It was a question which made sleep impossible for me also that night.
Eleven
We made an early start next morning. It had been a wretched night, not improved by a false alarm from Holden during the small hours when he fancied he had seen a shadow moving further down the tunnel. Fortunately he had not fired, as he might well have injured himself with the ricochet but the infernal noise of the klaxon which tumbled us from broken sleep, and the equally noisy inquest which followed, made rest for the remaining hours impossible. By five we were moving forward again, myself at the controls of Number 1 which, despite his previous instructions, the Professor had insisted should lead.
It was a position of honour, as Van Damm had said, but I could not help wishing as I juggled with the steering handles, that Number 2 had gone ahead as planned, as the lead under our present conditions was a far from relaxing station. It did not seem to worry Scarsdale who kept his night-glasses rigidly inclined through the windshield and occasionally gave me instructions to reduce or increase speed. Van Damm's voice came through on the radio at ten minute intervals and to outward purposes all was as it had been the previous day; but there had been a subtle change with the finding of Zalor's body and for myself I knew that I could never again regard these tunnels in quite the same way.
They had always been sinister — I was conscious of that the first instant the tractor rumbled beneath the great portico — but the knowledge that we had also now to deal with some force inimical to life charged every foot of the way with unknown terror. It could not be ruled out, however, that Zalor had been the victim of some quite natural disaster; a beast of the order of a mountain Hon, which perhaps inhabited the deepest caverns? But even as Van Damm put forward the supposition my own secret voices were mocking the theory; on what would living creatures of that sort subsist in these arid tunnels? And surely we should have seen some evidence of them long before now?
Beasts leave droppings or some other signs of their passing, but there had been no evidence of life of any sort. And then there was Holden's reaction; given that he might well have a nature particularly sensitive to death but Zalor's end had been so horrible that Holden had, for a time, been almost out of his mind; and even Scarsdale's grim resolve had been shaken. There remained other problems also; not least the puzzle of how the dwarf had managed to cover such a vast distance to arrive at the caves before the expedition. Or had he perhaps companions at Nylstrom who had carried him with them across the desert more swiftly than our tractors could travel?
There were endless possibilities here and my mind revolved them equally endlessly; the truth was that the alternatives were so disquieting that I was determined to find a natural explanation, however bizarre, which could be made to fit. In the meantime my hands automatically carried out their tasks; the wind blew with increasing warmth; and the needle of the compass pointed obstinately almost due north.
But we were not to travel very far today before a major landmark was reached; it was something after seven a.m. and the mileage indicator registered, I think, around eighty-four miles before I began to sense a slight change in the atmosphere. It was nothing immediately definable but I was conscious that Scarsdale had noted it also. I saw that he had his head cocked on one side, as though he were listening. But I noticed, a short while later, that he was not listening but looking at something. It was quite five minutes more, however, before I myself became aware of the phenomena which had arrested his attention.
This was mainly due to two factors; one, the position of the searchlight which reflected back a steady glow from the rocky walls of the corridor; and my own position, down below the chart-table where the upper edge of the windscreen prevented me from seeing the object of the Professor's curiosity. But as we progressed towards our eighty-fifth mile beneath the mountains there could no longer be any doubt. It was growing lighter.
We were five miles in depth below the mountain tops, according to Scarsdale's calculations and yet a form of twilight existed which made the full-time use of the searchlights unnecessary. We had now almost reached the ultimate point of the Professor's original exploration and from now on we would all be traversing unknown territory. The light underground at this point seemed to emanate from some phosphorescent source high up in the impenetrable fastness of the roof.
Curiously, it appeared directed entirely downwards, instead of at the sides of the tunnel so that the source of the illumination and the structure and height of the roof itself remained hidden. The light was bluish in tinting and gave a corpse-like pallor to the objects beneath and to our own faces, but it was a relief to be no longer within the stygian blackness through which we seemed to have been moving so long.
The light grew in strength, but at no time did it become strong enough to approximate to what we called earthlight — that is, ordinary daylight above — and at its greatest intensity resembled that of dusk in the tropics in the few moments before the sun disappears below the horizon. Nevertheless, it was a great boon to be able to move about and to perceive objects from a distance.
A short while after I was able to steer the tractor visually from surrounding observations, we came out from the tunnel and the vibrations which had been accompanying us for the past two days, died away. We were running on something which felt like and resembled the black sand in the mountain gorge. As soon as this occurred, Scarsdale called a halt, the searchlights were switched off and we all got out the tractors.
It was an extraordinary sight; we were in a vast cavern lit by the flickering, ghostly blue light which made the far distance shimmer and undulate. We appeared to be on a wide shore composed of the dark sand and a shingle-like substance, which grated beneath our feet. The light seemed to come from a 'sky' far above our heads but which Scarsdale explained was emanating from the phosphorescence in the roof of the cavern at a vast distance above us; this was the reason why we were still unable to see the limit of the gigantic geological formation which formed the cave.
We stayed near the tunnel entrance for about half an hour while my companions took measurements and navigational positions while I tried, possibly unsuccessfully, to capture something of the scene on film; the tunnel entrance into the vast cave was quite small at this point and appeared to be the only means of entry. The chisel-like marks on the engineered wall just ended, as though the tunnellers had got tired of their immense task and the surface of the cave interior was of natural rock.
I found myself next to Van Damm as we all wandered around, marvelling at the strange quality of the shimmering light.
'What I can't understand, doctor,' I said to Van Damm,' is how this ancient people realised they would come to this cavern.'
Van Damm smiled. 'Rather ask yourself, Plowright, whether the people who inhabited this cavern were not more concerned with breaking out and drilling a communication tunnel through the mountains to the open air and the valley beyond.'
The explanation was so simple and logical that I must have looked as foolish as I felt for Van Damm burst into a short,
barking laugh and said, 'Don't look so crest-fallen, man. Like many laymen you were merely working from the wrong premises.'
He excused himself and went to consult with Scarsdale while I finished my photographic work and collected my apparatus. The wind still blew freshly from the north but now it had a more glutinous taste to it; it was difficult to describe but I felt somehow as I had once felt when taken as a child on a long-promised first trip to the seaside.