Ten seconds after entering the arroyo I was stumbling along in an absolute blackness. It almost seemed to me that I could reach out my hands and touch it, as one would touch a wall. Or perhaps not exactly that, for a wall is hard, and this darkness was soft and yielding, in the manner of enveloping hangings. Directly above me was a narrow, jagged, and irregular strip of sky with stars. I splashed in the brook, finding its waters strangely warm, rustled through the grasses, my head back, chin out, hands extended as one makes his way through a house at night. There were no sounds except the tinkle of the sulphurous stream: successive bends in the canon wall had shut off even the faintest echoes of the bacchanalia on the beach.

The way seemed much longer than by daylight. Already in my calculation I had traversed many times the distance, when, with a jump at the heart, I made out a glow ahead, and in front of it the upright logs of the stockade.

To my surprise the gate was open. I ascended the gentle slope to the valley's level--and stumbled over a man lying prostrate, shivering violently, and moaning.

I bent over to discover whom it might be. As I did so a brilliant light seemed to fill the valley, throwing an illumination on the man at my feet. I saw it was the Nigger, and perceived at the same instant that he was almost beside himself with terror. His eyes rolled, his teeth chattered, his frame contracted in a strong convulsion, and the black of his complexion had faded to a washed-out dirty grey, revolting to contemplate. He felt my touch and sprang to his feet, clutching me by the shoulder as a man clutching rescue.

"My Gawd!" he shivered. "Look! Dar it is again!"

He fell to pattering in a tongue unknown to me--charms, spells, undoubtedly, to exorcise the devils that had hold of him. I followed the direction of his gaze, and myself cried out.

The doctor's laboratory stood in plain sight between the two columns of steam blown straight upward through the stillness of the evening. It seemed bursting with light. Every little crack leaked it in generous streams, while the main illumination appeared fairly to bulge the walls outward. This was in itself nothing extraordinary, and indicated only the activity of those within, but while I looked an irregular patch of incandescence suddenly splashed the cliff opposite. For a single instant the very substance of the rock glowed white hot; then from the spot a shower of spiteful flakes shot as from a pyrotechnic, and the light was blotted out as suddenly as it came. At the same moment it appeared at another point, exhibited the same phenomena, died, flashed out at still a third place, and so was repeated here and there with bewildering rapidity until the walls of the valley crackled and spat sparks. Abruptly the darkness fell.

As abruptly it was broken again by a similar exhibition; only this time the fire was blue. Blue was followed by purple, purple by red. Then ensued the briefest possible pause, in which a figure moved across the bars of light escaping through the chinks of the laboratory, and then the whole valley blazed with patches of vari-coloured fire. It was not a reflection: it was actual physical conflagration of the solid rock, in irregular areas. Some of the fire shapes were most fantastic. And with the unexpectedness of a bursting shell the surface of the ground before our feet crackled into a ghastly blue flame.

The Nigger uttered a cry in his throat and disappeared. I felt a sharp breath on my neck, an ejaculation of surprise at my very ear. It was startling enough to scare the soul out of a man, but I held fast and was just about to step for............