Almost immediately, a low sound came from the distant city. It was a pulsing drone that came through the microphone in a weird cadence; a low, beating drone, like some wild music. Louder and stronger it grew, rising in pitch slowly, then it suddenly ended in a burst of rising sound--a terrific whoop of alarm.

As if by magic, every ship in the air above the city shot downward, dropping suddenly out of sight. In seconds, the air was cleared.

"It seems they've spotted us," said Arcot in a voice he tried to make nonchalant.

A fleet of great, long ships was suddenly rising from the neighborhood of the central building, the tallest of the group. They went in a compact wedge formation and shot swiftly down along the wall of the invisible cone until they were directly over the low building nearest the _Ancient Mariner._ There was a sudden shimmer in the air. In an instant, the ships were through and heading toward the _Ancient Mariner_ at a tremendous rate.

They shot forward with an acceleration that was astonishing to the men in the s.p.a.ceship. In perfect formation, they darted toward the lone, shining ship from far-off Earth!

XIV

The four earthmen watched the fleet of alien ships roar through the air toward them.

"Now how shall we signal them?" asked Morey, also trying to be nonchalant, and failing as badly as Arcot had.

"Don't try the light beam method," cautioned Arcot. The last time they had tried to use a light beam signal was when they first contacted the Nigrans. The Nigrans thought it was some kind of destruction ray. That had started the terrible destructive war of the Black Star.

"Let's just hang here peaceably and see what they do," Arcot suggested.

Motionless, the _Ancient Mariner_ hung before the advancing attack of the great battle fleet. The shining hull was a thing of beauty in the golden sunlight as it waited for the advancing ships.

The alien ships slowed as they approached and spread out in a great fan-shaped crescent.

Suddenly, the _Ancient Mariner_ gave a tremendous leap and hurtled toward them at a terrific speed, under an acceleration so great that Arcot was nearly hurled into unconsciousness. He would have been except for the terrific ma.s.s of the ship. To produce that acceleration in so great a ma.s.s, a tremendous force was needed, a force that even made the enemy fleet reel under its blow!

But, sudden as it was, Arcot had managed to push the power into reverse, using the force of the molecular drive to counteract the attraction the aliens had brought to bear.

The whole mighty fabric of the ship creaked as the t.i.tanic load came upon it. They were using a force of a million tons!

The mighty lux beams withstood the stress, however, and the ship came to a halt, then was swiftly backing away from the alien battle fleet.

"We can give them all they want!" said Arcot grimly. He noticed that Wade and Fuller had been knocked out by the sudden blow, but Morey, though slightly groggy, was still in possession of his senses.

"Let's not," Morey remonstrated. "We may be able to make friends with them, but not if we kill them off."

"Right!" replied Arcot, "but we're going to give them a little demonstration of power!"

The _Ancient Mariner_ leaped suddenly upward with a speed that defied the eyes of the men at the rays of the enemy ships. Then, as they turned to follow the sudden motion of the ship--_it was not there!_

The _Ancient Mariner_ had vanished!

Morey was startled for an instant as the ship and his companions disappeared around him, then he realized what had happened. Arcot had used the invisibility apparatus!

Arcot turned and raced swiftly far off to one side, behind the strange ships, and hovered over the great cliff that made the edge of the cleft that was the river bed. Then he snapped the ship into full visibility.

Wade and Fuller had recovered by now, and Arcot started barking out orders. "Wade--Fuller--take the molecular ray, Wade, and tear down that cliff--throw it down into the valley. Fuller, turn the heat beams on with all the power you can get and burn that refuse he tears down into a heap of molten lava!

"I'm going to show them what we can do! And, Wade--after Fuller gets it melted down, throw the molten lava high in the air!"

From the ship, a long pencil of rays, faintly violet from the air they ionized, reached out and touched the cliff. In an instant, it had torn down a vast ma.s.s of the solid rock, which came raining down into the valley with a roaring thunder and threw the dirt of the valley into the air like splashed mud.

Then the violet ray died, and two rays of blinding brilliance reached out. The rock was suddenly smoking, steaming. Then it became red, dull at first, then brighter and brighter. Suddenly it collapsed into a great pool of white-hot lava, flowing like water under the influence of the beams from the ship.

Again the pale violet of the molecular beams touched the rock--which was now bubbling lava. In an instant, the great ma.s.s of flaming incandescent rock was flying like a glowing meteor, up into the air. It shot up with terrific speed, broke up in mid-air, and fell back as a rain of red-hot stone.

The bright rays died out, but the pale fingers of the molecular beams traced across the level ground. As they touched it, the solid soil spouted into the air like some vast fountain, to fall back as frost-covered powder.

The rays that had swung a sun into destruction were at work! What chance had man, or the works of man against such? What mattered a tiny planet when those rays could hurl one mighty sun into another, to blaze up in an awful conflagration that would light up s.p.a.ce for a million light years around with a mighty glare of light!

As if by a giant plow, the valley was torn and rent in great streaks by the pale violet rays of the molecular force. Wade tore loose a giant boulder and sent it rocketing into the heavens. It came down with a terrific crash minutes later, to bury itself deep in the soil as it splintered into fragments.

Suddenly the _Ancient Mariner_ was jerked violently again. Evidently undaunted by their display of power, the aliens' rays had gripped the Earthmen's ship again and were drawing it with terrific acceleration.

But this time the ship was racing toward the city, caught by the beam of one of the low-built, st.u.r.dy buildings that housed the protective ray projectors.

Again Arcot threw on the mighty power units that drove the ship, bracing them against the pull of the beam.

"Wade! Use the molecular ray! Stop that beam!" Arcot ordered.

The ship was stationary, quivering under the t.i.tanic forces that struggled for it. The enemy fleet raced toward them, trying to come to the aid of the men in the tower.

The pale glow of the molecular beam reached out its ghostly finger and touched the heavy-walled ray projector building. There was a sudden flash of discharging energy, and the tower was hurled high in the air, leaving only a gaping hole in the ground.

Instantly, with the collapse of the beam that held it, the _Ancient Mariner_ shot backward, away from the scene of the battle. Arcot snapped off the drive and turned on the invisibility apparatus. They hung motionless, silent and invisible in the air, awaiting developments.

In close formation, one group of ships blocked the opening in the wall of rays that the removal of one projector building had caused. Three other ships went to investigate the wreck of the building that had fallen a mile away.

The rest of the fleet circled the city, darting around, searching frantically for the invisible enemy, fully aware of the danger of collision. The unnerving tension of expecting it every second made them erratic and nervous to the _n_th degree.

"They're sticking pretty close to home," said Arcot. "They don't seem to be too anxious to play with us."

"They don't, do they?" Morey said, looking angry. "They might at least have been willing to see what we wanted. I want to investigate some other cities. Come on!" He had thoroughly enjoyed the rest at the little mountain lake, and he was disappointed that they had been driven away.

Had they wanted to, he knew, they could easily have torn the entire city out by the roots!

"I think we ought to smash them thoroughly," said Wade. "They're certainly inhospitable people!"

"And I, for one, would like to know what that attraction ray was," said Fuller curiously.

"The ray is easily understood after you take a look at the wreck it made of some of these instruments," Arcot told him. "It was projected magnetism. I can see how it might be done if you worked on it for a while. The ray simply attracted everything in its path that was magnetic, which included our lux metal hull.

"Luckily, most of our apparatus is shielded against magnetism. The few things that aren't can be repaired easily. But I'll bet Wade finds his gear in the galley thrown around quite a bit."

"Where do we go from here, then?" Wade asked.

"Well, this world is bigger than Earth," said Morey. "Even if they're afraid to go out of their cities to run farms, they must have other cities. The thing that puzzles me, though, is how they do it--I don't see how they can possibly raise enough food for a city in the area they have available!"