'They might get lucky and hit him but more likely they'd just tear up the walls and overload the ventilation system with loose, high inert velocity crud. Rog, you better get into this discussion too,' Larry addressed the image on a visiphone.

'Fans to blow the smoke back down the tunnel?' a dispatcher suggested.

'Fans? In an inertialess field? You've got to be kidding,' another dispatcher said, mockingly.

'Electro-static Precipitation?'

'Rog, do we have a precipitator?' Larry asked.

'Yes. It weighs two tons and is embedded in concrete in Central Air.'

'Check with Moorpark Research for a high voltage power supply. Fifty to a hundred thousand volts and up.'

'No good! You would have to lay the line. All the intruder would have to do is fire at the power supply or lines. If he hits it, it's gone.'

'Get Dr. Kevin into the discussion anyway. He might have some ideas we can use.'

'Can we reverse the ventilation?'

'No. You'd loosen six-month-old dust and blow it out the entrances to the tunnels; besides, the artificial gravity is mechanically fixed to only operate in one direction,' Rog said.

'How about a physical barrier? A wall or something?'

'If he has smoke bombs, he's probably got other kinds of bombs too.'

'An explosion? In an inertial field? You've got to be kidding,' another dispatcher chimed in, getting back for the comment made about his suggestion to use fans.

'It's worth a try.'

They agreed, and a.s.signed the dispatcher making the suggestion to take care of the details of building a portable blockade.

'How about stopping the smoke bombs he's set off by putting them in containers?'

'Can you find the smoke bombs in the smoke?'

'Sure, the air only goes one way. The monitors have them on their plates.'

'Great, get containers to the patrol in 2 North.'

'We'll have to try to catch him by surprise. All he has to do is drop a bomb on the other side of a ventilator from a camera and he'll be hidden in smoke again.'

'OK, get containers to all of the patrols.'

'I have some vacuum-tight shipping containers that will work perfectly,' Dr. Kelvin said. 'We're just off tunnel 2 North at H, so using ours will be faster than sending them out from Security.'

He disappeared for a few moments to give instructions.

'How did the intruder destroy the first vault?' Rog Philips asked.

Larry explained his theory.

'Has the smoke cleared so someone can find out where he cut the hole? It'll give us an idea as to where he's going to cut the next one.'

Lt. McQueen turned the job over to a dispatcher with the admonition, 'Make d.a.m.ned sure the patrol 4546

hunting for that hole understands that they've got to have clean air! Otherwise the dust will tear them apart when they come out! Armor will not protect them!'

'The spy-ray team says he's stopped. Probably the other side of the first ventilator in J,' a dispatcher reported.

'Gentlemen, we're running out of time,' Larry announced. 'Are there any more ideas?'

'The spy-ray team says he's turned around and headed back north toward 2 North.'

'Any indication yet of material acc.u.mulating in the exhaust vents?'

'I'll check ... negative,' a dispatcher answered.

'Notify the patrols directly any time you hear he moves.

Don't bother asking permission or anything. Anyone have any idea what made him move back?

'He has at least three ventilator intakes to get past. Could that have anything to do with it?'

Rog Philips asked.

'There are no essential systems in the north end of J,' a dispatcher offered. 'They're mostly spread around tunnel Zero and the Dome.'

'Where have you got patrols?'

'At the ventilator west of J in 2 North. At both vents in J north of 1 North. At the intersections of J and 1 North. J and Zero, and around the corner at I and 1 North. There's also a six-man reserve group at I and Zero.'

'He's stopped.'

'Has he been using the handles for transportation?'

'Bill, ask the spy-ray team that question,' Larry directed a dispatcher.

'The patrol at I and 2 North vent has the containers.'

He advanced very slowly, probably with the smoke. He retreated on handles. He's still waiting,'

the dispatcher reported for the spy-ray team.

'Find out the spy-ray team's best guess as to how far he is from the intersection. If it's more than a couple hundred feet, send the patrol in to can the smoke bomb in 2 North. Have the spy-ray team watch for any possible contact between the patrol and the intruder. If he moves farther north, tell them to leave the bombs and get out of the smoke.'

'If our men are in position, why can't we shut off the transportation handles to slow up the intruder?' Dr. Kelvin asked. 'To cut his mobility?'

'Can you just cut out his section, Rog?'

'No, I have to cut the whole J tunnel.'

'It's still a good idea,' Larry said. 'How soon can you get it done?'

'Five to 10 minutes.'

'Good. Get someone going on it, Rog. Any other ideas?'

'Commit some of the reserves to the vent in J between 1 North and Zero.'

'Good,' Larry said, and directed a dispatcher to take care of it.

'I have an idea,' Hanovich said, making his first contribution to the effort. 'It's a desperate last resort type of thing but I think it will work.' He frowned.

'Go on.'

'Evacuate the travel tunnels and ...' he paused, dramatically, 'turn off the artificial gravity!'

There was a silence so thick it could almost be cut. Dr. Kelvin was the first to break it with a single word, 'Sneaky!'

Rog Philips deliberately looked at his watch. 'Have the men in the south Bergenholm vault turn off their artificial gravity unit,' he said. 'The other generator is in the west Bergenholm vault.

I'll meet you there, Col. Hanovich, with your key in 10 minutes.'

It took the men in the control center a moment to realize what had just happened. Two keys were needed to get into a vault, and Hanovich had one. Philips had deliberately invited Hanovich, whose consideration for his own hide was well known, into what might become the firing line. He had flung the gauntlet at Hanovich's feet in a challenge that he could neither ignore nor delegate.

The whole room was silent as they looked at Hanovich. Would he venture into personal danger? To mask his smile, Larry turned and looked at Rog's image. He was almost certain that Rog had both his own and the Mayor's key already. Otherwise, how had he gotten into the south vault?

Hanovich licked his lips. 'I'll be there,' he said, the stress apparent in his voice.

Larry turned and called 'Good luck' at Hanovich as he left. He got a strange, half-frightened smile back.

'Is the patrol into the first Bergenholm area yet?' Larry asked.

'Yes. The smoke bomb stopped. The chamber around the vault is still full of dust and debris.

They're checking outside in tunnel A and 2 North for holes. They haven't found any yet.'

'Why tunnel 2 North?'

'They couldn't find anything in tunnel A.'

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'It's got to be there. Look, the vault door faces north, away from us, right? We saw the left wall collapse, so the attack came from east of the vault, or tunnel A. Let's see. Copernicus is about 100 north longitude. The tangent of 100 is between .15 and .20, or about 20 feet up or down per 100 feet. Huh! Is the vault floor level with the travel tunnels?'

'I don't know.'

'Did they look in the entrance and exit shafts?'

They hadn't.

'The intruder's coming back on the handles,' a dispatcher announced.

'Warn everyone to get set. He's coming south in tunnel J, right?'

'Right.'

'How's the barrier coming?'

'They're making a d.a.m.n project out of it. It'll be another 30 minutes before they even get started,' came the answer.

'I'll give the countdown to when he'll be back in his original position,' Larry heard a dispatcher warn the tunnel patrols. 'Five, four, three .. :' Larry looked at a plate showing the monitor's view of the patrol at the edge of the smoke in tunnel J. 'Two, one ... He's stopped.' Then the dispatcher swore.

Larry only caught a flash of it as it went through the TV camera's field of view. A smoke bomb had been tied to a handle of the transportation system. It streaked along the travel tunnel past the patrol, trailing a dense cloud of smoke. The patrol was lost from sight.

CHAPTER ELEVEN.

... A CRISIS.

The equipment was brought out by a man Pete had never seen before, in a moon creeper unlike any other. It had eight wheels, four of which were raised in the 'air'. The driver, a tall, alert, wiry man with an air of authority, introduced himself as Steve Tolliver. As he got out and walked toward Pete, it was obvious that he had had little experience walking on the moon with a vacuum suit and 'moonshoes'. He seemed to catch on fast.

'What is it?' Pete asked, waving at the eight-wheeled vehicle.

'It's a relic. A centuries old Northrop Mooncar. It was built for the Apollo Program back before World war III. They found two of them when we got here. The other one is back in the new Smithsonian on Earth. This one was dug out and renovated for this run. I made sixty-five on the trail you checked. They have four wheels for high speed travel, eight wheels for heavy going, and on dust you can turn the wheels around a common center and paddle out. I don't understand why they aren't used instead of tracked crawlers.'

'Politics!' Pete commented. 'President Witherspoon has a nice work project going in North America, and he doesn't want to lose it. We have to renovate every creeper we get. Half of them aren't even airtight!'

Pete spent an hour surveying the inside of the slide around Harv with the shadow magnetometer. He located and marked Harv with careful accuracy using the spy-ray attachment, but there were other objects in the slide which Pete couldn't account for. Pete searched somewhat far afield knowing Tolliver was watching him, until he found one of the objects near the surface. He moved a couple of rocks away, and found a small piece of what looked like the side of an old sewer pipe! Having antic.i.p.ated the problem, his body shielded what he was doing from Tolliver. A hand signal to the creeper caused it to flash a.n.a.lyze the object. Pete then dropped the 'piece of pipe' and half covered it with several other rocks he 'examined.'

A little later Pete explained to Tolliver and Harvey what he planned to do to extract Harvey. 'It will take too long to just cut through the slide, in spite of the power we have available. In addition, the average ground temperature is -100 F., it will take over twenty-four hours before the walls and floor of the slice would be cool enough to do the fine work of making an escape hole for Harv. We can cut a series of small holes faster than large slices, and the cooling time will be less. This will save time, since the necessary final clearances and cuts have to be made with the same accuracy in either case. So, first we cut a drain hole at the bottom of the slide under Harv's position. Then a small hole connecting to it about ten feet from the exit side of Harv's creeper. We enlarge the hole keeping about ten feet away. The original hole acts as a drain. When we get a little below Harv's level, we stop cutting and use a tractor beam mounted on a creva.s.se bridge to pull rock from Harv into the hole we cut. The creeper should only be exposed to about two thousand BTU per hour, which it should be able to take care of with ease. We melt and flush the rock down the drain. Once Harv's out we cut a ramp in one side of the hole, wait until it cools, and then pull the creeper out using a couple of winches.'

They were enlarging the drain hole when Pete took off a few minutes to go back to his creeper.

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'What did the a.n.a.lyzer show?' he asked the creeper when he was inside.