The star Mira was unpredictably variable. Sometimes it was blazing, brilliant and hot. Other times it was oddly dim, cool, shedding little warmth on its many planets. Gresth Gkae, leader of the Mirans, was seeking a better star, one to which his "people" could migrate. That star had to be steady, reliable, with a good planetary system. And in his astronomical searching, he found Sol. With hundreds of ships, each larger than whole Terrestrial spaceports, and traveling faster than the speed of lig

ACE BOOKS, INC. 1120 Avenue of the Americas New York, N.Y. 10036 THE ULTIMATE WEAPON Copyright, 1936, by John W. Campbell Originally published as a serial in Amazing Stories under the title of Uncertainty . All Rights Reserved Cover by Gerald McConnell Printed in U.S.A....

Patrol Cruiser "IP-T 247" circling out toward Pluto on leisurely inspection tour to visit the outpost miners there, was in no hurry at all as she loafed along. Her six-man crew was taking it very easy, and easy meant two-man watches, and low speed, to watch for the instrument panel and attend ship into the bargain. She was about thirty million miles off Pluto, just beginning to get in touch with some of the larger mining stations out there, when Buck Kendall's turn at the controls came along. Bu

The IP-M-122 picked them up. The M-122 got out there two days later, in response to the calls the T-247 had sent out. As soon as she got within ten million miles of the little tender, she began getting Cole's signals, and within twelve hours had reached the tiny thing, located it, and picked it up. Captain Jim Warren was in command, one of the old school commanders of the IP. He listened to Kendall's report, listened to Cole's tale—and radioed back a report of his own. Space pirates in a large s

Gresth Gkae , Commander of Expeditionary Force 93, of the Planet Sthor, was returning homeward with joyful mind. In the lock of his great ship, lay the T-247. In her cargo holds lay various items of machinery, mining supplies, foods, and records. And in her log books lay the records of many readings on the nine larger planets of a highly satisfactory planetary system. Gresth Gkae had spent no less than three ultra-wearing years going from one sun to another in a definitely mapped out section of

There was a glint of humor in Buck Kendall's eyes as he passed the sheet over to McLaurin. Commander McLaurin looked down the columns with twinkling eyes. "'Petition to establish the Lunar Mining Bank,'" he read. "What a bank! Officers: President, General James Logan, late of the IP; Vice-president, Colonel Warren Gerardhi, also late of the IP; Staff, consists of 90% ex-IP men, and a few scattered accountants. Designed by the well-known designer of IP stations, Colonel Richard Murray." Commander

The apparatus of the magnetic shield had been completed two days later, and set up in Buck's own laboratory. On the bench was the powerful, but small, little projector of the straight magnetic field, simply a specially designed accumulator, a super-condenser, and the peculiar apparatus Devin had designed to distort the electric field through ninety degrees to a magnetic field. Behind this was a curious, paraboloid projector made up of hundreds of tiny, carefully orientated coils. This was Buck's

"Hello, Tom?" The telephone rattled in a peeved sort of way. "Yes, it is. What now? And when am I going to see you in a social sort of way again?" "Not for a long, long time; I'm busy. I'm busy right now as a matter of fact. I'm calling up the vice-president of Faragaut Interplanetary Lines, and I want to place an order." "Why bother me? We have clerks, you know, for that sort of thing," suggested Faragaut in a pained voice. "Tom, do you know how much I'm worth now?" "Not much," replied Faragaut

Faragaut looked unsympathetically at Buck Kendall, as he stood glaring perplexedly at the apparatus he had been working on. "What's the matter, Buck, won't she perk?" "No, damn it, and it should." "That," pointed out Faragaut, "is just what you think. Nature thinks otherwise. We generally have to abide by her opinions. What is it—or what is it meant to be?" "Perfect reflector." "Make a nice mirror. What else, and how come?" "A mirror is just what I want. I want something that will reflect all th

Grimly Buck Kendall looked at the reports. McLaurin stood beside him, Devin sat across the table from him. "What do you make of it, Buck?" asked the Commander. "That we have just one island of resistance left on the Jovian worlds. And that will, I fear, vanish. They haven't finished with their arsenal by any means." "But what was it, man, what was it that ruined those ships?" "Vibration. Somehow—Lord only knows how it's done—they can project electric fields. These projected fields are oscillated

" They can't take this, at least," sighed McLaurin as they retreated from Luna. "I didn't think they could—right away. I'm wondering though if they haven't something we haven't seen yet. Besides which—give them time, give them time." "Well, give us time, too," snapped McLaurin. "How are you coming?" Buck smiled. "I'm sure I don't know. I have a machine but I haven't the slightest idea of whether or not it's any good." "Why not?" "I can destroy—I hope—but I can't build up their ray. I can't test

Sadly the convalescent Gresth Gkae listened to the reports of his lieutenants. More and more disgraced he felt as he realized how badly he had blundered in reporting the people of this system unable to cope with the attackers' weapons. Gresth Gkae looked up at his old friend and physician, Merth Skahl. He shook his head slowly. "I'm afraid, Merth Skahl. I am afraid. We have, perhaps, made a mistake. The better and the stronger alone should rule. Aye, but is the stronger always the better ? I am

Buck Kendall entered the Communications room rather furtively. He hated the place. Cole was there, and McLaurin. Mac was looking tired and drawn, Cole not so tired, but equally drawn. The signals were coming through fairly well, because most of the disturbance was rising where the signals rose, and all the disturbance, practically, was magnetic rather than electric. "Deenmor is sending, Buck," McLaurin said as he entered. "They're down to the last fifty-five tons. They'll have more time now—a re

Buck Kendall with a slow smile, looked out of the port in the thick metal wall. The magnetic shield of the Lunar Fort was washed constantly with the fires of exploding magnetic bombs. The smile spread broader. "My friends," he said softly, "you can pull from now till doomsday as far as I'm concerned, and you won't even disturb us now." He looked back over his shoulder into the power room. A hunched bulk, beautifully designed and carefully finished, the apparatus that created 'Uncertainty of the

The interstellar liner "Mirasol" settled gently to Sthor, having circled wide of Asthor, and from her hold a cargo of the heavy Jovian elements was discharged, while a mixed stream of Solarians and Mirans came from her passenger quarters. A delegation of Mirans met the new Ambassador from Sol, Commander McLaurin, and conducted him joyfully to the Central Government Group. Beside the great buildings, a battered, scarred interstellar ship lay, her rear section a mass of great patches, rudely appli