chamber, undoubtedly the work of human hands; a room awe-inspiring to behold, and even more than awe-inspiring in the reflections it forced upon their minds. Passages radiated on either hand to mysterious depths, and great bulks loomed in the spectral light. Justus Miles gave a low cry of amazement when a closer investigation revealed those bulks to be the wrecks of mighty and intricate machines, the use of which it was vain to conjecture. He looked at Ward.

"Solino spoke of a city down in the ocean. Can this be it?"

Ward shook his head. "Everything here is old, abandoned. Look—what is that?"

The figure of a giant creature, carved either from stone or marble and encrusted with phosphorous, stood lowering in their path. It was that of a winged beast with a human head. Its features were negroid in character; and so malignant was the expression of the staring face, so lifelike the execution of the whole statue, that a chill of fear ran through their veins. It was in Ward's mind that this gigantic carving was akin to the ones he had seen in Egypt, and as old, if not older.

Beyond the statue the rail curved and the grade leveled; and, rounding the bend, they were amazed to come upon a sort of "yard" where the rail stopped. In that enclosure, on several sidings, were submarine cars similar to the wrecked one they had abandoned. But that was not the sight which brought them to a breathless halt. Beyond the sidings stood what appeared to be a small building of gleaming crystal.

After a moment of breathless wonder they cautiously approached the bizarre structure. No dampness or phosphorus impaired the clarity of its walls. The material composing them felt vibrantly warm to the touch. It was not glass, yet it was possible to look without difficulty into the interior of the building, which appeared to be one large room containing nothing but a central device not unlike the filaments of an electric bulb. In fact, the whole building, viewed from the outside, reminded the two adventurers of a giant light globe. The filaments radiated a steady and somehow exhilarating light. The door—they knew it was a door because an edging of dark metal outlined its frame—gave admittance to the room.

"Shall we?" questioned Miles; and Ward answered doubtfully, "I don't know. Perhaps...."

But at last they turned the golden knob, felt the door give to their pressure, and stepped through the entrance into the soft radiance of the interior. Unthinkingly, Ward released his hold on the knob and the door swung shut behind them. Instantly there was a flash of light, and they were oppressed by a feeling of nausea: and then, out of a momentary pit of blackness, they emerged to find that the room of crystal had oddly changed its proportions and opaqueness. "Quick!" cried Ward; "let us get out of this place." Both men found the door and staggered forth.

Then, at sight of what they saw, they stood rooted to the spot in sheer amazement. The gloomy tunnel and the sidings of submarine cars had vanished, and they were standing in a vast hall, an utterly strange and magnificent hall, staring up into the face of a creature crudely human and colored green!

The green man was almost of heroic proportions; he was clad in but a breech-clout, and was so broad as to appear squat in stature. He carried a short club, and appeared almost as dumbfounded as the two Americans. A moment he regarded them, then, with a ferocious snarl of rage, he hurled himself upon the startled Ward and half clubbed, half pushed him to the floor. Recovering from his momentary inaction and realizing the danger in which his friend stood, Miles shouted and leaped upon the green man's back, fastening his sinewy fingers about the giant's throat.

But the latter was possessed of incredible strength, and, straightening up, he shook off Miles as a bear might shake off an attacking dog, and threw him heavily to the floor. Then the green giant whirled up his club, and it would have gone hardly with Miles if Ward had not remembered his automatic and fired in the nick of time. As if poleaxed, the green man fell; and both the adventurers recovered their feet.

"Look out!" shouted Ward.

Through a wide entrance came charging a dozen greenish giants. Miles fired both his pistols. The leader of the greenish men paused in mid-leap, clawing at his stomach.

"This way, Kid!" yelled Ward; "this way!"

Taking advantage of the confusion in the ranks of the attackers, the two sprang to where an exit in the far wall promised an avenue of escape. Down a broad passage they rushed. Seemingly the passage ended in a cul-de-sac, for a wall of blank whiteness barred further progress. Behind them came charging the greenish giants uttering appalling cries. Desperately the two Americans turned, resolved to sell their lives as dearly as possible; but at that moment happened a sheer miracle. The blank wall divided, revealing a narrow crevice through which they sprang. Noiselessly the crevice closed behind them, shutting out the green pursuers, and a voice said—a voice in precise but strangely accented English:

"We have been expecting you, gentlemen, but—where is Solino?"

Never would Miles and Ward forget the amazement of that moment. They were in a place which looked not unlike a huge laboratory. Then they saw it was a lofty room containing a variety of strange mechanisms. But it was not on these their eyes focussed. Confronting them in odd wheelchairs, with hairless heads projecting from tubular containers like the one they had seen encasing the man at the control board of the submarines, were all of half a hundred crippled men!

"Good Lord!" exclaimed Miles, "I must be seeing things!"

"Where is Solino?" demanded the voice in strangely accented English.

Ward saw that the question came from an individual in a wheelchair a few feet in front of them.

"Solino is dead," he answered.

"Dead?" A ripple of sound came from the oddly seated men.

"Yes, the submarine car was wrecked in the tunnel, and everyone aboard was killed save us two."

The hairless men looked at one another. "This is Spiro's work," said one of them, still in English; and another said, "Yes, Spiro has done this."

Miles and Ward were recovering somewhat from their initial astonishment. "What place is this?" asked the former.

"This is Apex—or, rather, the Palace of the Heads in Apex."

The Palace of the Heads! The two Americans tried to control their bewilderment.

"Pardon us if we don't understand. Everything is so strange. First the submarine was wrecked. Then we entered the crystal room and the tunnel vanished. We can't understand how this place can be at the bottom of the Atlantic."

"It isn't at the bottom of the Atlantic."

"Not at the bottom? Then where?"

"It isn't," said the voice slowly, "in your world at all."

The import of what was said did not at first penetrate the minds of the Americans. "Not in our world?" they echoed stupidly.

"Come," said the crippled man smiling inscrutably, "you are tired and hungry. Later I shall explain more." His strangely colored eyes bored into their own. "Sleep," said his voice softly, imperatively; and though they fought against the command with all the strength of their wills, heaviness weighted down their eyelids and they slept.

From dreamless sleep they awakened to find that fatigue had miraculously vanished, that their wounds were healed and their bodies and clothes were free of slime and filth. All but one of the crippled men—for so in their own minds they termed the odd individuals—had gone away. That one was the man who had first addressed them.

"Do not be alarmed," he said. "In our own fashion we have given you food and rest and attended to your comfort."

Ward smiled, though a trifle uncertainly. "We are not easily frightened," he