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 mass of the ship. To produce that acceleration in so great a mass, 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 titanic 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 mass 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.