The tunnel led at a slightly less than 45-degree angle upward and through the mountain. There was no estimating its distance. When Joe came out at the other end, however, his shoulders and hands and knees were rubbed raw and bleeding even with the protection of towels.

"I don't understand," von Richthofen said. "It seems to me that the mountains were shaped there to prevent men from getting to the end of The River. Why was this tunnel bored through solid rock to give intruders passage? And why wasn't a tunnel placed in the first cliff?"

"A tunnel in the first cliff might have been visible to whatever sentinels or patrols there are in that area," Clemens said. "But the second cliff was hidden in mist."

"That chain of white towels would be even more outstanding," the German said.

"Maybe it was placed there not too long before Joe got there," Clemens said. Von Richthofen shivered.

"For Heaven'th thaketh, let me tell thith! After all, it ith my tale."

"And a big one, too," Clemens said, looking at Joe's huge buttocks. "Thtickth and thotneth may break my boneth."

The party pushed on over another tableland for about ten miles. They slept or tried to, ate, and began climbing. Now, though the mountains were very steep and rough, they were scalable. Their chief enemy was lack of oxygen. They gasped for breath and had to halt often to rest.

By now Joe's feet were hurting him, and he was limping. He did not ask if he could rest. As long as the others walked, so would he.

"Joe can't stay on his feet as long as a human," Clemens said. "All of his species suffer from flat feet. Their weight is just too much for a biped that size. I wouldn't be surprised if his kind became extinct on Earth because of broken arches."

"I know one thpetthimen of Homo thapienth who'th going to suffer from a broken nothe if he don't keep hith nothe out of my buthineth, vhich ith telling thith thtory," Joe said.

They climbed until The River, broad as it was, was only a thread below them. Much of the time they could not see even that thread because of the clouds. Snow and ice made climbing even more dangerous. Then they found a way downward to another plateau and groped through the fog against a wind that howled and beat at them.

They found themselves beside a tremendous hole in the mountains. Out of the hole rushed The River, and on every side except Riverward the mountain rose straight and smooth. The hole was the only way to go. Out of it blasted a roar so loud they could not hear each other, the voice of a god who spoke as loud as death.

Joe Miller found a narrow ledge entering the cave high above the waters. Joe noticed that the leader had now dropped back behind him. After a while, the titanthrop became aware that all of the pygmies were looking to him as their guide and helper. When they shouted to make themselves heard above the bellow, they called him Tehuti. There was nothing unusual in that, but before this he had detected overtones of jesting in their use of the name, No more. Now he was truly their Tehuti.

Clemens interrupted again. "It was as if we called the village idiot Jehovah or something like that. When men have no need of gods, they mock them. But, when afraid, they treat them with respect. Now, you might say, Thoth was leading them into the opening into the Underworld.

"Of course, I'm only indulging in mankind's vice of trying to make a symbol out of coincidence. If you scratch any dog, you'll scare out a flea."

Joe Miller was breathing heavily through his grotesque nose, and the vast chest rose and fell like a bellows. Clearly, the reliving of that experience had aroused the old terror, in him.

The ledge was not like the tunnel in the mountain. It had not been prepared. It was rough, and there were gaps in it, and sometimes it ran so high that Joe had to crawl to squeeze between the ledge and the roof of the cavern. The darkness blinded him as if his eyes had been plucked out. His sense of hearing did not help him; the bellow filled his ears. Only his touch was left to guide him, and he was so agitated that he sometimes wondered if that were betraying him. He would have quit except that, if he did, the men behind him would not have been able to go on.

"Ve thtopped tvithe to eat and voneth to thleep," Joe said. "Jutht vhen I vath beginning to think ve might crawl until ve ran out of food, I thaw a grayneth ahead. It vathn't a light. Jutht a leththening of the darkneth."

They were out of the cave, in the open air, on the side of the mountain. Several thousand feet below them was a sea of clouds. The sun was hidden behind the mountains, but the sky above was not yet dark. The narrow ledge continued, and they crawled on their bloodied hands and knees downward now, since the ledge had narrowed to nothing.

Trembling, they clung to the tiniest of fingerholes. A man slipped and fell and clutched another man! Screaming, both disappeared into the clouds.

The air became warmer.

"The River was giving up its heat," Clemens said. "It not only originates at the north pole, it also empties there after picking up heat in its serpentine wanderings over the entire planet. The air at the north pole is cold but not nearly as cold as that on Earth. This is all speculation, of course."

The party came to another shelf on which they could stand, facing the mountain, and proceed sidewise, Like crabs. The shelf curved around the mountainside. Joe halted. The narrow valley had widened into a great plain. He could hear, far below, the dash of surf against rock.

Through the twilight, Joe could see the mountains ringing the sea of the north pole. The cloud-covered waters formed a body about sixty miles in diameter. The clouds were thicker at the opposite end of the sea. He didn't know why then, but Sam had explained that the clouds hid the mouth of The River, where the warm waters came into contact with the cold air. Joe took a few more steps around the curve of the ledge.

And he saw the gray metal cylinder sitting on the path before him.

For a moment, he did not understand what it was, it looked so alien. It was so unexpected. Then it flowed into familiar lines, and he knew it was a grail left by a man who had come before him on this dangerous path. Some unknown pilgrim had survived the same perils as he. Up to that point, that is. He had put the grail down to eat. The lid was open, and there was the stinking remnant of fish and moldy bread within it. The pilgrim had used the grail as a pack, perhaps hoping he might come across a grailstone and recharge it.

Something had happened to him. He would not have left the grail there unless he had been killed or had been so frightened he had run away without it. At this thought, Joe's skin chilled.

He went around the outcropping that was sitting at a point where the ledge went around a shoulder of granite. For a moment, his view of the sea was blocked. He went around the outcropping—and he cried out.

he men called and asked what troubled him.

He could not tell them because the shock had taken away his newly learned speech, and he spoke in his native tongue.

The clouds in the middle of the sea had roiled away for a few seconds. The top of a structure projected from the clouds. It was cylindrical and gray, like the top of a monster grail.

Mists rose and fell around it, now revealing, now veiling.

Somewhere in the mountains ringing the" polar sea, a break existed. At that moment, the low sun must have passed this notch in the range. A ray of light fell through the notch and struck the top of the tower.

Joe squinted his eyes and tried to see into the brightness of the reflection.

Something round had appeared just above the top of the tower and was settling down toward it. It was egg-shaped and white, and it was from this that the sun was sparkling. The next instant, as the sun passed by the notch, the sparkle died. The tower and the object above it faded into darkness and mist. Joe, crying out at the sight of the flying object, stepped back. His leg struck the grail left by the unknown pilgrim.