Barney Carroll took a deep breath and let the power switch fall home. Current meters swung across their scales for an instant, and then the lights went out in the housel "Fuse blew," said Barney shortly. He fumbled his way through the dark house and replaced the fuse. He returned smiling. "Fixed that one," he told Jim. "Put a washer behind it.""O.K. Hit the switch again."

Barney cranked the power over, and once more the meters climbed up across the scales. There was a groaning sound from the tube, and the smell of burning insulation filled the room. One meter blew with an audible sound as the needle hit the end stop, and immediately afterward the lights in the entire block went out.

"Fix that one by hanging a penny behind it," said Jim with a grin.

"That's a job for Martian Electric to do," laughed Barney.

Several blocks from there, an attendant in the substation found the open circuit-breaker and shoved it in with a grim smile. He looked up at the power-demand meter and grunted. High for this district, but not dangerous. Duration, approximately fifteen seconds. Intensity, higher than usual but not high enough to diagnose any failure of the wiring in the district. "Ah, well," he thought, "we can crank up the blow-point on this breaker if it happens again."

He turned to leave and the crashing of the breaker scared him out of a week's growth. He snarled and said a few choice words not fit for publication. He closed the breaker and screwed the blow-point control up by two-to-one. "That'll hold 'em," he thought, and then the ringing of the telephone called him to his office, and he knew that he was in for an explanatory session with some people who wanted to know why their lights were going on and off. He composed a plausible tale on his way to the phone.

Meanwhile, he wondered about the unreasonable demand and concluded that one of the folks had just purchased a new power saw or something for their home workshop.

"Crack the juice about a half," suggested Barney. "That'll keep us on the air until we find out what kind of stuff this thing takes. The book claims about one tenth of the current-drain for this unit. Something we've missed, no doubt."

"Let's see that circuit," said Jim. After a minute, he said: "Look, guy, what are these screws for?"

"They change the side plate voltages from about three hundred to about three hundred and fifty. I've got 'em set in the middle of the range."

"Turn us on half voltage and diddle one of "em."

"That much of a change shouldn't make the difference," objected Barney.

"Brother, we don't know what this thing is even for," reminded Jim. "Much less do we know the effect of anything on it. Diddle, I say."

"O.K., we diddle." Barney turned on half power and reached into the maze of wiring and began to tinker with one of the screws. "Hm-m-m," he said after a minute. "Does things, all right. She goes through some kind of resonance point or something. There is a spot of minimum current here. There! I've hit it. Now for the other one."

For an hour, Barney tinkered with first one screw and then the other one. He found a point where the minimum current was really low; the two screws were interdependent and only by adjusting them alternately was he able to reach the proper point on each. Then he smiled and thrust the power on full.

The current remained at a sane value.

"Now what?" asked Barney.

"I don't know. Anything coming out of the business end?""Heat."

"Yeah, and it's about as lethal as a sun lamp. D'ye suppose the Martians used to artificially a.s.sist their crop by synthetic sunshine?"

Barney applied his eye to a spectroscope. It was one of the newer designs that encompa.s.sed everything from short ultraviolet to long infrared by means of fluorescent screens at the invisible wave lengths. He turned the instrument across the spectrum and shook his head. "Might be good for a chest cold," he said, "but you wouldn't get a sunburn off of it. It's all in the infra. Drops off like a cliff just below the deep red.

Nothing at all in the visible or above. Gee," he said with a queer smile, "you don't suppose that they died off because of a pernicious epidemic of colds and they tried chest-cooking en ma.s.se?"

"I'd believe anything if this darned gadget were found in a populated district," said Jim. "But we know that the desert was here when the Martians were here, and that it was just as arid as it is now. They wouldn't try farming in a place where iron oxide abounds."

"Spinach?"

"You don't know a lot about farming, do you?" asked Jim.

"I saw a cow once."

"That does not qualify you as an expert on farming."

"I know one about the farmer's daughter, and-"

"Not even an expert on dirt farming," continued Jim. "Nope, Barney, we aren't even close."

Barney checked the book once more and scratched his nose.

"How about that eighty-four cycle supply," asked Jim.

"It's eighty-four, all right. From the Martian habit of using twelve as a base, I've calculated the number to be eighty-four."

"Diddle that, too," suggested Jim.

"O.K.," said Barney. "It doesn't take a lot to crank that one around from zero to about fifteen thousand c.p.s. Here she goes!"

Barney took the main dial of the beat-frequency oscillator and began to crank it around the scale. He went up from eighty-four to the top of the dial and then returned. No effect. Then he pa.s.sed through eighty-four and started down toward zero.

He hit sixty cycles and the jackpot at the same time!

At exactly sixty cycles, a light near the wall dimmed visibly. The wallpaper scorched and burst into a smoldering flame on a wall opposite the dimmed light.

Barney removed the BFO from the vicinity of sixty cycles and Jim extinguished the burning wallpaper.

"Now we're getting somewhere," said Barney.

"This is definitely some sort of weapon," said Jim. "She's not very efficient right now, but we can find out why and then we'll have something hot.""What for?" asked Barney. "n.o.body hates anybody any more."

"Unless the birds who made this thing necessary return," said Jim soberly. His voice was ominous. "We know that only one race of Martians existed, and they were all amicable. I suspect an inimical race from outer s.p.a.ce-"

"Could be. Some of the boys are talking about an expedition to Centauri right now. We could have had a visitor from somewhere during the past."

"If you define eternity as the time required for everything to happen once, I agree. In the past or in the future, we have or will be visited by a super race. It may have happened six thousand years ago."

"Did you notice that the electric light is not quite in line with the axis of the tube?" asked Barney.

"Don't turn it any closer," said Jim. "In fact, I'd turn it away before we hook it up again."

"There she is. Completely out of line with the light. Now shall we try it again?"

"Go ahead."

Barney turned the BFO gingerly, and at sixty cycles the thing seemed quite sane. Nothing happened.

"Shall I swing it around?"

"I don't care for fires as a general rule," said Jim. "Especially in my own home. Turn it gently, and take care that you don't focus the tube full on that electric light."

Barney moved the tube slightly, and then with a cessation of noise, the clock on the wall stopped abruptly. The accustomed ticking had not been noticed by either man, but the unaccustomed lack-of-ticking became evident at once. Barney shut off the BFO immediately and the two men sat down to a head-scratching session.

"She's good for burning wallpaper, dimming electric lights, and stopping clocks," said Barney. "Any of which you could do without a warehouse full of c.o.c.keyed electrical equipment. Wonder if she'd stop anything more powerful than a clock."

"I've got a quarter-horse motor here. Let's wind that up and try it."

The motor was installed on a bench nearby, and the experiment was tried again. At sixty cycles the motor groaned to a stop, and the windings began to smolder. But at the same time the big tube began to exhibit the signs of strain. Meters raced up their scales once more, reached the stops and bent. Barney shut off the motor, but the strains did not stop in the tube. The apparent overload increased linearly and finally the lights went out all over the neighborhood once more.

"Wonderful," said Barney through the darkness. "As a weapon, this thing is surpa.s.sed by everything above a fly swatter."

"We might be able to cook a steak with it-if it would take the terrific overload," said Jim. "Or we could use it as an insect exterminator."

"We'd do better by putting the insect on an anvil and hitting it firmly with a five-pound hammer," said Barney. "Then we'd only have the anvil and hammer to haul around. This thing is like hauling a fifty-thousand-watt radio transmitter around. Power supplies, BFO, tube, meters, tools, and a huge truck full of spare fuses for the times when we miss the insect. Might be good for a central heating system.""Except that a standard electric unit is more reliable and considerably less complicated. You'd have to hire a corps of engineers to run the thing."

The lights went on again, and the attendant in the substation screwed the blow-point control tighter. He didn't know it, but his level was now above the rating for his station. But had he known it he might not have cared. At least, his station was once more in operation.

"Well," said Barney, getting up from the table, "what have we missed?"

Altas said: "Now your unit is operating at its correct level. But, son, you've missed one thing. It is far from efficient. Those two leads must be isolated from one another. Coupling from one to the other will lead to losses."

"Gosh," said Than, "I didn't know that."

"No, for some reason the books a.s.sume that the tower engineer has had considerable experience in the art. Take it from me, son, there are a lot of things that are not in the books. Now isolate those leads from one another and we'll go on."

"While you're thinking," said Jim, "I'm going to lockst.i.tch these cables together. It'll make this thing less messy." Jim got a roll of twelve-cord from the cabinet and began to bind the many supply leads into a neat cable.

Barney watched until the job was finished, and then said: "Look, chum, let's try that electric-light trick again."

They swung the tube around until it was in the original position, and turned the juice on. Nothing happened.

Barney looked at Jim, and then reached out and pointed the big tube right at the electric light.

Nothing happened.

"Check your anode voltages again."

"All O.K."

"How about that aligning job?"

Barney fiddled with the alignment screws for minutes, but his original setting seemed to be valid.

"Back to normal," said Barney. "Rip out your cabling."

"Huh?"

"Sure. You did something. I don't know what. But rip it out and fan out the leads. There is something screwy in the supply lines. I've been tied up on that one before; this thing looks like electronics, as we agree, and I've had occasion to remember coupling troubles."

"All right," said Jim, and he reluctantly ripped out his lock-st.i.tching. He fanned the leads and they tried it again.

Obediently the light dimmed and the wallpaper burned.

"Here we go again," said Jim, killing the circuits and reaching for a small rug to smother the fire. "Nowonder the Martians had this thing out in the middle of the desert. D'ye suppose that they were trying to find out how it works, too?"

"Take it easier this time and we'll fan the various leads," said Barney. "There's something tricky about the lead placement."

"Half power," announced Barney. "Now, let's get that sixty cycles."

The light dimmed slightly and a sheet of metal placed in front of the tube became slightly warm to the touch. The plate stopped the output of the tube, for the wallpaper did not scorch. Jim began to take supply line after supply line from the bundle of wiring. About halfway through the mess he hit the critical lead, and immediately the light went out completely, and the plate grew quite hot.

"Stop her!" yelled Barney.

"Why?"

"How do we know what we're overloading this time?"

"Do we care?"

"Sure. Let's point this thing away from that light. Then we can hop it up again and try it at full power."

"What do you want to try?"

"This energy-absorption thing."

"Wanna burn out my motor?"

"Not completely. This dingbat will stop a completely mechanical gadget like a clock. It seems to draw power from electric lights. It stops electromechanical power. I wonder just how far it will go toward absorbing power. And also I want to know where the power goes."

The tube was made to stop the clock again. The motor groaned under the load put upon it by the tube.

Apparently the action of the tube was similar to a heavy load being placed on whatever its end happened to point to. Barney picked up a small metal block and dropped it over the table.

"Want to see if it absorbs the energy of a falling object- Look at that!"

The block fell until it came inside of the influence of the tube. Then it slowed in its fall and approached the table slowly. It did not hit the table, it touched and came to rest.

"What happens if we wind up a spring and tie it?" asked Jim.

They tried it. Nothing happened.

"Works on kinetic energy, not potential energy," said Barney.

He picked up a heavy hammer and tried to hit the table. "Like swinging a club through a tub of water," he said.

"Be a useful gadget for saving the lives of people who are falling," said Jim thoughtfully.

"Oh, sure. Put it on a truck and rush it out to the scene of the suicide."

"No. How about people jumping out of windows on account of fires? How about having one of thethings around during a flier-training course? Think of letting a safe down on one of these beams, or taking a piano from the fifth floor of an apartment building."

"The whole apartment full of furniture could be pitched out of a window," said Barney.