The Secret Life of Machines (1988) s01e01 Episode Script
The Vacuum Cleaner
1 [Door opens, footsteps.]
[Creak!.]
[THUD!.]
[Jazzy music: 'The Russians Are Coming' - Val Bennett.]
[vaccum cleaner noise.]
[Jazzy music: 'The Russians Are Coming' - Val Bennett.]
[TV static noise.]
[Jazzy music: 'The Russians Are Coming' - Val Bennett.]
[Steam hisses.]
[Jazzy music: 'The Russians Are Coming' - Val Bennett.]
[Jazzy music: 'The Russians Are Coming' - Val Bennett.]
[sewing machine rattles.]
[Jazzy music: 'The Russians Are Coming' - Val Bennett.]
[Whoop!.]
[Jazzy music: 'The Russians Are Coming' - Val Bennett.]
[Noise of vacuum cleaner.]
Tim: The modern vacuum cleaner is a wonderful contraption.
It's really quite magical the way it make dirt vanish from completely inaccessible places And before it was invented houses were just much much dirtier places.
More like my workshop Though even my workshop isn't usually quite as dirty as this! It may be a myth that vacuum cleaners are labour saving devices.
It's said that people spend just as long cleaning their houses today as they did a hundred years ago.
But these machines certainly have made houses cleaner! Well in this programme I hope to look at exactly how vacuum cleaners work and how they evolved [Birds tweeting.]
Without vacuum cleaners the only way to clean carpets and upholstery was to take them outside and beat them An activity that was traditionally performed just once a year.
The spring clean.
There was considerable incentive to invent a cleaning machine.
Particularly because Victorian houses were so cluttered and full of soft furnishings Numerous patents for sweeping and beating machines were taken out from the 1850s onwards and some of these did include primitive suction devices.
[Engine noise.]
But the practical vacuum cleaner had to wait for the arrival of reasonably small and efficient power sources.
By 1900 the first internal combustion engines had appeared and amongst other things they were used to power compressors to generate compressed air.
[Compressed air.]
Several Edwardians experimented with cleaning carpets and upholstery with compressed air but the problem was that the dust just went everywhere.
And then settled back down exactly where it had come from.
A demonstration of this rather inadequate cleaning system, on cleaning railway carriages in St.
Pancras station, in 1901, was witnessed by an engineer called Herbert Cecil Booth.
Booth was a civil engineer who designed bridges and the enormous big wheels popular at the turn of the century.
This one was put up in Blackpool in 1896 It seemed obvious to Booth that sucking the dirt into a container through a filter would be a more sensible idea.
And his very first experiment: holding a hankie over a sofa and sucking hard through it left the hankie filthy.
And proved the principle to himself.
His first machine was simply a cloth bag to collect the dirt and a suction pump.
It worked well but it was very large so it had to be parked outside customers houses.
[boing.]
It became known as the noisy serpent, and he was frequently sued for frightening passing horses.
[Horse neighs.]
[Screech.]
[Boing.]
The success of Booth's machine was largely due to the coronation of Edward VII in 1902.
Woman: Oh! Dust! There's dust on the.
Tim: In all the preparations it hadn't been noticed until the last minute that the carpets under the throne in Westminister Abbey were filthy.
Booth's machine was the only effective way of cleaning the carpet without removing it.
Man: We'll vacuum you too.
Oops! [Wheels rattling.]
Tim: The king later heard of this and ordered a demonstration at Buckingham Palace, buying two machines.
King Edward: Your appawatus is fwightfully impwessive! Booth: Oh thank you very much sir, thank you very much.
Ho Ho! Tim: Booth added clear inspection tubes so people could watch the dirt being sucked in And the machines became prime attractions at fashionable soirees.
With royal patronage the success of the machine was assured Man: A most marvellous modern invention! Booth's machine caught the public imagination but was much too large and cumersome for most homes.
So various other manufacturers started introducing much smaller hand powered machines.
This one's the sweepervac.
Made in San Fransisco.
The British Queen it doesn't seem to be doing very much this one.
A bit difficult to use too.
The star.
This one feels more comfortable.
just swept up a feather.
And, er, what's this one called? The Reeves pneumatic broom.
doesn't sweep very much up at a time nearly got that bit of dirt, no.
Most of these machines would have been considerably less effective than a simple dustpan and brush.
But at the time there was a phobia against dust which was believed to be full of germs.
A French doctor in 1907 wrote "Dry sweeping and dusting are homicidal practices they consist of taking dirt which has been lying on the floor and on the furniture mixing it with the atmosphere and causing it to be inhaled by members of the household.
In reality it would be infinitely preferable to leave the dust alone where it was.
" Well in reality these machines were so ineffective that they probably did just that.
This is the daisy number 2.
Nice action, nice crank and bellows but I don't actually think it is getting anything off the carpet.
And, er, this one is the baby daisy [clanking.]
though it's much bigger than the daisy number 2.
[Clanking, squeaking and creaking.]
It's slightly difficult coordinating all the actions at once.
Doesn't seem to be doing too well either.
Meanwhile in America a caretaker called Spangler had patented a portable vacuum cleaner powered by an electric motor.
He sold the patent to a harness maker called Hoover who was worried that his trade was falling as more people changed from riding horses to driving cars.
Hoover was very successful and started producing machines in other countries including Britain.
# In the carpet, in the carpet, excavating through the pile worked a pit gang, called 'The Grit Gang', digging deeper all the while.
Oh my carpet, oh my carpet, oh my carpet don't forget - with a Hoover, yes a Hoover, we will beat the blighters yet.
Oh my carpet, oh my carpet, oh my carpet don't forget - with a Hoover, yes a Hoover, we will beat the blighters yet.
Tim: The basic modern Hoover has really changed very little.
We've cut part of this one away so you can see what's inside.
This is the fan that does the sucking and it makes the brushes and beater bars go round as well.
The dirt is dislodged by the rotating brushes, sucked straight through the fan and into the dust bag at the back The cylinder type of vacuum cleaner is slightly different.
It's actually more like Booth's original machine I'll take the bottom off this one In this sort, the dust comes straight into the dust bag, and the air passes straight through the paper that acts as a filter, and goes through the fan and finally out the grille on the top of the machine.
So the positions of the fan and the dustbag are reversed.
And because it's only clean air which is passing through the fan the shape of the vanes can be much more intricate.
So this sort usually has a much stronger sort of sucking power.
And the bin type and the more modern flattened cylinder types are just the same as this, though the layout leaves slightly more room for bigger dustbags.
The upright vacuum cleaner with a rigid dustbox is a sort of hybrid.
We've cut one in half so you can see what's inside.
It has rotating brushes just like a hoover, but inside the air and the dirt come straight up the back and into the dustbag, so its layout in some ways is more like the cylinder vacuum cleaner, because it's only clean air that comes out of the bottom of the dustbag and goes through the enclosed fan and then finally comes out the back of the machine.
Well there are advantages and disadvantages of all these different types of vacuum cleaner and a recent Which survey found that in overall performance there's really very little to choose between them all.
By the 1920s many companies were producing electric vacuum cleaners.
Booth himself had started making them himself, under the trade name Goblin.
One of his employees was a man called Bill Sutton.
Bill: I joined Goblin in 1929, although I'd a relative with the company many years before, so I knew quite a bit about the vacuum cleaner business as a youngster.
This model was produced in 1908 and appeared at the first Ideal Home Exhibition Bill to Tim: Would you like to do a bit of cleaning if I operate it? Tim: Oh I see it's a two-person machine? Bill: Yes, oh yes.
Bill: If I turn this handle, you do the cleaning.
[chugging noise.]
Tim: It's getting something up.
Bill: In fact they used to at the exhibition, have to go back to the factory and make another one if they sold one.
Tim: Although better than most hand powered vacuum cleaners it was still rather inconvenient.
so Booth started developing his own electric models.
Bill: As you'll see it's got the old dolly switch and some very old fashioned flex.
They wouldn't pass it with the approvals board today.
[chuckles.]
Tim: Where does the dust go? Bill: Well it actually goes in here.
Tim: Oh I see, yes.
Bill: And you undo this to get at the dirt, to empty the machine.
This machine was first produced in 1930, rather a unique machine in that it gives you the upright situation for easy cleaning.
It sold for 5 pound, 19 and sixpence, at that time.
But the interesting thing is that for dusting, all you need to do is undo the dustbag from this position here and put your arm through the dustbag and do your dusting.
It did have some other tools for it, for dusting but of course that's another story.
Bill: This particular model, a Goblin ace is 210 Volts, whereas today the standard voltage is 240.
In the 30s, in Bristol there were two voltages, in London they went down as far as 100 Volts in certain places.
Tim: Were there electricity shops where you could sell these things? Bill: Oh no.
The electrical shops weren't in existence then, there was only a cycle shop who did the odd electrical product.
[Footsteps.]
[Knocking on door.]
Bill: The industry had to employ vast numbers of direct-selling people, In fact Goblin had 2,500 at peak, of people knocking doors.
Woman: Oh! Salesman: You've heard of the radio, you've now got electricity, but this is what you haven't got A vacuum cleaner! Look, it is Woman: Well I don't know Salesman: No, look, I'll just take this wire, plug it into your sockets like that and we will have a demonstration.
Salesman: If you are okay to stand up a minute madam, See! Now, did you know, in that chair is hidden dirt.
Every part of your house has got hidden dirt.
Look, it's all in there now madam.
Look.
This is what you were sitting on.
Woman: gasps Dust! Ohhh! Bill: The sales mostly had to be made of an evening, because the only person who was entitled to sign a hire purchase agreement was the husband and in most cases sales had to be made on a Friday or Saturday evening when the pay packet came in otherwise you didn't get the deposit.
Tim: I'm now going to look at the various parts of the vacuum cleaner in greater detail.
First the motor: electric motors are rather baffling devices but they all depend basically on the ability of electricity to magnetise things.
If I wrap a bit of wire around a nail, Oh dear, got it tangled up The more turns, the stronger the magnetism.
I'm going to use 12V DC from a car battery, and of course you must never ever use mains for something like this! The nail becomes magnetic when I complete the circuit and when I break it again, most of the magnetism is lost.
And if I wrap the wire around a little copper tube and hold it above the nail then the magnetic attraction will pull the nail off the table.
[Spark crackles.]
[clinkclink.]
(whispers) lets get it slightly more [Clink clink.]
This is an industrial electromagnet, the coil of wire is in here, and this is the lump of metal it pulls in.
This one's actually, um, out of a fruit machine, it's the device that pushes the coins out when you win.
[coins clanking.]
Well I use these devices a lot on the machines that I make.
I made this for a local solicitor, it was a portrait of the founder of the firm, his great uncle and he wanted to be able to control it, so it would react to his clients sometimes dubious confidences.
[clunk.]
[Buzz.]
In the end he got cold feet, and placed the control box so that the clients themselves could use it.
Well if you look at the back you can see that the device that makes the wig go up and down in the air is one of these electromagnets [BZZZZZT BZZZZT.]
And by themselves, these electromagnets can only produce this rather jerky, linear action.
but it's not actually too difficult to use the electromagnetic attraction make something rotate.
Rex: To show the principles of a simple electric motor, I've made a motor out of virtual rubbish: Nails, a hacksaw blade, an old needle, a cork and a dogfood can.
The commutator, as the part in the vacuum cleaner motor I've made from a cork, with wires running up there.
It acts as a sort of rotating switch, each wire is attached to a coil.
When the wires are in contact with the brass strips, current passes through, so at one time, only one pair of coils are energised.
These pair of coils here are magnetised by the electric current and they're attracted to this pair of coils, now when it pulls to there, these coils switch off and it brings on the next pair of coils, which are attracted to there, and of course they switch off bringing in the next pair causing a rotating motion.
I'll switch on.
[Grinding motor noise.]
Tim: The vacuum cleaner motor doesn't at first sight look like Rex's tin can motor, but if you look inside you can see it has a lot of the same elements.
This is the commutator, the rotating contacts.
These are the coils of wire rotating around the shaft, and these are the coils of wire round the outside making them both magnetic.
Well in fact there are many different types of electric motor, but they all depend upon the basic ability of electricity to produce magnetism.
[Baby babbles.]
It's really quite difficult to imagine how inconvenient the world must have been without any electric motors.
Most of the machines in the home depend on them: Vacuum cleaners, power tools, washing machines, fridges, tape recorders and countless other gadgets.
Steam engines, their predecessors, were hot and heavy and needed several hours stoking to get up pressure before they would work.
Factories used to have a single steam engine connected to every machine in the place by a very elaborate set of belts and clutches.
This was not very convenient or safe in a factory and totally impractical in the home.
Baby: babble babble oooopsaoooopsa Man: OHHH! The bit that actually does the sucking is the enclosed fan next to the motor.
I can show you where the air goes if I hold some smoke over it [Vacuum cleaner noise.]
You can see that all the air is actually drawn straight through the middle of the motor to get to the fan, and the reason for this is that it helps to keep the motor cool.
You can often feel the air coming out of the end of a vacuum cleaner is quite warm, and without this air passing through the motor it would very quickly overheat.
The fan itself works with these rotating vanes, that whizz round and round and fling the air outwards.
The air comes in the middle and the vanes go round flinging the air outwards, and then there's a second set of vanes that doesn't rotate, a static set, and these channel the air back to the middle again.
And then there's another set, a second set of rotating vanes, that fling the air outwards, and finally there's a second set of static vanes that channel the air back to the middle again.
[whirring noise.]
And having these two stages doubles the suction power.
Well one surprising thing about these fans is that they need less power to work when the inlet is blocked up.
I can show you this, with this meter which shows how much current the motor is using.
And, er, if I turn it on [Vacuum cleaner noise.]
You can actually hear the pitch of the motor rising when I block the inlet up and that's because it's actually running faster.
But of course it is also overheating because there is no air passing through it, so it's not really a very good idea.
[Vacuum cleaner noise.]
The power of the fan is quite surprising, here we fixed the outlet of a vacuum cleaner to a plastic bag.
The air pressure in the bag can quite comfortably lift my van off the ground.
[Vacuum cleaner noise.]
The vacuum cleaner actually has the power to inflate things on a much larger scale.
This is a pig built for the Pink Floyd by a local firm.
Once it is inflated, a miniture car vacuum cleaner is enough to compensate for the air lost through any holes, and keep it full of air.
And a full size vacuum cleaner can keep enormous things inflated.
The only time I've ever used a vacuum cleaner, was for a machine which didn't need any of its impressive power.
This is a collecting box I made for an charity society called 'Common Ground'.
It's a sort of pun on its name showing a bit of ground being shared by different sorts of creature.
The ground is actually a bit of rubber, I did my first experiments holding bits of rubber over a vacuum cleaner nozzle [Vacuum cleaner noise.]
Underneath, each of er, each footprint is connected to the suction pump at the bottom here, by one of these hoses, via a valve, each one by a separate valve, actually out of a washing machine.
And this timer down the bottom here turns the valves on in sequence.
[motor noise stops.]
[ping.]
The last important part of the vacuum cleaner is the dustbag which acts as the filter.
The paper of cloth contains minute holes which trap most of the dirt, but let the air pass straight through.
Of course any bits of dirt that are smaller than the size of these holes which are about 1/200th of a mm in diameter, will pass straight through the bag.
I can show you this with this smoke cartridge that contains minute particles of red dye.
If I put it next to the nozzle, you'll see the dye come straight through the machine and out through the grille here.
[Click.]
Oh I forgot to turn it on.
[Vacuum cleaner noise.]
Normally about 15% of household dust is below this critical size and passses straight through the machine.
[Vacuum cleaner noise continues.]
Rex used to repair domestic appliances, and found often people didn't realise this.
Rex: Sometimes I would be called out to a machine that wasn't working, and the customer had actually fitted a plastic bag inside the cloth bag so they could dispose of the dirt easily.
Well this of course completely blocked the airflow and there was no suction at all, and obviously it wouldn't work.
Even the disposable paper bags need changing quite frequently, some customers used to use one paper bag and empty it continuously.
And they do lose their efficiency, and the little pores in the paper get blocked with dust and they just don't work.
Occasionally, one or two clients had actually had a machine for ten years or so, and they'd still got the original packet of paper bags, and had only ever used one.
Tim: The vacuum cleaner is really quite a simple machine, a motor a fan, and a dustbag.
But it does have a particularly hard life being pushed and tugged about all the time.
Although they used to be sold with lifetime guarantees, today they rarely last more than a few years.
The modern vacuum cleaner may not be perfect, but it is extraordinarily good value for money.
In 1950 a vacuum cleaner cost about the same amount as the average weekly wage.
Today, it costs a lot less than half that.
An enormous amount of energy and cunning has gone into reducing the manufacturing costs, and perhaps for their price today we can't really expect them to last for very long.
Although vacuum cleaners are now rather flimsy and unsatisfying machines, and their short lifespan is ecologically very unsound, they do retain more character than most [rocket ignites.]
other household machines, and I can't help rather liking them.
[rocket noises continue.]
[Jazzy music: 'Take 5' - Dave Brubeck.]
[Creak!.]
[THUD!.]
[Jazzy music: 'The Russians Are Coming' - Val Bennett.]
[vaccum cleaner noise.]
[Jazzy music: 'The Russians Are Coming' - Val Bennett.]
[TV static noise.]
[Jazzy music: 'The Russians Are Coming' - Val Bennett.]
[Steam hisses.]
[Jazzy music: 'The Russians Are Coming' - Val Bennett.]
[Jazzy music: 'The Russians Are Coming' - Val Bennett.]
[sewing machine rattles.]
[Jazzy music: 'The Russians Are Coming' - Val Bennett.]
[Whoop!.]
[Jazzy music: 'The Russians Are Coming' - Val Bennett.]
[Noise of vacuum cleaner.]
Tim: The modern vacuum cleaner is a wonderful contraption.
It's really quite magical the way it make dirt vanish from completely inaccessible places And before it was invented houses were just much much dirtier places.
More like my workshop Though even my workshop isn't usually quite as dirty as this! It may be a myth that vacuum cleaners are labour saving devices.
It's said that people spend just as long cleaning their houses today as they did a hundred years ago.
But these machines certainly have made houses cleaner! Well in this programme I hope to look at exactly how vacuum cleaners work and how they evolved [Birds tweeting.]
Without vacuum cleaners the only way to clean carpets and upholstery was to take them outside and beat them An activity that was traditionally performed just once a year.
The spring clean.
There was considerable incentive to invent a cleaning machine.
Particularly because Victorian houses were so cluttered and full of soft furnishings Numerous patents for sweeping and beating machines were taken out from the 1850s onwards and some of these did include primitive suction devices.
[Engine noise.]
But the practical vacuum cleaner had to wait for the arrival of reasonably small and efficient power sources.
By 1900 the first internal combustion engines had appeared and amongst other things they were used to power compressors to generate compressed air.
[Compressed air.]
Several Edwardians experimented with cleaning carpets and upholstery with compressed air but the problem was that the dust just went everywhere.
And then settled back down exactly where it had come from.
A demonstration of this rather inadequate cleaning system, on cleaning railway carriages in St.
Pancras station, in 1901, was witnessed by an engineer called Herbert Cecil Booth.
Booth was a civil engineer who designed bridges and the enormous big wheels popular at the turn of the century.
This one was put up in Blackpool in 1896 It seemed obvious to Booth that sucking the dirt into a container through a filter would be a more sensible idea.
And his very first experiment: holding a hankie over a sofa and sucking hard through it left the hankie filthy.
And proved the principle to himself.
His first machine was simply a cloth bag to collect the dirt and a suction pump.
It worked well but it was very large so it had to be parked outside customers houses.
[boing.]
It became known as the noisy serpent, and he was frequently sued for frightening passing horses.
[Horse neighs.]
[Screech.]
[Boing.]
The success of Booth's machine was largely due to the coronation of Edward VII in 1902.
Woman: Oh! Dust! There's dust on the.
Tim: In all the preparations it hadn't been noticed until the last minute that the carpets under the throne in Westminister Abbey were filthy.
Booth's machine was the only effective way of cleaning the carpet without removing it.
Man: We'll vacuum you too.
Oops! [Wheels rattling.]
Tim: The king later heard of this and ordered a demonstration at Buckingham Palace, buying two machines.
King Edward: Your appawatus is fwightfully impwessive! Booth: Oh thank you very much sir, thank you very much.
Ho Ho! Tim: Booth added clear inspection tubes so people could watch the dirt being sucked in And the machines became prime attractions at fashionable soirees.
With royal patronage the success of the machine was assured Man: A most marvellous modern invention! Booth's machine caught the public imagination but was much too large and cumersome for most homes.
So various other manufacturers started introducing much smaller hand powered machines.
This one's the sweepervac.
Made in San Fransisco.
The British Queen it doesn't seem to be doing very much this one.
A bit difficult to use too.
The star.
This one feels more comfortable.
just swept up a feather.
And, er, what's this one called? The Reeves pneumatic broom.
doesn't sweep very much up at a time nearly got that bit of dirt, no.
Most of these machines would have been considerably less effective than a simple dustpan and brush.
But at the time there was a phobia against dust which was believed to be full of germs.
A French doctor in 1907 wrote "Dry sweeping and dusting are homicidal practices they consist of taking dirt which has been lying on the floor and on the furniture mixing it with the atmosphere and causing it to be inhaled by members of the household.
In reality it would be infinitely preferable to leave the dust alone where it was.
" Well in reality these machines were so ineffective that they probably did just that.
This is the daisy number 2.
Nice action, nice crank and bellows but I don't actually think it is getting anything off the carpet.
And, er, this one is the baby daisy [clanking.]
though it's much bigger than the daisy number 2.
[Clanking, squeaking and creaking.]
It's slightly difficult coordinating all the actions at once.
Doesn't seem to be doing too well either.
Meanwhile in America a caretaker called Spangler had patented a portable vacuum cleaner powered by an electric motor.
He sold the patent to a harness maker called Hoover who was worried that his trade was falling as more people changed from riding horses to driving cars.
Hoover was very successful and started producing machines in other countries including Britain.
# In the carpet, in the carpet, excavating through the pile worked a pit gang, called 'The Grit Gang', digging deeper all the while.
Oh my carpet, oh my carpet, oh my carpet don't forget - with a Hoover, yes a Hoover, we will beat the blighters yet.
Oh my carpet, oh my carpet, oh my carpet don't forget - with a Hoover, yes a Hoover, we will beat the blighters yet.
Tim: The basic modern Hoover has really changed very little.
We've cut part of this one away so you can see what's inside.
This is the fan that does the sucking and it makes the brushes and beater bars go round as well.
The dirt is dislodged by the rotating brushes, sucked straight through the fan and into the dust bag at the back The cylinder type of vacuum cleaner is slightly different.
It's actually more like Booth's original machine I'll take the bottom off this one In this sort, the dust comes straight into the dust bag, and the air passes straight through the paper that acts as a filter, and goes through the fan and finally out the grille on the top of the machine.
So the positions of the fan and the dustbag are reversed.
And because it's only clean air which is passing through the fan the shape of the vanes can be much more intricate.
So this sort usually has a much stronger sort of sucking power.
And the bin type and the more modern flattened cylinder types are just the same as this, though the layout leaves slightly more room for bigger dustbags.
The upright vacuum cleaner with a rigid dustbox is a sort of hybrid.
We've cut one in half so you can see what's inside.
It has rotating brushes just like a hoover, but inside the air and the dirt come straight up the back and into the dustbag, so its layout in some ways is more like the cylinder vacuum cleaner, because it's only clean air that comes out of the bottom of the dustbag and goes through the enclosed fan and then finally comes out the back of the machine.
Well there are advantages and disadvantages of all these different types of vacuum cleaner and a recent Which survey found that in overall performance there's really very little to choose between them all.
By the 1920s many companies were producing electric vacuum cleaners.
Booth himself had started making them himself, under the trade name Goblin.
One of his employees was a man called Bill Sutton.
Bill: I joined Goblin in 1929, although I'd a relative with the company many years before, so I knew quite a bit about the vacuum cleaner business as a youngster.
This model was produced in 1908 and appeared at the first Ideal Home Exhibition Bill to Tim: Would you like to do a bit of cleaning if I operate it? Tim: Oh I see it's a two-person machine? Bill: Yes, oh yes.
Bill: If I turn this handle, you do the cleaning.
[chugging noise.]
Tim: It's getting something up.
Bill: In fact they used to at the exhibition, have to go back to the factory and make another one if they sold one.
Tim: Although better than most hand powered vacuum cleaners it was still rather inconvenient.
so Booth started developing his own electric models.
Bill: As you'll see it's got the old dolly switch and some very old fashioned flex.
They wouldn't pass it with the approvals board today.
[chuckles.]
Tim: Where does the dust go? Bill: Well it actually goes in here.
Tim: Oh I see, yes.
Bill: And you undo this to get at the dirt, to empty the machine.
This machine was first produced in 1930, rather a unique machine in that it gives you the upright situation for easy cleaning.
It sold for 5 pound, 19 and sixpence, at that time.
But the interesting thing is that for dusting, all you need to do is undo the dustbag from this position here and put your arm through the dustbag and do your dusting.
It did have some other tools for it, for dusting but of course that's another story.
Bill: This particular model, a Goblin ace is 210 Volts, whereas today the standard voltage is 240.
In the 30s, in Bristol there were two voltages, in London they went down as far as 100 Volts in certain places.
Tim: Were there electricity shops where you could sell these things? Bill: Oh no.
The electrical shops weren't in existence then, there was only a cycle shop who did the odd electrical product.
[Footsteps.]
[Knocking on door.]
Bill: The industry had to employ vast numbers of direct-selling people, In fact Goblin had 2,500 at peak, of people knocking doors.
Woman: Oh! Salesman: You've heard of the radio, you've now got electricity, but this is what you haven't got A vacuum cleaner! Look, it is Woman: Well I don't know Salesman: No, look, I'll just take this wire, plug it into your sockets like that and we will have a demonstration.
Salesman: If you are okay to stand up a minute madam, See! Now, did you know, in that chair is hidden dirt.
Every part of your house has got hidden dirt.
Look, it's all in there now madam.
Look.
This is what you were sitting on.
Woman: gasps Dust! Ohhh! Bill: The sales mostly had to be made of an evening, because the only person who was entitled to sign a hire purchase agreement was the husband and in most cases sales had to be made on a Friday or Saturday evening when the pay packet came in otherwise you didn't get the deposit.
Tim: I'm now going to look at the various parts of the vacuum cleaner in greater detail.
First the motor: electric motors are rather baffling devices but they all depend basically on the ability of electricity to magnetise things.
If I wrap a bit of wire around a nail, Oh dear, got it tangled up The more turns, the stronger the magnetism.
I'm going to use 12V DC from a car battery, and of course you must never ever use mains for something like this! The nail becomes magnetic when I complete the circuit and when I break it again, most of the magnetism is lost.
And if I wrap the wire around a little copper tube and hold it above the nail then the magnetic attraction will pull the nail off the table.
[Spark crackles.]
[clinkclink.]
(whispers) lets get it slightly more [Clink clink.]
This is an industrial electromagnet, the coil of wire is in here, and this is the lump of metal it pulls in.
This one's actually, um, out of a fruit machine, it's the device that pushes the coins out when you win.
[coins clanking.]
Well I use these devices a lot on the machines that I make.
I made this for a local solicitor, it was a portrait of the founder of the firm, his great uncle and he wanted to be able to control it, so it would react to his clients sometimes dubious confidences.
[clunk.]
[Buzz.]
In the end he got cold feet, and placed the control box so that the clients themselves could use it.
Well if you look at the back you can see that the device that makes the wig go up and down in the air is one of these electromagnets [BZZZZZT BZZZZT.]
And by themselves, these electromagnets can only produce this rather jerky, linear action.
but it's not actually too difficult to use the electromagnetic attraction make something rotate.
Rex: To show the principles of a simple electric motor, I've made a motor out of virtual rubbish: Nails, a hacksaw blade, an old needle, a cork and a dogfood can.
The commutator, as the part in the vacuum cleaner motor I've made from a cork, with wires running up there.
It acts as a sort of rotating switch, each wire is attached to a coil.
When the wires are in contact with the brass strips, current passes through, so at one time, only one pair of coils are energised.
These pair of coils here are magnetised by the electric current and they're attracted to this pair of coils, now when it pulls to there, these coils switch off and it brings on the next pair of coils, which are attracted to there, and of course they switch off bringing in the next pair causing a rotating motion.
I'll switch on.
[Grinding motor noise.]
Tim: The vacuum cleaner motor doesn't at first sight look like Rex's tin can motor, but if you look inside you can see it has a lot of the same elements.
This is the commutator, the rotating contacts.
These are the coils of wire rotating around the shaft, and these are the coils of wire round the outside making them both magnetic.
Well in fact there are many different types of electric motor, but they all depend upon the basic ability of electricity to produce magnetism.
[Baby babbles.]
It's really quite difficult to imagine how inconvenient the world must have been without any electric motors.
Most of the machines in the home depend on them: Vacuum cleaners, power tools, washing machines, fridges, tape recorders and countless other gadgets.
Steam engines, their predecessors, were hot and heavy and needed several hours stoking to get up pressure before they would work.
Factories used to have a single steam engine connected to every machine in the place by a very elaborate set of belts and clutches.
This was not very convenient or safe in a factory and totally impractical in the home.
Baby: babble babble oooopsaoooopsa Man: OHHH! The bit that actually does the sucking is the enclosed fan next to the motor.
I can show you where the air goes if I hold some smoke over it [Vacuum cleaner noise.]
You can see that all the air is actually drawn straight through the middle of the motor to get to the fan, and the reason for this is that it helps to keep the motor cool.
You can often feel the air coming out of the end of a vacuum cleaner is quite warm, and without this air passing through the motor it would very quickly overheat.
The fan itself works with these rotating vanes, that whizz round and round and fling the air outwards.
The air comes in the middle and the vanes go round flinging the air outwards, and then there's a second set of vanes that doesn't rotate, a static set, and these channel the air back to the middle again.
And then there's another set, a second set of rotating vanes, that fling the air outwards, and finally there's a second set of static vanes that channel the air back to the middle again.
[whirring noise.]
And having these two stages doubles the suction power.
Well one surprising thing about these fans is that they need less power to work when the inlet is blocked up.
I can show you this, with this meter which shows how much current the motor is using.
And, er, if I turn it on [Vacuum cleaner noise.]
You can actually hear the pitch of the motor rising when I block the inlet up and that's because it's actually running faster.
But of course it is also overheating because there is no air passing through it, so it's not really a very good idea.
[Vacuum cleaner noise.]
The power of the fan is quite surprising, here we fixed the outlet of a vacuum cleaner to a plastic bag.
The air pressure in the bag can quite comfortably lift my van off the ground.
[Vacuum cleaner noise.]
The vacuum cleaner actually has the power to inflate things on a much larger scale.
This is a pig built for the Pink Floyd by a local firm.
Once it is inflated, a miniture car vacuum cleaner is enough to compensate for the air lost through any holes, and keep it full of air.
And a full size vacuum cleaner can keep enormous things inflated.
The only time I've ever used a vacuum cleaner, was for a machine which didn't need any of its impressive power.
This is a collecting box I made for an charity society called 'Common Ground'.
It's a sort of pun on its name showing a bit of ground being shared by different sorts of creature.
The ground is actually a bit of rubber, I did my first experiments holding bits of rubber over a vacuum cleaner nozzle [Vacuum cleaner noise.]
Underneath, each of er, each footprint is connected to the suction pump at the bottom here, by one of these hoses, via a valve, each one by a separate valve, actually out of a washing machine.
And this timer down the bottom here turns the valves on in sequence.
[motor noise stops.]
[ping.]
The last important part of the vacuum cleaner is the dustbag which acts as the filter.
The paper of cloth contains minute holes which trap most of the dirt, but let the air pass straight through.
Of course any bits of dirt that are smaller than the size of these holes which are about 1/200th of a mm in diameter, will pass straight through the bag.
I can show you this with this smoke cartridge that contains minute particles of red dye.
If I put it next to the nozzle, you'll see the dye come straight through the machine and out through the grille here.
[Click.]
Oh I forgot to turn it on.
[Vacuum cleaner noise.]
Normally about 15% of household dust is below this critical size and passses straight through the machine.
[Vacuum cleaner noise continues.]
Rex used to repair domestic appliances, and found often people didn't realise this.
Rex: Sometimes I would be called out to a machine that wasn't working, and the customer had actually fitted a plastic bag inside the cloth bag so they could dispose of the dirt easily.
Well this of course completely blocked the airflow and there was no suction at all, and obviously it wouldn't work.
Even the disposable paper bags need changing quite frequently, some customers used to use one paper bag and empty it continuously.
And they do lose their efficiency, and the little pores in the paper get blocked with dust and they just don't work.
Occasionally, one or two clients had actually had a machine for ten years or so, and they'd still got the original packet of paper bags, and had only ever used one.
Tim: The vacuum cleaner is really quite a simple machine, a motor a fan, and a dustbag.
But it does have a particularly hard life being pushed and tugged about all the time.
Although they used to be sold with lifetime guarantees, today they rarely last more than a few years.
The modern vacuum cleaner may not be perfect, but it is extraordinarily good value for money.
In 1950 a vacuum cleaner cost about the same amount as the average weekly wage.
Today, it costs a lot less than half that.
An enormous amount of energy and cunning has gone into reducing the manufacturing costs, and perhaps for their price today we can't really expect them to last for very long.
Although vacuum cleaners are now rather flimsy and unsatisfying machines, and their short lifespan is ecologically very unsound, they do retain more character than most [rocket ignites.]
other household machines, and I can't help rather liking them.
[rocket noises continue.]
[Jazzy music: 'Take 5' - Dave Brubeck.]