It came from beneath our feet, a sound in the earth. We seemed to hear it with our feet as much as with our ears. Its dull resonance was muffled by distance, thick with the quality of intervening substance. No sound that I can imagine could have astonished us more, or have changed more completely the quality of things about us. For this sound, rich, slow, and deliberate, seemed to us as though it could be nothing but the striking of some gigantic buried clock.
Boom? Boom? Boom.
Sound suggestive of still cloisters, of sleepless nights in crowded cities, of vigils and the awaited hour, of all that is orderly and methodical in life, booming out pregnant and mysterious in this fantastic desert! To the eye everything was unchanged: the desolation of bushes and cacti waving silently in the wind, stretched unbroken to the distant cliffs, the still dark sky was empty overhead, and the hot sun hung and burned. And through it all, a warning, a threat, throbbed this enigma of sound.
Boom? Boom? Boom?
We questioned one another in faint and faded voices.
"A clock?"
"Like a clock!"
"What is it?"
"What can it be?"
"Count," was Cavor's belated suggestion, and at that word the striking ceased.
The silence, the rhythmic disappointment of the silence, came as a fresh shock. For a moment one could doubt whether one had ever heard a sound. Or whether it might not still be going on. Had I indeed heard a sound?
I felt the pressure of Cavor's hand upon my arm. He spoke in an undertone, as though he feared to wake some sleeping thing. "Let us keep together," he whispered, "and look for the sphere. We must get back to the sphere. This is beyond our understanding."
"Which way shall we go?"
He hesitated. An intense persuasion of presences, of unseen things about us and near us, dominated our minds. What could they be? Where could they be? Was this arid desolation, alternately frozen and scorched, only the outer rind and mask of some subterranean world? And if so, what sort of world? What sort of inhabitants might it not presently disgorge upon us?
And then, stabbing the aching stillness as vivid and sudden as an unexpected thunderclap, came a clang and rattle as though great gates of metal had suddenly been flung apart.
It arrested our steps. We stood gaping helplessly. Then Cavor stole towards me.
"I do not understand!" he whispered close to my face. He waved his hand vaguely skyward, the vague suggestion of still vaguer thoughts.
"A hiding?place! If anything came?"
I looked about us. I nodded my head in assent to him.
We started off, moving stealthily with the most exaggerated precautions against noise. We went towards a thicket of scrub. A clangour like hammers flung about a boiler hastened our steps. "We must crawl," whispered Cavor.
The lower leaves of the bayonet plants, already overshadowed by the newer ones above, were beginning to wilt and shrivel so that we could thrust our way in among the thickening stems without serious injury. A stab in the face or arm we did not heed. At the heart of the thicket I stopped, and stared panting into Cavor's face.
"Subterranean," he whispered. "Below."
"They may come out."
"We must find the sphere!"
"Yes," I said; "but how?"
"Crawl till we come to it."
"But if we don't?"
"Keep hidden. See what they are like."
"We will keep together," said I.
He thought. "Which way shall we go?"
"We must take our chance."
