Original subtitles

[narrator] Could this 3,000-year-old gold cone

reveal the secrets of the cosmos.

It can predict the future, can communicate

with allegedly supernatural forces.

[narrator] Was this strange cube created to win the war for Hitler?

A handwritten note says "Taken from Germany,

from the nuclear reactor that Hitler tried to build."

[narrator] And could this weird looking clock change the world?

It really was a work of engineering genius.

[narrator] These are most remarkable

and mysterious objects on Earth.

Hidden away in museums, laboratories and storage rooms.

Now, new research and technology

can get under their skin like never before.

We can rebuild them,

pull them apart and zoom in

to reveal the unbelievable,

the ancient,

and the truly bizarre.

These are the world's strangest things.

In a glass case, in a Berlin museum sits a bizarre looking gold cone.

It's a 3,000-year-old relic thought to contain

the secret knowledge of a Bronze Age culture.

A device for predicting the future.

[Maggie] If the theories behind it are true,

this is truly a revelation.

[narrator] Now we're bringing every detail

of this astonishing artifact

out into the light.

It's utterly jaw dropping in its, in its splendor.

[narrator] It's 29-inches long,

crafted from wafer thin gold alloy

and covered with intricate, cryptic patterns.

There are 21 horizontal bands and almost 2,000 symbols

[narrator] And experts think these images

are far more than just decoration.

They believe they form a highly complex celestial code,

one that some believe they have finally cracked.

[Mark] It's a very remarkable artifact.

It's beautiful, meticulously done.

And if you imagine this was done during the Bronze Age,

that is really astonishing.

[narrator] Where did it come from?

What do these cryptic symbols mean?

What exactly is it?

This peculiar cone is acquired by the Berlin Museum of History and Prehistory

from an antiques market in 1996.

So they only have a rough idea

of exactly where it is originally discovered.

[Ben] It was believed to have been found somewhere

north of the Alps, Germany or Switzerland.

It dates to between a 1,000 to 800 BC.

So we think it comes from the Urnfield culture.

[narrator] The Urnfield dominate much of Central Europe

from 1,300 to 750 BCE.

They're called the Urnfield culture because they practice cremation burials

and they bury their dead in urns, in cremation burial cemeteries.

So you get these fields of urns, the Urnfield culture.

[narrator] One theory is that this could be an ornate funeral urn,

but speculation doesn't end there.

[Mark] There are a lot of guesses of what it is.

It could be a phallic symbol.

It could be a containment for arrows.

It could be something just decorative.

[narrator] Others have suggested that it might be a vase

or even an ornamental cover for a ceremonial standard.

But archeologists now believe its size and shape hold the answer.

When you look at the objects you know, you might turn around.

You notice that it's got a hole in the base about the size of a human head.

[narrator] This leads experts to a surprising conclusion.

The thinking is that it's a hat.

That that's exactly what it's for.

[narrator] This is now considered the dominant theory

for this strange object.

It has even become known as the Berlin Gold Hat, after the museum where it's kept.

But it really stands out for a hat.

It's a really unusual level of decadence and scale

for this particular archeological period.

This hat is an amazing piece of craftsmanship.

You know, even today, it would be very impressive

to create such a beautiful object out of gold.

[narrator] If it's difficult to make today,

how on earth did Bronze Age metal workers pull it off 3,000 years ago?

Chemical analysis of the hat's gold reveals that whoever made it,

had a sophisticated understanding of metals.

[Anna] If this hat was made of just pure gold,

it probably buckle under its own weight

because the walls are so thin.

[narrator] To overcome this,

the hats maker mixes gold with other metals.

[Anna] The mixture is about 9.8% silver,

0.4% copper and 0.1% tin.

That makes it much stronger and more rigid so that it can stand up under its own weight.

These goldsmiths clearly knew what they were doing.

This is actually about the right ratio that we use for 22 karat gold today.

[narrator] These are astonishing lengths to go to for just a hat.

An analysis of its construction reveals something even stranger.

When you X-ray the Berlin gold hats, there are no seams in it,

so this whole object has been beaten out of a single piece.

[narrator] The gold alloy has been worked to an extraordinary degree.

This is only possible because the arrangement of atoms in gold

make it uniquely malleable, so it can be worked in a way no other metal can be.

If you beat gold onto a flat surface,

you can create a really thin piece of gold leaf that is just a few atoms thick.

It's so thin that you can actually see light through it.

[narrator] Which explains the hats delicate construction.

The single sheet of gold that this hat is made out of

is just the thickness of a few sheets of paper.

This means that the gold from the whole hat

is the equivalent of a cube about that size.

[narrator] It's already an incredible achievement

for a Bronze Age craftsman.

But there's far more to it.

Every one of the almost 2,000 intricate symbols is individually crafted.

That was probably made from a mixture of two technique

called repousse and chasing.

With repousse what you do is you create a sort of rough shape

on a mold and you hammer the gold from behind

in order to create the relief of the pattern.

After that, you do chasing which is using smaller tools

to add to the intricate fine details onto the front.

[narrator] The finished piece could have taken months to make.

Why expend all this precious resource and concentrated effort on a hat?

Is there more to this mysterious object than meets the eye?

Detailed analysis of these decorations suggests

that the Berlin Gold Hat is anything but a regular piece of head wear.

Experts now believe that some symbols represent the sun,

others the moon.

This leads to an astonishing conclusion.

The Berlin Gold Hat may be a celestial calendar

that can predict the future.

[narrator] Experts believe this 3,000-year-old Gold Hat

may actually be a celestial calendar

used to predict the future.

The Bronze Age people who made it

measure time using the phases of the moon

to count months,

but the annual cycle of the sun to measure years,

and that is a problem for them.

[Maggie] The lunar cycle and the solar cycle

don't mesh up very well.

12 lunar cycles don't add up to one solar cycle.

It takes the earth 365 and a quarter days to go all the way around the sun.

But it takes the moon 29 and a half days to go around the earth.

[narrator] So 12 lunar months

is 11 and a half days short of a full year.

And if you rely on the sun and the moon to know when you should plant

or harvest or hunt, this is a problem.

Your two essential calendars are getting more and more out of sync

with each other all the time.

In 432 BCE,

Greek astronomer Meton observes

that it takes 19 years for the moon cycle to come back into sync with the sun.

He uses this to come up with a fix.

The ancient Greeks decided to fit in with the Meton cycle

to add an extra lunar month

for 7 of the 19 years

when the two calendars were out of sync.

[narrator] This fix keeps the lunar and solar calendars

approximately in sync

until they actually line up again every 19 years.

What astonishes archaeologists

is that the symbols on the Gold Hat

provide a way of calculating exactly the same fix

to correct for this difference.

[Maggie] It seems to be a... an indication of a cross reference

between the lunar calendar and the solar calendar.

What's more, it looks as if

they actually keep the two calendars in check.

[narrator] Astronomers call this an intercalary correction.

What makes this so exciting

is that the Hat appears to predate Meton's discovery

by an incredible 500 years.

If the theory of this hat is correct,

then it shows that these what we consider to be primitive people

had a detailed understanding of astronomical cycles.

To actually do this calculation,

they would have to do very, very detailed observations

over long periods of time.

So it shows a sophistication that is unexpected.

[narrator] This would be an astonishing claim to make

based on a single artifact.

But the Berlin Gold Hat is not alone.

[Mark] There are three other objects that are very similar.

Two of them are from today modern Germany,

from Schifferstadt and from Nurnberg... Nuremberg,

and another one is from Poitiers in France.

[narrator] The patterns on the other hats

have not yet been closely studied,

but they are organized in comparable sequences.

So it's assumed they have a similar purpose.

3,000 years ago,

this level of astronomical knowledge may have seemed magical.

[Mark] We have an object here

that allows you to predict the future

when it comes to sun and moon,

it allows you to communicate with supernatural forces.

[narrator] That sounds as much like religion as astronomy.

[Ben] When we're studying people in the past,

it's really important for us to remember

that religion and everyday life

don't sit apart from each other.

They're completely intertwined and completely interwoven.

Your spiritual well-being had a direct relationship and a direct effect

on things like the success of your crops,

the happiness of your family,

the security of your community.

[narrator] So if the Hat is a supernatural predictor

of the future,

is it also part of religious life?

And if so, who or what is being worshiped?

On the top of the Hat is an eight-pointed star.

Some archaeologists believe it represents the sun,

which is highly significant

because in the ancient world, sun worship is a recurring theme.

Sun gods are known

through history all over the world.

For example, in Shinto,

there's Amaterasu, the Sun Goddess,

the prime ruler of the universe.

The Lozi tribe in Zambia believe

that their kings are direct descendants

from the Sun God and the Moon Goddess.

[narrator] And around 1,340 BCE,

one of the greatest civilizations of the ancient world

also became dedicated sun worshipers.

[Rebecca] There was one moment in ancient Egypt

where the Sun God was raised above all of the other gods

and worship was dedicated completely to him.

This God was called the Aten

and he was created by a pharaoh called Akhenaten.

He built sun temples

of absolutely unbelievable size

and he created a brand new city

that was totally dedicated to the Sun God.

[narrator] Sun cults are well known in Europe too.

So it would fit with what we know

if the Berlin Gold Hat is worn by a revered figure,

perhaps a high priest in a European sun cult,

a holy person or leader who can interpret the meaning

and importance of its markings.

This would have invested that person with immense power

the power to effectively predict the astronomical future,

perhaps when to sow crops, when to harvest, things like that.

Having that sort of knowledge,

especially in that sort of culture,

would have been immensely powerful.

[narrator] The Berlin Gold Hat

is transforming our understanding

of European life in the Bronze Age.

It suggests that these were highly sophisticated people

with the patience to make what we consider

scientific observations over decades,

possibly centuries.

It's amazing how much you can tell about an entire culture

just by looking at a weird hat.

In the summer of 2013,

Professor Timothy Koeth at Maryland University receives a package

containing a curiously heavy two-inch black cube.

It comes with a message.

A handwritten note says,

"Taken from Germany

from the nuclear reactor that Hitler tried to build.

Gift of Ninninger."

[narrator] What is this strange cube?

Why is it sent to a Maryland professor?

Did Hitler really have an atomic program?

Did he try to create a Nazi atom bomb?

Is it really from a Nazi reactor?

[narrator] Is a small cube sent to an American professor

at a Maryland university

part of a Nazi nuclear program?

Now, using the latest technology,

we can examine it in minute detail to uncover its secrets.

It measures two inches along each face

and it's a dark charcoal-black color.

The surface is pockmarked with voids, imperfections, and machined slots.

The cube weighs about five pounds,

unexpectedly heavy for such a small object.

Only one material fits the bill,

uranium.

It's well documented that Hitler dreams of having a Nazi atom bomb.

I don't think there was really any doubt in anyone's mind

that if Hitler had an atomic weapon, he... he would use it,

he would use it as soon as he had it.

[narrator] Could the tiny cube

really be part of that project?

Uranium has a special property

essential to making an atom bomb,

it's radioactive.

That means that there are so many subatomic particles

packed into its nucleus that it's... it's barely stable

and it occasionally sheds little clusters

of subatomic particles as radiation.

[narrator] What makes the cube so special

is that it's not simply raw uranium.

[Philip] It was clear that this little cube of uranium had been processed.

So it had been refined from uranium ore,

and then it had the sort of tell-tale markings

of having been cast in some way.

So this was clearly a very deliberately human-made object.

[narrator] But is it a Nazi cube?

The first step is to analyze its chemistry.

[Dougal] When you look at the composition of this cube,

it's pure uranium,

it's not been enriched.

[narrator] The most radioactive part of pure uranium

is the isotope U-235.

But it makes up just 1% of the material.

So uranium is now enriched

to increase the radioactive U-235 content.

[Dougal] Almost all of the uranium that we use

in modern day is enriched uranium.

That gives us a really good fingerprint as to where the cube has come from

because the time that we were starting to play around with uranium

in any great depth

was towards the end of World War II.

[narrator] So it is World War II uranium.

But if Hitler has the raw material for making a nuclear bomb,

why doesn't he use it...

or does he?

In December 1938, at a Berlin laboratory,

German scientists Otto Hahn and Fritz Strassmann

do something that changes the world forever.

They split the atom.

[Tim] They were doing this by firing neutrons

at the uranium targets,

and the amazing discovery wasn't just that they,

say, chipped off a little bit of it.

They essentially split into two other elements, cesium and barium.

[narrator] What makes this discovery

the genesis of the most dangerous weapon on earth

is that the weight of the two new elements is less

than the weight of the original uranium.

Some mass has gone missing.

Essentially, what's happening is that

some of the initial mass of that nucleus,

rather than just ending up

in the mass of the, the two fragments,

some of it is being converted directly into energy.

[narrator] And the tiny amount of mass

produces a truly vast amount of energy.

[Philip] If you could find a way of sustaining that process,

then you could build... a bomb.

[narrator] The discovery is a Pandora's box.

Because it comes at one of the most perilous moments in world history.

[Sascha] The timing of this discovery

is extremely... crucial.

Germany is under the dictatorship of Adolf Hitler,

plans are being drawn up for invasion of Poland.

So, the world is on... the knife edge of war.

And into this extraordinarily... fraught moment

arrives the beginnings of the most powerful weapon that human beings

will ever develop.

[narrator] And what's worse is that leading the race

to develop the first nuclear bomb

are the Nazis.

[narrator] An innocent looking metal cube

that arrived through the post at Maryland University

turns out to have a dark and disturbing past.

It may be part of the Nazis' attempt

to develop an atomic bomb... before the Allies could.

The same month that World War II begins, September 1939,

the German Nazi government establishes the Uranverein,

the Uranium club.

There's an immense number of incredibly intelligent,

well-trained people,

including... Werner Heisenberg,

who's one of the fathers of quantum physics.

[narrator] Heisenberg and his team of scientists

end up in a location straight out of a Hollywood movie.

A secret lab under a medieval castle

on the edge of the Black Forest.

[narrator] Beneath Haigerloch Castle in Southwest Germany,

Heisenberg's team begins to construct

what he calls his uranium machine.

It's built around hundreds of tiny cubes of pure uranium.

We know it better as a nuclear reactor,

the first step on the road to an atom bomb.

[Philip] And when the splitting apart of uranium happened, crucially,

it releases neutrons

and neutrons are the particles that induce that splitting in the first place.

[narrator] Each time a uranium atom splits,

it produces more than one neutron,

each of which can split another uranium atom,

creating an exponentially increasing release of energy.

It immediately became clear to these physicists

that what you've got here is the potential for a self-sustaining process,

a chain reaction.

[narrator] The amount of uranium needed to create

a chain reaction is called the critical mass.

[Philip] So what they did was to come up with a design

where you'd assemble this critical mass of uranium

from small pieces, from these cube blocks.

[narrator] The arrangement of the cubes looks like some kind of lethal candelabra.

Expanding and rotating the cube reveals machined notches

in the middle of two edges.

These fit perfectly with the wires used to suspend Heisenberg's cubes.

This is definitively a Nazi cube.

So why doesn't it lead to the Nazis building the ultimate weapon?

The reason is simple.

They run out of time.

In April 27, 1945,

the Allies advance enough into Germany,

they actually capture the main site

where this experimentation was happening.

[narrator] Most of the scientists and facilities are captured.

Three months later,

the US Manhattan Project

proves just how dangerous the atom bomb really is.

On July 16,

1945,

the Trinity test

and the first successful atomic explosion happens.

And the world will never be the same again.

Oppenheimer, who was managing the project,

actually quoted the Indian epic, the Bhagavadgita,

"I am become Death, Destroyer of Worlds."

[narrator] In the end, America's victory in the race to harness

the deadly power of the atom appears decisive.

But how close did the Nazis actually come to winning the atomic race?

US scientists chemically test the cubes,

looking for the fingerprints of the new elements produced

when uranium atoms are split.

[Dougal] When you analyze this cube,

it's just uranium. There's no cesium in it at all.

So it didn't really get that far.

[narrator] It's clear Heisenberg's uranium machine never works,

yet the Manhattan Project creates a working nuclear reactor by late 1942.

Why don't the Nazis have the same success?

[Philip] One of the problems was simply the disruption of the war.

Berlin was suffering so heavily from bombing

that it was decided that they had to shift the whole thing, including all the uranium

out of Berlin and down South.

[narrator] And Nazi ideology causes a massive brain drain.

[Tim] A lot of the brightest minds in Physics

had actually left Germany at that time

and gone on to the United States.

[narrator] Ironically, many of them end up working on the Manhattan Project.

But perhaps the Nazis' greatest problem of all

is their belief in competition at all costs.

[Philip] Heisenberg wasn't the only one working on uranium projects.

He had a competitor, a rival really, called Kurt Diebner,

who was engaged in a completely different project.

And so, you know, this was also a hindrance,

the... their resources were split

and their energies were split,

and there was this rivalry between the two groups.

[narrator] Now, newly declassified documents

have revealed that if not for that rivalry,

the race for a Nazi atom bomb could have turned out very differently.

So recently, looking through the archives, they realized that

within the Heisenberg site,

there were about 660 cubes.

There were about 400 cubes at the other sites,

and the rough estimates of what was required

in order to get the reactor up and functional

was on the order of a thousand.

And so, they actually had the uranium resources they need

in order to drive a functional nuclear reactor.

It was just the choice to split the cubes up among multiple sites,

prevented them from achieving that.

[narrator] So, the only thing left to answer is,

how does a Nazi cube end up on the desk of a Maryland professor?

And who is Ninninger?

[narrator] How does a key part of the Nazi nuclear program

end up in the office of a Maryland university professor?

Declassified papers show that the cubes were shipped back to the States.

This is where Ninninger comes in, he's one of the managers on the Manhattan Project

and he is the one who takes

receipt of a bunch of these cubes,

so we know that they crossed his desk at some point.

Ninninger dies in 2004, and according to his wife,

he left the cube to a friend who then gave it to another friend.

And through this kind of improbable chain of

pass the cube, it eventually ends up on the desk

of a Maryland physicist.

[narrator] In a different version of history,

the two-inch cube could have been the first step

to Nazi Germany winning the nuclear race.

Instead, Hitler's Nazi nuclear program ends up

as a paperweight.

In a locked cabinet at London's Science Museum,

is a unique 290-year-old work of mechanical genius.

This incredible device is designed to help

build empires and create unimaginable wealth.

Huge money making,

vast money making.

An untold new sort of money making,

that's going to blow all other types of moneymaking out of the water.

[narrator] To understand why, you need to get right inside it.

This is H1.

It was completely revolutionary.

[narrator] In 1736, H1 is the most advanced clock on the planet.

It stands just 24 and a half inches tall.

Its mechanical skeleton is made from brass, bronze and steel,

and it's unlike any other clock.

Its decorated face has four dials with strange double ended hands,

parts of its mechanism move with almost supernatural grace,

and inside some components have been precision machined

from a rare tropical hardwood.

It's almost like a living thing.

When it's built, these odd mechanisms make it

one of the most accurate clocks on the planet.

A clock designed to change the world.

Who makes it?

What is it for?

How can one machine be so important?

H1 is created to achieve two things,

power and money.

So the beginning of the 18th century,

Europeans are seeing a way of just taking over the world basically.

They think, oh, well, we can take what we like,

and the only competition is between each other.

The whole globe is there seemingly

up for grabs and they are grabbing.

[narrator] Europeans prefer to call it the Golden Age of Exploration.

It relies on one thing, ships.

Europe had bigger, better, faster, stronger, more robust ships

that could handle the big crossings,

that could handle the storms,

that could move large cargoes,

and it was this that unlocked the world.

[narrator] But navigating the world's oceans can go horribly wrong.

Errors, calculating a ship's position

often result in unintended contact with land,

which rarely ends well for the ships involved.

In the 50 years before 1714,

around 27 ships are lost due to navigational errors.

Losing one of this ships is a big deal.

I mean, economy busting sort of a big deal, really, when you think about it.

We know of at least one cargo

that probably would have been worth about a billion.

One ship.

[narrator] Any country that can stop this by cracking the navigation problem

will hold all the cards for world trade and empire building.

The British government wants to win this race.

So, in 1714, they offer up to £20,000 for a solution,

the equivalent of over $5 million today.

It was a huge sum and it wasn't particularly prescriptive.

You know, you could come up with pretty much

any sort of solution that you thought would work.

But if they believed it really had, if you really solved it

and they tested it and it worked,

big money.

[narrator] Clockmaker John Harrison wants to win this prize with H1.

It's jam packed with the most sophisticated technology in the world,

because cracking navigation is very tough.

Even though we're on a sphere, you can think about it

is an X and a Y coordinate first.

So, North South gives you your, your latitude

and then the East West as your longitude.

[narrator] Latitude is easily ascertained from the position of the sun or stars.

H1 is created to find longitude,

something that has confounded sailors for thousands of years.

The catch phrase discovering longitude became a sort of way of saying

that something was completely impossible.

[narrator] Yet the basic principles don't seem all that complex.

[Daniel] We grid out longitude by drawing circles

all the way around the earth through the poles,

and you divide the earth up by degrees,

and it looks a bit like the segments of an orange.

[narrator] And measuring longitude is all about time.

Have you ever wondered

why noon in New York is five hours later than noon in London?

It's because that's how long it takes the earth to rotate

from the sun directly overhead in London to the sun directly overhead in New York.

To make more accurate measurements, longitude is divided into 360 degrees.

Each one of those degrees represents 60 miles

and so that's the relationship between time and location.

[narrator] Every four minutes, the earth rotates by one degree.

So, if you accurately know the time at a fixed place called the prime meridian

and you know how much later or earlier noon is where you are,

you can calculate your longitude.

All you need to crack longitude is to know

what the time is at your prime meridian when you're away at sea.

And that is H1s purpose.

Sounds simple, but it really isn't.

To win the top prize from the British government,

H1 must keep phenomenally accurate time.

[Tim] In order to achieve that prize,

the clock could gain or lose no more than three seconds per day.

[narrator] Accurate enough clocks do exist,

but they use a swinging pendulum that only works in a very stable environment,

which is pretty much everything a ship is not.

An 18th century ship was about the worst place

to try and put a precision instruments on, like a precise pendulum clock.

When I've sailed ships like that, they get into heavy weather,

they roll from side to side, they pitch up and down.

Temperatures are going from tropical down to freezing back up again.

If you've got a precision mechanism, it simply can't handle this

and that was the challenge.

[narrator] It seems impossible,

which is probably why the cash prize is so great.

So, can H1 achieve the impossible and snatch the prize?

[narrator] Clockmaker John Harrison creates H1

to solve an unsolvable problem,

calculating a ship's position, East or West longitude.

This has confounded mankind for thousands of years.

What makes him think he can crack it?

So, Harrison came into this not as an amateur.

He was actually an established clockmaker

with a track record of building very accurate timepieces.

[narrator] But Harrison brings more than just

superior clock making to cracking longitude.

He also has a deep understanding of the fundamental science.

So, the first sort of intractable problem

with putting a precision clock at sea was the pendulum,

because as it swings and the ship rolls,

that disturbs the pendulum's motion

and the pendulum is the heart of making the timekeeper work.

So, Harrison has a brilliant idea, which might seem slightly counterintuitive.

He puts what are essentially two pendulums on the clock

and they sit next to each other, they pivot in the center.

They've got little ball weights on the top and bottom,

and they move in opposition to each other.

And what that does is as the ship moves back and forth and sways,

as it impacts one pendulum in one way,

that's counteracted actually in the other pendulum.

And so together they can cancel out a lot of the ship's motion.

[narrator] One of Harrison's other great enemies is friction.

Friction is a real problem because

friction is where two things rub against each other.

It slows things down, they jam, they stick.

[narrator] Clockmakers usually use oil to reduce friction by lubrication,

but that is a problem for H1.

The issue there is that as oil cools down, it's going to become thicker.

As it heats up it's thinner

and that's going to be another error source for the clock mechanism.

[narrator] To solve this, Harrison comes up with a counterintuitive idea.

He uses wood.

Wood just seemed odd in the precision clock, but it's the perfect material.

He uses wood to actually make the clock

lubricate itself without any little drops of oil all over it.

He makes the places where the mechanism fit together

out of a tropical hardwood called Lignum Vitae.

And Lignum Vitae kind of... it sweats some oil out of itself all the time.

So it's always got a slightly oily sheen,

but it's actually within the wood.

And what that actually did was allow for the clock

to rotate around without the need for putting an external oil.

[narrator] The first true marine chronometer

is packed with revolutionary innovations.

It takes Harrison five years

to combine all this brilliance into one clock, H1.

The finished clock has four dials,

the bottom one shows the day, on the right as the hour hand,

its double ended pointer goes around once every 24 hours.

The dial on the left shows minutes.

It is also double ended and rotates once every two hours.

At the top, the second hand completes one revolution every two minutes.

H1 is unlike any clock seen before.

But is it enough to secure the prize?

In 1736, Harrison takes H1 on a test voyage to Lisbon and back.

They set off down the channel, turn left, head down to Lisbon,

and by all accounts, it goes appallingly.

The weather is really bad.

Harrison gets appallingly sick. He's completely unable to look after his clock.

And when they get to Lisbon, and the clock hasn't performed particularly well,

Harrison's baby has not done its job.

[narrator] But after a little R and R in Lisbon

things improve enormously on the voyage home.

[Daniel] Harrison's got his sea legs

and the weather's not quite as bad,

and he looks after his beautiful H1

and it seems to perform brilliantly.

And when they make landfall,

it's when you sight lands

as they reach Britain,

the captain is absolutely convinced he's seeing the Starts,

which is Start Point.

[narrator] Start Point is near Plymouth on the South Coast of England.

But according to H1, they are actually seeing The Lizard,

the most southerly point in the country, 70 miles to the west.

And sure enough, Harrison's right

because his clock is absolutely bang on.

[narrator] The impossible longitude problem has been cracked.

H1 is the first clock that proves

that you can navigate at sea, that you can calculate and measure longitude

using a clock.

[narrator] Having proven H1 works,

Harrison is in line to win the fortune offered by the government.

All H1 must do is complete a voyage to the West Indies

to demonstrate its long-distance prowess.

But it never happens because there is a problem,

not with the clock, but with its perfectionist creator.

[Tim] It was actually Harrison himself,

who stepped back and said, no, no,

I'd actually like to perfect this clock.

I can do better.

And he's the one who actually said that the H1 clock was not good enough.

[narrator] Harrison spends five years refining H1 into H2,

but he abandons that untested to make an even more perfect version, H3.

H3 takes a further 19 years to design and build,

but H3 isn't to his liking either.

H4 is finally ready in 1761,

31 years after Harrison started on H1.

[Tim] So Harrison's son takes the H4

and goes on a 81-day voyage and at the end of it,

they end up only five seconds off, which is almost

30 times better than what was required for the longitude prize.

[narrator] By the time Harrison finally receives his money, he is 80 years old.

He dies three years later.

He doesn't live to see marine chronometers

become the gold standard for navigation at sea.

It all began with this clock, the quite remarkable H1.

And although, it is no longer run,

nearly three centuries after it was created,

H1 still works.