"Bye!" "Don't do anything I wouldn't do!" "Come for a drink?"
[Jazzy music: 'The Russians Are Coming' - Val Bennett]
Tim: Today, electric light is completely taken for granted,
though without it, our lives would be infinitely more difficult and dangerous.
Creating all this light has taken an enormous amount of effort and ingenuity.
In this programme, Rex and I are going to look at the evolution and workings of this almost indispensible invention.
The first form of artifical light was obviously fire
Once the fire was burning well, you could take out a
branch and use it as a primitive sort of torch.
Trouble was, these tended to go out.
Some countries had particularly resinous woods like pitch-pine that burn particularly well.
Most countries developed some way of using oil or fat for light.
The aincient Greeks and Romans squashed the oil out of olives,
poured it into a bowl, with some sort of a wick
(muttered) soaked in oil,
which they then lit.
Pretty puny flame! Oh no, it is just about alight.
Northern European countries developed the candle.
but these weren't like modern candles, they were made of animal fat,
and they smelt pretty disgusting,
and they tended to spit, and every few minutes you'd have to trim the wick.
[bird tweeting]
[THUD]
Tim: Meanwhile whole animals and birds were used as candles in some parts of the world, particularly petrels.
Woman: Here we have the early 'petrel' lighter!
Man: Not so good as the candlefish.
A little slippery, but very effective.
Woman: As for me, boyo, I have a penguin to keep me warm (chuckles)
Keeps alight for hours. Weighs a ton though, ohh dear!
Tim: These early candles produced so little light that most people went to bed soon after sunset.
Man: I'm trying to get some sleep, put that bloody penguin out!
Tim: Psychologists now believe that sleep evolved mainly to protect us from the dark. [Howling noise]
Tim: The possibility of using electricity for lighting was first suggested in 1810 by Humphrey Davy
Shorting out a large battery he'd been given, the electricity arced through the air bridging the gap
Almost like lightning.
This intense light formed the basis of the first commercial arc lights in the 1840s [buzzing of arcing electricity]
They needed to have quite an elaborate clockwork mechanism
to move the electrodes progressively closer together as they gradually burnt away.
Arc lamps continued to have specialist uses like film lighting until quite recently.
However, the large amount of current used prevented them ever becoming widely adopted.
Meanwhile lighting had started to improve in the early 19th century with the introduction of gaslight.
By 1850 it had been installed in most cities
although the search for a better electric light continued.
Humphrey davy had also noticed that electricity
heats up any wire it's passing through to some extent.
And that it was possible to make a wire glow white hot.
[Loud thrumming noise] Tim: We're using a welder as a power supply here
and we should be able to turn out the lights and see if it'll give off enough light.
It's only glowing at the bottom... but it should...
(that's it) [thrumming continues]
The problem is that at some point it gets so hot
that it starts to melt!
[crackle] Tim: Whoops
Tim: However (to Rex) we'd better have the lights back on.
Carbon melts at a much higher temperature than most sorts of metal
and several inventors started experimenting with carbon filiments.
Rex had this idea that we could do this with a pencil...
[sparks] Tim: Whoops!
... pencil lead that is also made out of graphite, sort of carbon.
[hissing]
So first we've got to burn off the wood round the lead.
Well this works much better than the steel rod
But the trouble is, that even the carbon filiment doesn't last for very long
because it reacts with the air and it slowly deteriorates.
Tim: Get it a bit hotter than that.
[sparking noises]
The solution to this problem is to enclose the filament in a
glass container, and pump the air out so that it can't react with it,
and that's the reason for the light 'bulb'.
Well, Rex and I have had some success with making a lightbulb like this
enclosing the pencil lead in the milk bottle.
And now we turn on the vacuum pump and start pumping out the air.
[loud rattling noise from vaccum pump]
Tim: And connect it up...
Rex: Put the power on very slowly.
Tim: Oh yes...
Rex: It's still got a bit of air in there....
Tim: Yes. Rex: Okay. Like that. If we switch it on...
as the air is pumped out, this is actually sucking more of the
err, any air that is trapped in the filiment out as well.
Tim: We should be able to,
Tim: (to Rex) If you let go we should be able to turn the light out,
should be able to make it work as a proper bulb, yeah.
Rex: Can turn it up now.
Tim: You can turn it up. Now it's working. Can't we?
Nearly as good as an ordinary lightbulb really.
A chemist from Newcastle called Joseph Swan,
tried repeatedly to make a lightbulb like this in the 1860s,
But eventually gave up concluding that his vaccum pump just wasn't good enough.
15 years later, discovering a better sort of pump, he tried again,
and succeeded in 1878.
Meanwhile Thomas Edison, here seen in his old age,
had started experimenting in America in 1877.
Backed by a lot of money, and a dedicated team at his laboratory,
he developed a similar lightbulb within two years.
Swan and Edison faced enormous difficulties, even once their bulbs were working.
There was no electricity to plug into at the time.
Edison in particular had to dig up the roads to lay his cables
and even built the first powerstations to enable his lights to be used.
Then to persuade people to buy his electricity he staged lots of publicity stunts.
Particularly with people wearing lightbulbs in unusual places.
The task of persuading people to install electricity wasn't made any easier,
because the original gas lights, just, erm, simple gas flames,
had been dramatically improved in the 1870s with the invention of the gas mantle.
This is made of a material which glows white hot at a particularly low temperature
now if I light the whole thing up now then it should all burst into light.
I've got these two in my kitchen, I just like the soft greenish light they cast.
They don't smoke or smell and they are as bright as ordinary electric lights.
Many houses didn't install electricity until the 1930s because their gas lights were so good.
[Rex scrapes chair]
[1930s music] Woman: Oh Daddy, for Pete's sake stop messing about.
I'll never get these... (fades out)
Tim: Electricity finally triumphed because it could be used for so many other things besides lighting.
Woman: Oh Bother!
Man: You know there's only one plug in this room,
and we've already got the fire, and the clock and the radio,
and the standard lamp connected to it!
Now you want the table lamp for your sewing machine!
Woman2: Nevermind dear, we'll manage somehow.
If father wants to play about at being an electrician,
we mustn't begrudge him a little clean fun.
Tim: The main improvement in an ordinary modern bulb,
is that it has a filiment made of a metal called tungsten.
It's easier to see in a clear bulb.
This metal has the highest melting point of any metal.
With tungsten filiments, our milkbottle lights work nearly as well as real lightbulbs.
In a real bulb though, the tungsten...
[clank clank clank]
[Glass shatters]
...is coiled up, and if you look at it under a magnifying glass,
the coil is made up of another even finer tiny coil.
It's called a coiled coil.
The more compactly a filament can be wound, the less heat it loses to the surroundings and the brighter it glows.
[plink]
[Man Groans] Woman: Oh no! The bulb's gone again!
[Rousing circus music]
Voiceover: We wouldn't have to go through this performance... (fades out)
Tim: Lightbulbs never last forever because at their working temperature,
2,500 degrees centigrade, the filiment gradually evaporates.
Man: Oy! Where's the bulb?
Moustached man: I'll get one of the new ones...
Voiceover man: Thorn EMI double life lightbulbs.
Double life, but not double the cost.
Tim: In the late '50s a dramatically improved sort of filiment bulb was invented:
Tungsten-halogen.
These are used for outside lights,
for, er, car headlights
and for tiny little shop spotlights.
They give off twice as much light as ordinary bulbs,
running at a higher temperature, and even so they last twice as long.
This is because they have minute traces of gases inside called halogens,
which repel the evaporating Tungsten from the surface of the bulb,
making it redeposit itself back on the filiment, a sort of cycle.
This only works if the glass is kept very hot, 250 degrees centigrade,
that's easily enough to boil water
[bubbling of boiling water]
The problem with any sort of filiment light though
is that it's extremely wasteful of energy.
An ordinary lightbulb only gives out 10% of it's electricity as light, all the rest is wasted as heat.
And even the most efficient tungsten-halogen bulb only gives out 25% as light.
There's more to lighting though than simple efficiency. It's also extremely decorative.
And there's an astonishing range of decorative bulbs available.
[Circus music: 'Entry of the Gladiators' - Julius Fučík]
I incorporate light in all sorts of things that I make.
This ring was inspired by these little bright red lights, they looked to me sort of like modern jewels.
This is a bedside light that I made, like a sort of office block with its window cleaners.
This is a nuclear mint in here
It's a packet of mints I bought at the shop of our local nuclear reactor's visitor centre.
I lit it to make it look suitably dangerous.
Lights aren't only decorative, films in particular have always used them for their dramatic effect.
Molly: No, you're wrong!
Woman: That's how you always intended to spend the evening. Not with George at all!
Molly: Don't say that! [Light switch clicking]
Woman: And for a very good reason!
Molly: Now you keep quiet! Don't say that! Now keep quiet. [Music speeds up sinisterly]
Woman: Molly, now listen to me. Listen to me Molly. [Music returns to original tempo]
Molly: I don't have to listen to you!
Woman: I think I know the truth Molly!
Molly: No you don't! You don't know anything at all!
Woman: I think I know the truth about George!
Molly: You can't, you don't.
Woman: You couldn't have met George tonight!
Molly: No! No! Noooo!
Woman: Because there isn't any George!
Molly: No! No! No! [cries] [Music signifies impending doom]
Molly: Please!
[Music gets louder and more sinister]
[music signifying flying]
Wizard: Well. How's this Nancy? Better huh!
Nancy: Oooh! This is wonderful!
I wished I had one of those magic wands!
So I could fly around whenever I wanted to!
Nothing simpler Nancy. Here! [expanding wand whoops]
However, that wand is important for much more important things than flying around through the air!
It's a fluorescant light tube!
Tim: Today's efficient fluorescant lights developed from the original arc lights.
This tiny high voltage arc... [buzzing of arc]
doesn't reach far, or give off much light.
But, erm, if I connect the wires to the ends of this glass tube.
Switch it on again. Switch off the lights.
And start pumping the air out of the tube [loud clanky vacuum pump]
Instead of forming an arc, the electricity fills the entire tube with a glowing discharge.
This is the basis of fluorescant, and many other types of electric light.
Although in basic form it's not really bright enough to be useful.
When it was first discovered, these tubes were bent
into funny shapes and demonstrated as wonders of science.
If I apply a voltage to this one, you can see it glow. [buzzing]
And over here they have a selection that we borrowed from the Royal Institution.
Called Giessler tubes, and they were made in the 1860s.
[Buzzing noises]
In 1905 a French inventor called Georges Claude found that
a newly discovered gas, neon, made the tube glow bright red.
He immediately realised its potential for illuminated signs
and by the 1920s had managed to sell a large number of franchises especially in America.
The first fluorescant light was introduced in 1939
this is the same idea as our vacuum tube, except there's a little tungsten filiment at each end
The idea is that heating these up for a moment, encourages the electricity to start flowing.
In the tube there's a starter to do this switching,
and a ballast to limit the amount of current that can pass through it.
The inside of the tube is filled with a mixture of argon and mercury vapour.
This is giving out mostly ultraviolet light, that's why I'm wearing these protective goggles.
But fortunately there are chemicals that can convert
the ultraviolet to visible light. A property called fluorescance.
If I switch the light off for a minute you can see that they're actually just white powders.
Tube manufacturers mix these fluorescant materials
creating any colour, or combination of colours they want.
(muttered) See if I can get some for...
These are coated onto the inside of the tube.
Neon tubes can also be coated in phosphors creating almost a complete spectrum of colours.
Rex: The odd thing about fluorescant tubes is that you don't even
have to connect them to the electricity to make them work.
If I put this one in a microwave oven...
Switch on...
[Microwave whirrs]
It will work and if you excite it by a radio frequency,
or a very high frequency, it will also work without being connected. Like this.
[Loud buzzing noise]
I've got another milk bottle here, and we've put fluorescent materials inside this,
stuck it on the inside.
I've evacuated this one, that's connected up to my vacuum pump,
and if I connect this up to our high frequency again...
....we'll have a fluorescant milk bottle.
[buzzing]
I've made ordinary filiment light bulbs which appear to be normal,
But if you look at this one, it's a big trick,
there's actually wires running up the back of my hand to a battery.
This was made for a magician.
Fluorescant tubes are highly efficient, giving out 4 times as much light
for the same amount of electricity as an ordinary light bulb.
They've become the standard lighting for factories, shops and offices,
Providing uniform brightness over vast areas.
However, architects and designers now often deliberately use
lighting to create different moods.
Architect: (German accent) Lighting is not only
bulbs, no, is an environment enhancing, ambiance arousing concept.
[Audience sigh, mutter boredly]
Architect: Look please at the stylish desk light
vich offers zuperb visual clarity for verkstations.
Woman: Ohh! Perfect! Beige is such a tricky colour to work with... [knitting needles click]
Architecht: And zis versatile grid makes imaginative and creative focus for reception areas.
Lad: (Geordie accent) Aye aye!
Disco Lights! [Disco music]
Smashin'!
Architect: Now a soft diffuse light for those relaxing coffee breaks.
Hippy: And for my yoga!
"ommmmmmm"
Architect: Finally this suggestive personal light, for those confidential business propositions.
Bloke: (seductively) heeeeey
Well Brenda, how about it?
Architect: Zat concludes my... [Enthusiastic applause]
Tim: An ever increasing range of practical, efficient lights is available
small fluorescants complete with control gear
that plug into an ordinary light socket have been developed.
I've recently converted my workshop to them.
They're expensive, but they last for 8,000 hours, and they're very efficient.
If everyone had them, Britain would use about 10% less electricity.
Then tubes full of mercury and other gasses called halides have been developed.
my workshop's full of them at the moment, because they're used as modern film lights.
Then tubes full of sodium, originally just used as street lights,
are now increasingly used indoors, in public places.
These are twice as efficient again as fluorescent lights,
although they do give everything a rather horrid orange colour.
In fact any light modifies the colours of the surfaces that it shines on.
though our eyes normally compensate for this so we don't notice the difference.
With a partition to separate the two lights you can see how
dramatic the differences can be.
The reasons for these differences in colour, is that every sort of light creates a slightly different spectrum of colours.
With this slit I've left in my workshop window, and a prism,
I should be able to separate out the spectrum of daylight.
Literally the colours of the rainbow.
Afilter called a difraction grating has the same effect in separating colours.
With a difraction grating over half of the camera lens,
I can split any light up into its spectrum of colours.
A filiment light always has a complete spectrum,
although there is rather more red and yellow and less blue
than there is in daylight, creating a warm sort of effect.
All the other lights we have been looking at have a less even spectrum.
This fluorescent light for instance creates quite distinct separate bands of colour.
The sodium light, creates almost only orange light,
which is why it is so bad at distinguishing colours.
True colours can really only be seen in daylight.
[Door rattles]
Daylight is also simply much brighter than most artificial light.
In the camera you have to shut down the iris,
literally making a smaller hole for it to look out of.
Our eyes do this automatically, so we don't notice the difference in brightness,
just as we don't notice the differences in colours.
[Music]
Tim: Daylight also has theraputic qualities
which led to enthusiasm for artificial sunlight.
Amelia: You certainly have got your ideas attuned to modern things in double quick time.
You've been thinking electrically.
Woman: Ah you know Amelia, this artificial sunbathing's a marvellous tonic.
Voiceover: I'll bet you feel braced-up no end. Is that teapot ready?
Now pull up to the fire ladies and make yourselves comfortable and have a cup of tea.
It's nice when there are no men about, to sit about the fire and have a good gossip isn't it?
Hippy: Oh dear, it says in here if I have to work indoors all day,
I should be taking lots of extra vitamins!
[rattle glug glug glug]
That's better!
EWWW TERRY!
That's DISGUSTING!
[splat]
You should be getting out into the fresh air, that'll get rid of your spots!
[loud head scratching] Brian? Did you know that working indoors speeds up the balding process?!
Brenda! Do you ever feel under the weather from working in artificial light?
Brenda: No, I keep fit down the leisure centre. Dancercise!
Poor Joan's depressed, she needs to get out.
But Mr Jones is fine, he's happy pottering around the golf course.
Boss: (shouting) I said I want that file NOW!
[SLAM]
Brenda: She's the one, stress. I'll pop this in 'er in tray.
[Clock ticks loudly]
[Hippy typing slowly]
Boss: I presume this is YOURS!
I don't know what it was doing in MY in tray?
I don't subscribe to all this new age twaddle, unlike YOU.
Ohh, my head. I have to go out for a minute, get some fresh air.
Hippy: I knew it, I was right!
I do miss daylight myself when I've been indoors working at my desk for long periods,
I also feel slightly sad the night is never, ever completely dark anymore, even here in the country.
Making the stars dimmer and dimmer.
But despite its drawbacks, electric light is extremely useful
and there's also just something rather beautiful about it all.
[Jazzy music: 'Take 5' - Dave Brubeck]