"See you next week" "Bybye everyone" "Goodbye!" "Evening everybody..."
[Jazzy music: 'The Russians Are Coming' - Val Bennett]
Tim: Although today it's taken for granted that every office has a fax machine
only a few years ago, it was almost unknown.
Its recent appearance has made it, er, a wonder of the age.
And there is something quite magical about the way it converts a bit of paper into a stream of odd warbling noises
and then re-assembles it all at the receiving end.
But although it seems quite magical, the basic way it works is actually surprisingly simple.
[metronome ticks]
We're going to demonstrate this principle with a human fax.
Rex has got a big bit of paper just over the ridge
and I'm going to fax this message to him
using, er, these flags to signal to him.
We're going to walk over our bits of paper, using, er, metronomes to keep us in step
I'm going to hold up, er, the green flag to signal the start of each line
and I'm going to hold up the red flag whenever I step on a black bit of the paper.
[metronomes tick]
What's happening inside a real fax machine is surprisingly similar.
There's a sensor that reads a line at a time at the sending end
and a printer that prints out a line a time at the receiving end.
The lines are usually much too small to be visible
except at the tiny writing at the top of a fax which identifies where it's come from.
Of course there's a mass of electronics underneath, that converts the lines to sounds
that can travel over the telephone, but the basic idea is exactly the same as our human fax.
It's so simple it was first patented 150 years ago
long before the era of electronics, and over 30 years before the invention of the phone.
[farmyard animal noises] [door creaks] [whistling]
The inventor was a scotsman called Alexander Bain
who came from a remote croft in Caithness.
Bain: ...Nothing to do. There must be more to life than sheep!
His interest in the new science of electricity was inspired by a lecture
and he started experimenting in 1840. [Baa!]
Buying only a coil of wire, he used cattle jawbones for hinges and heather for springs.
He made batteries by sinking plates of different metals into the earth. [frightened sheep]
Clockmaker: I'll teach ye about the workings of the clock, young man.
Tim: During his apprenticeship, he invented the first electric clock.
Clockmaker: What have you done? Bain: Look sir! The first electric clock!
Clockmaker: It's hideous, go away!
Bain: There's no place for me here. [Baa!]
I shall go to London. Aye, and I'll invent the first fax machine! [modem tones]
Bain's fax machine was inspired by an earlier discovery
- that paper soaked in potassium ferrocyanide
turns black when electricity is passed through it.
So if I put it on this metal plate...
...and, ah, move a nail across it...
...it should change colour when I complete the circuit.
[electricity sparks]
Bain had the idea of using this paper to receive messages assembled out of printers' type.
So, if, erm, Rex - with a bit of help from Percy
- moves his nail across the raised part of a bit of type
...while I move my nail across the paper...
...we should be able to send the message in a series of lines
just like we did with the human fax.
Of course this time the message is being sent by pulses of electricity.
So it can be sent, like morse code, by - along telegraph lines.
[sparking] Bain fixed the nails of the sending and receiving ends to the
pendulums of his electric clocks.
This kept them in sync, however far apart they were.
However, having patented the idea in 1843, he never developed it.
The oldest existing fax machines are in the Musée national des Techniques, in Paris.
These magnificent contraptions, called pantelegraphs, were built by a French engineer
called Giovanni Caselli in about 1860.
The same idea as Bain's machine, but Caselli had perfected them
and actually ran the world's first commercial fax service between Paris and Leon.
The message to be sent was wrapped on one of these curved plates.
Instead of Bain's raised type, it was engraved out of very thin sheets of copper.
These machines don't work any more, but there would have been a stylus in here
the equivilant of our nail, to make the contact.
And it was moved across the message by this large pendulum
attracted from side to side by the large electromagnets.
At the receiving end, you'd put a bit of Bain's soggy paper on one of these curved plates
with another stylus resting on it.
Then, if you got the two pendulums swinging together,
[click!] the message could be reproduced.
In practice, getting the two pendulums to swing together, 250 miles apart
wasn't at all easy. They had to have a seperate clockwork chronometer at each end
to get them in sync before the message could be sent.
The definition the pantelegraph achieved was really quite extrodinary.
Unfortunately though, it was too far ahead of its time.
The pace of business life was so slow that there wasn't any real demand for it.
And it was abandoned after only 4 years due to lack of customers.
[hacksaw cutting metal] Rex: The thing that revived interest in fax machines after Caselli's failure...
...was the discovery of some electrical materials...
...were sensitive to light.
[sawing] In fact, this is quite a common phenomena...
And most semiconductors are light-sensitive to a degree. [sawing]
And if I cut the top off this power transistor...
[sawing] ...I can show you.
Connected up...
You can see on the meter when I put my hand over the transistor to cut the light off
...the resistance goes down, and when I remove it, it goes up.
And you could use this as a light-sensitive switch.
Tim: In a fax machine, light-sensitive switches made it possible to send messages written with ordinary paper and ink,
photos, and in fact any black and white image.
This is because... they work not only with a beam of light, but also with reflected light.
I've got a sawn-off transistor here, if I hold it over a bit of paper brightly lit by a spotlight
...only the white parts reflect enough light to switch the transistor. [high-pitched buzzer pulses with red light]
This is basically how a modern fax machine reads an image. [high-pitched buzzer pulses with red light]
[Beep! Beep! Whirr...] The paper is focussed onto this brightly-lit slot.
And a line at a time is focussed through this lens at the back...
...and onto the read head.
[urgent beeping] (I don't think it likes me fiddling with it!)
Inside there's 1728 tiny sensors: basically miniture versions of my sawn-off transistor.
This is the earliest existing photo sent by fax in 1906.
By the 1920s, fax had become a standard way of sending newspaper photos.
Voiceover: Speed, the life's blood of a newspaper!
Speed! Speed! Speed! Train! Telegraph! Airplane! And radio!
Get the story! Get it to the paper! Get the paper on the street!
[aeroplane engine splutters to life and revs up]
Every available development of science and engineering has been utilised
to get the story to the reader in the shortest possible time.
And now, the latest miracle of news-gathering: sending pictures by wire
has lifted the curtain on a new era in newspaper history.
It's only a matter of minutes after a news event has ocured, before newspapers all over the country
are carrying pictures, that tell the story more graphically and completely
than the printed word. By simply picking up a telephone and calling the paper.
Tim: Most of these machines work by wrapping the picture round a drum
and then moving a single sensor slowly along it.
This model shows the basic idea; the page transformed into a string of black and white bits
and then all recombined at the receiving end.
[Rattly chain and grinding noise]
Rex and I have had a go at sending a fax like this using our lathes.
I'm going to send a message, this message, to Rex.
Um, this is my light-sensitive switch, the sensor...
...put that in the lathe here...
...clamp it in.
Now, I've connected it up to this little sounder.
So that it'll squeak whenever it passes over a black bit of the message. [Loud high-pitched beeping]
[beeps with pattern of ink passing sensor]
Rex: This is the soggy paper, like we used over at Tim's workshop.
I've put this paper round a drum on my lathe.
And this bit of wire represents the nail we used.
Now this little sensor, this microphone, I'll put on the loudspeaker of the telephone.
and when it picks up the bleeps from Tim's sender unit on his lathe.
It will leave a mark, will go through here, will leave a mark on the paper through a sound-sensitive switch.
The same thing as if I shout into it. If I start the lathe up...
...if I start the lathe up, I'll er... [lathe motor spins up]
And you'll actually see it; the little light will come on if I shout
HELLO! - You can actually see the smoke coming off the paper where the current's going through
HELLO! ONE! TWO! THREE! ONE! TWO! THREE!
[lathe spins down] ...switch off again.
...and you can actually see the black marks left by my voice.
(loudly) Anything coming through yet, Tim?
TIM!
(from speakerphone) Can you hear me Tim?
Tim: Yeah I can hear you.
Rex: Can you send me the sync pulse through? Tim: Yeah, I'll just have to tape the, er, thing to the phone.
So with the microphone and my sounder connected to the handsets of our phones...
...um, we should be able to fax the message.
Rex: Okay, I'll tape mine on. Tim (on speakerphone): Okay, err...
Rex: I've just taped that on the edge of the speaker.
Tim: Right, get the lathe going, err... [lathe motor spins up]
The only thing is, I first have to send a pulse, once a revolution,
cos Rex has got to get his lathe going at exactly the same speed as mine.
[lathe rattles] [pip....pip.... from buzzer] Can you hear the pulse?
Rex (loudly): Right Tim, we've got sync, can you hear me!
Tim (speakerphone): Yeah, I can hear you.....(indistinct) Rex: Okay!
[pip....pip....pip....] [pip...beepetybeepetybib!......pip...beepetybeepetybib!......pip...beepetybeepetybib!]
Rex: It's coming through! Quite clearly now.
I can even see the first line before I stop, and it says "Utopia". [lathe noise]
I'll stop the lathe... [lathe spins down]
Ahh yes, the first line, is "Utopia", and the second line is "services"
but it is very wobbly; it's a job to keep it in sync
but it's not bad for a lathe!
This is the met station at Hemsby
where they send up hydrogen balloons with cheap, disposable instruments attached
to record weather conditions in the upper atmosphere.
The information from sites like Hemsby all over the country is collected at the Met. head office and assembled into the weather map.
A completed map is then sent back here by fax.
[noisy machinery] Although it looks quite neat and modern, the fax machine is still quite endearingly primitive.
It still uses Bain's soggy paper, and inside it's all very mechanical still.
Looks a bit like a lawnmower, actually.
I'll just stop it... [spins down]
This rotating helix; the bit in contact with the paper, slowly moves along the line.
...from one end to the other.
It has considerable drawbacks: for a start it only works with dedicated phonelines.
It creates quite large sparks across the paper as it prints out the message.
And this means that this contact strip has to be replaced every day or two.
Also the paper stops working as it dries out, and the vapour it gives out can be a health hazard.
The machine's days are numbered. They're gradually being replaced by a computer system.
It is extrodinary though, that although fax machines have had specialist uses like this for over 50 years
that they've only come into general use in the office in the last five.
Voiceover: Every year, more than two hundred million telegrams pass through the hands of...
Tim: The main reason why fax machines took so long to catch on, is that an alternative system
for sending written messages by telephone lines had already become established:
The teleprinter and telegram service.
Voiceover: The distant receiver records each letter on a moving paper tape.
An operator removes the tape, and gums it to the familiar yellow blanks.
Bain had pioneered teleprinters after he abandoned the fax.
But he got involved in furious patent battles
Judge: Mr Bain, the court finds you did not invent any of these things.
Bain: *sighs* That was my patent. Why did I leave Scotland? At least I could trust my sheep!
Tim: He died bitter and pennyless... Bain: Oh! Oh! *thud*
Tim: ...in a home for incurables, in 1877. [Baa! Baa!]
Salesman: You are about to witness a race between the Xerox telecopier transciever, and Speed Johnson
one of the fastest messengers in the world.
They will both attempt to get a copy of this important document to a destination at the other end of the city.
And they have to get it there in four minutes or less. Okay? On your mark, get set, GO!
[jolly piano music] Speed will be using an ordinary motorcycle
The telecopier, an ordinary telephone.
Tim: By the 1960s, electronics had advanced enough to revive interest in ordinary fax machienes, or 'telecopiers'.
They were very expensive, slow, and different manufacturers' machines were all incompatible with each other. [piano music continues]
Salesman: The telecopier copy has arrived, ladies and gentelmen, in exactly... 3:57!
[CRASH!]
The development that really made the fax machine practical was the digital fax,
this not only split the image up into lines, but into a complete grid of tiny squares.
So first you have to put the grid over the image...
...and then decide which squares are going to be white, and which squares are going to be black.
That's what I've done down here.
Well now I can send this to Rex, just like I did at the beginning of the programme,
square by square. The only difference is that this time Rex needs an assistant
because Rex is going to have to look at what he's doing to get the paint exactly in the squares
he's got a similar grid with the squares marked out, just like mine.
Right. Okay?
Assistant: START!... BLACK!... WHITE!... BLACK!... WHITE!... BLACK!... WHITE!... BLACK!... WHITE!...
The big advantage is that Rex should be able to reproduce exactly what I'm sending.
Even if I hold my flag up at slightly the wrong moment, Rex is unlikely to fill in completely the wrong square. [modem tones]
It's this precision that allows us to send digital faxes much faster without losing any quality in the reproduction. [modem tones]
A mathematician called Huffman, worked out all the different codes for the different run-lengths of black squares and white squares.
And he gave the shortest codes to the most common run-lengths on an ordinary typewritten letter.
If I put a mask over a line of the type...
...hold a magnifying glass over it...
you can see that there are a lot of thin black lines; these are each 2 squares wide
and if you look on the Huffman code, you can see because this is very common, it has a very short code.
If you look at the white spaces between the lines, you can see that they're much more variable in width
so all the white spacing have longer codes.
This is the same idea as morse code, where the vowels have shorter codes than the less common consonants.
And this explains why fax machines slow down when they're scanning a complicated image like a photograph
and speed up when they get to a bit of text.
[rips paper]
The familiar thermal fax paper simply works by turning black when it gets hot.
It should do in front of this fire.
A small heating element can blacken a very precise area of the paper.
This is basically what's inside the thermal printer of a fax machine.
It's a row of 1728 tiny heating elements.
One for each digital square of a line.
The only moving part is this roller that feeds the paper through the printer. [beep! whirr...]
This simplicity not only makes the machine very cheap, it also makes it extremely reliable.
The electronics in a fax machine are complicated not only because of the digital coding
but also because the machines have to talk to each other to start the message going.
This handshake procedure is pretty complicated, but Telecom research have lent us a fax analyser to show what's going on.
But the process is quite closely analagous to starting a telephone conversation.
So if I ring Rex now... what's this on? 525? Right.
You're engaged! Rex: I'll switch that off...
Rex: Stop, stop. Stop! Tim: Right, I'll try you again.
[modem tones] Rex: Hello, Rex here
[modem tones] Rex: You'll have to speak up.
Tim: Hello, Tim here. [modem tones]
Tim: Can you understand me if I speak this fast? [modem carrier]
Tim: wafflewafflewafflewafflewafflewaffle Rex: Yes, I understand you.
Tim: Okay: wafflewafflewafflewafflewafflewafflewafflewafflewafflewafflewafflewaffle
Tim: That's all I've got to say.
Rex: Okay, everything understood. Bye. Tim: Bye.
Tim: And that completes the handshake procedure.
Although the handshake is complicated, it happens completely automatically, so the machines remain extremely simple to use.
Mr Jones: What'll I have today then? Tim: I'm sure this is why they've become so popular in the office.
Boss: Mr Jones! What are you playing at, this is an office, not a fast food emporium!
Knitting pattern!
Joan, is this for you? I've told you 100 times, don't use the fax for your hobbies! Joan: Oh! *gulp*
Joan: Sorry. [heartbeat]
Oh, really!
Polly! I'm expecting a very important fax for work, I do not want the machine abused for private use!
And that goes for everybody!
This is the last straw!
[door slams]
Boss: Oh! Woman: Here you are luv, nice cuppa tea. And we've got you a private fax of your very own, happy now?
Man: Here it is... Boss: *sigh*
Tim: I hope I've managed to de-mystify these inscrutable machines a bit in this programme.
I have to admit thoug, I don't find the modern machines quite so appealing as the early ones.
I came back from Paris so enthused by the Pantelegraph that I couldn't resist having a go at trying to make one.
It may not be completely practical in an office, but there is something hypnotic about it...
[Jazzy music: 'Take 5' - Dave Brubeck]
[POP! Fizzle!] [bang-bang-bang-bang] [music continues]