The two women gazed in extreme darkness. The other side of the ridge of rock was black as night. From side to side the ridge extended, like a jagged knife edge on a prodigious scale; it seemed infinite in extent. Behind them—that is, at their feet-lay the stone-covered expanse they had just traversed; ahead of them there was—nothingness itself.

Cunora shook with fear and cold. "Let us not go on, Rolla!" she whimpered. "I like not the looks of this void; it may contain all sorts of beasts. I—I am afraid!" She began to sob convulsively. Rolla peered into the darkness. Nothing whatever was to be seen. It was as easy to imagine enemies as friends; easier in fact. What might not the unknown hold for them?

"We cannot stay here," spoke Rolla, with what energy her condition would permit. "We could not—hold on. Nor can we return now; They would surely find us!"

But Cunora's courage, which had never faltered in the face of familiar dangers, was not equal to the unknown. She wailed: "Rolla! A little way back—a hollow in the rock! 'Tis big enough to shelter me! I would— rather stay there than—go on!"

"Ye would rather die there, alone!"

Cunora hid her face. "Let me have half the food! I can go back to the pool—for water! And maybe," hopefully—"maybe They will give up the search in time."

"Aye," from Rolla, bitterly. "And in time Dulnop will die, if we do nothing for him—and for Corrus!"

Cunora fell to sobbing again. "I cannot help it! I am—afraid!"

Rolla scarcely heard. An enormous idea had just occurred to her. She had told the girl to think of Dulnop and Corrus; but was it not equally true that they should think of all the other humans, their fellow slaves, each of whom had suffered nearly as much? Was not the fire equally precious to them all?

She started to explain this to the girl, then abruptly gave it up. It was no use; Cunora's mind was not strong enough to take the step. Rolla fairly gasped as she realized, as no Sanusian had realized before, that she had been given the responsibility of rescuing A WHOLE RACE.

Fire she must have! And since she could not, dared not, seek it here, she must try the other side of the world. And she would have to do it— alone!

"So be it!" she said loudly in a strange voice. "Ye stay here and wait,
Cunora! I go on!"

And for fear her resolution would break down, she immediately crept over the edge. She clung to the rock as though expecting to be dragged from it. Instead, as she let her feet down into the blackness, she could feel solid rock beneath her body, quite the same as she had lain upon a moment before. It was like descending the opposite side of an incredibly steep mountain, a mountain made of blackness itself.

The women gave one another a last look. For all they knew, neither would gaze upon the other again. Next moment, with Cunora's despairing cry ringing in her ears, Rolla began to crawl backward and downward.

She could plainly see the sun's level rays above her head, irregular beams of yellowish light; it served slightly to illuminate her surroundings. Shortly, however, her eyes became accustomed to the darkness; the stars helped just as they had always helped; and soon she was moving almost as freely as on the other side.

Once she slipped, and slid down and to one side, for perhaps ten feet. When she finally grabbed a sharp projecting ledge and stopped, her vision almost failed from the terrible effort she had put forth. She could scarcely feel the deep gash that the ledge had made in her finger- tips.

After perhaps half an hour of hard work among bare rocks exactly like those she had quit, she stopped for a prolonged rest. As a matter of course, she stared at the sky; and then came her first discovery.

Once more let it be understood that her view was totally different from anything that has ever been seen on the earth. To be sure, "up" was over her head, and "down" was under her feet; nevertheless, she was stretched full length, face down, on the rock. In other words, it was precisely as though she were clinging to a cliff. Sky above, sky behind and all sides; there were stars even under her feet!

But all her life she had been accustomed, at night, to see that broad band of silver light across the heavens. She had taken it for granted that, except at two seasons of the year, for short periods, she would always see "the Silvery Way." But to-night—there was no band! The whole sky was full of—stars, nothing else!

It will be easier to picture her wonder and uneasiness if she is compared mentally with a girl of five or six. Easier, too, to appreciate the fact that she determined to go on anyhow. Mile after mile was covered in the darkness. Rolla was on the point of absolute exhaustion; but she dared not sleep until she reached a spot where there was no danger of falling. It was only after braving the gale for over four hours in the starlight that Rolla reached a point where she was no longer half crawling, half creeping, but moved nearly erect. Shortly she was able to face the way she was going; and by leaning backward was able to make swift progress. In another half-hour she was walking upright. Still no explanation of the mystery!

Finding a sheltered spot, she proceeded to make herself comparatively comfortable on the rock. Automatically, from habit, she proceeded to keep watch; then she must have remembered that there was now no need for vigilance. For she lay herself down in the darkness and instantly fell asleep.

Three hours later—according to the time kept by the watchers on the earth—Rolla awoke and sat up in great alarm. And small wonder.

It was broad daylight! The sun was well above the horizon; and not only the Sanusian but the people on the earth were vastly puzzled to note that it was the western horizon! To all appearances, Rolla had slept a whole day in that brief three hours.

Shortly her nerves were steady enough for her to look about, uncomprehendingly, but interestedly, as a child will. There was nothing but rock to be seen; a more or less level surface, such as she had toiled over the day before. The day before! She glanced at the sun once more, and her heart gave a great leap.

The sun was rising—IN THE WEST!

"'Tis a world of contraries," observed Rolla sagely to herself. "Mayhap I shall find all else upside down."

She ate heartily, and drank deep from her gourd. There was not a cupful remaining. She eyed it seriously as she got to her feet.

Another look back at that flat expanse of granite, which had so gradually and so mysteriously changed from precipice to plain, and Rolla strode on with renewed vigor and interest. Presently she was able to make out something of a different color in the distance, and soon was near enough to see some bona-fide bushes; a low, flowerless shrub, it is true, but at least it was a living thing.

Shortly the undergrowth became dense enough to make it somewhat of an effort to get through. And before long she was noticing all manner of small creatures, from bugs to an occasional wandering bird. These last, especially, uttered an abrupt but cheerful chirp which helped considerably to raise her spirits. It was all too easy to see, in her fancy, her lover helpless and suffering in the power of those cold- blooded, merciless insects.

In an hour or two she reached the head of a small stream. Hurrying down its banks as rapidly as its undergrowth would permit, Rolla followed its course as it bent, winding and twisting, in the direction which had always been north to her, but which the sun plainly labeled "south." Certainly the sun mounted steadily toward the zenith, passing successively through the positions corresponding to four, three and two o'clock, in a manner absolutely baffling.

About noon she came out of the canon into the foothills. Another brief rest, and from the top of a knoll she found herself looking upon a valley about the size of the one she called "home." Otherwise, it was very different. For one thing, it was far better watered; nowhere could she see the half-dried brownishness so characteristic of her own land. The whole surface was heavily grown with all manner of vegetation; and so far as she could see it was all absolutely wild. There was not a sign of cultivation.

Keeping to the left bank of the river, a much broader affair than any she had seen before, Rolla made her way for several miles with little difficulty. Twice she made wide detours through the thicket, and once it was necessary to swim a short distance; the stream was too deep to wade. The doctor watched the whole affair, purely as a matter of professional interest.

"She is a magnificent specimen physically," he said in his impersonal way, "and she shows none of the defects of the African savages."

And such was his manner, in speaking of his distant "patient," that Billie took it entirely as a matter of course, without the slightest self-consciousness because of Van Emmon and Smith.

All this while Rolla had been intent, as before, upon finding some of the coveted crystals. She had no luck; but presently she discovered something decidedly worth while—a fallen tree trunk, not too large, and near enough to the bank to be handled without help. A few minutes later she was floating at ease, and making decidedly better time.

A half-hour of this—during which she caught glimpses of many animals, large and small, all of which fled precipitately—and she rounded a sharp bend in the stream, to be confronted with a sight which must have been strange indeed to her. Stretching across the river was—a network of rusty wire, THE REMAINS OF A REINFORCED CONCRETE BRIDGE.

There was no doubt of this. On each bank was a large, moss-grown block of stone, which the doctor knew could be nothing else than the old abutments. Seemingly there had been only a single span.

The woman brought the log to the shore, and examined the bridge closely. Instinctively she felt that the structure argued a high degree of intelligence, very likely human. A little hesitation, and then she beached her log, ascended the bank, and looked upon the bridge from above.

A narrow road met her eyes. Once it might have been twice as wide, but now the thicket encroached until there was barely room enough, judged the doctor, for a single vehicle to pass. Its surface was badly broken up—apparently it had been concrete—and grass grew in every crack. Nevertheless, it was a bona-fide road.

For the first time in a long while, Rolla was temporarily off her guard. The doctor was able to impress her with the idea of "Follow this road!" and to his intense gratification the woman started away from the river at once.

Soon the novelty of the thing wore off enough for her to concern herself with fresh food. She discovered plenty of berries, also three kinds of nuts; all were strange to her, yet she ate them without question, and suffered nothing as a result, so far as the doctor could see.

The sun was less than an hour from the horizon when the road, after passing over a slight rise, swung in a wide arc through the woods and thus unveiled a most extraordinary landscape. It was all the more incredible because so utterly out of keeping with what Rolla had just passed through. She had been in the wilderness; now—

A vast city lay before her. Not a hundred yards away stood a low, square building of some plain, gray stone. Beyond this stretched block upon block—mile upon mile rather—of bona-fide residences, stores and much larger buildings. It is true that the whole place was badly overgrown with all sorts of vegetation; yet, from that slight elevation, there was no doubt that this place was, or had been, a great metropolis.

Presently it became clear that "had been" was the correct term. Nothing but wild life appeared. Rolla looked closely for any signs of human occupancy, but saw none. To all appearances the place was deserted; and it was just as easy to say that it had been so for ten centuries as for one.

"There seems no good reason why I should not go farther," commented Rolla aloud, to boost her courage. "Perchance I shall find the magic stone in this queer place."

It speaks well for her self-confidence that, despite the total strangeness of the whole affair—a city was as far out of her line as aviation to a miner—she went forward with very little hesitation. None of the wild creatures that scuttled from her sight alarmed her at all; the only things she looked at closely were such bees as she met. The insects ignored her altogether, except to keep a respectful distance. "These masters," observed Rolla with satisfaction, "know nothing of me. I shall not obey them till they threaten me." But there was no threatening.

For the most part the buildings were in ruins. Here and there a structure showed very little damage by the elements. In more than one case the roof was quite intact. Clearly the materials used were exceptional, or else the place had not been deserted very long. The doctor held to the latter opinion, especially after seeing a certain brown-haired dog running to hide behind a heap of stones.

"It was a dog!" the doctor felt sure. To Rolla, however, the animal was even more significant. She exclaimed about it in a way which confirmed the doctor's guess. On she went at a faster rate, plainly excited and hopeful of seeing something further that she could recognize.

She found it in a hurry. Reaching the end of one block of the ruins, she turned the corner and started to follow the cross street. Whereupon she stopped short, to gaze in consternation at a line of something whitish which stretched from one side of the "street" to the other.

It was a line of human skeletons.

There were perhaps two hundred in the lot, piled one on top of the other, and forming a low barrier across the pavement. To Rolla the thing was simply terrible, and totally without explanation. To the people on the earth, it suggested a formation of troops, shot down in their tracks and left where they had fallen. The doctor would have given a year of his life if only Rolla had had the courage to examine the bones; there might have been bullet-holes, or other evidence of how they had met their death.

The Sanusian chose rather to back carefully away from the spot. She walked hurriedly up the street she had just left, and before going another block came across two skeletons lying right in the middle of the street. A little farther on, and she began to find skeletons on every hand. Moreover—and this is especially significant—the buildings in this locality showed a great many gaps and holes in their walls, such as might have been made by shell-fire.

This made it easier to understand something else. Every few yards or so the explorer found a large heap of rust in the gutter, or what had once been the gutter. These heaps had little or no shape; yet the doctor fancied he could detect certain resemblances to things he had seen before, and shortly declared that they were the remains of motors.

"Can't say whether they were aircraft or autos, of course," he added, "but those things were certainly machines." Later, Rolla paid more attention to them, and the doctor positively identified them as former motor-cars.

The sun had gone down. It was still quite light, of course; darkness would not come for a couple of hours. Rolla munched on what food she had, and pressed on through the ruins. She saw skeletons and rusted engines everywhere, and once passed a rounded heap of rust which looked like nothing so much as a large cannon shell. Had the place been the scene of a battle?

Just when she had got rather accustomed to the place and was feeling more or less at her ease, she stopped short. At the same time the doctor himself fairly jumped in his chair. Somewhere, right near at hand, on one of the larger structures, a bell began to ring!

It clanged loudly and confidently, giving out perhaps thirty strokes before it stopped. The stillness which followed was pretty painful. In a moment, however, it was broken as effectively as any silence can be broken.

A man's voice sounded within the building.

Immediately it was replied to, more faintly, by several others. Then came the clatter of some sort of utensils, and sundry other noises which spoke loudly of humans. Rolla froze in her tracks, and her teeth began to chatter.

Next moment she got a grip on herself. "What difference doth it make, whether they be friend or enemy?" she argued severely, for the benefit of her shaking nerves. "They will give thee food, anyhow. And perchance they know where liveth the magic stone!"

In the end Rolla's high purpose prevailed over her weak knees, and she began to look for the entrance to the place. It was partly in ruins— that is, the upper stories—but the two lower floors seemed, so far as their interior could be seen through the high, unglazed windows, to be in good condition. There were no doors on that street.

Going around the corner, however, Rolla saw a high archway at the far corner of the structure. Approaching near enough to peek in, she saw that this arch provided an opening into a long corridor, such as might once have served as a wagon or auto entrance. After a little hesitation she went in.

She passed a door, a massive thing of solid brassy metal, such as interested the doctor immensely but only served to confuse the explorer. A little farther on, and the corridor became pretty dark. She passed another brass door, and approached the end of the pavement. There was one more door there; and she noted with excitement that it was open.

She came closer and peered in. The room was fairly well lighted, and what she saw was clear-cut and unmistakable. In the middle of the room was a long table, and seated about it, in perfect silence, sat an even dozen men.