Collected Stories Of Arthur C. Clarke (51 page)

Suck, bubble, bubble,
plop
…

‘Well, let’s hear the story. When did it happen?’

He sighed.

‘I’m almost sorry I mentioned it. Still, since you insist – and, of course, on the understanding that it doesn’t go beyond these walls.’

‘Er – of course.’

‘Well, Rupert Fenton was one of our lab assistants. A very bright youngster, with a good mechanical background, but, naturally, not very well up in theory. He was always making gadgets in his spare time. Usually the idea was good, but as he was shaky on fundamentals the things hardly ever worked. That didn’t seem to discourage him: I think he fancied himself as a latter-day Edison, and imagined he could make his fortune from the radio tubes and other oddments lying around the lab. As his tinkering didn’t interfere with his work, no one objected: indeed, the physics demonstrators did their best to encourage him, because, after all, there is something refreshing about any form of enthusiasm. But no one expected he’d ever get very far, because I don’t suppose he could even integrate
e
to the
x
.’

‘Is such ignorance
possible
?’ gasped someone.

‘Maybe I exaggerate. Let’s say
x e
to the
x
. Anyway, all his knowledge was entirely practical – rule of thumb, you know. Give him a wiring diagram, however complicated, and he could make the apparatus for you. But unless it was something
really
simple, like a television set, he wouldn’t understand how it worked. The trouble was, he didn’t realise his limitations. And that, as you’ll see, was most unfortunate.

‘I think he must have got the idea while watching the Honours physics students doing some experiments in acoustics. I take it, of course, that you all understand the phenomenon of interference?’

‘Naturally,’ I replied.

‘Hey!’ said one of the chess-players, who had given up trying to concentrate on the game (probably because he was losing). ‘
I
don’t.’

Purvis looked at him as though seeing something that had no right to be around in a world that had invented penicillin.

‘In that case,’ he said coldly, ‘I suppose I had better do some explaining.’ He waved aside our indignant protests. ‘No, I insist. It’s precisely those who don’t understand these things who need to be told about them. If someone had only explained the theory to poor Fenton while there was still time …’

He looked down at the now thoroughly abashed chess-player.

‘I do not know,’ he began, ‘if you have ever considered the nature of
sound
. Suffice to say that it consists of a series of waves moving through the air. Not, however, waves like those on the surface of the sea – oh dear no!
Those
waves are up and down movements. Sound waves consist of alternate compressions and rarefactions.’

‘Rare-what?’

‘Rarefactions.’

‘Don’t you mean “rarefications”?’

‘I do not. I doubt if such a word exists, and if it does, it shouldn’t,’ retorted Purvis, with the aplomb of Sir Alan Herbert dropping a particularly revolting neologism into his killing bottle. ‘Where was I? Explaining sound, of course. When we make any sort of noise, from the faintest whisper to that concussion that went past just now, a series of pressure changes moves through the air. Have you ever watched shunting engines at work on a siding? You see a perfect example of the same kind of thing. There’s a long line of goods wagons, all coupled together. One end gets a bang, the first two trucks move together – and then you can see the compression wave moving right along the line. Behind it the reverse thing happens – the rarefaction – I repeat,
rarefaction
– as the trucks separate again.

‘Things are simple enough when there is only one source of sound – only one set of waves. But suppose you have two wave patterns, moving in the same direction? That’s when interference arises, and there are lots of pretty experiments in elementary physics to demonstrate it. All we need worry about here is the fact – which I think you will all agree is perfectly obvious – that if one could get two sets of waves
exactly
out of step, the total result would be precisely zero. The compression pulse of one sound wave would be on top of the rarefaction of another – net result – no change and hence no sound. To go back to my analogy of the line of wagons, it’s as if you gave the last truck a jerk and a push simultaneously. Nothing at all would happen.

‘Doubtless some of you will already see what I am driving at, and will appreciate the basic principle of the Fenton Silencer. Young Fenton, I imagine, argued in this manner. “This world of ours,” he said to himself, “is too full of noise. There would be a fortune for anyone who could invent a really perfect silencer. Now, what would that imply …?”

‘It didn’t take him long to work out the answer: I told you he was a bright lad. There was really very little in his pilot model. It consisted of a microphone, a special amplifier, and a pair of loud-speakers. Any sound that happened to be about was picked up by the mike, amplified and
inverted
so that it was exactly out of phase with the original noise. Then it was pumped out of the speakers, the original wave and the new one cancelled out, and the net result was silence.

‘Of course, there was rather more to it than that. There had to be an arrangement to make sure that the cancelling wave was just the right intensity – otherwise you might be worse off than when you started. But these are technical details that I won’t bore you with. As many of you will recognise, it’s a simple application of negative feedback.’

‘Just a moment!’ interrupted Eric Maine. Eric, I should mention, is an electronics expert and edits some television paper or other. He’s also written a radio play about space flight, but that’s another story. ‘Just a moment! There’s something wrong here. You
couldn’t
get silence that way. It would be impossible to arrange the phase….’

Purvis jammed the pipe back in his mouth. For a moment there was an ominous bubbling and I thought of the first act of
Macbeth
. Then he fixed Eric with a glare.

‘Are you suggesting,’ he said frigidly, ‘that this story is untrue?’

‘Ah – well, I won’t go as far as that, but …’ Eric’s voice trailed away as if he had been silenced himself. He pulled an old envelope out of his pocket, together with an assortment of resistors and condensers that seemed to have got entangled in his handkerchief, and began to do some figuring. That was the last we heard from him for some time.

‘As I was saying,’ continued Purvis calmly, ‘
that’s
the way Fenton’s Silencer worked. His first model wasn’t very powerful, and it couldn’t deal with very high or very low notes. The result was rather odd. When it was switched on, and someone tried to talk, you’d hear the two ends of the spectrum – a faint bat’s squeak, and a kind of low rumble. But he soon got over that by using a more linear circuit (dammit, I can’t help using
some
technicalities!) and in the later model he was able to produce complete silence over quite a large area. Not merely an ordinary room, but a full-sized hall. Yes …

‘Now Fenton was not one of these secretive inventors who won’t tell anyone what they are trying to do, in case their ideas are stolen. He was all too willing to talk. He discussed his ideas with the staff and with the students, whenever he could get anyone to listen. It so happened that one of the first people to whom he demonstrated his improved Silencer was a young arts student called – I think – Kendall, who was taking physics as a subsidiary subject. Kendall was much impressed by the Silencer, as well he might be. But he was not thinking, as you may have imagined, about its commercial possibilities, or the boon it would bring to the outraged ears of suffering humanity. Oh dear no – He had quite other ideas.

‘Please permit me a slight digression. At College we have a flourishing Musical Society, which in recent years has grown in numbers to such an extent that it can now tackle the less monumental symphonies. In the year of which I speak, it was embarking on a very ambitious enterprise. It was going to produce a new opera, a work by a talented young composer whose name it would not be fair to mention, since it is now well known to you all. Let us call him Edward England. I’ve forgotten the title of the work, but it was one of these stark dramas of tragic love which, for some reason I’ve never been able to understand, are supposed to be less ridiculous with a musical accompaniment than without. No doubt a good deal depends on the music.

‘I can still remember reading the synopsis while waiting for the curtain to go up, and to this day have never been able to decide whether the libretto was meant seriously or not. Let’s see – the period was the late Victorian era, and the main characters were Sarah Stampe, the passionate postmistress, Walter Partridge, the saturnine gamekeeper, and the squire’s son, whose name I forget. It’s the old story of the eternal triangle, complicated by the villagers’ resentment of change – in this case, the new telegraph system, which the local crones predict will Do Things to the cow’s milk and cause trouble at lambing time.

‘Ignoring the frills, it’s the usual drama of operatic jealousy. The squire’s son doesn’t want to marry into the Post Office, and the gamekeeper, maddened by his rejection, plots revenge. The tragedy rises to its dreadful climax when poor Sarah, strangled with parcel tape, is found hidden in a mailbag in the Dead Letter Department. The villagers hang Partridge from the nearest telegraph pole, much to the annoyance of the linesmen. He was supposed to sing an aria while he was being hung:
that
is one thing I regret missing. The squire’s son takes to drink, or the Colonies, or both: and that’s that.

‘I’m sure you’re wondering where all this is leading: please bear with me for a moment longer. The fact is that while this synthetic jealousy was being rehearsed, the real thing was going on backstage. Fenton’s friend Kendall had been spurned by the young lady who was to play Sarah Stampe. I don’t think he was a particularly vindictive person, but he saw an opportunity for a unique revenge. Let us be frank and admit that college life
does
breed a certain irresponsibility – and in identical circumstances, how many of
us
would have rejected the same chance?

‘I see the dawning comprehension on your faces. But we, the audience, had no suspicion when the overture started on that memorable day. It was a most distinguished gathering: everyone was there, from the Chancellor downwards. Deans and professors were two a penny: I never did discover how so many people had been bullied into coming. Now that I come to think of it, I can’t remember what I was doing there myself.

‘The overture died away amid cheers, and, I must admit, occasional catcalls from the more boisterous members of the audience. Perhaps I do them an injustice: they may have been the more musical ones.

‘Then the curtain went up. The scene was the village square at Doddering Sloughleigh,
circa
1860. Enter the heroine, reading the postcards in the morning’s mail. She comes across a letter addressed to the young squire and promptly bursts into song.

‘Sarah’s opening aria wasn’t quite as bad as the overture, but it was grim enough. Luckily, we were to hear only the first few bars …

‘Precisely. We need not worry about such details as how Kendall had talked the ingenuous Fenton into it – if, indeed, the inventor realised the use to which his device was being applied. All I need to say is that it was a most convincing demonstration. There was a sudden, deadening blanket of silence, and Sarah Stampe just faded out like a TV programme when the sound is turned off. Everyone was frozen in his seat, while the singer’s lips went on moving silently. Then she too realised what had happened. Her mouth opened in what would have been a piercing scream in any other circumstances, and she fled into the wings amid a shower of postcards.

‘Thereafter, the chaos was unbelievable. For a few minutes everyone must have thought they had lost the sense of hearing, but soon they were able to tell from the behaviour of their companions that they were not alone in their deprivation. Someone in the Physics Department must have realised the truth fairly promptly, for soon little slips of paper were circulating among the V.I.P.s in the front row. The Vice-Chancellor was rash enough to try and restore order by sign language, waving frantically to the audience from the stage. By this time I was too sick with laughter to appreciate such fine details.

‘There was nothing for it but to get out of the hall, which we all did as quickly as we could. I think Kendall had fled – he was so overcome by the effect of the gadget that he didn’t stop to switch it off. He was afraid of staying around in case he was caught and lynched. As for Fenton – alas, we shall never know
his
side of the story. We can only reconstruct the subsequent events from the evidence that was left.

‘As I picture it, he must have waited until the hall was empty, and then crept in to disconnect his apparatus. We heard the explosion all over the college.’