the others long ago. The fact that they could not hear even faint sounds of the huge bombardment taking place in the outside world demonstrated more clearly than anything the immense thickness of the wall which barred their escape. The thought had occurred to Barnes twenty-four hours earlier and had so worried him that he had waited until the others were asleep before walking back down the tunnel. When he reached the far end he had listened carefully at the blocked entrance but no sound had penetrated from the outside world. They were well and truly sealed in at both ends. Taking a sip of water from his mug, he frowned.
Then, very carefully, he put the mug down on the hull and walked over to where Reynolds and Davis were working. He faced the wall and then turned sideways as though listening. It was a dramatic moment and Penn instantly guessed that something had happened because he got down off the tank and walked forward. Something in Barnes' attitude had attracted the attention of Reynolds and Davis and they stopped working.
'What is it?' asked Penn.
Barnes shook his head and faced the wall again, his hands on his hips, his eyes searching the surface carefully. When he spoke his voice was quiet. 'I think we're nearly through.' 'Why?' Penn asked quickly.
'I can feel a faint current of air - come and stand here.' 'My God! You're right! You're right!' They began to work feverishly at the point where Barnes had traced the air current's entrance, a point about four feet above the level of the tunnel floor. A quarter of an hour later they experienced another heart-lifting moment when Barnes told them to stop working for a minute while he put out the lamp. For a short time there-was no sound in the darkness of the tunnel while four pairs of eyes strained to see any sign of daylight in the wall. It was Barnes who spotted it first - a narrow, paper-thin slit along the upper surface of one large boulder.
'We're through,' shouted Davis. 'We're really through. Dear Mother of God, we're through!'
'Take it easy now,' warned Barnes, 'this could be tricky. There's still a solid mass of rock up there.'
He relit the oil lamp and when he turned round Davis was already inserting the crowbar into a corner near the end of the slit they had seen, his hands gripping the iron with a ferocious intensity as he drove the end deeper into the wall and began to twist and turn for leverage. Barnes opened his mouth and closed it again without speaking. The poor devil must have gone through even greater agonies than the rest of them with his memories of the mine trap he had escaped from. Barnes had realized this when he had treated Davis roughly, but any display of sympathy at that time could have destroyed the morale of all of them, and Barnes never forgot the dictum of Napoleon - morale is to the material as three is to one. So now he let Davis break loose as he dug and rammed the bar into the remaining barrier, punishing his hands with the force of his efforts and never even noticing the punishment. Penn spoke as he shovelled debris to expose the base of the remaining rocks. 'I'll tell you now, I never thought we'd make it.' 'We'll face tougher things than this before this war's over.' Within ten minutes Davis had prised the boulder loose and Reynolds was helping him to haul it back out of the wall, a boulder as large as the oil stove they carried inside Bert for emergency cooking arrangements. It came away suddenly. One moment Davis was leaning his full weight against the crowbar, sweat streaming down the sides of his face, and then the rock was shifting inwards, swaying gently before it toppled back into the tunnel, so unexpectedly that the two men had to jump sideways to avoid it. Picking up the oil lamp, Barnes held it behind his back and they all stared at the oblong of daylight. It was a memorable moment. Four-men, each of whom had secretly felt that they would never make it, knew now that they would live. There was a pause when no one spoke,