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"See you next week" "Bybye everyone"
"Goodbye!" "Evening everybody..."

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[Jazzy music: 'The Russians Are Coming' - Val Bennett]

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Tim: Although today it's taken for granted that every office has a fax machine

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only a few years ago, it was almost unknown.

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Its recent appearance has made it, er, a wonder of the age.

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And there is something quite magical about the way it converts a bit of paper into a stream of odd warbling noises

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and then re-assembles it all at the receiving end.

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But although it seems quite magical, the basic way it works is actually surprisingly simple.

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[metronome ticks]

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We're going to demonstrate this principle with a human fax.

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Rex has got a big bit of paper just over the ridge

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and I'm going to fax this message to him

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using, er, these flags to signal to him.

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We're going to walk over our bits of paper, using, er, metronomes to keep us in step

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I'm going to hold up, er, the green flag to signal the start of each line

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and I'm going to hold up the red flag whenever I step on a black bit of the paper.

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[metronomes tick]

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What's happening inside a real fax machine is surprisingly similar.

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There's a sensor that reads a line at a time at the sending end

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and a printer that prints out a line a time at the receiving end.

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The lines are usually much too small to be visible

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except at the tiny writing at the top of a fax which identifies where it's come from.

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Of course there's a mass of electronics underneath, that converts the lines to sounds

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that can travel over the telephone, but the basic idea is exactly the same as our human fax.

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It's so simple it was first patented 150 years ago

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long before the era of electronics, and over 30 years before the invention of the phone.

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[farmyard animal noises]
[door creaks] [whistling]

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The inventor was a scotsman called Alexander Bain

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who came from a remote croft in Caithness.

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Bain: ...Nothing to do.  There must be more to life than sheep!

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His interest in the new science of electricity was inspired by a lecture

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and he started experimenting in 1840.
[Baa!]

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Buying only a coil of wire, he used cattle jawbones for hinges and heather for springs.

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He made batteries by sinking plates of different metals into the earth.
[frightened sheep]

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Clockmaker: I'll teach ye about the workings of the clock, young man.

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Tim: During his apprenticeship, he invented the first electric clock.

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Clockmaker: What have you done?
Bain: Look sir! The first electric clock!

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Clockmaker: It's hideous, go away!

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Bain: There's no place for me here.
[Baa!]

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I shall go to London.  Aye, and I'll invent the first fax machine!
[modem tones]

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Bain's fax machine was inspired by an earlier discovery

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- that paper soaked in potassium ferrocyanide

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turns black when electricity is passed through it.

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So if I put it on this metal plate...

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...and, ah, move a nail across it...

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...it should change colour when I complete the circuit.

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[electricity sparks]

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Bain had the idea of using this paper to receive messages assembled out of printers' type.

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So, if, erm, Rex - with a bit of help from Percy

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- moves his nail across the raised part of a bit of type

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...while I move my nail across the paper...

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...we should be able to send the message in a series of lines

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just like we did with the human fax.

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Of course this time the message is being sent by pulses of electricity.

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So it can be sent, like morse code, by - along telegraph lines.

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[sparking]
Bain fixed the nails of the sending and receiving ends to the

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pendulums of his electric clocks.

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This kept them in sync, however far apart they were.

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However, having patented the idea in 1843, he never developed it.

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The oldest existing fax machines are in the Musée national des Techniques, in Paris.

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These magnificent contraptions, called pantelegraphs, were built by a French engineer

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called Giovanni Caselli in about 1860.

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The same idea as Bain's machine, but Caselli had perfected them

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and actually ran the world's first commercial fax service between Paris and Leon.

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The message to be sent was wrapped on one of these curved plates.

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Instead of Bain's raised type, it was engraved out of very thin sheets of copper.

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These machines don't work any more, but there would have been a stylus in here

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the equivilant of our nail, to make the contact.

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And it was moved across the message by this large pendulum

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attracted from side to side by the large electromagnets.

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At the receiving end, you'd put a bit of Bain's soggy paper on one of these curved plates

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with another stylus resting on it.

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Then, if you got the two pendulums swinging together,

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[click!]
the message could be reproduced.

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In practice, getting the two pendulums to swing together, 250 miles apart

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wasn't at all easy.  They had to have a seperate clockwork chronometer at each end

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to get them in sync before the message could be sent.

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The definition the pantelegraph achieved was really quite extrodinary.

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Unfortunately though, it was too far ahead of its time.

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The pace of business life was so slow that there wasn't any real demand for it.

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And it was abandoned after only 4 years due to lack of customers.

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[hacksaw cutting metal]
Rex: The thing that revived interest in fax machines after Caselli's failure...

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...was the discovery of some electrical materials...

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...were sensitive to light.

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[sawing]
In fact, this is quite a common phenomena...

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And most semiconductors are light-sensitive to a degree.
[sawing]

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And if I cut the top off this power transistor...

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[sawing]
...I can show you.

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Connected up...

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You can see on the meter when I put my hand over the transistor to cut the light off

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...the resistance goes down, and when I remove it, it goes up.

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And you could use this as a light-sensitive switch.

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Tim: In a fax machine, light-sensitive switches made it possible to send messages written with ordinary paper and ink,

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photos, and in fact any black and white image.

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This is because... they work not only with a beam of light, but also with reflected light.

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I've got a sawn-off transistor here, if I hold it over a bit of paper brightly lit by a spotlight

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...only the white parts reflect enough light to switch the transistor.
[high-pitched buzzer pulses with red light]

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This is basically how a modern fax machine reads an image.
[high-pitched buzzer pulses with red light]

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[Beep! Beep! Whirr...]
The paper is focussed onto this brightly-lit slot.

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And a line at a time is focussed through this lens at the back...

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...and onto the read head.

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[urgent beeping]
(I don't think it likes me fiddling with it!)

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Inside there's 1728 tiny sensors: basically miniture versions of my sawn-off transistor.

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This is the earliest existing photo sent by fax in 1906.

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By the 1920s, fax had become a standard way of sending newspaper photos.

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Voiceover: Speed, the life's blood of a newspaper!

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Speed! Speed! Speed!
Train! Telegraph! Airplane! And radio!

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Get the story! Get it to the paper! Get the paper on the street!

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[aeroplane engine splutters to life and revs up]

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Every available development of science and engineering has been utilised

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to get the story to the reader in the shortest possible time.

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And now, the latest miracle of news-gathering: sending pictures by wire

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has lifted the curtain on a new era in newspaper history.

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It's only a matter of minutes after a news event has ocured, before newspapers all over the country

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are carrying pictures, that tell the story more graphically and completely

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than the printed word.  By simply picking up a telephone and calling the paper.

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Tim: Most of these machines work by wrapping the picture round a drum

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and then moving a single sensor slowly along it.

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This model shows the basic idea; the page transformed into a string of black and white bits

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and then all recombined at the receiving end.

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[Rattly chain and grinding noise]

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Rex and I have had a go at sending a fax like this using our lathes.

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I'm going to send a message, this message, to Rex.

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Um, this is my light-sensitive switch, the sensor...

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...put that in the lathe here...

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...clamp it in.

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Now, I've connected it up to this little sounder.

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So that it'll squeak whenever it passes over a black bit of the message.
[Loud high-pitched beeping]

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[beeps with pattern of ink passing sensor]

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Rex: This is the soggy paper, like we used over at Tim's workshop.

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I've put this paper round a drum on my lathe.

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And this bit of wire represents the nail we used.

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Now this little sensor, this microphone, I'll put on the loudspeaker of the telephone.

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and when it picks up the bleeps from Tim's sender unit on his lathe.

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It will leave a mark, will go through here, will leave a mark on the paper through a sound-sensitive switch.

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The same thing as if I shout into it.  If I start the lathe up...

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...if I start the lathe up, I'll er...
[lathe motor spins up]

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And you'll actually see it; the little light will come on if I shout

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HELLO! - You can actually see the smoke coming off the paper where the current's going through

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HELLO!  ONE! TWO! THREE! ONE! TWO! THREE!

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[lathe spins down]
...switch off again.

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...and you can actually see the black marks left by my voice.

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(loudly) Anything coming through yet, Tim?

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TIM!

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(from speakerphone) Can you hear me Tim?

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Tim: Yeah I can hear you.

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Rex: Can you send me the sync pulse through?
Tim: Yeah, I'll just have to tape the, er, thing to the phone.

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So with the microphone and my sounder connected to the handsets of our phones...

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...um, we should be able to fax the message.

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Rex: Okay, I'll tape mine on.
Tim (on speakerphone): Okay, err...

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Rex: I've just taped that on the edge of the speaker.

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Tim: Right, get the lathe going, err...
[lathe motor spins up]

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The only thing is, I first have to send a pulse, once a revolution,

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cos Rex has got to get his lathe going at exactly the same speed as mine.

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[lathe rattles] [pip....pip.... from buzzer]
Can you hear the pulse?

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Rex (loudly): Right Tim, we've got sync, can you hear me!

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Tim (speakerphone): Yeah, I can hear you.....(indistinct)
Rex: Okay!

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[pip....pip....pip....]
[pip...beepetybeepetybib!......pip...beepetybeepetybib!......pip...beepetybeepetybib!]

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Rex: It's coming through!  Quite clearly now.

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I can even see the first line before I stop, and it says "Utopia".
[lathe noise]

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I'll stop the lathe...
[lathe spins down]

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Ahh yes, the first line, is "Utopia", and the second line is "services"

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but it is very wobbly; it's a job to keep it in sync

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but it's not bad for a lathe!

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This is the met station at Hemsby

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where they send up hydrogen balloons with cheap, disposable instruments attached

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to record weather conditions in the upper atmosphere.

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The information from sites like Hemsby all over the country is collected at the Met. head office and assembled into the weather map.

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A completed map is then sent back here by fax.

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[noisy machinery]
Although it looks quite neat and modern, the fax machine is still quite endearingly primitive.

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It still uses Bain's soggy paper, and inside it's all very mechanical still.

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Looks a bit like a lawnmower, actually.

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I'll just stop it...
[spins down]

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This rotating helix; the bit in contact with the paper, slowly moves along the line.

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...from one end to the other.

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It has considerable drawbacks: for a start it only works with dedicated phonelines.

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It creates quite large sparks across the paper as it prints out the message.

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And this means that this contact strip has to be replaced every day or two.

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Also the paper stops working as it dries out, and the vapour it gives out can be a health hazard.

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The machine's days are numbered.  They're gradually being replaced by a computer system.

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It is extrodinary though, that although fax machines have had specialist uses like this for over 50 years

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that they've only come into general use in the office in the last five.

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Voiceover: Every year, more than two hundred million telegrams pass through the hands of...

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Tim: The main reason why fax machines took so long to catch on, is that an alternative system

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for sending written messages by telephone lines had already become established:

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The teleprinter and telegram service.

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Voiceover: The distant receiver records each letter on a moving paper tape.

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An operator removes the tape, and gums it to the familiar yellow blanks.

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Bain had pioneered teleprinters after he abandoned the fax.

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But he got involved in furious patent battles

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Judge: Mr Bain, the court finds you did not invent any of these things.

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Bain: *sighs* That was my patent.  Why did I leave Scotland?  At least I could trust my sheep!

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Tim: He died bitter and pennyless...
Bain: Oh! Oh!  *thud*

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Tim: ...in a home for incurables, in 1877.
[Baa!  Baa!]

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Salesman: You are about to witness a race between the Xerox telecopier transciever, and Speed Johnson

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one of the fastest messengers in the world.

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They will both attempt to get a copy of this important document to a destination at the other end of the city.

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And they have to get it there in four minutes or less.  Okay?
On your mark, get set, GO!

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[jolly piano music]
Speed will be using an ordinary motorcycle

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The telecopier, an ordinary telephone.

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Tim: By the 1960s, electronics had advanced enough to revive interest in ordinary fax machienes, or 'telecopiers'.

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They were very expensive, slow, and different manufacturers' machines were all incompatible with each other.
[piano music continues]

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Salesman: The telecopier copy has arrived, ladies and gentelmen, in exactly... 3:57!

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[CRASH!]

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The development that really made the fax machine practical was the digital fax,

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this not only split the image up into lines, but into a complete grid of tiny squares.

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So first you have to put the grid over the image...

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...and then decide which squares are going to be white, and which squares are going to be black.

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That's what I've done down here.

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Well now I can send this to Rex, just like I did at the beginning of the programme,

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square by square.  The only difference is that this time Rex needs an assistant

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because Rex is going to have to look at what he's doing to get the paint exactly in the squares

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he's got a similar grid with the squares marked out, just like mine.

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Right.  Okay?

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Assistant: START!... BLACK!... WHITE!... BLACK!... WHITE!... BLACK!... WHITE!... BLACK!... WHITE!...

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The big advantage is that Rex should be able to reproduce exactly what I'm sending.

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Even if I hold my flag up at slightly the wrong moment, Rex is unlikely to fill in completely the wrong square.
[modem tones]

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It's this precision that allows us to send digital faxes much faster without losing any quality in the reproduction.
[modem tones]

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A mathematician called Huffman, worked out all the different codes for the different run-lengths of black squares and white squares.

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And he gave the shortest codes to the most common run-lengths on an ordinary typewritten letter.

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If I put a mask over a line of the type...

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...hold a magnifying glass over it...

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you can see that there are a lot of thin black lines; these are each 2 squares wide

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and if you look on the Huffman code, you can see because this is very common, it has a very short code.

225
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If you look at the white spaces between the lines, you can see that they're much more variable in width

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so all the white spacing have longer codes.

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This is the same idea as morse code, where the vowels have shorter codes than the less common consonants.

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And this explains why fax machines slow down when they're scanning a complicated image like a photograph

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and speed up when they get to a bit of text.

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[rips paper]

231
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The familiar thermal fax paper simply works by turning black when it gets hot.

232
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It should do in front of this fire.

233
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A small heating element can blacken a very precise area of the paper.

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This is basically what's inside the thermal printer of a fax machine.

235
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It's a row of 1728 tiny heating elements.

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One for each digital square of a line.

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The only moving part is this roller that feeds the paper through the printer.
[beep! whirr...]

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This simplicity not only makes the machine very cheap, it also makes it extremely reliable.

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The electronics in a fax machine are complicated not only because of the digital coding

240
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but also because the machines have to talk to each other to start the message going.

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This handshake procedure is pretty complicated, but Telecom research have lent us a fax analyser to show what's going on.

242
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But the process is quite closely analagous to starting a telephone conversation.

243
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So if I ring Rex now... what's this on?  525?  Right.

244
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You're engaged!
Rex: I'll switch that off...

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Rex: Stop, stop.  Stop!
Tim: Right, I'll try you again.

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[modem tones]
Rex: Hello, Rex here

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[modem tones]
Rex: You'll have to speak up.

248
00:21:45,599 --> 00:21:48,098
Tim: Hello, Tim here.
[modem tones]

249
00:21:48,099 --> 00:21:51,598
Tim: Can you understand me if I speak this fast?
[modem carrier]

250
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Tim: wafflewafflewafflewafflewafflewaffle
Rex: Yes, I understand you.

251
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Tim: Okay: wafflewafflewafflewafflewafflewafflewafflewafflewafflewafflewafflewaffle

252
00:22:00,599 --> 00:22:02,598
Tim: That's all I've got to say.

253
00:22:02,599 --> 00:22:08,399
Rex: Okay, everything understood.  Bye.
Tim: Bye.

254
00:22:08,400 --> 00:22:12,999
Tim: And that completes the handshake procedure.

255
00:22:14,000 --> 00:22:21,798
Although the handshake is complicated, it happens completely automatically, so the machines remain extremely simple to use.

256
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Mr Jones: What'll I have today then?
Tim: I'm sure this is why they've become so popular in the office.

257
00:22:27,000 --> 00:22:32,899
Boss: Mr Jones!  What are you playing at, this is an office, not a fast food emporium!

258
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Knitting pattern!

259
00:22:37,500 --> 00:22:46,098
Joan, is this for you?  I've told you 100 times, don't use the fax for your hobbies!
Joan: Oh! *gulp*

260
00:22:46,099 --> 00:22:50,899
Joan: Sorry.
[heartbeat]

261
00:22:50,900 --> 00:22:53,598
Oh, really!

262
00:22:53,599 --> 00:23:04,199
Polly!  I'm expecting a very important fax for work, I do not want the machine abused for private use!

263
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And that goes for everybody!

264
00:23:07,200 --> 00:23:10,699
This is the last straw!

265
00:23:11,700 --> 00:23:12,798
[door slams]

266
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Boss: Oh!
Woman: Here you are luv, nice cuppa tea.  And we've got you a private fax of your very own, happy now?

267
00:23:24,000 --> 00:23:28,558
Man: Here it is...
Boss: *sigh*

268
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Tim: I hope I've managed to de-mystify these inscrutable machines a bit in this programme.

269
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I have to admit thoug, I don't find the modern machines quite so appealing as the early ones.

270
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I came back from Paris so enthused by the Pantelegraph that I couldn't resist having a go at trying to make one.

271
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It may not be completely practical in an office, but there is something hypnotic about it...

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[Jazzy music: 'Take 5' - Dave Brubeck]

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[POP!  Fizzle!] [bang-bang-bang-bang]
[music continues]