1
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"Bye!" "Don't do anything I wouldn't do!" "Come for a drink?"

2
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[Jazzy music: 'The Russians Are Coming' - Val Bennett]

3
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Tim: Today, electric light is completely taken for granted,

4
00:00:28,358 --> 00:00:32,436
though without it, our lives would be infinitely more difficult and dangerous.

5
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Creating all this light has taken an enormous amount of effort and ingenuity.

6
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In this programme, Rex and I are going to look at the evolution and workings of this almost indispensible invention.

7
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The first form of artifical light was obviously fire

8
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Once the fire was burning well, you could take out a

9
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branch and use it as a primitive sort of torch.

10
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Trouble was, these tended to go out.

11
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Some countries had particularly resinous woods like pitch-pine that burn particularly well.

12
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Most countries developed some way of using oil or fat for light.

13
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The aincient Greeks and Romans squashed the oil out of olives,

14
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poured it into a bowl, with some sort of a wick

15
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(muttered) soaked in oil,

16
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which they then lit.

17
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Pretty puny flame! Oh no, it is just about alight.

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Northern European countries developed the candle.

19
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but these weren't like modern candles, they were made of animal fat,

20
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and they smelt pretty disgusting,

21
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and they tended to spit, and every few minutes you'd have to trim the wick.

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[bird tweeting]

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[THUD]

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Tim: Meanwhile whole animals and birds were used as candles in some parts of the world, particularly petrels.

25
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Woman: Here we have the early 'petrel' lighter!

26
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Man: Not so good as the candlefish.

27
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A little slippery, but very effective.

28
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Woman: As for me, boyo, I have a penguin to keep me warm (chuckles)

29
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Keeps alight for hours.  Weighs a ton though, ohh dear!

30
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Tim: These early candles produced so little light that most people went to bed soon after sunset.

31
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Man: I'm trying to get some sleep, put that bloody penguin out!

32
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Tim: Psychologists now believe that sleep evolved mainly to protect us from the dark.
[Howling noise]

33
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Tim: The possibility of using electricity for lighting was first suggested in 1810 by Humphrey Davy

34
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Shorting out a large battery he'd been given, the electricity arced through the air bridging the gap

35
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Almost like lightning.

36
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This intense light formed the basis of the first commercial arc lights in the 1840s
[buzzing of arcing electricity]

37
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They needed to have quite an elaborate clockwork mechanism

38
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to move the electrodes progressively closer together as they gradually burnt away.

39
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Arc lamps continued to have specialist uses like film lighting until quite recently.

40
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However, the large amount of current used prevented them ever becoming widely adopted.

41
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Meanwhile lighting had started to improve in the early 19th century with the introduction of gaslight.

42
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By 1850 it had been installed in most cities

43
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although the search for a better electric light continued.

44
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Humphrey davy had also noticed that electricity

45
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heats up any wire it's passing through to some extent.

46
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And that it was possible to make a wire glow white hot.

47
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[Loud thrumming noise]
Tim: We're using a welder as a power supply here

48
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and we should be able to turn out the lights and see if it'll give off enough light.

49
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It's only glowing at the bottom...  but it should...

50
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(that's it)
[thrumming continues]

51
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The problem is that at some point it gets so hot

52
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that it starts to melt!

53
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[crackle]
Tim: Whoops

54
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Tim: However (to Rex) we'd better have the lights back on.

55
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Carbon melts at a much higher temperature than most sorts of metal

56
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and several inventors started experimenting with carbon filiments.

57
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Rex had this idea that we could do this with a pencil...

58
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[sparks]
Tim: Whoops!

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... pencil lead that is also made out of graphite, sort of carbon.

60
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[hissing]

61
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So first we've got to burn off the wood round the lead.

62
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Well this works much better than the steel rod

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But the trouble is, that even the carbon filiment doesn't last for very long

64
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because it reacts with the air and it slowly deteriorates.

65
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Tim: Get it a bit hotter than that.

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[sparking noises]

67
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The solution to this problem is to enclose the filament in a

68
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glass container, and pump the air out so that it can't react with it,

69
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and that's the reason for the light 'bulb'.

70
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Well, Rex and I have had some success with making a lightbulb like this

71
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enclosing the pencil lead in the milk bottle.

72
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And now we turn on the vacuum pump and start pumping out the air.

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[loud rattling noise from vaccum pump]

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Tim: And connect it up...

75
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Rex: Put the power on very slowly.

76
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Tim: Oh yes...

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Rex: It's still got a bit of air in there....

78
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Tim: Yes.  Rex: Okay.  Like that.  If we switch it on...

79
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as the air is pumped out, this is actually sucking more of the

80
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err, any air that is trapped in the filiment out as well.

81
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Tim: We should be able to,

82
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Tim: (to Rex) If you let go we should be able to turn the light out,

83
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should be able to make it work as a proper bulb, yeah.

84
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Rex: Can turn it up now.

85
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Tim: You can turn it up. Now it's working. Can't we?

86
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Nearly as good as an ordinary lightbulb really.

87
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A chemist from Newcastle called Joseph Swan,

88
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tried repeatedly to make a lightbulb like this in the 1860s,

89
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But eventually gave up concluding that his vaccum pump just wasn't good enough.

90
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15 years later, discovering a better sort of pump, he tried again,

91
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and succeeded in 1878.

92
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Meanwhile Thomas Edison, here seen in his old age,

93
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had started experimenting in America in 1877.

94
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Backed by a lot of money, and a dedicated team at his laboratory,

95
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he developed a similar lightbulb within two years.

96
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Swan and Edison faced enormous difficulties, even once their bulbs were working.

97
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There was no electricity to plug into at the time.

98
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Edison in particular had to dig up the roads to lay his cables

99
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and even built the first powerstations to enable his lights to be used.

100
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Then to persuade people to buy his electricity he staged lots of publicity stunts.

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Particularly with people wearing lightbulbs in unusual places.

102
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The task of persuading people to install electricity wasn't made any easier,

103
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because the original gas lights, just, erm, simple gas flames,

104
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had been dramatically improved in the 1870s with the invention of the gas mantle.

105
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This is made of a material which glows white hot at a particularly low temperature

106
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now if I light the whole thing up now then it should all burst into light.

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I've got these two in my kitchen, I just like the soft greenish light they cast.

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They don't smoke or smell and they are as bright as ordinary electric lights.

109
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Many houses didn't install electricity until the 1930s because their gas lights were so good.

110
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[Rex scrapes chair]

111
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[1930s music]
Woman: Oh Daddy, for Pete's sake stop messing about.

112
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I'll never get these... (fades out)

113
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Tim: Electricity finally triumphed because it could be used for so many other things besides lighting.

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Woman: Oh Bother!

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Man: You know there's only one plug in this room,

116
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and we've already got the fire, and the clock and the radio,

117
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and the standard lamp connected to it!

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Now you want the table lamp for your sewing machine!

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Woman2: Nevermind dear, we'll manage somehow.

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If father wants to play about at being an electrician,

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we mustn't begrudge him a little clean fun. 

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Tim: The main improvement in an ordinary modern bulb,

123
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is that it has a filiment made of a metal called tungsten.

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It's easier to see in a clear bulb. 

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This metal has the highest melting point of any metal.

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With tungsten filiments, our milkbottle lights work nearly as well as real lightbulbs.

127
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In a real bulb though, the tungsten...

128
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[clank clank clank]

129
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[Glass shatters]

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...is coiled up, and if you look at it under a magnifying glass, 

131
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the coil is made up of another even finer tiny coil.

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It's called a coiled coil. 

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The more compactly a filament can be wound, the less heat it loses to the surroundings and the brighter it glows.

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[plink]

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[Man Groans]
Woman: Oh no! The bulb's gone again!

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[Rousing circus music]

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Voiceover: We wouldn't have to go through this performance... (fades out)

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Tim: Lightbulbs never last forever because at their working temperature, 

139
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2,500 degrees centigrade, the filiment gradually evaporates.

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Man: Oy! Where's the bulb?

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Moustached man: I'll get one of the new ones...

142
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Voiceover man: Thorn EMI double life lightbulbs.

143
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Double life, but not double the cost.

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Tim: In the late '50s a dramatically improved sort of filiment bulb was invented:

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Tungsten-halogen. 

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These are used for outside lights, 

147
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for, er, car headlights

148
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and for tiny little shop spotlights. 

149
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They give off twice as much light as ordinary bulbs,

150
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running at a higher temperature, and even so they last twice as long. 

151
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This is because they have minute traces of gases inside called halogens,

152
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which repel the evaporating Tungsten from the surface of the bulb,

153
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making it redeposit itself back on the filiment, a sort of cycle. 

154
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This only works if the glass is kept very hot, 250 degrees centigrade,

155
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that's easily enough to boil water 

156
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[bubbling of boiling water]

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The problem with any sort of filiment light though 

158
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is that it's extremely wasteful of energy.

159
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An ordinary lightbulb only gives out 10% of it's electricity as light, all the rest is wasted as heat.

160
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And even the most efficient tungsten-halogen bulb only gives out 25% as light. 

161
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There's more to lighting though than simple efficiency. It's also extremely decorative.

162
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And there's an astonishing range of decorative bulbs available.

163
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[Circus music: 'Entry of the Gladiators' - Julius Fučík]

164
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I incorporate light in all sorts of things that I make.

165
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This ring was inspired by these little bright red lights, they looked to me sort of like modern jewels.

166
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This is a bedside light that I made, like a sort of office block with its window cleaners.

167
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This is a nuclear mint in here

168
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It's a packet of mints I bought at the shop of our local nuclear reactor's visitor centre.

169
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I lit it to make it look suitably dangerous. 

170
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Lights aren't only decorative, films in particular have always used them for their dramatic effect.

171
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Molly: No, you're wrong!

172
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Woman: That's how you always intended to spend the evening.  Not with George at all!

173
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Molly: Don't say that!
[Light switch clicking]

174
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Woman: And for a very good reason!

175
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Molly: Now you keep quiet! Don't say that! Now keep quiet.
[Music speeds up sinisterly]

176
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Woman: Molly, now listen to me. Listen to me Molly. 
[Music returns to original tempo]

177
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Molly: I don't have to listen to you!

178
00:12:27,736 --> 00:12:29,344
Woman: I think I know the truth Molly!

179
00:12:29,345 --> 00:12:32,197
Molly: No you don't! You don't know anything at all!

180
00:12:32,198 --> 00:12:34,198
Woman: I think I know the truth about George!

181
00:12:34,199 --> 00:12:35,188
Molly: You can't, you don't.

182
00:12:35,189 --> 00:12:37,128
Woman: You couldn't have met George tonight!

183
00:12:37,129 --> 00:12:39,286
Molly: No! No! Noooo!

184
00:12:39,287 --> 00:12:40,687
Woman: Because there isn't any George!

185
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Molly: No! No! No! [cries]
[Music signifies impending doom]

186
00:12:44,088 --> 00:12:45,088
Molly: Please! 

187
00:12:45,089 --> 00:12:50,601
[Music gets louder and more sinister]

188
00:12:50,702 --> 00:12:52,002
[music signifying flying]

189
00:12:52,603 --> 00:12:55,999
Wizard: Well. How's this Nancy?  Better huh!

190
00:12:56,000 --> 00:12:58,479
Nancy: Oooh! This is wonderful!

191
00:12:58,480 --> 00:13:00,680
I wished I had one of those magic wands!

192
00:13:00,681 --> 00:13:03,397
So I could fly around whenever I wanted to!

193
00:13:03,398 --> 00:13:06,433
Nothing simpler Nancy. Here!
[expanding wand whoops]

194
00:13:06,434 --> 00:13:11,218
However, that wand is important for much more important things than flying around through the air!

195
00:13:11,219 --> 00:13:14,222
It's a fluorescant light tube!

196
00:13:14,223 --> 00:13:19,485
Tim: Today's efficient fluorescant lights developed from the original arc lights.

197
00:13:19,486 --> 00:13:24,024
This tiny high voltage arc...
[buzzing of arc]

198
00:13:24,625 --> 00:13:27,576
doesn't reach far, or give off much light.

199
00:13:27,577 --> 00:13:34,315
But, erm, if I connect the wires to the ends of this glass tube.

200
00:13:39,254 --> 00:13:43,708
Switch it on again. Switch off the lights. 

201
00:13:43,709 --> 00:13:47,316
And start pumping the air out of the tube 
[loud clanky vacuum pump]

202
00:13:48,817 --> 00:13:54,702
Instead of forming an arc, the electricity fills the entire tube with a glowing discharge. 

203
00:13:54,703 --> 00:13:59,126
This is the basis of fluorescant, and many other types of electric light. 

204
00:13:59,527 --> 00:14:03,348
Although in basic form it's not really bright enough to be useful.

205
00:14:03,349 --> 00:14:06,974
When it was first discovered, these tubes were bent

206
00:14:06,975 --> 00:14:11,269
into funny shapes and demonstrated as wonders of science. 

207
00:14:11,270 --> 00:14:16,193
If I apply a voltage to this one, you can see it glow.
[buzzing]

208
00:14:17,094 --> 00:14:23,649
And over here they have a selection that we borrowed from the Royal Institution.

209
00:14:23,650 --> 00:14:28,025
Called Giessler tubes, and they were made in the 1860s. 

210
00:14:28,026 --> 00:14:30,087
[Buzzing noises]

211
00:14:30,488 --> 00:14:34,803
In 1905 a French inventor called Georges Claude found that 

212
00:14:34,804 --> 00:14:39,675
a newly discovered gas, neon, made the tube glow bright red. 

213
00:14:39,876 --> 00:14:44,096
He immediately realised its potential for illuminated signs

214
00:14:44,097 --> 00:14:50,324
and by the 1920s had managed to sell a large number of franchises especially in America.

215
00:14:52,025 --> 00:14:56,000
The first fluorescant light was introduced in 1939

216
00:14:56,001 --> 00:15:02,696
this is the same idea as our vacuum tube, except there's a little tungsten filiment at each end

217
00:15:02,697 --> 00:15:09,938
The idea is that heating these up for a moment, encourages the electricity to start flowing. 

218
00:15:10,739 --> 00:15:13,827
In the tube there's a starter to do this switching,

219
00:15:13,828 --> 00:15:17,773
and a ballast to limit the amount of current that can pass through it.

220
00:15:17,774 --> 00:15:22,766
The inside of the tube is filled with a mixture of argon and mercury vapour.

221
00:15:22,767 --> 00:15:28,579
This is giving out mostly ultraviolet light, that's why I'm wearing these protective goggles.

222
00:15:28,580 --> 00:15:31,666
But fortunately there are chemicals that can convert 

223
00:15:31,667 --> 00:15:35,817
the ultraviolet to visible light. A property called fluorescance.

224
00:15:35,818 --> 00:15:39,473
If I switch the light off for a minute you can see that they're actually just white powders.

225
00:15:39,474 --> 00:15:45,431
Tube manufacturers mix these fluorescant materials 

226
00:15:45,432 --> 00:15:49,946
creating any colour, or combination of colours they want.

227
00:15:49,947 --> 00:15:51,572
(muttered) See if I can get some for...

228
00:15:51,573 --> 00:15:55,956
These are coated onto the inside of the tube.

229
00:16:00,832 --> 00:16:09,303
Neon tubes can also be coated in phosphors creating almost a complete spectrum of colours.

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Rex: The odd thing about fluorescant tubes is that you don't even 

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have to connect them to the electricity to make them work.

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If I put this one in a microwave oven...

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Switch on...

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[Microwave whirrs]

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It will work and if you excite it by a radio frequency,

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 or a very high frequency, it will also work without being connected. Like this.

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[Loud buzzing noise]

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I've got another milk bottle here, and we've put fluorescent materials inside this,

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stuck it on the inside.

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I've evacuated this one, that's connected up to my vacuum pump,

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and if I connect this up to our high frequency again...

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....we'll have a fluorescant milk bottle.

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[buzzing]

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I've made ordinary filiment light bulbs which appear to be normal,

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But if you look at this one, it's a big trick, 

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there's actually wires running up the back of my hand to a battery.

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This was made for a magician. 

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Fluorescant tubes are highly efficient, giving out 4 times as much light

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for the same amount of electricity as an ordinary light bulb. 

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They've become the standard lighting for factories, shops and offices,

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Providing uniform brightness over vast areas. 

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However, architects and designers now often deliberately use 

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lighting to create different moods. 

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Architect: (German accent) Lighting is not only 

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bulbs, no, is an environment enhancing, ambiance arousing concept.

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[Audience sigh, mutter boredly]

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Architect: Look please at the stylish desk light 

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vich offers zuperb visual clarity for verkstations.

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Woman: Ohh! Perfect! Beige is such a tricky colour to work with...
[knitting needles click]

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Architecht: And zis versatile grid makes imaginative and creative focus for reception areas.

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Lad: (Geordie accent) Aye aye! 

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Disco Lights!
[Disco music]

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Smashin'!

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Architect: Now a soft diffuse light for those relaxing coffee breaks.

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Hippy: And for my yoga!

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"ommmmmmm"

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Architect: Finally this suggestive personal light, for those confidential business propositions.

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Bloke: (seductively) heeeeey

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Well Brenda, how about it?

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Architect: Zat concludes my...
[Enthusiastic applause]

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Tim: An ever increasing range of practical, efficient lights is available

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small fluorescants complete with control gear 

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that plug into an ordinary light socket have been developed.

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I've recently converted my workshop to them.

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They're expensive, but they last for 8,000 hours, and they're very efficient.

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If everyone had them, Britain would use about 10% less electricity.

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Then tubes full of mercury and other gasses called halides have been developed.

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my workshop's full of them at the moment, because they're used as modern film lights.

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Then tubes full of sodium, originally just used as street lights,

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are now increasingly used indoors, in public places.

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These are twice as efficient again as fluorescent lights,

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although they do give everything a rather horrid orange colour.

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In fact any light modifies the colours of the surfaces that it shines on.

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though our eyes normally compensate for this so we don't notice the difference.

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With a partition to separate the two lights you can see how 

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dramatic the differences can be.

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The reasons for these differences in colour, is that every sort of light creates a slightly different spectrum of colours.

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With this slit I've left in my workshop window, and a prism,

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I should be able to separate out the spectrum of daylight.

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Literally the colours of the rainbow.

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Afilter called a difraction grating has the same effect in separating colours.

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With a difraction grating over half of the camera lens,

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I can split any light up into its spectrum of colours.

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A filiment light always has a complete spectrum,

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although there is rather more red and yellow and less blue 

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than there is in daylight, creating a warm sort of effect.

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All the other lights we have been looking at have a less even spectrum.

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This fluorescent light for instance creates quite distinct separate bands of colour.

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The sodium light, creates almost only orange light,

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which is why it is so bad at distinguishing colours.

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True colours can really only be seen in daylight. 

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[Door rattles]

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Daylight is also simply much brighter than most artificial light.

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In the camera you have to shut down the iris,

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literally making a smaller hole for it to look out of.

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Our eyes do this automatically, so we don't notice the difference in brightness,

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just as we don't notice the differences in colours.

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[Music]

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Tim: Daylight also has theraputic qualities 

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which led to enthusiasm for artificial sunlight.

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Amelia: You certainly have got your ideas attuned to modern things in double quick time.

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You've been thinking electrically.

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Woman: Ah you know Amelia, this artificial sunbathing's a marvellous tonic.

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Voiceover: I'll bet you feel braced-up no end.  Is that teapot ready?

315
00:22:10,999 --> 00:22:15,856
Now pull up to the fire ladies and make yourselves comfortable and have a cup of tea.

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It's nice when there are no men about, to sit about the fire and have a good gossip isn't it?

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Hippy: Oh dear, it says in here if I have to work indoors all day,

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I should be taking lots of extra vitamins!

319
00:22:30,087 --> 00:22:33,068
[rattle glug glug glug]

320
00:22:33,069 --> 00:22:34,369
That's better!

321
00:22:34,570 --> 00:22:37,239
EWWW TERRY! 

322
00:22:37,240 --> 00:22:39,140
That's DISGUSTING!

323
00:22:39,141 --> 00:22:39,890
[splat]

324
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You should be getting out into the fresh air, that'll get rid of your spots!

325
00:22:44,957 --> 00:22:51,427
[loud head scratching]
Brian? Did you know that working indoors speeds up the balding process?!

326
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Brenda! Do you ever feel under the weather from working in artificial light?

327
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Brenda: No, I keep fit down the leisure centre. Dancercise!

328
00:23:01,808 --> 00:23:04,625
Poor Joan's depressed, she needs to get out.

329
00:23:04,626 --> 00:23:08,398
But Mr Jones is fine, he's happy pottering around the golf course.

330
00:23:08,399 --> 00:23:11,210
Boss: (shouting) I said I want that file NOW!

331
00:23:11,211 --> 00:23:11,919
[SLAM]

332
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Brenda: She's the one, stress.  I'll pop this in 'er in tray. 

333
00:23:15,931 --> 00:23:18,325
[Clock ticks loudly]

334
00:23:18,326 --> 00:23:20,266
[Hippy typing slowly]

335
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Boss: I presume this is YOURS!

336
00:23:22,250 --> 00:23:25,007
I don't know what it was doing in MY in tray?

337
00:23:25,008 --> 00:23:29,292
I don't subscribe to all this new age twaddle, unlike YOU.

338
00:23:29,293 --> 00:23:33,747
Ohh, my head.  I have to go out for a minute, get some fresh air.

339
00:23:33,748 --> 00:23:35,896
Hippy: I knew it, I was right!

340
00:23:36,497 --> 00:23:42,403
I do miss daylight myself when I've been indoors working at my desk for long periods, 

341
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I also feel slightly sad the night is never, ever completely dark anymore, even here in the country.

342
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Making the stars dimmer and dimmer. 

343
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But despite its drawbacks, electric light is extremely useful 

344
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and there's also just something rather beautiful about it all.

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