our hearts sank. Were they worth a $1m or $100m or maybe $1bn?!! We had to persuade them that all the handling would be done by the Museum staff: we would never touch the fragments. Diplomacy is not really my strong suit—but when it is necessary, you have no choice. (And it was often necessary.) My experience making films helped a lot, since you often have to deal with difficult situations. Finally they agreed.

92

Before 2005, these were the main fragments that we knew about—with some additional small pieces that Price mentioned.

93

Then in 2005, Mary Zapheriopoulou called one of our team to say that she had discovered some trays of bits in the store room, labelled “Antikythera”. Were we interested? Of course, we were!

94

To cut a long story short, we ended up with 82 fragments. We would use both our new techniques on all the fragments, as well as taking a new set of still photos, which you can see here.

95

First Tom Malzbender came to Athens with his excellent team—Dan Gelb and Bill Ambrisco—and set up his PTM dome. This is covered in flashlights and takes a sequence of still photos with lighting from different directions. These images are then integrated by a computer into an interactive image.

96

This is Fragment C, where Rehm found the Egyptian calendar and the Parapegma. This image can be re-lit on the computer from any direction. Also a number of filters help with deciphering details...

97

...for example, specular enhancement is particularly powerful, yielding great clarity in the surface details. It is a wonderful tool for deciphering text characters.

98

It can be re-lit from any direction...

99

...enabling different details to be enhanced. And different text characters to be read. A week later, we had a superb data set.

100

But we didn’t yet have our X-ray machine. The Bladerunner—as they would call it because it was destined to be used on turbine blades—was far from being ready. It was in pieces: that’s the trouble with prototype technology. All the delays in getting permission had worked in our favour, but it still wasn’t ready. With days to go before it was due to be picked up, they had a nine-inch spark, which equates to several hundred thousand volts. Luckily it didn’t kill anyone but it destroyed three computers and other vital equipment. So they had to rebuild much of the machine. I was filming all of this with cinematographer, Stephen Macmillan. Then the Greek lorry driver turned up to pick it up. Stephen and I knew that our job was to keep the driver happy while they finished the machine.

101

We discovered that his favorite food was fish and chips! So we took him for fish-and-chips and we talked for hours about his family and the corrupt police that he would meet on the way to Athens. Apparently lorry drivers have to pay many small bribes to police to continue on their journeys. He was very good natured and patient. At around 2.00 am the next morning…

102

…we saw off the Bladerunner en route for Athens. Some days later, it arrived at the National Archaeological Museum in Athens with a police escort and was maneuvered into the Museum basement with a forklift.

103

It was pushed and shoved into the basement of the Museum and everything was set up by a superbly professional team.

104

It was a complex operation. Each day we would arrive at 7.00 am and work through the day, with lunch on the job, until around 7.00 pm. We had told the Museum that we might work some long days but this turned out to be every day. The Museum was not really used to this: they went into culture shock! There was a lot of tension around the project. I was used to that as a filmmaker but at times it got extreme.

105

One issue was the safety of the fragments. They were carried on flimsy stands down a winding stairs and through a door, past security guards and to the X-ray machine, where a dozen or more people were milling around. I became extremely anxious and had sleepless nights worrying. I tried to get proper protocols in place to ensure the safety of the fragments. Mary and I had some vigorous conversations about the safety of the fragments.

106

I think that Mary was as anxious as I was, but she didn’t really know how to deal with it. The conservators were fantastic with a very secure touch—you would entrust them with brain surgery—but we worried about the system for transporting the fragments. In the end nothing bad happened and we survived.

107

After two weeks, we had four days to go and we still hadn’t done all the small fragments. Then Mary and Eleni told us that we had to stop work. It was a bombshell!

108

We discovered what had happened. There had been a staff meeting with the Director. The women had told him that we worked these crazy hours and they had to be there the whole time. Could they have some time off in lieu when we had left? The Director said, no. So they had been forced to withdraw their services. Solving this problem took all of my filmmaking skills and some very skilled diplomacy from our Greek professors. Nietzsche wrote that, whatever does not kill you makes you stronger. This only goes to prove that Nietzsche never worked with the National Archaeological Museum in Athens! Talking of Nietzsche, I recently spoke in Basel. Two very congenial academics took me a tour of Basel, with its old 14th century houses, its cathedral and a plaque celebrating the Bernouilli brothers. But the highlight of the tour came when they showed me the street where Nietzsche caught syphilis!

109

We got stunning results with nearly a terabyte of data. These are tiny details—for example the teeth of the gears are about 1mm long and most of the text is less than 2 mm high, typically 1.6mm high. All of this detail preserved despite 2,000 years under water. We expected that the surface imaging would show us the inscriptions and the X-rays would show us the structure of the gears. So we were astonished when the X-rays also revealed many thousands of new text characters, hidden inside the fragments and unread for 2,000 years.

110

So we got all our data back home. I was charged with trying to sort out the mechanical structure. There was a severe technical problem with the X-ray CT data of Fragment A.

111

So I started with Fragment F—one of the fragments found by Mary in the Museum store. On the surface, it looks just like beach pebble, with the green perhaps indicating bronze. It is full of fascinating information.

112

This is a slice through our 3D X-ray data. To start with there is nothing of interest. I am going to go down through a sequence of parallel slices through the data.

113

Here maybe there is a hint of structure.

114

Here we begin to see some scales. This is the great power of X-ray CT—you can isolate a single slice.

115

Now we can see clearly defined scales...

116

...with beautiful definition.

117

Now we start to see scale divisions…

118

...and more scale divisions… Fragment F is rich in information. I developed a very simple strategy: focus on scale divisions. If you want to know what a scale does, you should try to find out how many scale divisions there were round the whole dial. It may seem an obvious strategy—but it had not been applied very well by previous researchers. These scale divisions...

119

...look very similar to those in Fragment A...

120

...which Price had recorded. They are visible on the surface and are part of the Lower Back Dial.

121

We can transfer these scale divisions onto the four-turn spiral scale.

122

And put them together with the divisions from Fragment F and from another small fragment, Fragment E. Now we have enough divisions to make a very good estimate of the total number of divisions round the whole dial.

123

You’ve probably guessed it! It is the remarkable answer, 223. The number on Fragment 19 that Rehm had seen a hundred years earlier. It is the Saros eclipse prediction cycle. The Lower Back Dial is an eclipse prediction dial. It was our first major breakthrough from our new data. The Saros cycle works like this. If you have an eclipse of either the Moon or Sun in one month and you look 223 months later, then you will get a very similar eclipse. This repeat goes on for 12 to 15 centuries. It really is a very good cycle.

124

But there was more to discover from Fragment F.

125

Between divisions I found blocks of text and symbols.

126

Here are some close-up X-ray slices. What did these mean?

127

And surrounding the dial there were dense inscriptions.

128

Remember that In Fragment A, Price had found similar blocks of text and symbols.

129

These are on the surface and can be viewed using HP’s beautiful surface imaging. I called them ‘glyphs’ and I am going to explain what they mean.

130

There were also similar inscriptions round the dial.

131

These glyphs occur at either six-month or five-month intervals or are adjacent—just like actual eclipses. They must surely be the eclipse predictions. The Saros Dial is a 223-lunar month dial over a four-turn spiral. The eclipses are indicated by glyphs, which indicate the type and time of the eclipse. Each glyph includes an index letter, which references inscriptions around the dial, with more information about the eclipses. It is a very ambitious and sophisticated eclipse prediction scheme, though far from being entirely accurate. I have been doing some research on this recently, which you can find by googling “Antikythera Plos One”. It’s an open-access online journal, which is free to all.

132

Let me just summarize here. This is the Saros Dial, with the glyphs, which indicate the eclipses around the four-turn spiral. We don’t yet know how the pointer for the Saros Dial was turned.

133

Let’s strip off the Back Plate to reveal the gears. The gears at the top are for the Metonic Dial, which we looked at already. I want to add those for the Saros Dial. The large cross-spoked gear is the Main Drive Wheel. It is turned by the small crown gear at the side, which was probably turned by a knob or a crank.

134

I want to show how the gear trains branch at axis m—the branch that we’ve seen to the Upper Back Dials and another branch to the Lower Back Dials. Axis m is really the only plausible axis from which to turn the Saros Dial. It goes through the Main Plate, which I have suppressed here so that you can see the gears. What I am going to show you is a complete departure from Price’s model and Wright’s later modification of Price.

135

For the 223-month cycle, I needed a gear with 223 teeth. 223 is a prime number, so it can’t be broken down into smaller gears.

136

This is the back of Fragment A. We want a gear with 223 teeth

137

There is really only one good candidate. e3 is the largest gear at the back of the fragment. It is not the ring gear which just a bit smaller and has 188 teeth; it’s the gear outside that, which is fixed to it.

138

The teeth can be seen more clearly in our X-ray CT. There are enough teeth to make a confident estimate that there were in fact 223 teeth. The Karakalos family estimated that it had 222 teeth and Price had explicitly rejected any idea that it might have 223 teeth. He wrote that the ratio “went the wrong way”. This was essentially because of his wrong Differential.

139

This is a computer model of these gears—the gear e3 with 223 teeth and the ring gear e4 with 188 teeth. At the moment, it is an orphan, detached from the rest of the Mechanism. How shall we turn e3?

140

Again, there really is no choice. It must be powered by a conjectural gear m3 and we give this a tooth count of 27 to make the ratios work. It also fits exactly into the space with this number of teeth.

141

As we saw before, axis m turns at this rate.

142

This means that the gear pair e3-e4 turns at this rate. This will turn out to be a very significant ratio, as we shall see later.

143

The next gear is f1, with 53 teeth, giving this ratio. Again, the mysterious prime number 53 is cancelled out.

144

We have gear f1 and there are sufficient teeth to be confident that it has 53 teeth. We are going to have to solve this mystery.

145

Now I will add the rest of the gearing. This is exactly what we need for a 4-turn dial, showing the 223 months of the Saros cycle. e3 had found no role in any previous model of the Mechanism.

146

Now I had a nice story: I knew that the Lower Back Dial was a Saros eclipse prediction dial; I knew how it was turned via a 223-tooth gear; and I and my colleagues had decoded much of the information in the glyphs. But I also had a huge problem, which took me months to sort out!

147

We can see the large gear pair e3, with e3 having 223 teeth. You will notice some fittings on this gear.

148

This is the back of Fragment A, which is the evidence we have for e3.

149

Stuck on the back of e3 are a couple of other gears and I want to highlight this system.

150

In close-up we see two gears. These were part of Price’s famous but wrong Differential.

151

This is an X-ray CT slice through this system. But these are not the gears that you see on the right: they are behind them. You will notice the pentagonal hub at the centre of e5.

152

If we take an X-ray CT slice one millimetre towards us, we see another pair of gears. These are the gears on the right. There are four gears in the system. It is to Price’s great credit that he saw this.

153

After months of puzzling and a fog of confusions, I got onto the plane from London to Athens.

154

I took my research notes with me.

155

I couldn’t work out what these four gears were doing there. They were part of Price’s Differential, but I knew that was wrong. They were part of Wright’s modification of Price, which generated the draconitic month by subtle choice of the gear counts of the four gears. I was sure that was wrong as well. I had taken months agonizing about this gearing system.

156

I took a huge spreadsheet with me with thousands of entries. This shows a small part of it. I was following Michael Wright’s paradigm by looking at all the possible gear counts for these gears, which you can see on the left. Could subtle choices of the tooth counts within the accepted possible ranges produce the right result? There were many possibilities of types of month. There was one output with a period of 26,000 years. Epicyclic gearing really is extraordinary. Could this be the precession of the equinoxes?! I couldn’t really make any headway. There were thousands of possibilities, most without any meaning.

157

I had also taken a paper on quasi-periodic motion by Giovanni Gallavotti.

158

This included a diagram showing the ancient Greek epicyclic theory of the Moon according to Hipparchus, which explained its variable motion through the zodiac.

159

Then I remembered a brief remark in a paper by Michael Wright about an observation that he had made, which he didn’t regard as important. It was in a throwaway paragraph in one of his papers.

160

I want to concentrate on the bottom gears. These are epicyclic gears, which are attached to e3.

161

You will see that there is a slot at the bottom of this gear. This was noticed in 1902 by Rados, but not understood. Price thought that it was evidence of a repair to a broken tooth that had subsequently dropped out. But Michael Wright made a far more astute observation.

162

He noticed that there is a pin on the gear k1, behind k2.

163

And this engages in the slot on k2. A tooth has broken off at this point. What on earth is that all about? Most people would think that this arrangement was useless. The gears would turn at the same rate and you might as well just fix them together.

164

Wright made another crucial observation. He said that the two gears k1 and k2 turn on eccentric axes. K1, the gear at the back, turns on the blue axle and k2, in front of it, turns on the pink axle. This induces a variable motion in the gear k2. I am going to show you how this works with an animation. Forget for the moment that these are epicylcic gears—I will come back to that later. The animation shows what happens when the eccentric axes are fixed.

165

This is the gear with the pin that sits on one of the eccentric axes. On top of it is the gear with the slot that sits on the other offset axis. When the pin is further out from the slot, the driven gear moves slower and lags behind the driving gear; when the pin is closer to the centre, it drives the gear faster and the driven gear moves ahead. This is how the system induces the variable motion.

166

Wright discarded this idea because it didn’t work in his model, where e3 turned much too fast for it to work. In our model it doesn't—recall that in our model e3 turns very slowly to drive the Saros pointer. I came to believe that this system must model the variable motion of the Moon. And that to do this, all four gears in the system should have equal tooth counts. Without the pin-and-slot, this would mean that the system didn’t change the rotation at all—completely useless. So Wright’s paradigm had to change. First I need to tell you about the orbit of the Moon.

167

This is my contribution to Shakespeare scholarship! You will all recall how Romeo swears his love for Juliet by the Moon. Juliet, “O swear not by the Moon...” We don’t know what sort of variability in the Moon she was talking about. Probably the phase cycle of the Moon. My own belief is that, if she knew the full picture, she would have walked away there and then—and saved herself a lot of grief! So—in case you find yourselves in the same position, where your partner swears their love by the Moon—I am going to give you the full picture!

168

In modern terms, the orbit of the Moon is an ellipse, with the Earth at one of the foci. This diagram exaggerates the eccentricity of the ellipse. The point when the Moon is closest to the Earth is called Perigee. That’s when the Moon is moving fastest relative to the zodiac. The point when the Moon is furthest from the Earth is called Apogee. That’s when the Moon is moving slowest relative to the zodiac. If we follow the Moon from a prominent star back to the same star, that’s called the sidereal month and is on average 27.32 days. If the Moon starts at Apogee at a prominent star and goes round through its orbit back to the same star—its sidereal cycle—you might think that it will return to its Apogee.

169

But in fact the Line of Apsides, which is the long axis of the elliptical orbit, has moved round by around 3°. So the Moon must catch up with the Line of Apsides to get back to Apogee—to its slowest motion. This cycle of the Moon, from its slowest motion back to its slowest motion, is called the anomalistic month and it is just a bit longer than the sidereal month—only about 5½ hours longer. The ancient Greeks knew about this cycle, as did the ancient Babylonians before them. And all this knowledge is built into the Antikythera Mechanism.

170

We need to understand the ancient Greek theory of the Moon’s variable motion. This is known as the lunar anomaly. This theory explains the variable motion of the Moon as the addition of two simple circular motions. A constant rotation on the so-called Deferent, with period of the sidereal month.

171

Plus a second circular motion in the form of a small epicycle, carried by the deferent, which models the variable motion of the Moon. The epicycle turns in the opposite direction to the deferent with the period of anomalistic month relative to the deferent. I am going to play an animation, which shows the resultant orbit generated by this theory.

172

The epicycle is turning backwards relative to the deferent almost as fast as the deferent is turning forwards. This means that the pink pin representing the Moon turns anticlockwise very slowly – in parallel with the Line of Apsides. The result is an orbit that looks very much like an off-centre circle. In fact it’s very subtly different and each time the Moon orbits, it follows a slightly different path. The blue arrow shows the direction of the Mean Moon – the Moon’s average position. The pink arrow shows the actual Moon according to the theory. Sometimes it lags behind the Mean Moon, and sometimes it is ahead. Notice at the end that the blue arrow is horizontal, but the pink arrow has not yet got back to apogee. It needs to travel onwards until it reaches the red Line of Apsides. A key idea in this theory is that the period of the Moon’s variable motion is the anomalistic month, which is just slightly longer than the sidereal month.

173

The idea is that this system models the ancient Greek epicyclic theory of the Moon. This is the addition of two circular motions with the deferent turning at the rate of the mean sidereal month and the deferent at the rate of the anomalistic month—in other words, the orbit of the Moon from apogee back to apogee. The crucial question is: how fast must e3 rotate in order for it to model this theory?

174

The answer is the difference between the rotations of the sidereal and the anomalistic months. We can calculate this from a combination of the Metonic and Saros cycles. (I will leave you to do the arithmetic.) This results in a very familiar ratio. This is the rotation that we have already calculated for the rotation of e3. We can calculate this and the result is 0.112579655 to nine places of decimals. So now we understand the 53 tooth gears. The first ensures that e3 turns at the rate of the Line of Apsides of the Moon and the other two cancel out the 53 where it is not wanted.

175

When I was on the plane, I knew what the target was for the rotation of the large 223-tooth gear, e3. But this gear already has a rotation to turn the Saros Dial. There was some choice on the input gear m3 that turned e3.

176

I thought that it had 27 teeth. So I tried this. Too big!

177

Then I tried 26 teeth. Too small! Mathematicians are strange people, as I am sure you know. Sometimes they do crazy, impossible things.

178

So I tried the impossible 26.5 teeth for m3. It was exactly the right answer, to nine places of decimals. I sat bolt upright in my seat. It couldn’t be a coincidence! I immediately realized that twice 26.5 is 53: Michael Wright’s 53-tooth gear that I had changed to 54 teeth. Then everything fell into place! There was a cascade of consequences.

179

Let me show you how this works. The inputs to this system are the rotation of e3 that we encountered earlier, with the bizarre prime 53, which we now understand.

180

The other input is the rotation of the mean sidereal month that resulted from Price’s Metonic gear train.

181

You will notice the pentagon on the hub that carries the mean sidereal month rotation and the hole through the middle of it.

182

e5 with 50 teeth sits on the pentagonal hub and carries the mean sidereal month rotation. Notice that there are two offset axes on the right. Their separation is about a millimetre.

183

k1, also with 50 teeth, is the gear with the pin and it sits on the larger of the two eccentric axes. (An important insight was that all four gears in the system have the same number of teeth. Without the pin-and-slot, this would be a useless arrangement, which would give a unity ratio.)

184

And the slot on k2 engages with this pin. What is the point of this arrangement? As we have seen, the answer lies in the eccentric axes on which the gears turn. As they turn, sometimes the pin is closer to the outside of the slot, when k2 turns more slowly, and sometimes to the inside, when k2 turns faster. This induces a variable rotation in k2.

185

This variable motion outputs at e6. With equal gears, the whole point of the system is to introduce the variable motion.

186

This is not at all the obvious way to model the epicyclic theory of the Moon.

187

Mounting the Pin & Slot epicyclically changes its period of variation from the sidereal to the anomalistic month. It was an incredible idea by the designer. It is a work of genius. But there was still an outstanding problem. What I had found was that the rotation of e6 modelled the variable motion of the Moon. But where did this output end up? It had always been assumed that the epicyclic system at the back outputs to the Back Dials. I couldn’t work it out.

188

Here is a profile view of the same gearing. A couple of weeks later I got a call from Mike Edmunds in the Canary Islands. Could the output go back through the large gear e3 and up to the back dials? I told him that I thought not and put down the ‘phone. I immediately realized that he was right and I called him back.

189

I want to concentrate on this area.

190

If I now add the output at e6, it goes back through the hole in the pentagon that we noticed earlier, then to e1 with 32 teeth.

191

e1 then engages with an equal sized gear, b3, that reverses its direction of rotation. From there it goes up to the front dials. It was obviously insane to attempt to do this in the 2nd century BC. You would have thought that was enough and you would then simply add a pointer to show the variable position of the Moon in the zodiac.

192

But they had a special kind of insanity. They added a device to display the phase of the Moon.

193

Here is another angle. You can see the semi-silvered ball that displays the phase of the Moon as well as the lunar pointer that shows the position of the Moon in the zodiac. The Moon phase device was identified by Michael Wright. It occurs much later in history on many medieval astronomical clocks.

194

Strip off the cover and you can see the gears. It is an exquisite differential device, with an epicyclic crown gear, carried round by the casing of the lunar phase mechanism, which engages with an equal-toothed gear on the Sun output. This differential device that subtracts the solar rotation from the lunar rotation to get the phase. It does exactly the same as Price’s Differential in his old model in Gears from the Greeks. Price had the right idea in the wrong place and made it much too complicated.

195

The gear in the centre is the 53-tooth gear. It turns the large gear pair, e3-e4, at the correct rate, so that the period of variability of the output of the pin-and-slot device is the anomalistic month. The diagram shows how this is geometrically equivalent to the ancient Greek theory of variable lunar motion. The output then goes up through the hole in the pentagon to the Moon phase mechanism and the lunar pointer, to show the variable motion of the Moon through the zodiac.

196

This is a gear diagram of the whole Mechanism, except the planets at the front. It’s not easy to understand at first glance! You can see the 53-tooth gear, which Michael Wright identified. And how this turns e3. You can see the pin-and slot that generates the variable motion and how its output goes up to the front dials. I hope that I have given you some insights into the research that created this model.

197

This entirely new model of the Antikythera Mechanism became part of our first publication in the prestigious science journal, Nature, which gave us huge worldwide publicity. It was a heady experience. As a research team, we had clung on by our fingernails through years of frustrations and setbacks. There were many times when we were sure that the project would fail. I found a persistence and focus in doing this project, which I never knew I had. Maybe Nietzsche was right: it didn’t kill me and in many ways I became stronger! I was extremely privileged to be in the right place at the right time with the right skills to make a contribution to this research.

198

What is the answer to the Gears, the Moon and the Antikythera Mechanism? The answer is 53 !!

199

It really is incredible that sponge divers in 1901 should recover a corroded lump that contains two gears with 53 teeth and evidence of a lost technological revolution. We should never forget that this device is from ancient Greece. It re-writes the rules on the history of ancient technology. It challenges us to re-think this history and to question all the assumptions about it. I would like to end on a quote from Derek de Solla Price’s 1959 Scientific American article. “It is a bit frightening to know that just before the fall of their great civilization the ancient Greeks had come so close to our age, not only in their thought, but also in their scientific technology.” So that is how I spent much of my mis-spent middle age!

200

Questions?

©2015 Tony Freeth. All rights in this presentation are reserved.

Please respect copyright.