“Two hours at least: probably more.”
“I said an hour.”
“All right.” I rose from the chair where I’d just seated myself and pushed the papers to one side. “Get someone else to work the damn thing out.”
He looked at me for a long moment, the slaty milky eyes without expression, then said evenly: “You take very many chances, Bentall.”
“Don’t talk rubbish.” If I couldn’t do anything else I could at least sneer at him. “When a man takes chances he can either win or lose. I can’t possibly win anything now, and God knows I’ve nothing to lose.”
“You’re wrong, you know,” he said pleasantly. “There is something you can lose. I can take your life away from you.”
“Have it and welcome.” I tried to ease the burning pain in my shoulder and arm. “The way I feel right now I’m just about finished with it anyway.”
“You have a remarkable sense of humour,” he said acidly. Then he was gone, banging the door shut behind him. He didn’t forget to turn the key in the lock.
Half an hour passed before I even bothered looking at Fairfield’s papers, I’d more important things to think about than those. It was not the most pleasant half-hour of my life. The evidence was all before me now, Bentall with the bunkers off-at last-and I knew the truth, also at last. Counterespionage, I thought bitterly, they should never have let me out of the kindergarten, the wicked world and its wicked ways were far too much for Bentall, if he could put one foot in front of the other without breaking an ankle in the process that was all you could reasonably expect of him. On flat ground, of course. By the time I’d finished thinking, my morale and self-respect had shrunk so much you’d have required an electronic microscope to find them, so I reviewed all that had happened in the hope of discovering one instance where I had been right, but no, I’d a perfect and completely unmarred record, one hundred per cent wrong all along the line. It was a feat that not many people could have matched.
The one redeeming feature about being utterly wrong, of course, was that I’d also been wrong about Marie Hopeman. She had had no special instructions from Colonel Raine, she had never fooled me once. This was no mere hunch or opinion, it was a provable certainty. It was, I knew, rather late in the day to arrive at this knowledge, I couldn’t see that it was going to alter anything now, but in different circumstances … I gave myself up to the very pleasant contemplation of what things might have been like in different circumstances and was just finishing off the towers and battlements of a particularly enchanting dream castle in the air when a key turned in the lock. I’d barely time to open the folder and scatter a few papers around before LeClerc and a Chinese guard came in. He glanced down at the table, Malacca cane swinging idly in his hand.
“How is it coming, Bentall?”
“Very difficult and very complicated and continual interruptions by you don’t help me any.”
“Don’t make it too difficult, Bentall. I want this test rocket wired and fused and ready to take off in two and a half hours.”
“Your wants are a matter of complete indifference to me,” I said nastily. “What’s the hurry, anyway?”
“The Navy is waiting, Bentall. We mustn’t keep the Navy waiting, must we?”
I thought this one over, then said: “Do you mean to tell me that you have the colossal effrontery to keep in radio touch with the Neckar?”
“Don’t be so naive. Of course we’re in touch. There’s no one more interested than myself to have the Black Shrike land on time, on target. Apart from which, the one sure way to rouse their suspicions and send them steaming back at high speed to Vardu is not to keep in touch with them. So hurry it up.”
“I’m doing my best,” I said coldly.
When he left, I got down to working out the firing circuits. Apart from the fact that they were coded, the instructions for the wiring were such as could have been carried out by any reasonably competent electrician. What could not have been done by the electrician was the calculation of the settings on the time clock-part of the mechanism in the box attached to the inside of the outer casing-which regulated the ignition of the nineteen propellant cylinders in their proper sequence.
From his notes it appeared that even Fairfield himself had been doubtful about the accuracy of his own recommendations as to firing sequences and times: they had been worked out on a purely theoretical basis, but theory and practise weren’t the same things at all. The trouble lay in the nature of the solid fuel propellant itself. A completely stable mixture in limited quantities and at normal temperatures, it became highly unstable under extremes of heat and pressure and beyond a certain unknown critical mass: the trouble was that no one knew the precise limits of any of those factors, nor, even more worrying, did they know how they reacted upon one another. What was known was the highly lethal results of instability: when the safety limit was passed the fuel changed from a relatively slow burning propellant to an instantaneously explosive disruptive estimated, weight for weight, at five times the power of T.N.T.
It was to reduce the danger of mass that the propellant had been fitted in nineteen separate charges and it was to reduce the danger of too suddenly applied pressure that the charges had been arranged to ignite in seven consecutive stages: but, unfortunately, no one could do anything about the danger of heat. The propellant had its own inbuilt oxidising agent, but not nearly enough to ensure complete combustion: two high-speed turbine fans which started up two seconds before the ignition of the first four cylinders supplied air in quantity and under high pressure for the first fifteen seconds until the missile reached a high enough speed to supply itself with sufficient air through its giant air-scoops. But as the Black Shrike was absolutely dependent on its air supply, it meant that it had to leave the earth on a very flat trajectory indeed in order not to run out of atmosphere before the propellant burnt out: it was not until all the fuel was consumed that the missile’s automatic brain lifted it sharply out of the atmosphere. But the need for even half a minute’s supply of air meant a tremendous air resistance generating extremely high temperatures and while it was hoped that the water-cooled porcelain nose would cope* with part of the heat, no one knew what temperature would be generated in the heart of the rocket. All in all, I thought, it looked like a very dicey deal indeed.
The two switch-boxes I’d seen attached to the inner casing had both to be set before firing-the ‘On’ switch closed the firing circuits, the ‘Armed’ switch closed the circuit for the suicide box: if anything went wrong with the rocket in flight, such as a deviation to land or shipping lanes, it could be electronically instructed to commit suicide. In normal missiles fuelled by lox and kerosene, the flight could be stopped simply by sending out a radio message that automatically cut off the fuel supply: but there was no way of shutting off a solid fuel already in combustion. The cylinder I had seen in the middle of the propellant at the top of the rocket had been a sixty pound charge of T.N.T., fitted with a primer, and the hole I had seen in the centre of the primer was to accommodate a 77 grain electrically fired fulminate of mercury detonator, which was connected to the cable I’d seen dangling in the vicinity. The circuit for this was triggered, as were all controls in the rocket, by radio, a certain signal on a certain wavelength activating an electrical circuit in the same box as the one that contained the timing mechanism for the firing circuits: this current passed through a coil which in turn activated a solenoid switch-a soft iron core in the centre of the coil-and this completed the circuit which fired the detonator in the T.N.T. charge. Again Fairfield had been very doubtful of the outcome: what was intended was that the explosion of the T.N.T. should disintegrate the rocket: but it was just as likely, he had thought, that the instantaneous change in heat and pressure would cause the whole rocket to blow up in sympathetic detonation.
If I was picked as the first man to go to the moon, I thought, I’d just as soon not travel on the Black Shrike. Let someone else go first while Bentall remained earthbound and watched for the explosion.
I reached for the typewriter, made a list of which coloured and numbered firing cables marked which fuel cylinders, worked out an average of Fairfield’s suggested figures for the timing sequences and stuck the paper in my pocket. I’d just done this when Hewell appeared.