Morningways turned purple but said nothing. And now he had to nerve himself to turn his back on them in order to write on the blackboard. As he spoke he had to raise his voice above the din of general conversation that was the permanent background to his classes. ‘Anyway,’ he shouted, ‘let’s see how much about the electroscope you have learned so far.’ He always phrased his sentences back-to-front, and part of the game was to answer his questions in the same vein.
Mockson said: ‘When on the top you put a positive charge, the leaves inside the flask are opened out.’
Morningways was so used to his own idiosyncrasy being imitated that he no longer noticed it. ‘Quite correct, Mockson.’ The right course would now have been to ask the subsequent question to the next boy; but he was so relieved that somebody knew something that he stuck to Mockson. ‘And can you explain to the class why this is so?’
Mockson suppressed a giggle. Riddle, sitting next to him, was eating an enormous bar of chocolate — as if he weren’t fat enough already. ‘The reason is,’ said Mockson, playing for time, ‘the reason is—’ And then he remembered vaguely; it was important to phrase the answer in the approved style. ‘Because something repels something, the reason is,’ he explained.
‘That’s a bit vague,’ said Morningways, ‘but it’ll do, perhaps, for the moment. Now, tell me how you would set about discharging the electroscope.’
‘I would the electrode to earth connect.’ This received a hilarious ovation from the rest of the boys.
Morningways said: ‘That’s perfectly correct. But there’s no need to talk Chinese.’
Riddle spoke with his mouth full of chocolate. ‘I don’t have to connect mine to earth,’ he said triumphantly. ‘It does it all by itself.’
‘Well now, that’s remarkably interesting,’ said the science master, wondering what unspeakable trick was about to be sprung. ‘Do you mind if I come and look?’ Rather hesitantly, Morningways walked round the end of one of the long trestle tables and came up to Riddle, who looked at him challengingly, the bar of chocolate held firmly in his chubby hand. The whole class was watching, unusually silent now, as if suspecting that ‘Old Stinks’ was, as usual, about to be had.
Morningways rubbed his fountain-pen on a piece of cloth, thus charging it with static electricity. Then he touched the electrode at the top of the instrument. Immediately the leaves flew apart. He waited and watched, and sure enough, the leaves began to fold together again. He frowned.
‘That’s very funny,’ he said.
‘Funny ha-ha or funny peculiar?’ enquired Mockson.
‘Funny peculiar,’ said Morningways, forgetting to be on the defensive for a moment. ‘There must be something wrong with the electroscope. Mockson! Hand me yours. Thank you.’ Once again he charged his pen, touched the top of the electroscope and the leaves opened as before.
Then they closed again, quite slowly and deliberately. Mockson spoke seriously. ‘It didn’t do that a minute ago,’ he said.
‘Well, let’s put it back again.’ Mockson took it from Morningways, and placed it on the bench before him. On being tested once more, it behaved normally, remaining charged.
Boys are strange creatures. Up to now they had been mocking the wretched Morningways until he had actually come to dread every class he took. For weeks he had tried to think of something that might genuinely interest the boys and so make them more easily controlled. Now the unexpected had happened, butter wouldn’t have melted in their hungry mouths. Slowly they began to gather round the bench, each competing for a good view of the offending electroscope. They watched the science master move the humble apparatus — it only consisted of a glass jar with an attachment on the top, from which was suspended, within the jar, two thin pieces of gold leaf — they watched him move the thing back to its original position near Riddle. It did the same, inexplicable thing.
Then Morningways had a wild idea. So wild that for once he was laughing at himself, instead of leaving it to the boys to ridicule him. ‘Riddle, put that bar of chocolate down a minute. Over there.’ He indicated an empty bench. ‘You can have it back in a moment.’ Bemused, Riddle did as he was told without protest, wondering what it all meant. There was absolute silence now, as once again Morningways rubbed the pen on a duster and held it against the electrode. The leaves opened up again, and they all waited, hardly breathing.
They waited a full two minutes, but the electroscope remained charged. Then Morning ways walked over to the empty bench and retrieved the mangled piece of chocolate, held it close to the electroscope. It discharged rapidly. A concerted, sotto voce gasp from the boys.
At that point the headmaster came in on his tour of inspection. He was actually very surprised at the pitch of enthralled attention that prevailed in the laboratory, but was careful not to show it. He swept in, using one of his well-practised entrances, sweeping the air with his gown in a beautifully executed tight turn. ‘Ah, Morningways! An interesting experiment, I see!’ He strode up to the bench. ‘Well, what’s it all about?’
Morningways gave him a complete demonstration. And although the Head shot Riddle a meaningful look when he learned the ownership of the chocolate, he did not interrupt until Morningways had finished. Then he said: ‘Well, I’m not a science man myself, but I take it you are suggesting that the chocolate’ — and again he paused over the word, catching Riddle’s eye as he did so — ‘is discharging the electroscope without touching it. Is that unusual?’
‘It’s not only unusual, Mr Ripley,’ said Morningways, ‘it’s impossible!’
‘Nonsense!’ roared the Head. ‘It can’t be! I’ve just seen it with my own eyes. Or’ — and here he laughed boomingly — ‘or is it some scientific conjuring trick? If so, I demand,’ he added with heavy humour, ‘as Headmaster, to be let into the secret!’
The science master did not laugh. ‘No, sir, it is not a trick.’
‘Well then, don’t you know the explanation?’
Morningways turned round and faced him hesitantly, and yet with a firmness he had never displayed before. His expression puzzled the Headmaster. Indeed, everything about the situation — the silence of the boys, their interest, the bar of chocolate openly displayed before him — puzzled him considerably.
‘There is only one possible explanation,’ said the junior man. ‘You see, the only thing that could discharge that electroscope, without touching it, is a quantity of electrons—’
‘I’m sorry,’ said the Head rather irritably, ‘technicalities of that sort are lost on me. Stick to the curriculum, man! Can’t you put it simply?’
‘Simply put,’ said Morningways, ‘that bar of chocolate is radioactive.’
‘What? But… but the boy has been eating it!’
‘Have you seen the afternoon papers?’ said Morningways.
‘Yes. What about them?’
‘The scare about the beans. They’ve now come up with the truth.’
The Headmaster nodded. He was quite calm now. ‘I see.’ He turned to Riddle, who looked extremely guilty. The Head’s voice was surprisingly gentle. ‘Listen, my boy,’ he said. ‘I promise you that you won’t be punished, but you must tell me the truth. It is more important than you can possibly know that you should. Do you understand that?’ The boy nodded gratefully. ‘Now, you must tell me exactly where you got this chocolate and how much you have eaten. But for pity’s sake be truthful about it.’
Riddle’s face turned scarlet. ‘My uncle sent it.’
‘But how? Relatives aren’t supposed to send you food.’
‘Yes,’ said Riddle, now warming to the happy task of telling the truth for once, without the prospect of a painful experience at the end of it, ‘but you see, sir, it was supposed to be books. The chocolate was packed between the two outside ones.’ A triumphant grin went with this revelation.