THE descent to the chamber of the White Witch was quickly made. There, the party of three paused briefly to catch breath and to view again the weird figure which captured the imagination.

A tunnel, at times narrow and low, wound deeper and deeper into the earth. Judy and Kathleen kept close to their guide. In the stillness of the cavern they could hear his somewhat labored breathing, for even the slightest sound was magnified.

They came presently to another small chamber where they paused, speechless. Stalactites sparkled like jewels, standing out in the most fantastic shapes.

Judy could imagine animal figures, all in a variety of color, milky white, red, green and black. The colors, Captain Hager explained, came from mineral infiltration.

“No wonder Bart couldn’t resist this cave,” Judy remarked in awe, entranced. “It’s like a fairyland! How I wish all the Scouts could see it!”

In close formation, the three went on into the cavern depths. A cooler wind met them, but from where it arose they gained no clue.

The going had become harder now, and after edging through a narrow space, the three stopped for a moment beside a translucent column which rose from the floor to the roof.

As they stood thus, there came a deafening crash behind them.

Judy and Kathleen froze in their tracks, too terrified to utter a sound.

“A cave-in behind us?” Kathleen finally asked in a choked whisper.

“It’s nothing,” the captain reassured her. “Sounded like a blast of dynamite far away. Like enough the rangers are blasting a tree stump somewhere in the park area.”

“But it sounded as if the cave roof had fallen!” Judy said, still shaken.

“All sounds underground are magnified,” Captain Hager explained. “Even the dripping of water can be very loud. Off to the right there is a Talking Grotto. But we will not explore that passage, for Bart would not waste time there.”

To proceed, it was necessary to creep across a slippery formation which resembled a frozen waterfall. They passed through a room which was cluttered with grotesque toadstool types of stalagmites, and then came to formations so delicate that they appeared as a lacy cobweb.

As they sat down to rest their legs for a moment, Captain Hager told the girls that the beautiful pillars they had seen farther back were made by the joining of stalactites and stalagmites. The growth of formations, he added, was much faster than generally believed. Varying rainfall, the thickness of the rock penetrated by water, and the rate of drip, all affected the deposits, he explained.

“All water that goes into a cave, must come out somewhere,” the captain continued. “During a hard rain storm, this cave could be dangerous at the lower levels.”

“You mean we’d get the rain down here?” Kathleen questioned in amazement.

“Belatedly, yes. Shortly now, you’ll see the underground river. During the dry months it shrivels, but in the rainy season, it thunders through the chasms like a mad demon.”

“I hope it doesn’t storm today,” Kathleen said nervously.

“The day was clear,” Captain Hager reassured her. “And there has been no recent rain to flood the underground stream.”

Farther on, the girls came to a series of small pools in which there were blind fish. They did not tarry long, but continued through another long, narrow passage.

“Do you suppose Bart came this way?” Judy finally asked. “Couldn’t he have taken any number of branch-offs?”

“The branch-offs are dead-end streets, so to speak,” replied the captain. “If I know that lad, we’ll find him at the siphon, or we’ll not find him this voyage. Tired?” “My legs feel sort of cramped,” Judy confessed, ashamed of her weariness. “But I’m all right.”

“We’re nearing the end,” the captain encouraged the girls. “The last few yards are the hardest. Then we’ll bring up at the siphon.”

“And if Bart isn’t there?” asked Judy.

The old captain did not answer. He gazed thoughtfully at his sturdy boots, tested his light briefly on the limestone wall, and then signaled that he was ready to resume the descent.

Not far beyond the point where they had rested, the three explorers came to a chamber so large that it seemed to have no surrounding walls.

At its entrance, Captain Hager hesitated, seemingly reluctant to go on.

“If we continue to the siphon, we must cross this chamber, with no wall to guide us,” he explained. “Beyond, in the darkness, there is a single narrow passageway leading on. If we hit the target, we’ll soon be at the end of the cave. If we miss, we may spend hours, trying to grope our way. We’ll be like a ship wallowing without chart or compass. Unless you have plenty of nerve—”

“We have,” Judy said resolutely. “We’ve come so far now, we can’t turn back without learning whether or not Bart is in the cave.”

“Aye, I figured you’d say that,” Captain Hager replied.

He then uncoiled a length of nylon rope, tying it first about his own waist, then around Kathleen, and finally about Judy, who would bring up the rear.

“We must keep close together,” he warned. “If we do, there is no danger. Even if we miss the passageway on the first try, we will find it. Full steam ahead, my hearties!”

For a few feet the girls followed along a rough, jagged wall before moving slowly out into the vast room. The silence and immensity of the cavern were momentarily terrifying, for Captain Hager’s light revealed only a dark void ahead.

By supreme effort Judy and Kathleen held their nerves in rigid check. Each step seemed to be taking them deeper and deeper into oblivion. A dozen doubts assailed them. Would Captain Hager ever find the narrow passage leading out of the chamber? And if they should be successful in reaching the siphon, would not the return be even more difficult?

The darkness seemed endless, but finally Captain Hager’s light revealed a rough wall ahead. A wave of relief washed over Judy and Kathleen. But it was short lived.

Their guide had paused to move the flash beam slowly along the solid wall, first to the right, then to the left. He muttered something, but his words were indistinguishable.

“Are—are we lost?” Kathleen asked.

The captain deliberately did not answer. After a moment, he started on again, groping along the wall. Kathleen did not repeat her question.

For awhile Captain Hager kept on, the girls directly behind, following blindly. Then suddenly the old man seemed to relax, and they heard him give a throaty chuckle.

“Hear that?” he demanded.

Judy and Kathleen already had distinguished the distant sound of running water. The underground stream!

At the same instant that they heard the splash of water, Captain Hager’s flash beam focused upon the narrow opening in the cavern wall—the passageway for which he had searched.

“We near the end,” he said simply.

They moved quickly through the narrow corridor. The thunder of a distant waterfall they never were to see, was louder now in their ears.

The floor of the passageway sloped sharply downward. Kathleen slipped but did not fall, for Judy caught her arm to give her support.

Abruptly, the corridor turned, and the girls saw water ahead. The underground stream, quiet and dark, emerged from a wall of rock to flow tranquilly beneath the slightly arched cave-roof above.

Captain Hager halted. “We’ve come to the end,” he announced.

Judy and Kathleen were stunned. “The end,” Judy repeated, scarcely comprehending. “But I thought—”

“We can proceed no further without wading along the river bed,” the captain explained. “The water gradually deepens until it rises to the ceiling. At that point, one must dive through and swim underwater, or turn back.”

He focused his light to the right, and the girls saw the meeting place of wall and water.

“The siphon?” Judy asked.

“Aye, how far it goes, no man knows. It may extend for only a few feet or yards. Then again, it may run on indefinitely, with nary a pocket of air.”

“Bart—?” Judy hesitated to ask the question that was foremost in her mind.

“Surely he wouldn’t be crazy enough to try to swim through the siphon!” Kathleen exclaimed.

“The lad is a true spelunker, like his father. He has the courage of a lion, and the muscles of a young bear. Since he was a mere boy, he’s studied and dreamed about this cave.”

“But we’ve seen no evidence that he’s anywhere in the cavern,” Judy said hopefully.

“No evidence?” Captain Hager’s voice was muted, as his light came to focus upon a rock shelf a few feet above the river bed.

For a moment, neither Judy nor Kathleen understood.

Then, they fully comprehended. There on the rock ledge, set heel to heel, was an empty pair of shoes. Beside them, in a neat roll, was Bart’s shirt and jacket.