‘We’ve managed to get the lengths of pipe into the Dark area, and the gun chamber is there also. There’s trouble keeping handling equipment working so far into the Pen, but we’ve managed somehow. We should be ready to start firing sometime tomorrow. Have you been able to get the extra stuff I asked for?’
‘Most of it’s outside on the carriers, and the generators will arrive in the morning. Here’s the wide-band radiation monitor, trolley-mounted as specified. I only hope it fits into the pipe.’
‘I’ll try it out,’ said van Noon. ‘I can run it through our test length and if it doesn’t fit we can modify it before it goes into the Pen.’
He wheeled the small apparatus-laden trolley to the length of pipe that ran down the workshop where they had been fabricating the gun chamber. The trolley fitted easily into the interior of the pipe and, to give himself a little practice, he crawled in after it and pushed it before him. The iron confines of the pipe returned the sound of the small rollers with a noise like a train speeding through a tunnel. When van Noon reached the far end he found that Jacko had returned and was peering anxiously down the pipe.
‘Why the sound effects, Fritz?’
‘Eh? Oh, this? It’s the radiation detector. It’s obvious that even the iron of the pipe can’t do more than attenuate some wave lengths of the electromagnetic spectrum—and the same presumably applies to the negative spectrum. So just to be on the safe side Courtney has knocked up a combined range monitor which should cover anything likely to be dangerous but not detectable by our own senses. I don’t expect that we’ll encounter any such radiation, but it’s better to be safe than sterile.’
‘Agreed,’ said Jacko. ‘We’re taking enough chances with the unknown already. I’ve just come back out of the Pen, and we’re right on schedule. The first firing can take place at mid-day tomorrow.’
‘I’ll be there,’ said Fritz. ‘I’m particularly interested in knowing what happens to the core which we leave in the pipe. If the Dark is true radiation-type phenomena, there won’t be any core material. But if it’s something else, we may have to think again.’
The null-pressure suits obtained from Space Command were far more suitable for working under deep Pen conditions than the expeditionary clothing had been. Specifically designed for work on asteroids and similar bodies under a pressure dome but exposed to extremes of stellar heat and cold, the suits were the finest flexible radiation foils that had yet been devised. In the Pen, of course, no pressurized dome was needed, but the suits ensured that the searching fingers of negative-heat were no longer a danger or of major discomfort to the UE squad.
But the drag of the anti-momentum was not so easily avoided. Close to the wall of the Dark it exhibited an almost treacle-like resistance to movement which was common to both men and machines alike. The adaptations of technique needed for working in an environment possessing such a high quasi-viscosity were numerous, but the combined ingenuity of the Unorthodox Engineering squad was equal to the challenge. Somehow the impossible had been accomplished, and the structural components of van Noon’s tunnel had been patiently swung into place ready for the projected penetration of the Dark.
‘Ready to fire?’
Jacko nodded. ‘First shot in thirty seconds.’
They were watching the scene by the light of two large continuously operating lasers which Courtney had managed to obtain. These were directed on the point where the leading end of the pipe was pressed hard against the Dark perimeter. The illumination, spread slightly by deliberate diffusion with mesh screens, was adequate despite the negative-radiation loss. The backscatter illumination was also quite useful around the working area, but was attenuated sharply and unnaturally with distance. The power for the lasers had to be derived from outside the Pen via cable, and the negative-electrical loss was such that two large generators were needed to drive sufficient energy in to keep the lasers in operation.
The first shot was fired. The sound of the explosion was incredibly muted, and the tongue of flame from the reaction chamber was quickly quenched and drained. Van Noon examined the junction between the pipe and the Dark.
‘I think it’s working, Jacko. Only millimetres so far, but it’s definitely going in. Keep firing rapidly but erratically. Let me know when you’re in about a metre. Then I want to go down inside the pipe and see if any sort of core is left.’
By reason of good organization on Jacko’s part they had penetrated a metre by late afternoon. Then the gun chamber was removed to allow access to the free end of the pipe. Van Noon had a line measured to a pipe’s length minus one metre, and one end he left clamped to the free end of the pipe while he took the rest of the line inside to give him an indication of his position. Ten minutes later he came out jubilant.
‘No core material, Jacko. The pipe is clear to the very end, and then the Dark begins again. That means we’ve got a metre of clear tunnel already and no complications so far. Now I want firings to continue right round the clock, as close-spaced as possible without setting up a standard repetition rate. If you scatter the charges round the area a bit so that each has to be fetched from a slightly different distance, that should be sufficient. But I want the depth of penetration per shot carefully watched, and if it varies very much from the existing rate, cease firing and let me know.’
It took forty hours to drive the first length of pipe into the Dark. By this time a second length had been added to the first and there were indications that the depth of penetration per shot was increasing. The second was driven home in twenty-five hours, partly due to the decreasing resistance it encountered, and partly due to the increasing proficiency of the shot-firers.
The third pipe was inserted in seventeen hours, and the fourth, in twelve. The time for subsequent pipes decreased in rough proportion. The tenth went half way, and then the indications were that no great resistance was being offered to it by the Dark since the assembly of pipes now moved forward the full theoretical distance per shot that they would have moved in the Pen itself. Jacko brought his charts to van Noon.
‘I think we’re through, Fritz. These seem to show that the Dark is a relatively thin-wall phenomenon with its effects decreasing with depth of penetration and reaching virtually zero at about ninety-five metres. God alone knows what’s at the other end.’
‘Take the gun chamber off, Jacko, but be careful in case something unexpected comes out of the pipe. If nothing happens in half an hour then I’m going through to have a look.’
Nothing did happen. The end of the pipe protruding from the Dark remained empty, silent and cold; and there was no way of telling what lay at the far end. A laser directed down the pipe returned nothing but light- scatter from walls and motes of dust. The only factor of note was a strong current of air entering the pipe as though to equalize some unexplained deficiency in pressure.
Finally van Noon hoisted the radiation trolley into the pipe and followed it in.
‘I’m going down a bit, Jacko, for a preliminary survey. Stand by with some weapons in case I come out fast with something after me.’
‘Nothing doing!’ said Jacko. ‘If you’re going down that pipe, then I’m coming too.’
Fritz nodded. ‘All right, let’s get on with it. The situation won’t improve itself by waiting.’
He crawled into the pipe. With some misgivings, Jacko followed him in. Ahead of Fritz the radiation trolley clattered on the metal and raised a multitude of clamorous echoes which engulfed them in a tide of sound. Inside the pipe the negative-sound attenuation apparently did not operate to anything like the same degree as that encountered in the Pen. The radiation monitor gave no indication of any increase in rate above the slow background count, and they considered it safe to continue.
Occasionally van Noon stopped and let the echoes die, but nothing else disturbed the silence except their own breathing and their own awkward movements in the confines of the pipe. Then after what seemed an eternity of crawling the clatter of the trolley ceased again and van Noon stopped and half twisted himself to look back.
‘Jacko,’ he said urgently, ‘think very carefully. Are you absolutely sure how many lengths of pipe we drove into the Dark?’
‘A bloody fine time to be concerned about the economics of the project.’
‘Stuff the economics! Are you
‘Certainly. Ten in all. Why?’
‘I’ve been counting the joins. I’m now in the twelfth pipe, that’s why.’
‘Don’t make jokes like that, Fritz. You’ll give me heart failure.’
‘I wasn’t joking. The rollers on the trolley drop into the flange gap at every join, and I have to ease them over. That’s what made me start counting how many joins I’d passed.’
‘So you’re now in the twelfth pipe out of the original ten,’ said Jacko, still not fully convinced. ‘That’s quite a
