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 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.