"Look!" cried the Arcturian, pointing down through the window, his eyes staring. "Below us-look!"
I gazed down, then felt the blood drive from my heart at what I saw. For directly beneath us one of the vast prominences of flaming gas was suddenly shooting up from the nebula's surface, straight toward us, a gigantic tongue of fire beside which our ship was but as a midge beside a great blaze. I shouted, sprang to the control, but even as I laid hands on the levers there was a tremendous rush of blinding flame all about our ship, and then we three had been flung violently into a corner of the pilot room and the cruiser was being whirled blindly about with lightning speed by the vast current of flaming gas that had gripped it.
All about us was the thunderous roaring of the fires that held us, and now as we sprawled helpless on the room's floor I sensed that our ship was falling, plunging down with the downward-sinking geyser of flame that held it. Struggling to gain my feet, while the pilot room spun dizzily about me, I glimpsed through the shifting fires outside the window the nebula's flaming surface, just below us, a raging sea of fiery gas toward which we were dropping plummet-like. Then, as a fresh gyration of the plunging ship flung me once more to the floor, I heard the thundering roar about us suddenly intensified, terrible beyond expression, while now through the window was visible only a single solid mass of blinding flame, and while our cruiser at the same moment rocked and whirled crazily beneath the impetus of a dozen different forces. And as understanding of what had happened flashed across my brain I cried out hoarsely to my two companions.
"The nebula!" I cried. "The current that held us has sucked us down into the nebula itself!"
All about us now was only one tremendous sheet of fire, whose heat was rapidly penetrating through even our heat-resistant walls and windows. Swiftly the air in the little pilot room was becoming hot, suffocating, and already the walls were burning to the touch. The ship, I knew, could not stand such heat for many minutes more, yet every moment was taking us farther into the nebula's fiery depths, whirling us wildly on with velocity inconceivable. Borne by its mighty interior currents we were sweeping on and on into that universe of flame, its vast fires roaring about us like the thunder of doom, deafening, awful, a cosmic, bellowing clamor that was like the mighty shouting of a universe made vocal.
On and on it roared, about us, and on and on we whirled into the depths of those mighty fires, toward our doom. The air had become stifling, unbreathable, and the walls were beginning to glow dully. Now, with a last effort, I dragged myself from support to support until I had clutched the control levers, opening them to the last notch. Yet though the generators beneath hummed with highest power it was as though they were silent, for in the grip of the nebula's giant fire-currents the cruiser plunged madly on. And as its whirling catapulted me again to the room's corner, where my two companions clung, I felt my lungs scorching with each panting breath, felt my senses leaving me.
Then, through the unconsciousness that was creeping upon me, I heard a grating wrench from somewhere in the cruiser's walls, a loud and ominous cracking, and knew that under the terrific fires around us those walls were already warping, giving way. Another wrenching crack came, and another, sounding loud in my ears above the thunderous roar of the flames about us. In a moment the walls would give completely, and in the rushing fires of the nebula about us we would meet the end. In a moment-
But what was that? The thunderous clamor about us had suddenly dwindled, ceased, and at the same moment our ship had righted itself, was humming serenely on. Slowly I raised my head, then stared in utter astonishment. The fires outside the windows, the terrific sea of flame about us, had vanished, and we were again flashing on through open space. And now Jor Dahat beside me had seen also, and was rising to his feet.
"We're out of the nebula!" he cried. "That current must have taken us back up to the surface-back out into space again-"
He was at the window now, gazing eagerly out, while I struggled up in turn. And as I did so I saw awe falling upon his face as he gazed, and heard from him a whispered exclamation of utter astonishment. Then I, too, was on my feet, with Sar Than, and we were at the window beside him, staring forth in turn.
My first impression was of vast space, a colossal reach of space that stretched far away before us, and into which our ship was racing on. And then I saw, with sudden awe and wonder, that this vast space was not the unlimited, unbounded space we were accustomed to, but was limited, was bounded, bounded by a colossal sheet of flowing flame that hemmed it in all directions. Above and below and before and behind us stretched this mighty wall of flame, a gigantic shell of fire that enclosed within itself the vast space in which our cruiser raced, a space large enough to hold within it a dozen solar systems like my own. Stunned, we gazed out into that mighty flame-bounded space, and then I flung out a hand toward it in sudden comprehension.
"We're inside the nebula!" I cried. "It's hollow! This vast open space lies at its heart, and those currents carried us down into it!"
For I saw now that this was the explanation. Unsuspected by any in the Galaxy the mighty nebula was hollow, its gigantic globe of flaming gas holding at its heart this mighty empty space, a space mighty in extent to our eyes, but small compared to the thickness of the great shell of fire that enclosed it. And down through that fire, that vast ocean of flame, the currents of the nebula had brought us, from its outer surface, down into this great space at its heart of which none had ever dreamed, and into which we had been the first in all the Galaxy to penetrate.
While we gazed across it, stunned, our cruiser was racing on into this vast hollow, away from the wall of flame behind us from which we had just emerged. And now, as we flashed on, Sar Than cried out too and pointed ahead. There, standing out black against the encircling walls of fire in the distance, was a small round spot, a spot that was growing to a black globe as we hurtled on toward it, a globe that hung motionless at the center of this mighty space, here at the nebula's heart. We were racing straight into the great cavity toward it and now there came a low exclamation from Jor Dahat, beside me, as his eyes took in the great globe ahead.
"A planet!" he whispered. "A planet here-within the nebula!"
My own eyes were fixed upon it, and slowly I nodded, but made no other answer as we flashed on toward the object of our attention, the black sphere ahead. And now as we swept on we saw that it was a sphere of truly titanic dimensions, larger by far than any of the Galaxy's countless worlds, and that as it hung there, at the nebula's heart, it was slowly revolving, spinning, as fast or faster than the nebula itself. Black and mighty it hung there, while all around it, millions of miles from it, there flamed the nebula's encircling fires. On and on we raced toward it, and for all those minutes of flashing flight none of us spoke, and there was no sound in the pilot room but the throbbing drone of the generators below. I think that we all felt instinctively that in the grim, colossal globe ahead lay the answer to what we had come to solve, and as we hurtled on toward it we watched it broadening before us in tense silence.
Larger and larger it was becoming, larger until its great black circle filled half the heavens before us. By then I had decreased our speed to a fraction of its former figure, and as we swept in toward the giant world I lessened it still further. Slowly, ever more slowly we moved, and now were circling above the great black planet, were beginning to drop cautiously down toward it. Eagerly we watched as the mighty world's surface changed from convex to concave, and as we dropped on we saw the needle of our atmosphere-pressure dial moving steadily forward, to show that this strange world had air, at least. Then all else was forgotten as our eyes took in the scene below.