[MUSIC]
Stanford University.
This program is brought to by
the Stanford Humanities Center.
For more information please
visit us at shc.stanford.edu.
Good evening.
My name is Grant Parker.
On behalf of Stanford's Department of
Classics, I'd like to welcome you to
the 12th Lawrence Eitner Lecture
on Classical Art and Culture,
a lecture series aimed at presenting
classical antiquity to a wider public.
It's wonderful to see such
a good turnout this evening.
The series has been indulged by Peter and
Lindsay Joost our cherished friends and
benefactors of many years, friends
of benefactors of Stanford Classics.
And in honor of Lawrence Eitner,
who died in 2009.
Born 80 years previously in
what was then Czechoslovakia,
Lawrence Eitner started in Germany and
fleeing Nazi atrocities,
came to the United States, starting
at Duke and Princeton Universities.
At Stanford from 1963 to 1989,
Professor Eitner served as director
of Stanford's Art Museum, now known as
the Cantor Art Center, for a long time.
He also chaired what was then
the Department of Art and Architecture.
He was himself a distinguished
expert on French romantic painting,
especially, Jericho,
with a dozen books to his name.
In naming these annual lectures after him,
we honor the memory of a renowned scholar,
teacher, and writer,
who oversaw the process that raised our
university's art museum from
the doldrums to prominence.
From 1,400 to 33,000 square feet.
Today I'm thrilled to we welcoming,
as our speaker, Dr. Tony Freeth.
Who joins us from his home base in London.
Surely, the first Eitner lecturer to
have all his degrees in mathematics,
from Cambridge and Bristol universities.
Doctor Freeth spent 23 very successful
years in film and television,
as an award winning director of for
Thames Television, the BBC and
Channel 4 on scientific, cultural and
social issues, as well as medical science.
In the new millennium, the television
cameras have turned instead on
Tony himself, for
his work on the Antikythera Mechanism.
The extraordinary device about
which he will tell us today.
In making sense of this artifact,
dubbed by several writers as
the world's first computer.
I think we'll get to decide for ourselves.
Tony is the expert, the one who's
research finally lead to that
aha moment in understand
this intriguing object.
More than a century after
it's discovery in 1900.
His interpretations, published in
nature and other top journals,
are the radical new advances and the
definitive interpretations that would have
been unthinkable without his
mathematician's background, to say nothing
about his director's pragmatism in
getting complicated projects together.
Tony, your appearance today as the Eitner
lecturer is a timely demonstration
of what stunning results come from
collaborative, bridge-building research.
And further that Classical Antiquity
has not finished telling us
whatever it has to say.
We'll be looking forward
tremendously to your lecture.
The Antikythera Mechanism,
a shocking discovery from Greece.
>> [APPLAUSE] Thank you very much for
the introduction, Professor Parker,
what you see here is X-ray
slices through the main
surviving fragment of
the Antikythera Mechanism.
You can see all the details of the gears,
the pins,
the bearings the arbors, the inscriptions.
It's a truly complicated device.
It's also probably the most
extraordinary artifact ever
discovered from the ancient world, and one
of the true wonders of the ancient world.
It's a work of genius,
which continues to surprise and
shock us as we discover more about it.
I have to say I've had a really
great time here in California.
I love Stanford University.
I bought the cap.
>> [laughter]
>> It's got a fantastic logo on it.
It says fear the tree.
>> [LAUGH]
>> What I've come here to say is
Fear the Antikythera Mechanism.
>> [LAUGH]
>> It will challenge all
your preconceptions about
the classical world.
First, I'd like to thank
Professor Walter Scheidel for
inviting me to give this lecture, and
Professor Grant Parker, who has given
me a very generous and warm welcome and
taken me on some very memorable tours
of the campus, thank you very much.
I would also like to thank my good
friend and long time Antikythera
collaborator Tom Malzbender,
who's some where here in the audience and
his fiance Alice Trand for
their very warm, generous and
thoughtful, and considerate
hospitality while I've been here.
They nearly killed me,
they took to Yosemite Valley, and
they took me walking up to
the top of Yosemite Falls,
I'm not a young man any longer, and I very
nearly didn't make it down, I have to say.
So I am very pleased to be
here to give this lecture,
but it was an absolutely
fantastic experience.
I would also like to thank
Peter Lindsay Joost, for
the very imaginative and
generous support for this lecture series.
This very challenging and
interesting lecture series.
I have to say, it's a great privilege to
be here at Stanford giving this lecture.
And I'm not really sure
that I'm quite up to it.
But what I do know is that
the Antikythera mechanism is up to it.
So I hope you're going to forget
my inadequacies while you're
dazzled by the genius
of the ancient Greeks.
What I want to tell you is, what I want to
talk to you about is why the Antikythera
mechanism was such a shocking
discovery from ancient Greece.
I'm going to take you on
a voyage of discovery.
Through the key questions
to establish its identity.
What, where, when, who and why.
The story starts,
obviously with its discovery and
with a man called Fotis Lindiakos,
seen here with his family
in a small island called Symi
in the eastern Mediterranean.
Which is a sponge fishing island, and
Lindiakos ran sponge fishing boats.
In 1900, he sent a sponge
fishing boat off to travel
west across the Mediterranean to
the normal sponge fishing grounds.
And when they reached a tiny
island called Antikythera,
they encountered a severe storm.
They had to take shelter from the storm.
But when the storm subsided, the captain,
Dimitrios Kondos, decided to send
down one of the youngest divers,
Elias Studi Artis, to see what he
might find in the local waters.
And Stadiatis came up a few minutes
later trembling in fear, and
said that he'd seen a heap of
dead naked people underwater.
These turned out to be sculptures
scattered on the sea floor,
along with a lot of other artifacts,
amphorae and so on.
He'd stumbled on an ancient wreck.
So the captain himself went down and
found a bronze arm,
which he brought to the surface.
They had commercial pressures.
They had to get on with their
sponge fishing tour, so they
went carried on taking the bronze arm with
them and eventually went back to Symi.
There, apparently,
they debated as to what they might do.
Should they perhaps, next season,
go back and plunder the wreck?
Or should they tell the authorities?
And I don't know why it happened,
but I'm sure we're all grateful
that they did tell the authorities.
Who organized the first major
underwater archaeology in history?
The Greek navy provided a gunboat, the
Mykali, to stand by to deter looters and
the sponge fishermen themselves were
commissioned to carry out the dive.
You can see them in the top
right picture there.
In 1900, they didn't have too
much luck because of storms, but
in 1901, they started to bring
up some very serious artifacts.
It was a stunning find.
It was a true treasure ship.
It was full of wonderful
bronzes that you can see here.
Superb glassware, much of it intact.
Some jewelry, amphorae, tableware,
many, many other objects.
But one object that no one noticed or
regarded at the time, was a corroded lump.
It must have come out of
the sea in one piece.
This is the earliest picture
we have of it, taken in 1902.
And it was taken along with
all the other artifacts to
the National Archeological Museum and
set aside in a store of
stuff to be examined later.
And then a visiting former minister,
Valerios Stais,
came to the museum and
he noticed that it had split apart,
and inside there were these gear wheels.
These weren't crude mechanical gears
that you might find in a windmill or
a water mill, these were precision gears
with teeth about a millimeter long.
It was a truly shocking discovery.
They simply should not have been
there in an ancient Greek artifact.
So the key question was,
what on earth is this object?
And I'm going to spend
most of this presentation
telling you some of the answers to that.
In the early days, there was
a lot of confusion and arguments.
Some people thought it was
a navigation instrument.
It did come from a ship, after all.
And some thought it might be a geared
astrolabe, which is a device for
tracking the stars,
which was closer to the truth.
But as with so many academic disputes,
it was very heated and quite controversial
dispute, and both sides were wrong.
>> [LAUGH]
>> But
there was one man in this early period
who did make significant progress,
called Albert Rehm.
He was a philologist,
a German philologist,
expert on ancient languages, and
a remarkable man in many ways.
Later, in 1930, he would become
rector of Munich University,
but he was strongly anti-Nazi.
>> And he was forced out of his job and
forced into what they called
internal exile in Germany,
and he was only reinstated into
his job at the end of the war.
Back in 1905, though,
he started to look at the fragments,
particularly this Fragment C.
This is one of the main fragments.
The main fragments are lettered A,
B, C, etc.
And on the face of this fragment,
he noticed some inscriptions,
hard to read inscriptions.
And he read the name of an Egyptian
month name written in Greek.
And there were a lot of divisions
that were clearly day divisions.
So this was an Egyptian calendar.
He identified an Egyptian
calendar dial in fragment C.
He inferred also that there must
have been a zodiac dial, and
he read some more faint inscriptions
on the surface of the fragment,
which he transcribed,
you can see on the right.
And this he identified as a parapegma,
named for
a star calendar in the ancient world.
So Rehm had clearly determined that
the device was astronomical in nature.
This is a page of Rehm's
unpublished research notebooks.
He did publish a couple of papers.
But the most interesting work
that he did remained in his
unpublished research notebooks.
They're a gold mine of interesting
ideas and thoughts, and
I've highlighted a marginal note there,
and you can see the numbers 76 there and
19, and the word Kallippischen and
the word Metonischen.
This is another page of his notebooks, and
you can see the number 223.
The fact that these numbers are in
his notebooks means that Rehm
must have seen this fragment here,
which we call Fragment 19.
Less than 5 cm long, very tiny fragment.
And we sometimes call it the user
manual for the mechanism,
because it describes the underlying
principles on which the mechanism worked.
I'm gonna show you that with a beautiful
technique which was invented by
Tom Malzbender, who I'm currently staying
with, who was then at Hewlett-Packard.
Which looks at the surfaces of objects and
enhances the clarity of the surface
details, and as you can see,
the text absolutely leaps out with this.
This is jumping ahead,
in a sense, in the story, but
it's absolutely a key technique that
we use for looking at the inscriptions.
What Rehm must have seen was firstly 19
years for the Metonic Cycle, Metonischen.
And this is a cycle of the moon,
which in fact,
originated in 5th century BC Babylon.
They're named after a Greek astronomer,
Meton of Athens.
He also saw 76 years for
the Kallippic cycle.
This is an improvement by the Greek
astronomic Kallippos Of the Metonic Cycle.
He took four Metonic Cycles and
took out a single day.
And he also read Sigma Kappa Gamma 223
in the ancient Greek letters for numbers
system, which is for the lunar months
of the Saros eclipse prediction cycle.
And I'm going back to describe the Metonic
and Seros cycles in detail later.
These are the key cycles you need to know
to understand how the mechanism worked.
In order to understand
what these cycles mean,
I'd just like to talk a little
bit about ancient astronomy.
When the ancients viewed the skies,
every night they would see the whole
dome of stars,
which they referred to as the thick stars,
heave over from east to west as the earth
spins in the opposite direction.
But they notice the movements of some
astronomical bodies relative to the stars.
And these were the sun, the moon and the
five planets known in the ancient world.
And they all seemed to follow the same
sort of path through the sky,
which is known as the ecliptic.
And the reason they do that in
modern astronomical terms is that
the solar system,
these are all the bodies that are close
to us, lies pretty much in a flat disk.
And these movements were
in the opposite direction
to the movements of
the stars predominantly.
They also defined a band of stars around
the ecliptic and called it the zodiac,
and divided it into the 12
customary signs that we know of.
There's Virgo and Libra.
And this gave a frame of reference for
defining the positions of
the astronomical bodies.
For example, the moon there we might
think was about six degrees in Libra.
I'm going to now take a snapshot
of the moon on a particular night,
near a prominent star
at a particular phase.
And it's moving relative to the stars
in the direction of the arrow.
And exactly 19 years later,
I'm going to take another snapshot and
you'll see that it looks identical.
And that the reason for
this is the Metonic Cycle.
In that 19 years, the moon has gone
through exactly 235 lunar months,
that's the phase cycle of the moon,
from new moons, through full moon,
back to new moon.
So the moon is at the same
phase after 19 years and
it's been through 254 sidereal months.
This is the basic orbital cycle
of the moon around the earth.
The cycle of the moon against the stars,
so
it's in the same position
relative to the prominent star.
So this is a brilliant
predictive cycle for the moon.
Rehm was the first person to
really understand the essence
of the Antikythera mechanism as
an astronomical calculating machine.
He realized that it used Bronsky wheels
to calculate these astronomical cycles.
He got the mechanics completely wrong,
he simply didn't have enough data.
But he had these
extraordinarily prescient ideas.
You'll see at the top there's
four coaxial pointers.
And this is the form we think now
that the front of the mechanism took.
Here's another page of Rehm's notebooks.
And I just want to translate
a couple of phrases here.
The first says Epicycle.
And the second says, eccentric in turning,
it turns an epicycle.
Well, what are epicyclic gears?
If you imagine a conventional
mechanical clock,
it has gears that turn on axles that
sit in bearings in fixed plates.
The bearings don't move, the axles
don't move, the gears turn around.
With epicyclic gearing,
the bearing is planted
on another gear so
that it turns around with that other gear.
The axle turns around
while the gear is turning.
Its really an extremely difficult to
understand, advanced form of gearing and
frankly utterly shocking to propose for
Ancient Greece.
You'd expect to have to wait til the
Middle Ages to find this sort of gearing.
It's a very subtle form of gearing.
Rehm had these, as I said,
got everything mechanically wrong, but
he had these extraordinarily
present ideas.
It's 100 years later that we realize
that he was correct about this.
He left this great legacy,
but very unresolved legacy.
And nearly half a century later,
the next researcher was the great Derek
de Solla Price, who started studying
the fragments in the early 1950s.
By 1959, he published a very famous
article in Scientific American.
He said, the mechanism is like a great
astronomical clock without an escapement.
At least 20 gears have been preserved,
including a very sophisticated assembly
of gears that probably functioned as sort
of epicyclic or differential gear system.
He probably got epicyclic gears from Rehm,
his differential gear system
became his most famous proposal.
Price was very persistent,
and more than a decade later,
he teamed up with a very distinguished, a
Greek radiologist, Charalambos Karakalos,
to carry out the first set of X-rays.
To their complete astonishment,
they found 27 gears in the main fragment.
It was a truly complex mechanism.
Now if you want to know what a mechanism
does, a geared mechanism that
reproduces astronomical cycles,
you want to count the teeth of the gears.
And in the right-hand picture
you can see that the teeth of
the gears have been marked for counting.
Nearly all the gears are partial
to get these sectors of gears.
And you have to make estimates
of the total number of
teeth on the original gear
from this partial information.
And this was done by Charalambos and
his wife, Emily.
And then they'd take the results to Price.
Let me give you one example here.
The Karakalos family said that this gear,
that's the gear that nearly fills that
square, you can see the teeth
in the top left corner there.
They estimated that this
gear had 128 teeth.
Now by this time, Price started to
argue with the Karakalos family,
much to their irritation
about their tooth counts.
And Price said he thought
this gear had 127 teeth.
Apparently they were very irritated.
They thought they'd done
the scientific thing and
that Price was massaging their figures.
Let me just look at that gear here
with one of our modern X-rays.
And you can see the huge advantage
of modern X-ray technology.
You can see the traces of
nearly all the teeth there.
You can make a very reliable
tooth count estimate.
And Price was correct about
the tooth-count, it had 127 teeth.
Well what's a tooth between
friends you might ask.
>> [LAUGH]
>> But it turned out to have great
significance because 127 is half of 254.
It's the large prime factor of 254,
the number of sidereal months
in a 19-year metonic cycle.
So what Rhem found in the inscriptions,
the metonic cycle,
Price found embedded in the gearing.
It was a very important discovery and
Price went much further than this.
He described how he thought
this gear was embodied
into the gear wheels of the device.
On the right there you can see
the main surviving fragment
with it's characteristic large wheel,
four spoked wheel,
sometimes called the Main Drive Wheel.
It goes round one turn a year.
On the left,
there's a computer reconstruction and
you can see a little crown input gear
which is where the device is turned from
probably by a knob or
a crank or something like that.
And if you look at the back of that gear
there, there's another smaller gear,
b2 64 teeth also goes around once a year.
Price sensed that there's another gear
that meshes with it, c1 with 38 teeth.
I should say this is
not an epicyclic gear.
I've suppressed the main plate here so
you can see the gears but
this sits on a fixed axis in
a bearing in the main plate.
And we can easily calculate how fast
this gear turns by the simple laws
of measuring gears.
We just divide the tooth counts and
it simplifies down to 32 over 19.
And 19 is clearly for the Metonic cycle.
Price then said there's
a couple more gears, 48 teeth,
24 teeth simply doubles the ratio.
The minus sign is because
each time you mesh two gears,
they turn in opposite directions.
So this is the basic way
the mechanism works.
It builds up increasingly
compounds gear trains to calculate
increasingly sophisticated ratios.
Then comes Price's 127 tooth gear,
meshes with another little gear,
e2 with 32 teeth and calculates.
You do the simple arithmetic
calculates 254 over 19 which
is the sidereal version
of the Metonic cycle.
It essentially calculates the average
position of the moon in the zodiac.
Now let me just look at
the output year for this.
It's got a rather strange little
pentagonal hub with a hole through it.
Price thought that the output of this gear
then went straight up to the front dials,
to the Zodiac dial that Riemann proposed
to show the average position of the moon
in the Zodiac.
But in fact, the gear train take
a completely extraordinary journey,
which I'm going to describe.
This wasn't a fancy on Price's part.
Here we have in modern x-rays all
the gears involved with this.
And usually for the Antikythera mechanism,
many of them are nearly complete.
We can count the tooth counts,
they all check out.
This is a completely established
part of the Antikythera mechanism.
Price also looked at the back of
the gears at the back of the mechanism.
And you'll notice there
are two large gears E3, E4.
And on them sit two Epicyclic gears K1,
K2.
Well, why do we use Epicyclic gearing?
One purpose for
them is that if you've just got fixed axis
gear trains as we've
seen Price's gear train.
Then we can simply multiply and
divide the tooth counts.
We can't add or subtract ratios,
we simply multiply and divide them.
If you want to add or subtract ratios,
you got to use Epicyclic gears.
It's not obvious,
it's a difficult concept.
What Price said was that this was
all part of a differential system.
Differential difference,
it calculated a difference.
He said it calculated
the difference between the basic
orbital cycle of the moon around
the earth, the sidereal cycle.
And from that it subtracted the orbit
of the Sun around the Earth.
Remember we're in geocentric,
Earth-centered astronomy here.
And that subtraction produces
the phase cycle of the Moon,
the lunar month, again, it's not obvious.
It was an absolutely brilliant
idea on Prices' part.
Unfortunately it was wrong.
And this, I think, set back
Price's research by a huge amount.
He became famous for this idea.
If you have a brilliant idea for
which you become famous,
it's kind of hard to challenge it.
And he didn't question it or challenge it,
he just got famous from it.
And one thing Price noticed in
the system is the large gear that E4,
we call it somewhat confusingly lowercase
e3 for very good reasons I won't go into.
The Krykos family estimated 222 teeth for
this gear, and
Price wrote that you might
think that this had something
to do with the 223 lunar
months of the cycle.
But in this context, it can have no
such meaning, and the reason for
that was that this large gear per
e3 went around much too fast for
it to have that sort of astronomical
meaning, so he discarded the idea.
He put together all his ideas about
the gearing into a complicated
gearing diagram.
These are two versions of it,
two schematic versions of it.
You can see in the middle there,
the little Metonic gear train
we followed in blue there.
And it is complicated, difficult to
understand, won't describe it in detail.
What I want to say about this model
is that everything else is wrong,
completely wrong.
His son Will is wrong,
his differential gear was wrong.
His four year dial was wrong.
And this is really where I
came in terms of research.
I wrote a paper called Challenging the
Classic Research, which criticizes this
model on the basis that it was far to
complicated for it's simple output.
It violated an essential
principle in science engineering,
computer science and technology, which
is that you should keep things simple.
It's sometimes called the KISS principle.
Keep it simple stupid, is the idea.
And it's a fundamental principle
that everybody in science goes by.
But Price, he didn't get everything wrong,
he understood the relative
position of the fragments.
He got a huge amount of right in fact,
which Redmond had not been able to do.
And he put this together into a basic
architecture of the mechanism
as a simple box with at the front on
the left there, you can see the dials,
a calendar dial and
the zodiac dial that Rem proposed.
And at the back he said
there's a Twin dial system,
with five turns at the top,
four turns at the bottom.
That I believe,
you've got completely right.
But you got the function
of these back dials wrong.
After 20 years of search,
he put everything together in a truly
great paper called, Gears from the Greeks.
By this time, Price was Avalon Professor
of the History of Science
at Yale University and this paper defined
the Antikythera mechanism for
the next generation.
It became the bible for later researchers.
And don't misunderstand me,
I really revere Price.
I think he is still the greatest
researcher in Antikythera research
history.
You don't just make progress in
science by getting everything right.
You make progress also by getting
things wrong in an interesting way.
And he set the agenda for
the whole future of research.
When he died at an early age, the mantle
was taken over by two more researchers.
On the left there, Professor Allan Bromley
from Sydney University,
a professor of computer science.
Seeing there I should say not with
the Antikythera mechanism, but
with part of one of
Charles Babbage's computing engines.
He was a considerable
expert on Charles Babbage.
And on the right there is Michael Wright,
who was then
a curator of mechanical engineering
at the Science Museum in London.
They had become skeptical about Price's
model I have to say some years before I
had, but unknown to myself.
And they determined to get
new x-rays to do new x-rays,
the problem with the Crackle's x-rays
was all the gears were overlapping.
They were two dimensional x-rays,
you couldn't easily
distinguish the 3D depth of the gears,
or the mechanical structure.
And they used this early technique of
3D x-rays called linear tomography.
I won't go into the technique,
it's very hard to interpret the results.
And I should say, sadly,
that Alan Bromley died
before the full fruits of his
research could take place.
But Michael Wright was
extremely persistent and
made some very fundamental discoveries on
the mechanism, which I've listed there.
I don't possibly have space here to go
into all of Michael Wright's research,
but he produced some very
important results and
I'm gonna talk about some
of these as I go through.
To start with, I'm gonna talk
about this Metonic Calendar.
That's the upper back
dial of the mechanism.
That's the dial which Price
said was a four year dial,
which was frankly a very boring and
simplistic idea.
But in Gears from the Greek's,
Price also wrote that
there's a possibility that
there might be 47 months for
each turn of this dial,
5 turns of the dial,
5 47s is 235 and
it might be a Metonic Calendar Dial.
But he threw away his brilliant idea and
it was taken up with great perception by
Michael Wright, who went much further.
He proposed gearing for
turning the pointer of this calendar dial.
I'm going to strip off the case and
show you the gearing.
It starts just the same
way as Price's Metonic
gear train, with a little gear with
38 teeth with the same result.
And then there is a gear with 53 teeth.
Now bear with me going through this
rather detailed look, it is really,
I assure you worth it.
Now I was a mathematician and
53 teeth, it's a bizarre prime number.
It's not a prime number you'd expect to
turn up, it's got no apparent meaning.
In my own developing model at the time,
I changed it to 54,
which turned out to be a huge mistake.
If we look at this gears with our x-rays,
we have enough teeth to make a tooth
estimate, and
53 is the correct answer for it.
Its meaning is extraordinary.
I'm gonna put the rest of the gear
train in, that Michael Wright proposed.
And you'll notice that there's
a second gear there with 53 teeth.
Which it's a conjectural gear, we don't
have any physical evidence for it, but
it must've been there.
Because we only want the ratio 5 over 19.
It's a 5 turn dial over 19 years.
So the 53 teeth gears
cancel each other out.
So what on Earth are they doing there?
Why is this gear train so complicated?
It dramatically seems to
contradict the KISS principle,
you should keep things simple.
Understanding this was understanding
the heart of the Antikythera Mechanism.
By 2005, Michael Wright had
produced the model which
had the planets at the front on
a very bold scheme he had with
eight coaxial pointers for
the dates sun, moon and five planets.
And I believe he's fundamentally
correct about that.
I have arguments with
him about the gearing,
I think his gearing is
far too complicated.
He revived Price's idea of a Metonic
Calendar with great perception and
proposed the gearing.
But for the bottom dial,
he had a Draconitic month dial.
Now the Draconitic month
is a month which is to
do with the possibility
of an eclipse happening.
And Michael Wright had
modified prices differential
to produce this Draconitic month.
Price's model produced the lunar month.
Michael Wright's modified the tooth
counts in the gears to produce
the Draconitic month.
And he said that it was displayed,
four Draconitic months were displayed over
the four turns of the dial on
a scale with 218 half days.
As soon as I read this,
I was sure that it had to be wrong.
In parallel with Michael Wright's work,
there was a new initiative set
up by a distinguished astronomer
at Cardiff University in Wales
called Professor Mike Edmonds in
the top left corner picture there.
And he gathered a group of people around
him, including Greek astronomers and
including myself,
who were interested in the mechanism.
Now by this time, I'd become completely
fascinated with the Antikythera Mechanism.
I become absolutely passionate about it.
Or as my wife sometimes puts it,
obsessed with it.
>> [LAUGH]
>> We also,
I was extremely frustrated
that we had no good data.
We didn't have a good set
of still photographs,
we couldn't find the Caraculus
x-rays anywhere, and
Michael Wright didn't want
to share his data with us.
So I started to look around for
new ways of gathering data on
the Antikythera mechanism.
And in a science magazine,
New Scientist, I found an article.
But a brilliant technique,
invented by Tom Malzbender,
who's sitting somewhere over there.
Can't see him, but who was then
at Hewlett-Packard Laboratories.
And this is the technique you saw with
fragment 19, for looking at surfaces.
This is what we wanted,
to see the inscriptions on
the surfaces of the fragments.
But we wanted to look inside them,
with the gears, with 3D X-rays.
And I found this, another world-leading
company called X-Tek Systems,
just northwest of London,
set up by Roger Hadland,
who's the man in the middle of
the bottom right group there.
And so we had all our techniques that
we wanted to use on the mechanism,
and the sticking point was getting
permission from the Greek authorities.
Now this took nearly five years.
At one stage, we were turned down,
early on in the process.
We then got a grant from
the Leverhulme Trust to fund everything.
And just about a month later,
we were turned down again.
So we had our technology teams, we had our
money, but we couldn't do our project.
And it was only cuz of the huge
persistence of Professor Xenophon Moussas,
who's in the bottom-left
to the top-left group,
that we actually finally got
permission to do the thing.
The whole thing was frankly
a nightmare and very tough for myself,
because we just spent years
failing to get our permissions.
But in the fall of 2005,
we ended up at the National Archeological
Museum in Athens and there we were looked
after by two senior staff, archeologists
Mary Zafeiropoulou on the left there and
Head of Chemistry, Dr. Eleni Magou.
When we started our studies,
we knew of these fragments here.
Plus a few more bits and pieces that
Price mentioned in gifts from the Greeks.
And then one day, Mary came to our team
and said she found some more boxes of
bits in the basement store of the museum,
might we be interested?
Well, of course they were labelled
Antikythera, of course we were interested.
To cut a long story short,
we ended up with 82 fragments in all.
And we took new still photographs of them,
which you can see here.
And we subjected all the fragments
to our two investigative techniques.
Bottom left, bottom right, you can see
Tom Malzbender with his mysterious dome
covered in flashlights that he uses for
his reluctance transformation imaging.
Or polynomial texture mapping,
as we knew it in those days.
Top left, you can see X-Tek Systems
manhandling an eight-ton X-ray machine
into the basement of the museum in Athens.
It was a special prototype machine
that they made for this project.
If you want to do 3-D X-rays,
you to be able to penetrate your samples
through all the angles,
including the long angles.
So they made an X-ray machine with
double the X-ray power of anything else
comparable in the world at the time.
So round there, you see a lot
more images of data gathering.
And of course, the most important
activity, there in the center,
which was having fine meals
in the restaurants in Athens.
After a week with Hewlett-Packard,
two and a half weeks with X-Tek Systems,
both brought superb teams and I have to
say they were wonderful teams to Athens,
we ended up with a superb set of data,
around a terabyte of data.
What you see there is a mixture
of still photographs,
the Hewlett-Packard surface imaging
technique, and slices through
the 3D X-ray volumes produced by
X-Tek Systems, some in false color.
The most important thing to realize about
this data is that everything you
see there is at millimeter scales.
Size of the teeth of the gear
is about a millimeter long.
All the text 2 millimeters rounded,
typically 1.6 millimeters, and
this exquisite details preserved
despite 2000 years under water.
We'd expected that the Hewlett-Packard
technique would show us
the inscriptions that covers
the surface plates and
that X-Tek's 3D X-rays would show
us the gears inside the fragments.
And that all turned to be true.
But another wonderful revelation
was that the X-rays also showed us
text inside the fragments,
completely invisible from the surface,
hidden for 2,000 years,
unread for 2,000 years.
Price found around 1,000 text characters.
We've now read between 3 and 4,000.
It was a wonderful revelation.
When we got this data, we all took it
back to our facilities to examine it.
And I was charged with trying to sort out
the mechanical structure of the device.
And I started not with the main fragment,
fragment A,
cuz we had some severe technical
difficulties with the data for that.
So I started with this little fragment F.
One of the fragments Mary had
found in the basement store,
around nine centimeters long.
And it looks like nothing special at all,
like something you might
pick up on a beach.
A bit of green suggesting some bronze,
maybe.
And I'm going to look at
it with x-ray slices.
I'm going to take a slice through
near the front of it there.
And there's really nothing
of any interest there.
And I'm going to go down through
the fragments in parallel slices,
close apart, to see what we can find.
If I go down through the fragment, I start
to see what looks like part of a dial.
When I go down further,
it becomes sharper.
And then i see these scale divisions,
and then more scale divisions.
And I developed a very simple strategy,
which is if you want to
know what a dial does and you've only got
part of it and you've got scale divisions.
In order to understand its function,
you want to try and
extrapolate the number of
divisions round the whole dial.
It's an obvious strategy,
but I have to say,
it was not followed with any great
consistency by previous researchers.
Now these scale divisions reminded me very
much of some more scale divisions that
Price had seen visible on the surface at
the back of main fragment, fragment A.
Looks very similar.
And I could determine the relative
orientations of the fragments and
put them together.
Together with another little fragment E,
with similar divisions in it.
And suddenly I had quite a lot of data
around this dial on which to extrapolate
the total number of
divisions round the dial.
And this came,
you may have guessed the answer already,
this is the number of divisions round the
dial, came to the remarkable number, 223.
It was clear that this must be
an eclipse prediction dial.
This was our first major
breakthrough from our new data.
I just want to explain a little bit
about the Saros Cycle and how it works.
If you have an eclipse of the sun or
the moon, in a particular month.
And you look 223 lunar months later,
just over 18 years later,
you get another very similar
eclipse of the sun or the moon.
And this repeat eclipse goes on
repeating for 12 to 15 centuries.
It's a very remarkable cycle.
It works because 223 lunar months
is the same as a whole
number of draconitic months.
This is a month that tells us
whether an eclipse is possible and
the fact that it's the same a whole
number of anomalistic month.
The anomalistic month is the variable
motion cycle of the moon.
The moon sometimes looks as if it's
going slower against the stars and
sometimes faster.
In modern terms, we know that
cuz it has an elliptical orbit,
sometimes it's further away.
And this ensures that the repeat
eclipse is very similar.
It's a remarkable chance resonance between
three of the orbital cycles of the moon.
Now there was more in this
little fragment F than that.
If you look between the scale divisions.
And I'll show you those
in some of x-ray slices.
You can see these little groups of text,
letters and symbols, which I call glyphs.
And if you look around the dial,
there's some inscriptions.
And again this reminded me of
what Price had seen visibly at
the back of Fragment A.
There's two glyphs there
that you can see and
around the dial some inscriptions,
hard to read inscriptions.
Again, beautifully enhanced with
Tom Waltz-Bender's technique.
So now I could trace all these
glyphs in our three fragments, A,
E, and F, and put them all round
the dial in their correct positions.
And you'll notice that lot of
them are six months apart.
Some of them just five months apart, and
some of them are in adjacent months.
This is exactly the pattern
of eclipses of the sun and
moon in the astronomical record.
So, the glyphs must be
the eclipse predictions.
I'd like to look more closely at them and
discuss what they mean.
There's clearly more information in
these glyphs than just the presence of
a lunar or solar eclipse.
So, let me decode some of their meaning.
At the top of some of them, there's
a sigma, which I soon realized stood for
Selene, the ancient Greek goddess of the
moon, clearly indicating a lunar eclipse.
At the top of some, eta, Helios,
god of the sun for a solar eclipse.
Some of the glyphs, like the one in
the middle there had both a sigma and
a letter.
For a month which had both lunar and
solar eclipse.
All the glyphs had this unusual anchor
type symbol which took me a long
to decode until I finally found it in
the book of ancient Greek horoscopes.
And it's a combination of omega and
rho, ligature of omega and
rho, standing for aura, Greek for hour.
And it's always followed by either a
letter or, in this case, a special symbol,
di gamma for the number six in
the Greek letters-for-numbers system.
So this indicates the hour of the eclipse.
The mechanism didn't just predict
the presence of an eclipse in
a particular month.
That the hour of the day of the eclipse
many years or decades hence.
Now at the bottom of all these glyphs,
there was another letter which
I'd seen but I hadn't understood.
And after our first paper
was published in nature,
a very distinguished historian
of ancient astronomy,
Professor Alexander Jones, came to
our conference that we organized and
he told me something that I've
missed about these letters.
I feel somewhat shame-faced to
admit that I missed this but
they are in alphabetical order.
And there's a whole alphabets
worth of index letters without
[INAUDIBLE] followed by that
second alphabet with bars on top.
And these must surely in some way refer
to the inscriptions around the dial.
So by this time,
I had a nice story that had the dial
as an eclipse prediction dial.
I had the glyphs and
this index letter system.
I can't go into the whole system,
I don't have space.
If you're interested,
you can Google Antikytheran plus one,
that's probably Library of Science one.
And it's an open access journal,
anyone can read it.
Just say that this is a prediction
scheme of quite astonishing ambition.
The index letters, you look at the index
letter in the glyph and you look at it
in the inscriptions and that tells
you characteristics of the eclipse.
It's an extraordinary scheme.
But going back to late 2005, what I wanted
to know was how was the point to turn,
like Michael Wright had determined how
the point it was turn for the upper dial.
So we need to go behind the plates and
look at the gearing.
That's all the gearing we saw for
Michael Wright's gearing for
the Metonic Calendar Dial.
And I want to turn the lower back dial.
And again, I've suppressed the main
plate so you can see the gears, but
there's really only one axis which can
turn this, and that's this little Axis m.
The gearing branch is here
to the upper-back dials and
to the lower-back dials.
And I need a gear with 223 teeth.
It's a prime number.
Can't break it down into smaller gearing.
And if you look at the back of
the main fragment, Fragment A,
there's really only one good
candidate gear, E3 there.
It's not the ring gear inside it,
its' the bigger gear,
slightly harder to see outside that.
This is the gear that Price called E4 and
the Karakolous family
counted its 222 teeth.
Price rejected the idea that it was
the 223 months of the Saros cycle.
But if we look in our x-rays
we can see many teeth.
We can make a reliable tooth count.
And 223 is the right answer.
Price had had again a brilliant idea,
which he'd thrown away.
And he threw it away because
of his differential.
Now let me put that into our gear diagram.
There's the gear pair there.
We need to turn it from this
little axis m here, and
now we can start to calculate
how fast these gears turn.
We know already how fast axis m turns.
It's this bizarre fraction with
the number 53 in, which you remember,
which cancelled itself up
in Wright's gear train.
We calculate how fast e3, e4 turn.
And we get this rather strange
fraction 9 x 53 over 223 x 19.
But it will turn out to be a very
significant ratio as we'll see.
The next gear in the train
is another gear with 53T.
By this time I was getting
extremely disturbed by all of this,
cuz again the 53 is cancelled out.
It's not used in this Gear train.
If we look at what we need, sorry,
just to say this is the gear,
reliable count says 53 teeth.
So it was correct.
If we look at the gear train,
we don't want 53 in the final answer.
We just want, it's a 4-turn dial.
2 to three months, 235 over 90,
and that's the mutonic cycle,
that's the ratio we want
to turn our Saros pointer.
We don't need this extraordinary bizarre,
strange and disturbing prime number 53.
So that's what we want for
the Saros pointer, this gear e3.
This large gear found no
role in any previous model.
Now it has two roles.
It turns, no sorry, it has one role.
It has a essential role in
turning the Saros pointer.
So everything now seems to
be going on the right lines.
In our modern X-rays, we can see all these
gears except for the conjectural one.
All the tooth counts check out.
It's a completely established part of
how the Antikythera mechanism works.
And so, this was a nice story.
I had the dial, I had the gearing.
But I also had a huge problem.
Which is,
if you look at the back of fragment A,
inside the large gear e3,
there's another couple of gears there.
They were part of what Price referred
to as his differential system,
which I was sure by that time was wrong.
I'm going to look at them more closely.
I'm going to examine them with our x-rays.
Now if you look there,
the gears on the left,
look like they're the gears on the right,
but they're not actually those gears.
I'll have to come forward a millimeter
towards us, and you see, then,
two more gears.
And these are the gears on the right.
There's four gears in the system.
To Price's great credit, he saw that.
And I want to look at the bottom gears,
which are epicyclic gears, k1 and k2.
And the particular feature of k2,
which is very evident there,
which is that it's got
this notch out of it.
Now this was noticed in 1902,
very early on, by Ragos.
But he didn't understand it.
It was noticed by Price who thought it
was evidenced that a tooth had broken and
been repaired and
the repair had dropped out.
But Michael Wright, with his new x-rays
made a far more acute observation.
He said that there's a pin on k1
which engages with a slot on k2,
and in that way,
gear k1 carries gear k2 around.
Now I think most people's reaction would
be that this is an entirely useless idea.
The gears will turn with the same speed,
and
you might simply just as well
attach them to the same axle.
But Wright made another really
astonishing observation,
he said that the gears turn on slightly
different axes, slightly eccentric axes.
The difference in the centers
is just about a millimeter.
And this makes all the difference.
I want you to forget for
a moment that these are epicyclic gears.
And I'm gonna show you a little animation
that shows what this system does.
I'm gonna imagine that k1 goes round at a
constant rate of the mean sidereal month.
That's the gear with the pin on there,
you can see k1.
And on top of it, sits k2.
And as the gears turn,
you'll see sometimes k2 is behind,
and sometimes it's ahead of the pin gear.
The slot gear is, you get this little
variation in the motion of the slot gear.
Notice that in this fixed axes situation,
the period of rotation of the slot gear is
the same as the input period, the sidereal
month, and I'll come back to that.
So going back to our actual mechanism,
the key question was could this model
the variable motion of the moon?
Wright considered this in a rather throw
away paragraph in one of his papers
and he discarded the idea.
Because in his model of 2005,
this large gear e3 rotated much too fast,
60 times too fast for
this to work in any meaningful way.
He rejected this idea for
exactly the same reason that Price
rejected the idea that
e3 might have 223 teeth.
The gear e3 turned much too fast.
But in my developing model, e3 turns,
you remember the Saros dial
which is a dial which has a period
of 18 years over a 4-turn cycle.
Everything is very slow.
So, it's going around very slowly.
So, maybe this is a promising idea.
The second key question is, why is the Pin
& Slot mounted epicyclically on e3?
And I'm going to explain why that is.
And I'm going to revert now to modern
astronomy to talk about the reason.
This is the lunar orbit.
And it's an ellipse as we
know in modern astronomy.
I've exaggerated the ellipse
there very much.
It's much more like a circle.
But it is elliptical.
Apogee is the point when the moon
is furthest from the Earth and
Perigee is when it's closest.
Apogee is when the moon appears to be
going slowest against the the stars,
cuz it's furthest away, and
perigee when it's going fastest.
And I want you to image the moon
starting the prominent star,
which you can see on the right,
going all the way round the zodiac, and
back to the same prominent star.
This is the Sidereal Month,
which we talked about,
period of about 27.32 days, on average.
Now, you might think that the Moon then
had got back to its slowest motion.
That apogee.
But in fact that's not case,
because the apogee has moved around,
a little bit, in the meanwhile.
It's just the so-called, lines of
apsogees, that joins perigee and apsogees,
processes around in a very slow
period of just under nine years.
So the anomalistic month, stay with
me if you can, the anomalistic month,
which is this month, the variable motion
cycle of the moon is just a little
bit longer than the sidereal month,
only about five and a half hours longer.
Remarkably, the ancient Babylonian
astronomers knew of this difference
between the sidereal and the anomalistic
month, as did the ancient Greeks.
But none of them knew
about elliptical orbits.
But the ancient Greeks were
brilliant geometers and they had
a very beautiful theory for explaining
this anomalous orbit of the Moon.
They said you can explain it as the sum
of two simple circular motions.
There's a large circular
motion with a period of
the sidereal month on which, and
a little epicyclic added circular motion
with the period anomalistic
month in the opposite direction.
Now that's all a bit of a mouthful so
I'm gonna show you
an animation of this theory.
The pink dot is the actual Moon,
and it traces out an orbit
which is like a squashed,
off-center circle.
Each time it's slightly different as
it goes around, and each time it takes
a bit longer than at the sidereal month
to get to the red line to get to apogee.
Sometimes the Moon is
behind the average moon.
And sometimes it's ahead of the Moon.
And it models the elliptical theory,
the modern theory of the Moon,
in a very beautiful way.
Yes, the red line there is equivalent
to the line of apsides of the orbit.
One end is where it's
furthest from the Earth,
and the other end where it's closest,
where it appears to be moving furthest.
So this is the ancient Greek
epicyclic theory of the Moon.
Very beautiful theory.
I'm gonna return to my mechanism
now to ask some questions.
And the key question is, how fast must
this large gear, e3, rotate so that this
little Pin & Slot device exactly models
this ancient Greek epicyclic theory?
You remember that its basic input
needs to be the sidereal month, but
the period of variability needs to
be this other slightly longer month,
the anomalistic month.
And I have to say this is indeed easy.
If you're encountering this for
the first time,
it may be you're not
following it total detail.
I want to give you a flavor
of what the thinking was.
So the question then is, how fast should
e3 rotate to make this Pin & Slot exactly
the equivalent, geometrically equivalent,
to the epicyclic theory of the Moon?
And the answer turns out to be that
it must rotate at the rotation which
is the difference between the sidereal
month and the anomalistic month.
Equivalent in modern terms of
the rotation of line of apsides,
the slow rotation with a period
of just under nine years.
Now we can calculate this from
the Metonic and Saros Cycles.
I'll let you do that as a little
exercise to do at home.
[LAUGH] I don't really have time,
but it's simple arithmetic.
And when we do that simple arithmetic,
we come out with
this fraction, 9 x 53 over 223 x 19.
Which you'll remember we already have
as the rotation of e3 when we were
calculating the gearing for
the lower back dial of Saros dial.
So now we understand what
the 53-tooth gear is doing there.
It's turning e3 at
exactly the right rate so
that the Pin & Slot models this
ancient Greek theory of the Moon.
It is, I have to say, extraordinary.
Now, e3,
it had no role in any previous models.
Now it's got two roles.
It turns the Saros pointer and
it carries epicyclically this
little Pin & Slot device,
to model the epicyclic theory of the Moon.
Let me put this together,
that's e3 rotating at this rate with
a period of just under nine years.
That's, you remember,
Price's little Metonic
gear train which output on a little
regular pentagon with a hole through it.
This calculates the mean sidereal month.
Let me show this in closeup.
There's a gear with 50 teeth sits
on there, meshes with the pin gear,
which also has 50 teeth,
on which sits the slot gear with 50 teeth.
And this generates this variable
motion and then it transmits it back,
reversing its direction onto
another gear with 50 teeth.
So to summarize this system,
we have the Pin
& Slot mounted epicyclically
to change the period in
which it delivers its variation from the
sidereal month to the anomalistic month.
It is a truly astonishing system.
I would say a shocking system.
It's, in my view, an incredible idea,
it's a work of absolute genius.
And realizing that this is how it worked,
a whole cascade of
consequences came out then.
That all the tooth counts could
be explained from the Metonic and
Saros cycle.
As often in science,
you make a breakthrough and
everything else follows from it.
It was a fantastic feeling of discovery.
But we hadn't really quite finished there.
That's the same gearing
seen from the side.
You can see the output which calculates
this variable sidereal month there.
And I'd assumed like everybody
else that the gearing at the back
of the mechanism went off to
the left to the back dials.
But this didn't seem to make much sense.
And then two or three weeks later,
I got a call from Mike Edmonds
with a very nice insight.
He said,
what if the output went the other way,
through the little hole,
you'll remember, in the pentagonal hub.
We can see all this stuff in our x-rays,
I should say, it's not made up.
And the output went up towards the zodiac
dial at the front of the device to show
the position of the Moon in the zodiac.
That's where you want this
sidereal month output.
You might consider that
this was a completely
crazy thing to attempt in ancient Greece.
But the craziness of
the designer didn't stop there.
The designer added another little
device on the end of this output.
And I'm going to show you
that from another angle.
And it shows the phase of the Moon.
This was a discovery by Michael Wright.
And I want to take the cover of
this off to show you how it works.
It's just got two little gears in it.
It's got an epicyclic crown gear
with 20 teeth, which meshes
with another little gear with 20 teeth
on the solar output of the device.
And it's a differential device.
It calculates the difference between
the sidereal rotation of the Moon
around the Earth, and the rotation of
the sun round the earth, the annual
cycle of the sun round the earth to
produce the phase cycle of the moon.
Now where have you heard that before?
That was what Price's differential did,
what Price's brilliant differential did.
But he got it in completely the wrong
place with this cumbersome system.
The genius who devised this device,
just two little gears which did
exactly what Price's differential did.
I just want to put all this together
to show you how the gearing relates to
the fragments and
what the whole thing looks like.
This is the back of fragment A..
These are the gears at the back there,
you can see the pin and slot there,
the gears for the top dials and
for the bottom dials.
These are the fragments that show the back
plates of the mechanism with the twin dial
system, top and bottom.
We come round now to
the front of fragment A.
And you can see these rather mysterious
fingers that point up from the main drive
wheel, which we believe are part of
a conjectural planetary system first
proposed by Michael Wright.
This is my radically
simplified gearing for it.
And it ends with Wright's proposal of
eight coaxial pointers, showing the date,
the sun, the moon, and all five
planets known in the ancient world.
This is fragment C, and it comes from
all over the front of the mechanism.
Quite a jigsaw puzzle to sort out.
The middle part of it shows
the moon phase device.
Then there's the zodiac and
calendar scales and
all of these plus these little
fragments here that show.
At the top, the star calendar the top and
bottom of the device.
Everything in the wooden box turned by
a little knob or crank at the side.
>> [LAUGH]
>> If that doesn't shock you,
I don't know what will.
>> [LAUGH]
>> [LAUGH] So
that's what I've going to say about what.
And I've got some short sections now
to further explore
the identity of the mechanism.
And one question is, where was it made?
Well, the archaeology is
the first port of call for this.
There have been two major studies on this,
both high quality studies.
Particularly the superb study
by the archaeologists at
the National Archaeological Museum in
Athens under their then Director Dr.
Nicholas Kaltsas.
Both studies agree about
the geographic origin of the cargo,
and it was scattered all over
the ancient Greek world.
Mostly in the eastern part, but
still some amphora from Italy,
coin from Syracuse, and so on.
The ship was almost certainly
traveling from east to west,
probably going to Rome but not definitely.
The route of the ship, whatever you read
on the internet, is not really known.
There's a lot of misinformation on the
internet about the Antikythera mechanism,
I have to say.
You have to be rather careful.
And the cargo really tells us almost
nothing about the origin of the mechanism.
So we want more sorts of information.
And there are some very remarkable,
classical texts by Cicero.
Who wrote first about a device made by
Posidonios which at each revolution
reproduces the same motions of the sun,
the moon, and the five planets that take
place in the heavens every day and night.
Sounds just like the Antikythera
mechanism, and Cicero knew Posidonius,
he was a pupil of Posidonius' in his
Stoic School of Philosophy in Rhodes.
So this might suggest there's
a connection with Rhodes.
But Cicero also wrote about Archimedes.
Archimedes was killed in
the Siege of Syracuse in 212 BC.
And Cicero reports that the victorious
Roman General Marcellus took just two,
they were described as globes,
fire eye, which are thought to
refer to these sort of mechanisms
that Archimedes had made.
And again, the description sounds
just like the Antikythera mechanism.
The motions of the sun and moon and
of those five stars which are called
wanderers, the five planets.
Archimedes had thought out a way to
represent accurately by a single device
for turning the globe those various and
divergent movements with their
different rates of speed.
Just like the Antikythera mechanism, but
Archimedes was based
in Syracuse in Sicily.
So I'm gonna add this to our map,
two possible origins,
widely spaced across
the ancient Greek empire.
But we'd like much better information
than this, and some comes from
essentially cultural information
in this little fragment B,
which is our evidence for the upper
back dial, the Metonic calendar dial.
Let me show you that fragment rotated and
with the little month divisions round
the 235 month dial indicated in blue.
And if you look very closely,
you can see some inscriptions
between the month divisions.
And I'll just go down through some x-rays.
Typically, you have to go down
through many x-ray slices.
In this case, it turned out to
be 60 slices to read the text,
cuz everything's uneven and
it's hard to read.
Let me just show you a close up
of one the month cells there,
and I can trace the text.
And I didn't have any
idea what this meant.
I don't read Greek,
I don't know ancient Greek, so
I talked to my Greek colleagues and
they couldn't work out what this meant.
And then we agreed to send
it to Alexander Jones.
And by return email he said he
believed that these were month
names written over several lines,
which certainly made sense.
Now it's kind of difficult to
figure out what that month name is.
But because the calendar has 235 months,
the month names will be repeated
many times around the dial.
So I can find the same month
name in another month cell,
put the information together,
and I get the month.
Now, after several weeks, or
even I think it was months of work,
Alex Jones and
I managed to decipher all 12 month names.
Or at least I deciphered 1 and
Alex deciphered 11.
>> [LAUGH]
>> He was the expert, and
that's what they look like.
We were extremely lucky that we just had
enough information from the x-rays and
some characters from
Tom Malzbender's PTMs to get
just enough information to
get all of the month names.
And there was a hidden
message in this calendar.
If you look at calendars
in the ancient world,
they're very individual to
individual city-states.
But the month names themselves
are scattered over a wide geography.
This was basically worked out by Alex
Jones, based on work by Catarina Trumpy.
If you look, say, at the blue month
names there, you can see on the map,
if you look very closely,
map prepared by Lena Anastasiou at
the Aristotle University of Thessaloniki.
You can see little blue squares.
The bigger the square,
the more the number of
months in the local calendar coincides
with the Antikythera calendar.
And you can see these blue squares
right across the ancient Greek world.
They don't tell us about geography.
If we look at the green month names,
in the little green squares,
you have to look quite carefully,
more in the eastern part,
but still scattered right across
a wide geographic distribution.
No good for
determining the origin of the mechanism.
But four of the months in red
there were exceptional months,
they were rare months, and they came
uniquely from the calendar of Corinth.
Or Corinth's colonies in
Northwestern Greece were in Sicily, and so
this established that the calendar
was a Corinthian calendar.
So very exciting new result.
And we got in more excited by
the idea that maybe this link
to mechanism to Sicily, and Archimedes.
But later work, by John Morgan and
Paul Iverson at Case Western University,
suggests that this is wrong.
They believe that this is
a calendar most likely from
the northwestern area of
Greece called Epiros.
Let me put that on the map,
that's Epiros there.
And this was quite convincing evidence
that there's a connection with Epiros.
This was a pretty surprising result.
I mean everyone had assumed up till
that point that the mechanism may be
came from Rhodes or Alexandria or
somewhere like that.
No one had suggested the Epiros
region of northwestern Greece.
And there was more information
in this little Fragment B.
If you look there,
there's a little subsidiary dial
inside the Metonic calendar dial.
Let me show you that in close up.
And one day I read
the word Nemea around it.
Had no idea what it meant.
Looked it up on the Internet, and
found that Heracles had
killed a lion there.
I don't know ancient Greek culture or
language, so
I have to try the Internet, and
Heracles had killed the lion there,
didn't seem particularly relevant
to the Antikythera mechanism.
So again, I sent it to Alex Jones.
Again, by returned emails, it was
seemed to be by return email by Alex.
He said that one of
the major athletic games,
the Panhellenic Games,
in Ancient Greece, was held at Nemea.
And again, we spent some weeks and
managed to decipher many
more names round this dial.
We found the Isthmian Games for
the games at Corinth.
The Pythian Games for the games at Delphi.
And finally, rather small I have to say,
the Olympia for
the Olympic Games at Olympia.
Now these are the major crown games
of the Panhellenic athletic cycle.
It established clearly that this was
an Olympiad dial, a four year dial.
Remember, Price had a four year dial, but
he put it in completely
the wrong place again.
Extraordinary, really.
But we have these crown games.
This was an Olympiad dial, but
you'd expect these crown
games to be on any dial, or
any mechanism had an Olympiad dial
would have these crown games.
They were the major games.
But in ancient Greece, there were
hundreds of little minor games and
there was one up here called the Naa and
another one here which was
pretty much undecipherable.
It was, clearly there was text there, but
none of us could work out
what the text might mean.
So, let me deal with the NAA first,
does anyone happen to know where
the Naian games, the NAA, were held?
Well, let me tell you,
they were held at Dodona in the Epiros
region of Northwestern Greece.
Dodona was a major oracular site,
second only to Delphi and
the Nayan games were held there,
so we were building up a very
nice confidence story about the origin
of the Antikythera Mechanism.
But there was a sting in
the tail of this research.
If I can go back to my dial.
A couple of years ago,
Paul Iverson made a suggestion for
what this other, minor games might be.
And he suggested the Halieia, and
I'm almost certain he's correct.
Well, again,
let me go back to my geography.
Does anyone know where
the Halieia were held?
No, they were held in Rhodes.
So our comfortable story fell apart.
And we really don't know
how to resolve this.
I think you have to make
up your own narrative.
It could have been made by somebody
in Rhodes for a client in Epiros,
or made by somebody in the Epiros
region who'd spent their youth
running in the games in Rhodes.
We really don't know, but
this is the best information we have
about the origin of the mechanism.
Still unresolved, but
very interesting, I think.
So let me look at when.
A crucial question for
determining the mechanism's identity.
Again, the archeology's the starting
point, both studies agree objects
from the wreck, 4th century BC to
the middle of the 1st century BC.
There's a general consensus that the wreck
was probably in about 65 BC, and
this gives us a terminus ante quem for the
mechanism in the mid first century, BC.
If I'm going to add this information
to a timeline this time,
these two studies say terminus
ante quem mid 1st century BC.
But obviously we want closer
information than this.
And there's information
in the inscriptions
of the epigraphic analysis
of the inscriptions.
And epigraphers,
of which I'm very much not one, look,
do stylistic analysis
of the letter forms and
can give information from that
about the date of the inscription.
They notice things like
the omicrons are all small,
the pis tend to have their second
leg shorter than the first, and
the top and
bottom strokes of the sigmas are splayed.
Now, I have to say, this process is
a bit more an art than a science,
and different epigraphers disagree.
Let me put some information about
different epigraphers' views
on our timeline.
Wilhelm, in the early days,
probably wisely gave a rather wide range.
[LAUGH] Merritt's worked with Price and
said basically first century
BC which agreed with Price.
He says the subtitle of Gears
from the Greeks is a calendar
computer from about 80 BC.
And he had an argument for
saying it was made in 80 BC,
which I think all of us
now believe is spurious.
Kritzas worked with our group and
brought the date considerably earlier.
And I've worked most recently
with Charles Crowther,
brilliant epigraphist
from Oxford University.
And he's brought the date even earlier,
but we'd still like a firmer date.
And some of the information
comes out of the astronomy.
Remember Rehmes cycles that he
identified in this fragment?
Well, the latest of these
is the Kallippic Cycle,
launched in a very
specific date in 330 BC.
So this gives us a terminus post quem for
the mechanism in 330 BC.
Let me add that to my timeline,
there it is.
Not a huge advance here-
>> [LAUGH]
>> But there's more in the astronomy
than that.
You remember that it took four
generation of research to work out this?
The mechanism exactly models the ancient
Greek epicyclic theory of the Moon.
In the 2nd century AD, Ptolemy attributed
this invention of this theory to
Hipparchos of Nicaea,
with those dates there.
But Apollonius of Perga, it's known,
developed epicyclic
theories of the planets.
And he was said to have been called
epsilon, because the shape of an epsilon
is like a crescent moon,
because of his work on the Moon.
So it seems very plausible, even likely,
that Apollonios might have developed
an epicyclic theory of the Moon.
So let me add that to our information,
depends who you believe invented
this epicyclic lunar theory.
So that's where it remained
until a year or two ago.
Some quite astonishing work
by an Argentinian researcher,
Christian Carmen, and
James Evans from Puget Sound University.
And they presented this work at
a conference in Leiden in the Netherlands.
And the arguments were so
difficult, I have to say, based on
complicated aspects of Babylonian eclipse
prediction practice, many assumptions.
And I think many of us got lost,
I certainly did,
around a third of the way through or
before then.
So when they announced their result,
which was astonishing,
I think they must have been
disappointed with our reaction.
They said that they'd sequentially
eliminated possibilities
to determine that the full moon of month
one of the dial is May the 12th, 205 BC.
Not any hundred-year range for
them, a particular day-
>> [LAUGH]
>> On which the Saros dial started.
Now I got lost even though I'd been
studying this dial pretty intensively.
And I'd been looking at the times
in the glyphs, the eclipse times.
And I believed that these times were not
based on observations by the Greeks or
even a set of earlier observations by,
say, the Babylonians.
I believed they were generated by
a simple mathematical model using
the methods of the time.
And I developed a mathematical model for
determining these times.
And it's quite a good model.
It's not unfortunately the exact model,
I'm still working on this.
But when I synchronize this
mathematical model of the eclipse
times with the astronomy,
it produced a unique fit.
That the full moon of Month 1
of the dial is May 12th 205 BC.
I was completely astonished by this.
My methods were very different
from Christian and Jim's.
In some ways,
our assumptions were contradictory.
And the dates was exactly the same.
>> [LAUGH]
>> Now I'd like to say
with confidence that I can tell
you this is the right date, but
the truth is I believe
this is the right date.
But we haven't yet
resolved what's going on here.
It's very difficult, I have to say,
the two papers are there.
Anyone's welcome to read them and try and
sort it out, but I'm still working on it.
I'm still working on this eclipsed times
model, which I've slightly improved.
But I'm looking for an exact model.
If they were using a mathematical model,
it should give the exact results.
And I've failed so far.
Most of the scientific research,
as you'll know, is about failure, really.
It's only occasionally
that you get successes.
So I don't think we've done enough yet
to persuade you as the academic
community that this is right.
I believe it's the right date,
and it's a very interesting date.
Let me put it on my timeline,
it agrees with the archaeology.
It agrees with the epigraphy,
if you agree with Charles Crowther.
It agrees with the epicyclic lunar theory,
if you
think it was invented by Apollonius, or
his contemporaries, or even earlier.
And it's a very interesting date,
it's much earlier than any previous date.
The earliest previous
date suggested is 150 BC.
General consensus is about 100 BC.
And I think it's a very interesting
date in terms of the next question,
which is who made the mechanism.
And I'm going to put up another timeline
there with some famous scientists and
astronomers listed with their dates there.
Some events you maybe familiar with
there to just locate in the history.
This is all happening
in the Hellenistic Era.
And this date really puts these
astronomers, scientists into the frame.
Archimedes was dead by just
seven years with this date.
My own belief is that Archimedes
probably started the tradition
of making these devices.
Sorry, started the tradition
of making these devices.
We can't be certain of that, but
the Cicero description is very remarkable.
Eratosthenes, I really don't know,
distinguished Greek astronomer, but
no obvious connection with the mechanism.
Apollonios, well,
his epicyclic theories of the planets
were almost certainly
incorporated into the mechanism.
The gearing's gone, so
we can't be certain.
And the theory of the Moon, which may well
be attributed to him, is also included.
Maybe Apollonius worked with Archimedes.
They knew each other, I understand,
but we really can't be sure.
And of course, it might have
been made by some unknown genius
who's been lost to history because
the historical record is so
fragmentary, which is you as
classicists will be all too aware of.
I'm going to finish on
an animation of the mechanism,
which is an exploded diagram which
comes together to form the mechanism.
Nearly all of this gearing,
particularly the gearing at the back,
is now established.
The planetary gearing at
the front is conjectural.
But something calculating the planets
was almost certainly there.
And I'd like to quote Derek de Solla
Price, who wrote it's frightening to know
that the Ancient Greeks, just before
the fall of their great civilization,
came so close to our own age.
Not only in their thought, but
in their scientific technology.
I would say that it's shocking.
And I am not going to
answer the question why.
I am going to incorporate that into
questions that you might have.
I have just put a list
of possibilities there,
and I thank you very much for
your attention.
>> [APPLAUSE]
>> Thank you very much indeed Tony we can
have one or
two questions.
Any responses?
>> Yeah?
>> Is this a new technological discovery
that could help with information
about this mechanism and techniques.
x-ray demography that willhelp
>> I think that we could do
another x-ray analysis.
X-ray technology's moved on and is higher
resolution and we might therefore be able
to resolve some of the uncertain letters
in the inscriptions and things like this.
But this is kind of a slightly
marginal process, I think.
And maybe the investment and
the difficulties of doing
it might not justify it.
I'd love to do it myself but
I blanch at the thought of another five
years to get permissions to do it.
The other obvious thing is that we'd love
to find another of these mechanisms.
And the problem is that this thing
sticks up like a sore thumb,
in terms of the history of technology.
The next mechanism you find that exists
is a device, about seven or 800 later.
Which is a Byzantine device called
the London sundial calendar,
very simple device,
had just about eight gears.
And it's as if technology went
backwards for that period.
And then you have to
go the 14th century to
an astronomical clock made by Richard of,
sorry about that.
That made by Richard of
Wallingford in Epsom Auburn.
So it sticks out there,
it doesn't have predecessors.
There must have been simpler
devices before this.
Nobody sort of sits down one day and
builds something as sophisticated as this.
It's impossible, isn't it?
There must have been some simple devices,
maybe something that would calculate the
mean position of the moon in the Zodiac,
a few gears like the Metonic gear train.
But all these artifacts are missing and
I think that the problem is bronze
artifacts that survived on the surface.
As it were, that when two shipwrecks
nearly all got melted down in later
history, one classicist told me
that after the sack of Corinth,
there were known to be, I think,
3000 bronze statues there, and
nothing at all survived,
she said, not even a big toe.
So the problem is that bronze things,
these mechanisms
they would have stopped working, and
they would have been melted down.
They were such a valuable material.
So we really have to look in shipwrecks.
And the optimistic thing is, now, that
there are really good technologies for
looking for shipwrecks,
particularly deep shipwrecks.
Recently in the, I think it's
called the archipelago they found
22 wrecks, unexplored wrecks.
There are probably just full of amphora,
but some day maybe not in my
lifetime somebody may find
another of these mechanisms and
give us much more information.
There's quite a lot of the Cicero's
in B.C. times, those Cicero's texts.
There's a quote from Vitruvius which
describes similar type of thing,
also first century B.C..
And in early centuries A.D.
there are other
quotes that describe similar devices used
by Astronomers and astrologists and so on.
So there's a sort of feeling
that they were around,
I'm sure it wasn't unique,
I'm sure it was copied.
I'm sure this wasn't the first
version of it because there are very,
very few mistakes in any
of the inscriptions, or
the way the gears are cut, there's
very few corrections that we can see.
So I don't know if that answers your
question, but that is hugely frustrating.
Just one more thing is that Pappus of
Alexandria in the fourth century AD
said that Archimedes had written
a treaties called On Sphere.
It's thought that treatise
refers to these mechanisms.
There's some argument
about whether it does or
whether the sphere might have
been actually more spherical.
Apart from that,
we would absolutely love
to find that treatise.
I understood for example there was
a possibility that there's another library
at Herculaneum, I don't know if
anyone knows about this, buried
deeper than the original library where
there's all these charred manuscripts.
Which they are beginning to be read,
so there's a chance
we might find some texts.
Remarkable things turn up and I hope so.
Yes sir.
>> If this technology had not been lost,
how far do you think we would be now?
>> Well, you know-
>> Where would be now?
>> After C Clark wrote, he said that
if the Ancient Greeks had understood
the power or
the strength of their technology Then
they would have been able to get to
the moon within the next 300 years.
We would not be exploring
the nearest stars.
It is a bit fanciful, honestly.
It is a bit speculative.
I don't know the answer.
I am not really a historian.
It is really much over to
you in terms of history.
And I put here, a whole, even why why it
was made is not clear, I put a whole lot
of ideas that the people have suggested
that it was a demonstration device.
I think it could be much more than that.
That it was some sort of rich person's
toy like a luxury astronomical watch
people might wear, or maybe.
It's been suggested it was an astrologist
tool but I don't think we believe that
because none of the inscriptions
contain any scrap of astrology.
It's all pure science that we can read,
and I think if it was designed for
astrology there would be a little piece of
our descendants and houses or whatever.
My own view is that it was made as
a mechanical cosmos by great scientists
of vision who realized that you could use
bronze-case wheels to model the cycles
of the cosmos I don't think it was
conceived as a calculating machine.
If you look, calculating machines
don't come till the 17th century with
Schickard's device and the and so on.
And I think they made this thing and
then maybe looked around at what elsecould
you apply this sort of technology to?
I think they answered well,
nothing, really.
Our normal daily lives don't follow
these cycles that the heavens do,
that are separate there.
And they didn't think of the conceptual
step of taking this technology,
perfectly capable of making an adding
machine or a multiplying machine.
I think that that took nearly
2,000 years to happen.
Because it's a huge conceptual
leap that they didn't think of.
But it's very speculative.
Was it a computer?
Well, I produced a film called
the World's First Computer, or
the BBC version's called
the 2,000 year old computer.
And I think in popular terms,
it's fine to call it a computer.
But in more technical terms,
it's not really a computer.
It doesn't have programs,
and stock programs, and
all the things we associated
with modern computing.
It's closer to being
a calculating machine, I think.
>> I hope you take one more question.
>> Obviously, there appears to be a lot
of precision metalworking in this.
Is this typical of
the metalworking at the time?
>> Well, there's two things I can think
of which show that they were very skilled
in metalwork.
First is, if you look at the jewelry,
ancient Greek jewelry,
it is exquisite, and
fine and very detailed.
They have the ability to
work at this small scale.
And the small scale itself is remarkable.
It must have been made to be portable.
The pinnacle of the eccentric axis is
just about 1.1 millimeters apart and
had to be quite accurate to properly
model the variable motion of the moon.
So it was made to very,
in all the text, this tiny text.
You imagine,
I haven't calculated it yet, but
it probably had 15 to 20,000
text characters on it,
on average 1.6 millimeters high.
One thing that is very remarkable
is this proposal by Michael Wright,
of this coaxial point
of system of the front.
You can imagine having to
make eight coaxial tubes that
fits closely inside each other.
And he often quotes the ancient Greek
aulos, which was a flute, that had
two concentric very tightly fitting tubes
to show that they had that capability.
But it's still remarkable.
I should say that at University
College London we're soon to begin
two doctoral programs,
one with an absolutely brilliant student.
We're going to explore
the making of the mechanism and
the techniques that we
used because it's not
put together like a modern clock with all
the gears separated with their spaces.
Many of the gears appear
to be touching each other.
They move,
they slide on these specials of sliders.
They have the main drive wheel has
these brackets that hold them down.
Completely against modern practice.
It's made in a different way.
Most of the models that you might see on
the web are made using modern principles.
We're exploring all those.
It's this sort of original language
of mechanical engineering and
how they did that.
So there's lots of questions
that we want to try and
answer in a very sort of experimental
archaeology type of way, really.
>> There are clearly many,
many more questions, and some of them,
in fact, on the board this very minute,
posed by Tony himself.
But for now, please join me in thanking
Tony for sharing such virtuosic-
>> [APPLAUSE]
>> For sharing such virtuisic study of
such fascinating material.
Thank you very much indeed.
>> Can I say one more thing?
>> Absolutely.
>> If Archimedes had
nothing to do with this,
it's certainly cleverer than anything
we know that Archimedes did make.
So if Archimedes didn't have
anything to do with it, who did?
This is a real question because
it is a device of genius.
Maybe there's somebody unknown, but
it is cleverer than any of
Archimedes' known devices.
Thank you very much all of you, thank you.
>> [APPLAUSE]
>> This program is brought to you by
the Stanford Humanities Center.
For more information,
please visit us at shc.stanford.edu.
For more, please visit us at stanford.edu.
