Jan looked at his shoulder. There was a gaping, angry wound in it. In some way this man had hurt him. He didn't stop to analyze how or why. The fact was there. He could either turn to run or advance to fight,—and he had never yet turned to run.

He had learned the trick of weaving in and slashing, and withdrawing quickly. This stood him in good stead. The queer thing in the man's hand barked at him, but missed hurting him each time.

Jan's knife reached in unerringly and slashed the wrist of the hand holding the spitting thing. The blood gushed out in a pulsating stream.

The man dropped the gun and tried to stem the flow. Jan took this opportunity to dart in again and slide his blade across the fat neck.

A look of horrible realization appeared in the man's eyes. He turned, stumbled forward, and fell headlong into the space above the mysteriously glistening square slab. The soles of his shoes seemed to hang in the air briefly before they followed the rest of him into nothingness.

Jan touched his hand gingerly to the raw wound in his shoulder. It was a day's journey to the healing spring where he could bathe the wound and plaster it with healing mud.

His eyes surveyed the scene for a last time, taking in the strange slab flush with the ground, the skeleton of girders that jutted out from each side of the gorge, and the strange heaps of steel and masonry on the other side. Then he turned and started back the way he had come. By the time he vanished over the rise he had settled into the long, easy trot that would carry him a good fifteen miles an hour all the way to the healing spring.

Behind him the glistening square slab rested, oblivious of his departure. The two halves of the wrecked bridge still reached yearning, torn arms toward one another; and across the gap the ruins of the huge city squatted in silence, coldly aloof.

A wind born leaf dipped down in coy flight to investigate the slab—and slipped past the veil. The fresh cut end of the stick Jan had cut formed a white dot on the green carpet of stunted grass. Bright red stained a large spot on the green and formed a ribbon that led to the edge of the square of cold luminescence;—the red trail of blood left by the strange visitor from out of the square. And in the clean blue sky a bright sun beamed benignly over all, ignoring—

"My leader!" Carl Grinch clicked his heels softly, and bowed stiffly from the waist. His high, intellectual forehead, clear blue eyes and finely cut features, together with his civilian garb, indicated that he was a scientist. He was, in fact, much more than a scientist. He was THE scientist of Aleme.

"At ease." The leader waved a gloved hand carelessly, a cruel smile twisting the harsh face of the dictator of Aleme and avowed leader of downtrodden masses in every country on Amba.

His eyes held a gleam of satisfaction as he watched the uneasy tenseness of the scientist. He gloried in a sadistic satisfaction at his power to snuff out the life of one so great,—or let him live to serve his Leader.

"I told you not to come to me until you had succeeded in the task I set you," Generalissimo Hute Hitle said coldly. "Your presence means that you have, no doubt?"

"Yes, my Leader," Carl Grinch smiled. "Everything is in readiness."

"Good," Hitle said. He rubbed his chin slowly, a smile of triumph creasing his face into unaccustomed wrinkles. "Now we can't lose. We will let loose the destruction and let it take its course. After it is over we will return to rule an unresisting planet. Explain again to me the theory of the device."

"The theory of operation of the devise is, of course, understandable only by a highly trained specialist," Carl Grinch said placatingly.

"You know what I mean," Hute Hitle snarled. "I'm not interested in what makes it work. Only in what it does."

"To begin with," Carl Grinch said. "Space has three dimensions. We live in those three dimensions of length, breadth, and thickness. This is