in silence, his keen mind considering every aspect of the motions possible, of velocity, of acceleration, of inertia. He already knew well Seaton's resourcefulness in crises and his physical and mental strength.

"As far as I can see, that might be safe," he admitted finally, "and we really should know something about it besides the theory."

"Fine, Mart—let's get busy! I'll be ready in five minutes. Yell for the girls, will you? They'd break us off at the ankles if we pull anything new without letting them in on it."

A few minutes later the "girls" strolled out into Crane Field, arms around each other—Dorothy Seaton, her gorgeous auburn hair framing violet eyes and vivid coloring; black-haired, dark-eyed Margaret Crane.

"Br-r-r, it's cold!" Dorothy shivered, wrapping her coat more closely about her. "This must be the coldest day Washington has seen for years!"

"It is cold," Margaret agreed. "I wonder what they are going to do out here, this kind of weather?"

As she spoke, the two men stepped out of the "testing shed"—the huge structure that housed their Osnomian-built space-cruiser, "Skylark II." Seaton waddled clumsily, wearing as he did a Crane vacuum-suit which, built of fur, canvas, metal and transparent silica, braced by steel netting and equipped with air-tanks and heaters, rendered its wearer independent of outside conditions of temperature and pressure. Outside this suit he wore a heavy harness of leather, buckled about his body, shoulders, and legs, attached to which were numerous knobs, switches, dials, bakelite cases, and other pieces of apparatus. Carried by a strong aluminum framework in turn supported by the harness, the universal bearing of a small power-bar rose directly above his grotesque-looking helmet.

"What do you think you're going to do in that thing, Dickie?" Dorothy called. Then, knowing that he could not hear her voice, she turned to Crane. "What are you letting that precious husband of mine do now, Martin? He looks as though he were up to something."

While she was speaking, Seaton had snapped the release of his face plate.

"Nothing much, Dottie. Just going to show you-all the zone of force. Mart wouldn't let me turn it on, unless I got all cocked and primed for a year's journey into space."

"Dot, what is that zone of force, anyway?" asked Margaret.

"Oh, it's something Dick got into his head during that awful fight they had on Osnome. He hasn't thought of anything else since we got back. You know how the attractors and repellers work? Well, he found out something funny about the way everything acted while the Mardonalians were bombarding them with a certain kind of a wave-length. He finally figured out the exact ray that did it, and found out that if it is made strongly enough, it acts as if a repeller and attractor were working together—only so much stronger that nothing can get through the boundary, either way—in fact, it's so strong that it cuts anything in two that's in the way. And the funny thing is that there's nothing there at all, really; but Dick says that the forces meeting there, or something, make it act as though something really important were there. See?"

"Uh-huh," assented Margaret, doubtfully, just as Crane finished the final adjustments and moved toward them. A safe distance away from Seaton, he turned and waved his hand.

Instantly Seaton disappeared from view, and around the place where he had stood there appeared a shimmering globe some twenty feet in diameter—a globe apparently a perfect spherical mirror, which darted upward and toward the south. After a moment the globe disappeared and Seaton was again seen. He was now standing upon a hemispherical mass of earth. He darted back toward the group upon the ground, while the mass of earth fell with a crash a quarter of a mile away. High above their heads the mirror again encompassed Seaton, and again shot upward and southward. Five times this maneuver was repeated before Seaton came down, landing easily in front of them and opening his helmet.

"It's just what we thought it was, only worse," he reported tersely. "Can't do a thing with it. Gravitation won't work through it—bars won't—nothing will. And dark? Dark! Folks, you ain't never seen no darkness, nor heard no silence. It scared me stiff!"

"Poor little boy—afraid of the dark!" exclaimed Dorothy. "We saw absolute blackness in space."

"Not like this, you didn't. I just saw absolute darkness and heard absolute silence for the first time in my life. I never imagined anything like it—come on up with me and I'll show it to you."

"No you won't!" his wife shrieked as she retreated toward Crane. "Some other time, perhaps."

Seaton removed the harness and glanced at the spot from which he had taken off, where now appeared a hemispherical hole in the ground.

"Let's see what kind of tracks I left, Mart," and the two men bent over the depression. They saw with astonishment that the cut surface was perfectly smooth, with not even the slightest roughness or irregularity visible. Even the smallest loose grains of sand had been sheared in two along a mathematically exact hemispherical surface by the inconceivable force of the disintegrating copper bar.

"Well, that sure wins the——"

An alarm bell sounded. Without a glance around, Seaton seized Dorothy and leaped into the testing shed. Dropping her unceremoniously to the floor he stared through the telescope sight of an enormous ray-generator which had automatically aligned itself upon the distant point of liberation of intra-atomic energy which had caused the alarm to sound. One hand upon the switch, his face was hard and merciless as he waited to make sure of the identity of the approaching space-ship, before he released the frightful power of his generator upon it.

"I've been expecting DuQuesne to try it again," he gritted, striving to make out the visitor, yet more than two hundred miles distant. "He's out to get you, Dot—and this time I'm not just going to warm him up and scare him away, as I did last time. This time that misguided mutt's going to get frizzled right.... I can't locate him with this small telescope, Mart. Line him up in the big one and give me the word, will you?"

"I see him, Dick, but it is not DuQuesne's ship. It is built of transparent arenak, like the 'Kondal.' Even though it seems impossible, I believe it is the 'Kondal'."

"Maybe so, and again maybe DuQuesne built it—or stole it. On second thought, though, I don't believe that DuQuesne would be fool enough to tackle us again in the same way—but I'm taking no chances.... O. K., it is the 'Kondal,' I can see Dunark and Sitar myself, now."

The transparent vessel soon neared the field and the four Terrestrials walked out to greet their Osnomian friends. Through the arenak walls they recognized Dunark, Kofedix of Kondal, at the controls, and saw Sitar, his beautiful young queen, lying in one of the seats near the wall. She attempted a friendly greeting, but her face was strained as though she were laboring under a burden too great for her to bear.

Trying to help her, half kneeling over her, Dunark struggled, his green skin paling to a yellowish tinge at the touch of the bitter and unexpected cold.

As they watched, Dunark slipped a helmet over his head and one over Sitar's, pressed a button to open one of the doors, and supported her toward the opening.

"They mustn't come out, Dick!" exclaimed Dorothy in dismay. "They'll freeze to death in five minutes without any clothes on!"

"Yes, and Sitar can't stand up under our gravitation, either—I doubt if