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00:00:19,519 --> 00:00:21,039
Daina Bouquin: A war is on.

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00:00:21,039 --> 00:00:24,640
And you are standing in the
dark.

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00:00:24,640 --> 00:00:27,280
It's 1943.

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00:00:27,280 --> 00:00:32,320
You are on the roof of a
building near Liverpool, wrapped

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00:00:32,320 --> 00:00:35,520
in a heavy trench coat that's
losing a fight against the damp,

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00:00:35,520 --> 00:00:37,039
biting cold.

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00:00:37,039 --> 00:00:41,200
The rim of a tin helmet presses
hard against your forehead.

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00:00:41,200 --> 00:00:45,119
In your numb hands you hold a
bucket of water.

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00:00:45,119 --> 00:00:49,600
You are looking up into the
blackout, waiting for incendiary

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00:00:49,600 --> 00:00:51,039
bombs to fall.

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00:00:51,039 --> 00:00:55,520
You're up here because a Nazi
propagandist on the radio has

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00:00:55,520 --> 00:00:59,600
promised that by morning, this
building, the Bidston

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Observatory, will be no more.

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Bombs do fall in the area.

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Windows shatter.

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00:01:12,319 --> 00:01:14,879
But the observatory stands.

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And when your shift on
fire watch ends, you go back

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00:01:19,680 --> 00:01:24,159
downstairs, deep into the
bunker-like basement to fight

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00:01:24,159 --> 00:01:26,400
the Second World War with a
pencil.

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00:01:26,400 --> 00:01:31,280
Because you are a computer, and
the Navy needs you.

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I'm Daina Bouquin, and this is
Found in the Machine.

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00:01:37,120 --> 00:01:43,760
Before the word computer meant
a machine on a desk, it was a

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job title.

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00:01:44,879 --> 00:01:47,599
Often the job title of a woman.

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In this case, the job title of
six young women in a basement

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who are hired for their
diligence, skill with numbers,

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and neat handwriting.

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On their desks are papers
covered in columns of numbers,

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00:02:02,239 --> 00:02:04,400
pages and pages of them.

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Hourly measurements of water
levels taken at ports and

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00:02:08,159 --> 00:02:10,560
harbors across Britain and
beyond.

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Some of the data is decades
old.

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00:02:13,199 --> 00:02:17,199
Some arrived by courier this
morning marked urgent.

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They are responsible for
predicting the tides.

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They are working under a man
named Arthur Doodson.

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Arthur is 53 years old, and he
is a brilliant mathematician.

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He is also deaf.

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00:02:32,240 --> 00:02:37,439
He cannot hear the German bombs
exploding outside, and he

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00:02:37,439 --> 00:02:40,719
cannot hear the metallic whirr
of the machines in the other

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rooms.

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00:02:41,360 --> 00:02:47,360
But in his own way, Arthur
Doodson listens to the ocean

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better than anyone else on
Earth.

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To Arthur, the tide is not
chaos.

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It is a cord.

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A cord made of the moon and the
sun and the shape of the ocean

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00:03:04,159 --> 00:03:08,000
floor and the shoulder of every
continent the water leans

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against.

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Pull those notes apart and you
have the variables that make the

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00:03:13,199 --> 00:03:13,840
tide.

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00:03:13,840 --> 00:03:17,759
Scientists realized this in the
nineteenth century.

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They realized that if you could
measure each of the influences

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that shape the water, you could
predict what the ocean would do

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00:03:25,919 --> 00:03:26,560
next.

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00:03:26,560 --> 00:03:32,879
But you needed the celestial
pulls, the local quirks of the

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00:03:32,879 --> 00:03:35,520
coastline, the depth.

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00:03:35,520 --> 00:03:38,879
You needed these harmonic
constituents.

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00:03:38,879 --> 00:03:43,039
Even if you had those
measurements though, you

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couldn't do this work quickly,
and not in your head.

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So they built mechanical
marvels.

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The Bidston Observatory has two
of them.

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One was the Bidston-Kelvin
machine, a descendant of Lord

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Kelvin's original tide predictor
design installed for Doodson in

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00:04:01,439 --> 00:04:02,719
the 1920s.

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00:04:02,719 --> 00:04:07,280
The other was the Roberts-Légé
machine, built in 1906 and later

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00:04:07,280 --> 00:04:08,960
acquired for Bidston.

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It weighs over a ton.

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They are analog computers.

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Glorious, intricate
contrivances of shining brass

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00:04:18,480 --> 00:04:22,000
and steel filled with wheels and
gears and pulleys.

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The way they work is
mesmerizing.

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There is a wire winding its way
over and under dozens of pulley

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wheels.

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Each wheel represents a
different force.

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The pull of the moon, the pull
of the sun, the wobble of an

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orbit.

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The women set the dials and
turn a crank to run the ocean

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forward in time.

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00:04:45,920 --> 00:04:52,240
It takes four hours to draw a
year, but the setup, the work to

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00:04:52,240 --> 00:04:56,399
tell the machine where to
start, takes days.

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00:04:56,399 --> 00:05:00,560
So day after day the women look
at pages of hourly water

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00:05:00,560 --> 00:05:01,199
levels.

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00:05:01,199 --> 00:05:05,519
They lay cardboard stencils
with cutout holes over the data,

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00:05:05,519 --> 00:05:08,560
multiplying the numbers that
show through by specific

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00:05:08,560 --> 00:05:09,360
weights.

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They do the differencing.

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They do the smoothing.

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Down in the basement they find
the harmonic constants.

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Then they set the brass dials
and crank the wheel.

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The wire pulls tight, moving a
pen across a rotating paper

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00:05:27,360 --> 00:05:30,160
drum, drawing a rolling line.

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The shape of a future ocean,
and the time it will take to

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rise.

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Across the English Channel,
German Field Marshal Erwin

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Rommel paces the sands of
France.

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He looks out at the water.

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The tides are massive.

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The vertical distance from low
to high tide exceeds six meters,

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nearly twenty feet.

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When the tide comes in, it
rushes at terrifying speed.

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The water rises roughly a foot
every 15 minutes.

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Rommel tells his officers the
Allies will come at high water.

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He cannot fathom that they
would force soldiers to run

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00:06:15,199 --> 00:06:18,959
across hundreds of yards of
open, muddy beach under heavy

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machine gun fire.

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He prepares for a high tide
invasion.

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He orders the beaches sewn with
iron.

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Thousands of obstacles and
mines, welded steel crossbars

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taller than a man, wooden stakes
angled at the sea, tipped with

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more mines and captured
artillery shells.

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00:06:41,279 --> 00:06:45,519
Three-ton Belgian gates rolled
into the shallows.

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He places them exactly where
they will be hidden just beneath

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the surface as the dark water
rises to midtide, ready to rip

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00:06:55,040 --> 00:06:57,680
the bottoms out of Allied
landing craft.

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To detonate when the ships come
near.

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00:07:00,639 --> 00:07:04,000
But Allied reconnaissance
planes photograph the traps.

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The commanders realize that a
high tide landing is a death

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00:07:08,319 --> 00:07:08,959
trap.

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00:07:08,959 --> 00:07:13,519
They realize they have to land
at low tide, so the demolition

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00:07:13,519 --> 00:07:16,240
engineers can see the steel
obstacles and blow them to

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00:07:16,240 --> 00:07:16,879
pieces.

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00:07:16,879 --> 00:07:22,959
But the tide must also be
rising, rising fast so the boats

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can unload their men and float
back out without getting

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stranded on the sand.

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00:07:27,199 --> 00:07:31,600
And they also need a bright,
late rising moon.

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Otherwise the paratroopers
won't be able to see their drop

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zones.

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And the daylight.

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They need an hour of daylight
to bombard the coast before the

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troops hit the sand.

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Daylight has to coincide with
low tide.

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And the invasion is huge.

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It spans five beaches Utah,
Omaha, Gold, Juno, and Sword.

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The water sloshes through the
English Channel like a funnel.

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The exact minute of low tide
differs by more than an hour

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00:08:06,800 --> 00:08:09,120
from one end of the invasion to
the other.

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00:08:09,120 --> 00:08:13,120
The landings have to be
meticulously staggered.

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They need to know exactly what
the water will do.

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They need someone to tell them
when the earth will cooperate.

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They need the moon, the sun,
the dawn, and the tides to

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00:08:26,079 --> 00:08:26,959
align.

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00:08:26,959 --> 00:08:34,080
On October 9th, 1943, Arthur
Doodson receives a three-page

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00:08:34,080 --> 00:08:37,120
handwritten letter marked MOST
URGENT.

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00:08:37,120 --> 00:08:42,799
It is from Commander William
Ian Farquarson, the Admiralty's

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superintendent of tides.

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00:08:44,480 --> 00:08:49,279
Farquarson cannot tell Doodson
the biggest secret of the war.

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He cannot say "Normandy."
Instead, he provides what data

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00:08:55,120 --> 00:09:01,360
he can for a location he calls
"Position Z." He writes quote,

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00:09:01,360 --> 00:09:04,799
"The place is nameless and the
constants inferred.

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00:09:04,799 --> 00:09:07,759
There is in fact very little
data for it.

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00:09:07,759 --> 00:09:12,080
I am gambling on the inferred
shallow water constants giving

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00:09:12,080 --> 00:09:16,080
something like the right
answer." Doodson looks at the

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00:09:16,080 --> 00:09:16,799
numbers.

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00:09:16,799 --> 00:09:20,879
Constants inferred from sparse
shallow water readings of nearby

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00:09:20,879 --> 00:09:24,240
ports gathered by British
reconnaissance teams in small

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00:09:24,240 --> 00:09:26,480
boats and submarines in the
night.

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Arthur knows the tides and
guesses the location of Position

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00:09:30,639 --> 00:09:33,279
Z, but he says nothing.

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00:09:33,279 --> 00:09:36,000
He and the six women just get
to work.

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00:09:36,000 --> 00:09:40,639
They do the painstaking
arithmetic, the harmonic

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00:09:40,639 --> 00:09:41,600
analysis.

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00:09:41,600 --> 00:09:44,159
They calibrate the brass
wheels.

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They turn the crank.

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The pulleys rise and fall.

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They carefully translate the
machine's raw output into tide

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00:09:52,480 --> 00:09:53,120
tables.

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They map the future of a
nameless coast.

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There are only three days in
June 1944 that work.

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00:10:02,639 --> 00:10:03,759
The fifth, the sixth, and the seventh. General
Dwight D.

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00:10:03,759 --> 00:10:07,679
Eisenhower chooses June 5th for
the invasion, but a massive

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00:10:07,679 --> 00:10:09,360
storm forces a delay.

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00:10:09,360 --> 00:10:12,240
It doesn't matter what the
tides do if the air won't

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cooperate.

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00:10:13,200 --> 00:10:16,879
Rommel sees the same rough
weather.

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00:10:16,879 --> 00:10:19,840
He looks at the tides and
concludes they are completely

175
00:10:19,840 --> 00:10:21,519
wrong for an invasion.

176
00:10:21,519 --> 00:10:25,120
Believing the Allies won't
come, he leaves his headquarters

177
00:10:25,120 --> 00:10:28,399
and drives to Germany to
celebrate his wife's birthday.

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00:10:28,399 --> 00:10:31,360
But the Allies do come.

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00:10:31,360 --> 00:10:38,080
On the morning of June 6, 1944,
the largest amphibious invasion

180
00:10:38,080 --> 00:10:41,120
in the history of the world
arrives on the coast of

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00:10:41,120 --> 00:10:42,240
Normandy.

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00:10:42,240 --> 00:10:45,600
The tide predictions hold.

183
00:10:45,600 --> 00:10:50,320
Water comes rushing in, rising
and rising.

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00:10:50,320 --> 00:10:54,080
On Omaha Beach, the American
demolition teams have only

185
00:10:54,080 --> 00:10:57,200
minutes to blast their channels
before the ocean swallows the

186
00:10:57,200 --> 00:10:57,840
traps.

187
00:10:57,840 --> 00:11:02,879
It is horrific.

188
00:11:02,879 --> 00:11:06,080
They knew it would be.

189
00:11:06,080 --> 00:11:13,360
Men in wool uniforms wading
through cold water, weighed down

190
00:11:13,360 --> 00:11:17,039
by their packs, running toward
the cliffs.

191
00:11:17,039 --> 00:11:19,039
Toward the wire.

192
00:11:19,039 --> 00:11:21,600
Toward the guns on the bluffs.

193
00:11:21,600 --> 00:11:24,799
Machine gun fire from the
heights.

194
00:11:24,799 --> 00:11:30,080
The blast of heavy artillery,
constant and deafening.

195
00:11:30,080 --> 00:11:35,440
Men waiting for their turn to
run, sitting in small boats,

196
00:11:35,440 --> 00:11:39,360
breathing in engine fumes,
watching their friends fall.

197
00:11:39,360 --> 00:11:45,759
More than half the engineers on
Omaha are killed.

198
00:11:45,759 --> 00:11:52,879
And the fast rising water lifts
the landing craft exactly as

199
00:11:52,879 --> 00:11:53,440
planned.

200
00:11:53,440 --> 00:12:00,320
They drop their ramps, they
unload the troops, they reverse

201
00:12:00,320 --> 00:12:01,679
back into the channel.

202
00:12:01,679 --> 00:12:07,039
The tide does what they said it
would do.

203
00:12:07,039 --> 00:12:18,240
The liberation of Europe was
paid for in blood and secured by

204
00:12:18,240 --> 00:12:22,639
the unimaginable bravery of the
men who plunged into the surf

205
00:12:22,639 --> 00:12:25,279
and ran into a killing field.

206
00:12:25,279 --> 00:12:31,519
But beneath the battle, beneath
the smoke and the cacophony of

207
00:12:31,519 --> 00:12:36,960
the guns, there was a rhythm, a
quieter one, dictated by the

208
00:12:36,960 --> 00:12:40,080
moon and the sun and the shape
of the ground the men ran

209
00:12:40,080 --> 00:12:40,960
across.

210
00:12:40,960 --> 00:12:45,919
It was drawn in pencil in a
basement near Liverpool by a

211
00:12:45,919 --> 00:12:50,159
deaf mathematician and six young
women whose names were left off

212
00:12:50,159 --> 00:12:51,759
the public records.

213
00:12:51,759 --> 00:12:54,399
But they did have names.

214
00:12:54,399 --> 00:13:01,600
And if you look hard, if you
look really hard, you can find

215
00:13:01,600 --> 00:13:07,679
two of them: Joan Rossiter and
Estelle Gilbert.

216
00:13:07,679 --> 00:13:12,000
Their names are mentioned in
reference nine of a Physics

217
00:13:12,000 --> 00:13:18,240
Today article published in 2011,
sixty-seven years after D-Day.

218
00:13:18,240 --> 00:13:22,720
The author had spoken to them a
decade earlier and wrote down

219
00:13:22,720 --> 00:13:23,600
their names.

220
00:13:23,600 --> 00:13:26,960
The other four are unknown.

221
00:13:26,960 --> 00:13:32,960
We only know the names of some
of the women who came later, and

222
00:13:32,960 --> 00:13:36,240
we only know them because they
wrote the records themselves.

223
00:13:36,240 --> 00:13:40,320
They wrote down what it was
like to operate the machines.

224
00:13:40,320 --> 00:13:44,559
They smiled in a group photo
taken sometime after the war.

225
00:13:44,559 --> 00:13:50,799
Joan Rossiter and Estelle
Gilbert are not in the photo.

226
00:13:50,799 --> 00:13:56,879
The women who helped calculate
the tides in 1944 were swallowed

227
00:13:56,879 --> 00:13:58,399
by a job title.

228
00:13:58,399 --> 00:14:00,480
They were just Computers.

229
00:14:00,480 --> 00:14:04,399
They were diligent and good
with numbers.

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00:14:04,399 --> 00:14:07,200
They had neat handwriting.

231
00:14:07,200 --> 00:14:13,759
And when the tide came in on
the morning of June 6th, 1944,

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00:14:13,759 --> 00:14:16,480
they were already working on the
next tide.

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00:14:16,480 --> 00:14:18,480
And the one after that.

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00:14:18,480 --> 00:14:20,960
Because a war was on.

235
00:14:20,960 --> 00:14:23,279
And the Navy needed them.

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00:14:23,279 --> 00:14:31,759
I'm Daina Bouquin, and this is
Found in the Machine.

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00:14:31,759 --> 00:14:39,919
If you want to support this
show, leave a rating or a review

238
00:14:39,919 --> 00:14:41,440
wherever you listen.

239
00:14:41,440 --> 00:14:44,480
Or share this episode with a
friend.

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00:14:44,480 --> 00:14:51,120
And if you'd like to hear what
didn't make it into this

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00:14:51,120 --> 00:14:56,720
episode, or see that group photo
of the women who calculated the

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00:14:56,720 --> 00:15:03,759
tides after the war, go to
notes.foundinthemachine.com.

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00:15:03,759 --> 00:15:06,240
Thanks for listening.