All language subtitles for Unearthed.(2016).S05E04.Curse.of.the.Seventh.Wonder.1080p.AMZN.WEB-DL.DD+2.0.H.264-Cinefeel_track3_[eng]

Narrator:
The lighthouse of alexandria --

One of the ancient
Seven wonders.

The world's tallest stone tower
For over 1,500 years,

It's an engineering marvel.

Build a skyscraper from stone --
You're crazy, you know?

We don't do that.

Narrator:
Once a shining beacon to the
Greatest city in ancient egypt,

Today, the lighthouse
Is lost in time.

Khalil: we are actually
Discovering for the first time

One of the wonders
Of ancient world.

Narrator:
Now investigators use innovative

Underwater digital-scanning
Technology

To uncover the hidden secrets
Of the vanished lighthouse.

They re-create ancient
Engineering techniques

To reveal the lost skills of
The civilization that built it.

Yeah, it's burning!
It's burning!

Hee-hee!
We set fire to it.

Narrator: to solve the mysteries
Of this ancient wonder,

We'll unearth its sunken ruins,

We'll resurrect
An ancient weapon of war,

And rediscover
Long-forgotten technology

To rebuild
The lighthouse of alexandria.

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Alexandria -- the last of
Ancient egypt's capitals

And still the largest city
On the mediterranean.

Legend has it that in 280 b.C.,

It's home to
A mighty mega structure

That no other ancient city
Can build.

At the entrance
To alexandria's port

Stands the tallest tower
In the world --

An egyptian skyscraper.

Immense bronze tritons,
Greek gods,

Keep watch over
The streets below

While mirrors beam
A blazing light across the sea,

Making alexandria visible to
Ships still a day's sail away.

Rumors even tell of a deadly
Weapon at the tower's summit.

Why do the egyptians build
This legendary lighthouse,

And what does it
Really look like?

♪♪

The lighthouse of alexandria
Stands for more than 1,500 years

Until 1303,
When an earthquake and tsunami

Send it crashing into the sea.

Today, the lighthouse,

Along with almost all
The ancient city,

Is gone.

Emad khalil is
A marine archaeologist.

He spent the last 25 years
Tracking down

Ancient alexandria's
Lost secrets.

This is the ideal place to start
Hunting for the lighthouse,

Mainly because of the material
We have here.

Narrator: emad explores
The citadel of qaitbay

On alexandria's waterfront.

Khalil: well, this would be
The most durable material.

It will withstand the weather
And the salt and so on,

And so this has probably came
From a maritime structure.

Narrator: it turns out

Parts of alexandria's
Fabled lighthouse survive.

Khalil: this fortress of qaitbay
Was built

Using some of the blocks
That existed in the lighthouse.

Narrator: and beneath the blocks
Hides another clue.

Inside the fort stands
A sacred mosque.

It should be facing mecca
To the southeast,

But this mosque faces north,
Towards the sea,

A clue that it stands on
The old lighthouse foundations.

On the roof of the mosque
Is a strange octagonal opening.

Can this help emad work out

What the ancient lighthouse
Looks like?

♪♪

Khalil: the structure of
This mosque is quite typical

Until you start looking up,
And this is very unusual.

It's very unusual to have
A square minaret, basically,

And part of it is octagonal,

And then another part
Is cylindrical.

That doesn't happen
In islamic architecture.

Narrator: emad is convinced
The mosque's distinctive design,

A square base topped
With an octagon and a circle,

Copies the shape
Of the lighthouse.

That's because 30 miles
West of alexandria,

There's an ancient structure
That follows this blueprint --

Abusir lighthouse.

It stands guard over
An ancient necropolis.

So what we have here, basically,
Is a typical hellenistic tomb --

An altar in the middle
And couches --

Two couches, one on each side --
To be used by visitors,

And then we have
The burial chamber.

You'll still see
The remains and the bones

And the remains of the deceased.

Narrator: on some of the walls,
Snake carvings offer protection

To the spirits of the dead,
Typical of a greek-style burial.

Khalil: all around us,
There are plenty of them.

There are, I think,
Over 13 of them,

Very much the same design --
Greek tombs.

And this is a building which was
Built during the same period,

During the same era,
In the shape of a lighthouse.

Narrator: emad thinks
The builders of these tombs

And the lighthouse
That guards them

Take inspiration from
The lighthouse of alexandria.

Khalil:
It's an evidence.

It gives us indication
That this is the shape

Of the original
Lighthouse of alexandria.

Narrator: abusir lighthouse is
A miniature copy

Of the ancient wonder.

♪♪

Only a few precious images

Of the lighthouse
Of alexandria survive,

And the lighthouse at abusir

Confirms they offer
A true glimpse

Of a lost wonder
Of the ancient world.

Khalil: so the builders of this
Were actually able to see

The original lighthouse
Of alexandria

And copy the design
Into this structure.

The ancient alexandria
Lighthouse had three levels --

A square one, an octagonal one,
And a cylindrical one

Very much similar
To this monument we have here.

Narrator: the lighthouse
Of abusir solves the mystery

Of the lighthouse
Of alexandria's appearance.

It's now clear
That it's a huge building

With a distinctive
Three-level design,

But the height
Of this ancient wonder

Is still shrouded in legend.

Some say the lighthouse
Is so tall

That a stone
Falling from its summit

Would take two days
To hit the ground...

...Others that sailors could see
The lighthouse beacon

Up to 300 miles out to sea.

Emad's challenge is to separate
Fact from fiction.

Can he use archaeological
Evidence to work out

How high the lighthouse of
Alexandria soars into the sky?

[ stone crumbling ]

[ stone crumbling ]

Narrator:
The lighthouse of alexandria,

One of the seven wonders
Of the ancient world,

Climbs into the sky
Like no other ancient building,

But just how tall
Does the lighthouse tower?

Archaeologist emad khalil
Believes

Alexandria's eastern harbor
Holds the answer.

In 1303, an earthquake destroys
Most of the lighthouse.

But its fallen remains
Still rest on the sea floor.

What we have here is
13,000 square meters

Of remains underwater.

Narrator:
Scattered across the seabed

Lie thousands of stone blocks...

...Among them,
Massive monoliths...

...The largest weighing
Over 70 tons.

The huge blocks piece together
To form the lighthouse door,

A towering gate
Over 40 feet high

And 16 feet across.

Flanking the entrance --
Colossal statues

Of egypt's king and queen,
Five times taller than a human.

Can this huge door reveal the
True height of the lighthouse?

♪♪

Khalil:
It's a huge puzzle, basically,

And you want to put it back
Together without a reference,

Without a picture
To base your reconstruction on,

And this is the main challenge
Of the site.

Narrator: this mammoth block is
A crucial piece of the puzzle.

It will help emad calculate
The lighthouse height.

This huge object, which is about
70 tons in weight,

Is the right side of the main
Entrance of the lighthouse,

The right side of the doorway
Of the lighthouse.

The angle here is where
The wooden door would have fit.

Narrator: working out the height
Of the lighthouse

From its broken pieces is tough.

Luckily, an arab writer
From the 14th century

Offers a helping hand.

He records some of the only
Reliable measurements

Of the lighthouse.

He measures the dimensions
Of its base

And the width of the doorframe

In an ancient unit
Called the span.

Looking at width of the doorway,
Of this side of the doorway,

We have 6-feet-10,

And now we can calculate
The actual evidence

To the literary sources,

Which mention that the
Measurement would be 10 spans.

Narrator: this recovered block
Allows emad to establish

That 1 alexandrian span
Equals 8 inches.

We can start rebuilding not just
The dimensions of the lighthouse

But the entire complex
Of the lighthouse.

Narrator:
Translating the ancient
Measurements reveals

That the lighthouse stands
On a 100-foot square base.

This gives emad a starting point

To estimate
The building's height.

He combines greek principles
Of proportion and imagery

From ancient coins
To finally get his result.

We think that it was 300 feet
In height, and so it --

Basically, it was
An ancient skyscraper.

Nothing like this
In the ancient world.

Narrator: the lighthouse
Of alexandria soars higher

Than any other stone tower
In the ancient world

And even the first
20th-century skyscrapers.

Why does it need
To stand so tall?

[ stone crumbling ]

[ stone crumbling ]

Narrator:
The lighthouse of alexandria,

One of the seven wonders
Of the ancient world --

At over 300 feet, it stands
Taller than any stone tower

Until the 20th century.

A lighthouse must shine far
And bright

To warn sailors away
From dangerous waters,

But even the tallest lighthouse
In america,

Cape hatteras light
In north carolina,

Stands just over 200 feet tall.

So why is the ancient
Lighthouse of alexandria

Over 100 feet taller?

Could this be
So it can guide ships along

The treacherous waters
Leading up to alexandria?

A clue lies 130 miles west
Of alexandria,

Off egypt's mediterranean coast
At marsa bagoush.

Beneath the calm surface
Lurk deadly rocks

And shifting sandbars
The size of houses.

Half buried in the sand

Lie the shattered remains
Of countless amphorae,

Ancient clay pots
For carrying wine and oil.

These shards span
2,000 years of history

And hint this bay
Is a ship's graveyard.

Is the colossal
Lighthouse at alexandria

Built to prevent
Endless shipwrecks?

Archaeologist emad khalil
And his team

Dive this site to investigate

If these broken pots
Are evidence of ancient wrecks.

They find undisturbed amphorae

On every descent
To the sea floor.

Khalil:
During diving, we just came
Across some shards of pottery

Inside the bay,
And the further we look,

We discover more pottery,
More ceramic,

And then we started discovering
Single amphorae,

Intact amphorae.

Narrator: in emad's search for
Evidence of wrecked ships,

The intact amphorae
Are a puzzle.

Khalil: finding an amphora
Or few amphoras

Does not definitely indicate
An existence of a shipwreck

Because amphoras
Could have fallen off a ship,

Thrown over a ship.

Narrator: to find shipwrecks
And help explain

The height
Of alexandria's lighthouse,

Emad must investigate further.

The team takes thousands
Of high-resolution photos

To build a digital model
Of the seabed.

The scan reveals
A surprising clue --

The distinct forms of anchors
From ancient ships.

Khalil: but finding an anchor --
Something else

Because anchors
Do not fall off ships.

Narrator:
The team discovers

A total of 14 anchors
In the bay.

Khalil: finding more than one
Anchor in the same place

Means that this had been
Used frequently by ships.

Marsa bagoush is an ideal
Example for a safe haven,

Or a safe natural anchor.

First of all, it's deep enough
For ships to come in.

Secondly, the entire bay
Is protected from both sides

By reefs,

So wherever the wind comes from,
It's still protected.

Narrator: the discovery here,
Not of the shipwrecks

But of a safe haven for ships,

Transforms emad's view
Of the lighthouse

Up the coast at alexandria.

Khalil:
To function as a lighthouse,

Which is to warn ships against
Dangerous places for sailing,

It does not need to be
300 feet high at all.

Narrator: the lighthouse
Does not need to warn ships

Of dangers along this coast.

Emad believes ancient ships
On their way to alexandria

Can navigate safely
Along egypt's coast without it,

And marsa bagoush is proof.

Half a mile behind
The beach dunes,

Emad's team makes
Another discovery

That reveals
Why ships anchor here

On their voyage to alexandria.

Khalil: so, what we have here,
Basically,

Is an exclusive network

Of underground wells
And cisterns.

Narrator:
This network of tunnels
Is over 2,000 years old

And contains hundreds
Of thousands of gallons

Of fresh water...

...A lifesaving resource
For the ancient crews

Sailing along the northern shore
Of the sahara desert.

Identifying certain spots
Along the north coast of egypt

That contain fresh water
Is an excellent advantage.

♪♪

Narrator: marsa bagoush is one
Of the most important anchorages

On egypt's coast,

A stopping-off point on the
Shipping lanes into alexandria.

Ancient sailors in these waters
Do not need a mega lighthouse

In alexandria to guide them
Along egypt's coast.

So is the purpose of
The lighthouse to help ships

Navigate
The treacherous approach

Into alexandria harbor itself?

Alexandria harbor was described
As dangerous to get in

Because of the series of rocks

Surrounding the entrance
Of the harbor.

If a ship captain was not
Confident

Or was not sure
Where to get in and out from,

They might end wrecking
Even inside alexandria harbor.

Narrator:
A tall lighthouse can warn ships
Away from dangerous shorelines

And help them
Avoid running aground,

But emad questions if a tall
Lighthouse helps captains

To enter alexandria's harbor.

This lighthouse was an obvious
Landmark that can be seen from,

You know,
50 kilometers out to the sea.

However, getting inside
And outside of the harbor

In this case, lighthouse
Would not be very useful at all.

In this case,
You need more detail,

More specific reference points.

Narrator:
Fortunately for ancient sailors,

The lighthouse isn't the only
Tall landmark in alexandria.

The ancient egyptians carve
Hundreds of granite blocks

Into monuments called obelisks.

Two of the most famous
Are cleopatra's needles.

Today, these obelisks stand
In london and new york.

They are already
More than 1,400 years old

When alexandria's rulers
Move them to their city.

They put up the needles
Side by side

In the center of the harbor,
Close to the shore --

A perfect landmark
For approaching ships.

As long as sailors head straight
For the obelisks,

Their ships are safe
From the treacherous reefs

Lining the port.

A 300-foot-tall lighthouse
Isn't needed to guide ships

Into alexandria,

So why is this structure
So tall?

Emad has a surprising theory.

He believes
It's not to warn people away

But to draw them into the city.

The lighthouse is
A gigantic billboard

That announces alexandria
To the world.

Khalil:
It would be a banner, basically,

To draw the attention of ships
And sailors coming into egypt.

They would head
For this new town,

The new town with this big,
Huge monument -- alexandria.

Narrator:
The alexandrians build the
Lighthouse so audaciously tall

To put their city on the map.

Nobody in ancient history
Ever tried again

To build a 300-foot stone tower.

So what are
The engineering secrets

That allow the lighthouse
To stand so tall

And for so long?

[ stone crumbling ]

[ stone crumbling ]

Narrator:
The lighthouse of alexandria
Stands more than 300 feet tall.

New york's flatiron building,

One of the world's first
Skyscrapers, is 20 feet shorter.

Abdelnaby:
To build a stone building

That is almost
Like a skyscraper,

There has to be some secret that
Made it survive for that long.

Narrator: structural engineer
Adel abdelnaby's day job

Is to make sure
New bridges don't collapse.

But today, he investigates
What type of stone

Alexandria's engineers
Used to withstand

The extraordinary weight
Of the lighthouse.

If you ask an engineer
If he or she can build

A skyscraper from stone,

They would think
You're crazy, you know?

We don't do that.

Narrator: stone is heavy,
Expensive, and hard to work,

And the higher you build,
The higher the risk

The building will collapse
Under its own weight.

But working in the capital
Of ancient egypt,

Alexandria's stone masons

Inherit a 2,500-year-old
Tradition of building big.

And they have
The building know-how

To pick just the right stone
For the job.

Abdelnaby:
We have egyptian pyramids.

They're built of limestone.

That's a structural material
That's taken care of

All this mass and weight
Of the pyramids.

You got -- the karnak temple
Is mainly of sandstone.

Narrator:
Limestone and sandstone,

The building blocks of egypt's
Ancient mega structures,

Last for millennia
In egypt's desert air.

Adel investigates
If they are tough enough

To support a lighthouse
Over 300 feet tall.

He uses the powerful vise
In his lab.

So what this does --
It applies a compression force

Until it crushes the sandstone.

Narrator:
The sandstone holds strong...

...Only to shatter
At 57,000 pounds.

We're gonna do a crush test
For the limestone.

And we're good to go.

Narrator:
The limestone is stronger...

...But still shatters
At 134,000 pounds.

It looks like neither limestone
Nor sandstone is strong enough

To withstand the natural forces
Acting on the lighthouse.

Abdelnaby: for a lighthouse,
It's a slender building,

So it gets very high stresses.

That's why you needed
A strong material

To support the building.

Narrator: with limestone
And sandstone both ruled out,

Adel tests a third stone
In the vise --

Pink granite.

This is the stone
That egyptian masons used

To carve out huge obelisks.

The granite is still
Going strong

When the vise maxes out at over
A quarter-million pounds.

Abdelnaby:
So you don't have a choice.

The best material to use
Is granite.

That's the only type
Of masonry blocks

That can survive
These conditions.

Narrator: granite blocks are
The perfect building material

To support the weight
Of a 300-foot lighthouse.

But how do
The lighthouse builders

Lock the thousands
Of stone blocks together?

Adel thinks they carefully shape
The stones for a perfect fit.

They chisel holes into
Neighboring blocks

And connect them with dowels.

Metal clamps lock
The blocks together,

And a special mortar of molten
Lead fills any remaining gaps

To seal the walls
Against the raging storms

And pounding waves
Of alexandria harbor.

But out here, not all dangers
Come from the sea.

Major earthquakes
Regularly shake

The foundations
Of alexandria's buildings.

Are the clamps connecting
The lighthouse blocks

Strong enough to hold out
Against these monstrous forces?

Adel doesn't think so.

Clamps are not enough to hold
These granite blocks together,

Will not give you
The resistance you need

For these strong
Earthquake forces.

Narrator: so how does this
Super-tall stone structure

Survive earthquakes
For over 1,500 years?

[ stone crumbling ]

[ stone crumbling ]

Narrator:
Alexandria stands in the center

Of an earthquake hot spot.

Archaeologists believe
The legendary lighthouse

Survives 20 major tremors,

Each topping 8
On the richter scale...

...Before finally
Falling into the sea

More than 1,500 years
After its construction.

Even today,
Earthquakes this powerful

Wreak total devastation.

The 2008 earthquake
In the chinese sichuan province

Hits 8 on the richter scale.

It kills 87,000 people
And leaves 5 million homeless.

So how does
The lighthouse of alexandria

Survive such deadly tremors
For over 1,500 years?

It could be because
The city is home

To some of the most
Brilliant minds in history.

Alexandria's rulers are hungry
For knowledge and power.

They make copies of all
Manuscripts entering the port

And put them into
The great library of alexandria.

This vast collection becomes
A beacon of intellect

That attracts scholars
From across the ancient world.

It's here that philosopher
Eratosthenes

First calculates the
Circumference of the earth...

...And the celebrated
Mathematician euclid

First records the fundamental
Principles of geometry.

The builders of the lighthouse
Live in a time

Of rapid scientific innovation,

And the engineering of their
Stone goliath is no exception.

Structural engineer
Adel abdelnaby

Is about to test
An ingenious invention

He believes
The ancient engineers used

To make their lighthouse
Quake-proof...

...A mortar of molten lead

That they'd pour
Between their building blocks.

Abdelnaby:
We do a lot of tests.

Usually, most of our tests
Are on modern building

Like steel and concrete,
Reinforced-concrete building,

But today, we're doing
The lighthouse test.

Narrator: adel uses
An earthquake simulator

To investigate
This special mortar.

He wants to find out
How it changes

The properties
Of the stone tower.

Abdelnaby:
Oh, that's good.

When you have an earthquake,

You're pretty much shaking
Your building back and forth,

So that generates huge forces,

So we're representing
These forces

By using an actuator here.

Has to be too tight.
We don't want any weak link.

The whole idea is that we're
Simulating earthquake loads

Until we fail this wall.

We're gonna see how much load
It's gonna take.

Narrator:
Adel's hydraulic pumps

Rock the granite wall
And its mortar

With a 10,000-pound force.

Abdelnaby: that's pretty much
Like an 8.0 earthquake.

Narrator: the lead compresses
As the wall shakes.

This give in the structure
Allows the wall

And the lighthouse to roll
With the punches during a quake.

Abdelnaby:
Still not broken,

Even with a magnitude-8.0
Earthquake.

It's pushing the steel,

And we can't break it
With this molten lead.

Narrator:
Adel inspects the damage.

Abdelnaby:
The wall is intact.

There is no even minor cracks.

Everybody would tell you
That's a wall

That has never experienced
An earthquake before.

That's a brand-new wall.

Narrator:
Adel believes alexandria's
Ingenious lead mortar

Protects the lighthouse walls

Against even the most powerful
Earthquakes.

I have never seen this type of
Behavior in any types of walls.

That's even stronger
Than reinforced-concrete walls

That we have tested before
In this lab.

Narrator: alexandria's
Granite-and-lead lighthouse

Appears indestructible.

Adel's tests reveal
How it can stand for so long,

Surviving 20 massive earthquakes
And more than 1,500 years.

The ancient egyptians build
The lighthouse

For the long haul.

They incorporate the smartest
Alexandrian engineering

Into its structure.

Adel believes they even use
The same tricks

That modern engineers use
To build skyscrapers

That can ride out
Monster quakes.

To build a skyscraper,

The ideal way to resist
Earthquake loads

Is to have very strong walls
At the outside of the building,

So that's exactly
What the egyptians did,

And that's exactly what we do
In modern days as engineers.

Now we realize that the
Egyptians have figured this out

Before we did.

Narrator:
The alexandrians know that a
Building with rigid foundations

Is vulnerable in an earthquake.

♪♪

So they build their lighthouse

So it can move freely
On its foundations

And ride out the tremors
Of a quake without breaking,

So how does the lighthouse
Finally fall?

Adel uses archaeological data
To simulate the exact forces

He believes destroy
The real lighthouse.

The yellow pixels reveal
A structural achilles' heel

Where the building fails.

We got a lot of movement

At the middle segment
Of the lighthouse,

And as you can see, there is
A partial collapse of this part,

And that matches very well
With the historical data

We have regarding the failure
Of the lighthouse of alexandria.

Narrator:
Adel's virtual model reveals

That it's the upper stories
That fail...

...Where adel believes
There's no lead mortar

To hold them together.

They didn't use lead at the top,

And that's why the collapse
Of the lighthouse

And the failure mainly happened

At the top segments
Of the lighthouse.

We saw that the base survived
In every single earthquake.

Narrator:
Engineering brilliance keeps
The lighthouse of alexandria

Standing for so long.

Its height and strength make it
A wonder of the ancient world,

But does an even greater
Achievement

Represent its crowning glory --

An ingenious mirror system

That turns the beacon of
Alexandria into a weapon of war?

[ stone crumbling ]

[ stone crumbling ]

Narrator:
The lighthouse of alexandria is
A marvel of ancient engineering,

Over 300 feet tall,

Standing for more than
1,500 years,

One of the seven wonders
Of the ancient world.

Is its real wonder its ingenious
And powerful beacon?

♪♪

At the base of the lighthouse --
An immense doorway.

It opens into a 240-foot shaft.

It makes it easy to winch up
Fuel to a chamber at the top.

In here, a mighty fire burns
Through the night.

Some scholars believe
A system of mirrors

Focuses the light so much

That the lighthouse is visible
35 miles away.

♪♪

But can it produce,
As rumors claim,

Enough heat
To set a ship on fire?

Marty jopson builds
Scientific models.

Today, at his workshop,

He investigates
If the lighthouse lives up

To its fearsome reputation...

As a death ray.

Marty uses modern equipment

To replicate the power
Of the ancient beacon.

Jopson:
I've taken a space blanket,

Sucked the air out from behind,

And you get a perfect parabola,

Which focuses the light
Into a point.

And the idea is,
I'm then gonna focus that

Onto this beautiful [laughs]
Model boat

When the sun comes out.

These are welding glasses
Because the focal spot

Is so bright,
It's quite dazzling.

Narrator: marty moves the target
Into the death ray's kill zone

And angles the mirror
To capture the sunlight.

I just need to bring this in
A little bit more

To about there.

Let's see how that is.

Right. Let's try and set it
On fire now.

Okay, sun's power on,
And full sun,

And, whoa, immediately,
It's burning!

That...

Narrator: the mirror focuses
The sun's rays

To scorch
The wooden ship's hull.

Yeah, it's burning!
It's burning!

Hee-hee!
We set fire to it.

Narrator: within seconds,
The whole ship is ablaze.

All of the energy of the sun
That's landing on this mirror

Is being concentrated to a point

About two centimeters
In diameter,

And that is then
Setting fire to it

Because the temperature there is
In excess of 550 degrees.

That has set fire to that,
I think.

Yep, that's set fire to that
Quite effectively.

Narrator:
Marty's built a miniaturized
Ship-burning weapon.

Can the ancient greeks
Do this on a larger scale?

Their biggest challenge --
To focus the light onto ships

Across a much greater distance.

Jopson:
Archimedes was an ancient greek,

And he was
A brilliant mathematician

And a brilliant inventor
And all sorts of things,

And there was a legend
That has it

That he built
Something like this --

A burning mirror
To set fire to the ships.

And we know that
He studied in alexandria.

Narrator: how can the greeks
Build a death ray

With the technology available
In the 3rd century b.C.?

Archimedes is one of
The most brilliant engineers

Of the ancient world,

Famous for designing
Fireball catapults

And ship-grabbing claws.

At the library of alexandria,

He studies the principles
Of optics and mirrors.

Some scholars believe
Metalworkers at this time

Have the skill to craft
Large high-precision mirrors.

It's technically possible
The lighthouse engineers

Combine archimedes' knowledge
Of optics

With superb craftsmanship

To create
A lighthouse death ray.

Now, there are lots of ways
You could do this.

The one of the ways that
We believe archimedes did it

Is that he might have had
Small hexagonal mirrors,

So sort of an array
Of little mirrors,

Each that could be focused
Separately.

You could've done it
With polished shields.

You could've done it with just,
Like, a big sheet of copper

Or brass that you polish
And get it into the right shape.

There's all sorts of different
Ways this could've been done.

Narrator: to be sure the
Lighthouse can function at night

As well as in bright daylight,
Marty has another test.

He's proved his device
Is a killer at short range.

But is it also a lifesaver
At long distance?

Normally,
When sun hits the mirror,

It's focused to a focal point,
Sort of about there, I reckon.

If we put some light here --
And it could be, say, a bonfire

At the top of the lighthouse
Of alexandria, for example --

Then what you'll end up with
Is a beam

That shoots across the valley,
Or at least that's the theory.

The sun's about to set,

So we can give this a try
And see how far we can see it.

Narrator: marty replicates
The lighthouse bonfire

With a small l.E.D. Bulb.

Jopson: power on.

So, let's see
Where I can see it from.

Narrator: as the sun drops
Behind the horizon,

Marty dashes 300 feet
To the end of the field.

Can he make out the bulb's light
Reflected in the mirror?

Ah! That is [laughs]
Ridiculously bright.

We're, what, 300 feet,
Something like that,

And it is one light
About, ooh, yea big

That's creating all that.

But the question is,
How bright will it be

If we go right down
In the valley?

♪♪

[ laughs ]

That is astonishing!
I'm gobsmacked.

It is so bright!

I mean, I reckon we've come down
About a mile away

Onto the main road, and it's --
I mean, you can see.

Sort of on the top of the hill,
You can see the car headlights,

And it is 10, 20, 30 times
Brighter than those,

And this is one l.E.D.

I mean, you could imagine that
If they had this

At the top of the lighthouse,

That would've been
Pretty astonishing.

Narrator: the lighthouse
Of alexandria is a marvel

Of ancient engineering...

...A combination of thousands
Of years of egyptian know-how

Into how to build big

And the technological genius
Of the ancient greeks.

Jopson: alexandria was
An extraordinary place.

It was a meeting place
Of brilliant minds.

Narrator: from its
Granite-and-lead construction...

...To its miraculous mirrors,

The architecture, scale,
And sheer ambition

Of the legendary lighthouse
Of alexandria

Combined to create a marvel
Of engineering brilliance

And a true wonder
Of the ancient world.

♪♪

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