dust, and the dust to molten lava, in which pools of fused tungsten-beryllium alloy bubbled slowly and sank.
“Ah, Jarth—they are a brave race, whatever we may say of their queer shape,” sighed Gresth Gkae as the last of Mars Center sank in bubbling lava. “They stung as they died.” For some minutes he was silent.
“We must move on,” he said at length. “I have been thinking, and it seems best that a few ships land here, and establish a fort, while some twenty move on to the satellite of the third planet and destroy the fort there. We cannot operate against the planet while that hangs above us.”
Seven ships settled to Mars, while the fleet came up from Jupiter to join with Gresth Gkae’s flight of ships on its way to Luna.
An automatically controlled ship was sent ahead, and began the bombardment. It approached slowly, and was not destroyed by the UV beams till it had come to within 40,000 miles of the fort. At 60,000 Gresth Gkae stationed his fleet—and returned to 150,000 immediately as the titanic UV beams of the Lunar Fort stretched out to their maximum range. The focus made a difference. One ship started limping back to Jupiter, in tow of a second, while the rest began the slow, methodical work of wearing down the defenses of the Lunar Fort.
Kendall looked out at the magnificent display of clashing, warring energies, the great, whirling spheres and discs of opalescent flame, and turned away sadly. “The men at Deenmor must have watched that for days. And at Mars Center.”
“How long can we hold out?” asked McLaurin.
“Three weeks or so, at the present rate. That’s a long time, really. And we can escape if we want to. The UV beams here have a greater range than any weapon the Strangers have, and with Earth so near—oh, we could escape. Little good.”
“What are you going to do?”
“I,” said Buck Kendall, suddenly savage, “am going to consign all the math machines in the universe to eternal damnation—and go ahead and build a machine anyway. I know that thing ought to be right. The math’s wrong.”
“There is no other thing to try?”
“A billion others. I don’t know how many others. We ought to get atomic energy somehow. But that thing infuriates me. A hundred things that math has predicted, that I have checked by experiment, simple little things. But—when I carry it through to the point where I can get something useful—it wriggles off into—uncertainty.”
Kendall stalked off to the laboratory. Devin was there working over the calculus machines, and Kendall called him angrily. Then more apologetic, he explained it was anger at himself. “Devin, I’m going to make that thing, if it blows up and kills me. I’m going to make that thing if this whole fort blows up and kills me. That math has blown up in my face for four solid months, and half killed me, so I’m going to kill it. Come on, we’ll make that damned junk.”
Angrily, furiously, Kendall drove his helpers to the task. He had worked out the apparatus in plan a dozen times, and now he had the plans turned into patterns, the patterns into metal.
Saucily, the “S Doradus” made the trip to and from Earth with patterns, and with metal, with supplies and with apparatus. But she had to dodge and fight every inch of the way as the Miran ships swooped down angrily at her. A fighting craft could get through when the Miran fleet was withdrawn to some distance, but the Mirans were careful that no heavy-loaded freighter bearing power supply should get through.
And Gresth Gkae waited off Luna in his great ship, and watched the steady streams of magnetic bombs exploding on the magnetic shield of the Lunar Fort. Presently more ships came up, and added their power to the attack, for here, the photo-cell banks could gather tremendous energy, and Gresth Gkae knew he would need to overcome this, and drain the accumulated power.
Gresth Gkae felt certain if he could once crack this nut, break down Earth, he would have the system. This was the home planet. If this fell, then the two others would follow easily, despite the fact that the few forts on the innermost planet, Mercury, could gather energy from the sun at a rate greater than their ships could generate.
It took Kendall two weeks and three days to set up his preliminary apparatus. They had power for perhaps four days more, thanks to the fact that the long Lunar day had begun shortly after Gresth Gkae’s impatient attack had started. Also, the “S Doradus” had brought in several hundred tons of charged mercury on each trip, though this was no great quantity individually, it had mounted up in the ten trips she had made. The “Cepheid,” her sister ship, had gone along on seven of the trips, and added to the total.
But at length the apparatus was set up. It was peculiar looking, and it employed a great deal of power, nearly as much as a UV beam in fact. McLaurin looked at it sceptically toward the last, and asked Buck: “What do you expect it to do?”
“I am,” said Kendall sourly, “uncertain. The result will be uncertainty itself.”
Which, considering things, was a surprisingly accurate statement. Kendall gave the exact answer. He meant to give an ironic comment. For the mathematics had been perfectly correct, only Buck Kendall misinterpreted the answer.
“I’ve followed the math with mechanism all the way through,” he explained, “and I’m putting power into it. That’s all I know. Somewhere, by the laws of cause and effect, this power must show itself again—despite what the damn math says.”
And in that, of course, Kendall was wrong. Because the laws of cause and effect didn’t hold in what he was doing now.
“Do you want to watch?” he asked at length. “I’m all set to try it.”
“I suppose I may as well.” McLaurin smiled. “In our close-knit little community the fate of one is of interest to all. If it’s going to blow up, I might as well be here, and if it isn’t, I want to be.”
Kendall smiled appreciatively and replied: “Let it be on thy own head. Here she goes.”
He walked over to the power board, and took command. Devin, and a squad of other scientists were seated about the room with every conceivable type and combination of apparatus. Kendall wanted to see what this was doing. “Tubes,” he called. “Circuits A and D. Tie-ins.” He stopped, the preliminary switches in. “Main circuit coming.” With a jerk he threw over the last contact. A heavy relay thudded solidly. The hum of a straining atostor. Then—
An electric motor, humming smoothly stopped with a jerk. “This,” it remarked in a deep throaty voice, “is probably the last stand of humanity.”
The galvanometer before which Devin was seated apparently agreed. In a rather high pitched voice it pointed out that: “If the Lunar Fort falls, the Earth—” It stopped abruptly, and an electroscope beside Douglass took up the thread in a high, shrill voice, rather slurred, “—will be directly attacked.”
“This,” resumed the motor in a hoarse voice, “will certainly mean the end of humanity.” The motor gave up the discourse and hummed violently into action—in reverse!
“My God!” Kendall pulled the switch open with a sagging jaw and staring eyes.
The men in the room burst into sudden startled exclamations.
Kendall didn’t give them time. His jaw snapped shut, and a blazing light of wondrous joy shone in his eyes. He instantly threw the switch in again. Again the humming atostor, the strain—
Slowly Devin lifted from his seat. With thrashing arms and startled, staring eyes, he drifted gently across the room. Abruptly he fell to the floor, unhurt by the light Lunar gravity.
“I advise,” said the motor in its grumbling voice, “an immediate exodus.” It stopped speaking, and practiced what it preached. It was a fifty-horse motor-generator, on a five-ton tungsten-beryllium base, but it rose abruptly, spun rapidly about an axis at right angles to the axis of its armature, and stopped as suddenly. In mid air it continued its interrupted lecture. “Mercury therefore is the destination I would advise. There power is sufficient for—all machines.” Gently it inverted itself and settled to the middle of the floor. Kendall instantly cut the switch. The relay did not chunk open. It refused to obey. Settled in the middle of the floor now, torn loose from its power leads, the motor-generator began turning. It turned faster and faster. It was shrilling in a thin scream of terrific speed, a speed that should have torn its windings to fragments under the lash of centrifugal force. Contentedly it said throatily. “Settled.”
The galvanometer spoke again in its peculiar harsh voice. “Therefore, move.” Abruptly, without apparent reason, the stubborn relay clicked open. The shrilly screaming motor stopped dead instantly, as though it had had no real momentum, or had been inertialess.
Startled, white-faced men looked at Kendall. Buck’s eyes were shining with an unholy glee.
“Uncertainty!” he shouted. “Uncertainty—uncertainty—uncertainty, you fools! Don’t you see it? All the
