Suddenly he heard two familiar sounds behind him, two dull thumps that sounded less like explosions than echoes, long drawn out, and receding into infinity. There was no other sound quite like them that he had ever heard.

They were the snap of the electrical discharge as the Atom Smasher began to operate, and why the snap had sounded like a heavy body falling a long distance away, was not known.

Tode had said one day, with what Jim had taken for sarcasm, that they represented the wave series of a single sound extended in time to make four-dimensional action, but Jim had never considered the explanation seriously.

That sound, bringing back all Jim's memories of their experiments, brought him to his feet sharply. He swung around. The surface of the pool was a bubbling, seething ma.s.s of mud and water. And over its surface that faint violet haze was beginning to spread.

In the center where the light was thickest, something like a gyroscope appeared to be revolving. Out of the gyroscope something was beginning to project--that infernal tube of Lucius Tode. And Jim knew that in the heart of the flame that enormous, distorted face of Lucius Tode would again be visible.

The human nervous system can only endure a certain amount of impact.

The sight of that ghastly flame, already condensing into a violet pillar, was more than Jim could stand. He dragged old Parrish to his feet and started off with him into the thickest part of the undergrowth.

A fearful scream behind him stopped him at the very edge of the scrub.

He looked back, still supporting the half-conscious old man in his arms. The violet flame was shooting up in a straight pillar, the whole central portion of the pool was dry, and the waters were heaped up all around it.

From the slightly elevated spot where Jim stood, he could see Tode holding Lucille in his arms in the very heart of the fire, which threw a pale, fluorescent light over their faces. Tode was wearing a spotted skin, like that of a leopard, and Lucille was in the blue frock that she had worn when Jim and she had dinner together two evenings before.

Jim dropped old Parrish, shouted in answer, and dashed back like a madman down the slope into the solid wall of water.

He fought his way desperately through that wall, which seemed of the consistency of soft rubber or treacle, as if some subtle change had taken place in its molecular isomers. It adhered to him without wetting him, and he plunged through it, hearing Lucille cry out again, and yet again.

And now he was through, and once more struggling over the viscid surface of the pond. Behind him he heard old Parrish blundering, and screeching at the top of his voice, but he paid no attention to him.

He could see Lucille more clearly, and the large, hazy outlines of Tode's features were beginning to a.s.sume the proper proportions. There was a diabolical leer upon Tode's face, unchanged during the five years since Jim had seen him last, except that it had become more evil, more powerful. The enormous and distorted face that Jim had seen had been simply due to the presence of some refracting medium.

The pillar of violet light was thinning, spreading out over the pool, but Jim could now see the scene more clearly than before, even as he rushed onward.

The machine was inside what looked like a flat boat, but more circular than a boat, and apparently was made of some metal resembling aluminum. Either from the metal hull or from the mechanism inside it there was emitted a pungent odor resembling chlorine.

The mechanism itself bore some resemblance to the old Atom Smasher of five years before, but it appeared to be immensely more complicated.

Wheels of various sizes were set at every conceivable angle around the central tube, from which the violet light was emanating, and all were rotating and gyrating so fast that they looked like discs of light.

The boat itself was trembling, and this movement appeared to be communicated to the boiling mud in the central part of the pool.

As Jim tried to leap down through the sucking mud to s.n.a.t.c.h Lucille from Tode, the latter stopped, straightened himself, and pointed a short tube at Jim's heart.

Jim felt as if an enormous, invisible force had struck him in the chest. It was apparently the same repulsive force that had driven back the waters. The shock was not a violent one. It did not throw him off his feet. It merely pushed him slowly and irresistibly backward.

And the whole picture was beginning to fade. Etched sharply in the violet light one moment, it now looked like a drawing that had been covered with tissue paper.

The outlines were dissolving into a haze--or, rather, each line seemed reproduced an infinite number of times, as the edge of a vibrating saw shows an infinitude of edges. The violet fire was becoming still more diffused. It hovered over the waters, a pale, flickering glow. And simultaneously the walls of water began to break and come surging forward.

Jim saw Lucille stretching out her arms toward him, and tried to struggle forward, but in vain. She cried out his name, and he put all his strength into that desperate futile struggle to reach her. But he was being borne backward by the invisible power in the tube. The rushing torrent was surging about his knees; grew waist deep: in another moment Jim was swimming for his life against the furious flood.

Suddenly, however, the tremendous pressure on his chest was relaxed.

Tode had turned the tube away from him. He was leaning forward out of the boat and grasped old Parrish, who had been flung violently against it by the dissolving waters.

The same flood carried Jim to the boat's side. Here, however, the flood was only knee deep, owing to the repulsion still being exercised by the violet light, which was glimmering feebly. Jim found his feet and leaped into the craft. He grasped Lucille in his arms.

He turned to confront Tode, who had just dragged old Parrish over the side. The three men confronted one another.

"Turn that tube on me, and I'll jump into your d.a.m.n machinery and bust it!" Jim shouted.

An ironical expression came on Tode's face. It was clear that he still considered himself master of the situation. "At the immediate moment, Dent, the lives of all of us depend upon your keeping absolutely still," he answered. "Take my advice and sit down!"

Jim saw Lucille's face, ghastly in the faint violet light that played about it. The girl had fainted. She was lying unconscious, her feet against the circular metal plate that protected the machinery, her head upon the rail that ran around the boat's upper edge. Tode, without waiting for Jim's answer, stepped over the plate and took his seat at a sort of instrument board with control levers and thumb screws that apparently controlled the needles on four dials. He touched a b.u.t.ton, and instantly the violet light disappeared.

With its vanishing, the waves came surging forward, and lapped violently against the hull, as if about to overwhelm the vessel, which, however, seemed immovable. It simply rose higher in the water.

Jim understood the cause of this. Those gyroscopes would retain the hull in the same position against anything but a mechanical force strong enough to ruin it. He watched Tode as he sat at the instrument board, which was illuminated by two tiny lights of what looked like mercury-vapor. His face, handsome and cruel as ever, was tense as he manipulated the thumb screws. Beside him lay Parrish, faintly whimpering. The old man had evidently abandoned all hope of effecting his escape, or of rescuing his daughter.

It was unbearable to have to sit there, knowing that the three of them were absolutely at Tode's mercy, and yet there was nothing else to do.

Tode looked up with a saturnine smile. "It's a delicate operation to blur the present without shooting out a hundred years or so in time,"

he said, "but my micrometer's pretty accurate, Dent. Don't move, I caution you!" He smiled again. "Yes, Dent, time is something like the fourth dimension of s.p.a.ce, as we believed in the old days, and I've proved it."

Jim saw Tode touch the screw that controlled the fourth dial, and instantly it was borne in on him that each of the dials controlled one spatial dimension. This fourth, then, was the time dimension!

Could it be true that Tode had solved the practical problem of traveling in time, theoretically implied since the discoveries of Einstein?

He had known in the old days that the Atom Smasher might be adapted to this purpose, but neither Parrish nor he had dreamed of turning aside from their endeavor to utilize it for the purpose of releasing atomic energy.

Thump! Thump! The familiar old sound, rushing back into memory after all those years, the release of the electrical discharge, echoing through infinity! The scrub around the pool blurred and was gone. A vast gray panorama extended itself on either side of them.

They were travelling--in s.p.a.ce--and time too. Jim no longer doubted.

And, chilled with horror, he sat there, his arm about Lucille's unconscious form.

CHAPTER III

_Into the Infinite_

How long he sat there he did not know. Minutes or hours seemed all the same to him. Nothing but that gray monochrome, of neither light nor darkness, that endless panorama of miles and years, blended together into this chaos!

But suddenly there came a shout from Tode. The blur ceased, the lights flickered. Again there sounded the two thumps of the electrical discharge. The vibrating mechanism grew steady. Above them, out of the grayness, a moon disclosed itself, then the pin-points of stars. All about them was an immense, sandy waste.

"Know where we are, Dent?" came Tode's chuckle.

Jim was not sufficiently master of himself to attempt to answer.

"We are on what will be the Russian steppes some fifty thousand years ahead of us in time," grinned Tode. "This is an interlude between two ice ages. Observe how pleasantly warm the climate is, for Russia.

Unfortunately the receding glaciers carried off the top-soil, which accounts for the barrenness of the district, but in another century this country will be overgrown with ferns, and inhabited by the mastodon and wild horse, and a few enterprising palaeolithic hunters, who will come in to track them down and destroy them with their stone axes."