simultaneously all four spheres vanished as if they had been mere illusions.
No longer could Davidson believe that the spheres had submerged into the ground. He hung scarcely thirty meters overhead and he saw no evidence of the earth receiving them. He looked forward to where he had last seen Hal-Al and Bailee, but he could not locate them, though the belt of darkness had been wholly withdrawn.
There seemed but one means by which this situation could have been achieved. These spheres were playing upon one another, and on the person of their escaped captors just ahead of them, some powerful, mysterious ray of light which caused everything in its path to become invisible. He was simply looking through these gliding globes as through a perfectly transparent pane of glass.
He flew just above the spot where he had last seen his friends which he judged would be the direction taken by the invisible ray and removing his cap dropped it from the plane. It turned over, caught the air like a little parachute, then vanished like a light snuffed out. It had fallen into the ray that made everything invisible in its path.
He was puzzled how to act. These damaged spheres could glide slowly forward, pick up the two men lying helpless in their path, by reason of the paralyzant ray still playing upon them, then proceed on their way. He could not follow the enemy concealed by this invisible ray unless he could occasionally glimpse a rock or tree disappear from sight in the path of the ray.
Yet could the spheres proceed at all, riddled as were their whole outer shells, if not their inner, by his bullets? Would they not have to play possum, lay quiet and wait for him to depart, or for help to arrive?
But now he believed he saw the spheres proceeding slowly forward, four faint ghosts of objective matter. He followed, questioning if he was not following his own illusions, and hesitating to drop a j-a-egg amidst the three smaller spheres lest his friends in the larger sphere might be injured by the explosion, or be slain by the enemy for his act.
They Retreat!
He continued to follow the four phantom spheres, till they came to the shore of a river when they again leaped into perfect visibility. The invisible ray had been withdrawn, or its power exhausted. In another moment the naked figure of Hal-Al sprang from the larger sphere, closely followed by that of Bailee.
Both men dashed for the river, which was scarcely thirty meters away, but before they reached it a ray of darkness came from one of the smaller spheres and smothered them in its obscurity.
Davidson shot down over this sphere and emptied his automatic into the lens from which the black ray proceeded. From within came the squeal as of a frenzied pig, then the engineer within the sphere seemed to go crazy. Like a mad brain in a great round skull and spinning wildly about, the sphere plunged into the river and disappeared in a swirl of bubbles.
Released from the paralyzant black ray, Hal-Al and Bailee sprang up and plunged into the water. Davidson gave a shout of gratification and flashing above the larger sphere dropped a j-a-egg just behind it and shot away like an arrow, before the force of the explosion could catch him. The egg failed to shatter the sphere which evidently was composed of some ductile material that could be pierced but not shattered but sent it spinning forward into the river, where it immediately sank.
He whirled about and returned to the scene, slipping another clip of cartridges into his automatic as he came. He must now depend on his automatic for instant action as he had emptied the cyclo-gun and had no more shells or j-a-eggs but in one of the locked chests aboard.
Two of the spheres remained, and he might not have any such luck with these as with the others. He maneuvered above them; he dared not charge them from the level or attempt to pick up the men in the water, for should they once succeed in directing the paralyzant ray upon him he would be totally helpless; and with him out of the fight Hal-Al and Bailee would be quickly recaptured.
He waited for the enemy's next move, expecting that they would make use of the black paralyzant ray to trap the two men in the water, but, instead, they turned the invisible ray upon themselves and vanished in that mysterious light. He strained his eyes and picked up their two faint ghosts, gliding slowly away. They had funked at last.
He delayed a few moments, then dropped to the surface of the water near where his friends were visible, leaving a little power on so that the hydro-plane would continue to run along the water, should he become helpless. He called for the men to clamber aboard.
"Wow!" yelled Bailee, scrambling to the floor of the plane, with Hal-Al beside him. "Let her out, corporal, and we'll come back with the flowers."
The plane rose to a height of about one hundred meters and the two dripping men sat up and solemnly shook hands. Suddenly Bailee gave a yell and pointed to the rail at his right.
CHAPTER III
The Vision
As Bailee pointed a huge dripping, naked red form of some half-human animal swung over the rail to the floor of the hydro-terra. Then Davidson saw a mass of naked legs, arms, thighs, knotted in fierce combat, and heard the cracking of sinews, snapping of teeth, and grunt of battle. From amongst the mass he picked a hideous half-hog, half-serpent head and smashed at it with a heavy wrench.
The tangle unknotted itself and Hal-Al and Bailee stood up. Seizing a coil of robe from a pin, they proceeded to tie the human monster to a bar of the plane, but he came to consciousness without any warning and, expanding his hairy
