Enigma

oddity of their situation struck Jericho. Pinker was probably personally responsible for sending—what?—a thousand German sailors to the bottom of the ocean, yet Cave's face was the closest he had come to the brutality of the Atlantic war.
    Someone asked what would happen next.
    'If one of the U-boats finds the convoy? It'll shadow it. Send a contact signal every two hours—position, speed, direction. That'll be picked up by the other hearses and they'll start to converge on the same location. Same procedure, to try to draw in as many hunters as possible. Usually, they try to get right inside the convoy, in among our ships. They'll wait until nightfall. They prefer to attack in the dark. Fires from the ships that have been hit illuminate other targets. There's more panic. Also, night-time makes it harder for our destroyers to catch them.'
    'Of course, the weather's appalling,' added Cave, his sharp voice cutting in to the silence, 'even for the time of year. Snow. Freezing fog. Green water breaking over the bows. That's actually in our favour.'
    Kramer said: 'How long do we have?'
    'Less time than we originally thought, that's for certain. The U-boat is faster than any convoy, but it's still a slow beast. On the surface it moves at the speed of a man on a bicycle, underwater it's only as fast as a man on foot. But if Donitz knows about the convoys? Perhaps a day and a half. The bad weather will give them visibility problems. Even so—yes—I'd guess a day and a half at the outside.'
    Cave excused himself to go and telephone the bad news to the Admiralty. The cryptanalysts were left alone. At the far end of the hut a faint clacking noise began as the Type-X machines started their day's work.
    'That'll be D-D-Dolphin,' said Pinker. 'Will you excuse me, G-G-Guy?'
    Logie raised a hand in benediction and Pinker hurried out of the room.
    'If only we had a four-wheel bombe,' moaned Proudfoot.
    'Well, we ain't got one, old love, so don't let's waste time on that.'
    Kramer had been leaning against one of the trestle tables. Now he pushed himself on to his feet. There wasn't room for him to pace, so he performed a kind of restless shuffle, smacking his fist into the palm of his left hand.
    'Goddamn it, I feel so helpless. A day and a half. A measly, goddamn day and a half jesus! There must be something. I mean, you guys did break this thing once, didn't you, during the last blackout?'
    Several people spoke at once.
    'Oh, yes.'
    'D'you remember that?'
    'That was Tom.'
    Jericho wasn't listening. Something was stirring in his mind, some tiny shift in the depths of his subconscious, beyond the reach of any power analysis. What was it? A memory? A connection? The more he tried to concentrate on it, the more elusive it became.
    'Tom?'
    He jerked his head up in surprise.
    'Lieutenant Kramer was asking you, Tom' said Logie, with weary patience, 'about how we broke Shark during the blackout.'
    'What?' He was irritated at having his thoughts interrupted. His hands fluttered. 'Oh, Donitz was promoted to admiral. We took a guess that U-boat headquarters would be pleased as Punch. So pleased, they'd transmit Hitler's proclamation verbatim to all boats.'
    'And did they?'
    'Yes. It was a good crib. We put six bombes onto it. Even then it still took us nearly three weeks to read one day's traffic.'
    'With a good crib?' said Kramer. 'Six bombes. Three weeks?'
    'That's the effect of a four-wheel Enigma.'
    Kingcome said: 'It's a pity Donitz doesn't get a promotion every day.'
    This immediately brought Atwood to life. 'The way things are going, he probably will.'
    Laughter momentarily lightened the gloom. Atwood looked pleased with himself.
    'Very good, Frank,' said Kingcome. 'A daily promotion. Very good.'
    Only Kramer refused to laugh. He folded his arms and stared down at his gleaming shoes.
    They began to talk about some theory of de Brooke's which had been running on a pair of bombes for the past nine hours, but the methodology was hopelessly skewed, as Puck pointed out.
    'Well, at least I've had an idea,' said de Brooke, 'which is more than you have.'
    'That is because, my dear Arthur, if I have a terrible idea, I keep it to myself.'
    Logie clapped his hands. 'Boys, boys. Let's keep the criticism constructive, shall we?'
    The conversation dragged on but Jericho had stopped listening a long time ago. He was chasing the phantom in his mind again, searching back through his mental record of the past ten minutes to find the word, the