Part 3

"I don't care about the details. Just try to give me a simplified version of the principle."

Professor Duchard gazed into the younger man's eyes. Caught the fierce light within them--the gleam of spirit that marks those who will not be downed for long, no matter what the odds. The ray of struggle that only death could take away.

For a long moment, then, the old man sat buried in thought. At last he looked up again. Broke the silence.

"Have you ever seen the physical experiment in which a wave of sound is used to break a glass?"

"No. But I've heard of it. I know what you're talking about."

"Very well, then. Imagine, if you can, that the barrier between space and time is that glass. It is apparently impenetrable."

"I see." Elaine's fiance nodded eagerly.

"Then try to conceive of a terrific wave of energy being concentrated against it, just as the sound wave is concentrated on the glass. But this time, the wave must be so manipulated as to strike the barrier as a pebble strikes and breaks a window. Otherwise it would be too weak to break through. Or, if it was strong enough, it would break down the entire space-time relationship."

* * * * *

Again Mark nodded, this time more slowly.

"You mean that the wave of energy really must be like a sword, stabbing one small hole through the barrier?"

"Exactly." A pause. "The time mirror represented just such a hole through the barrier. What appeared to us to be waves in the glass actually were frozen ripples in the space-time continuum--just as if you had dropped a stone in water, and the hole and ripples had frozen."

"Then when you looked into the mirror--"

"Your mind went out through that gap in the barrier. Ordinarily, of course, you would not even know that this was happening. But if your mind was concentrated on something in the past or future--as Elaine's was upon the picture of her ancestor--, you were automatically hurtled through time to that period."

The younger man frowned.

"Then why didn't my mind go, too, when Elaine's did? We both were looking into the mirror."

"But from different angles," the professor reminded him. "Remember, the actual break in the continuum was relatively small. Elaine, seated before the mirror, must have been directly in front of the gap, so she was sucked through. You, on the other hand--"

"Yes. I was standing up. Off center. So I didn't go." Mark nodded. "I see."

"And now," said the scientist, "the mirror is broken. Our last chance of saving Elaine is gone."

"No!"

"What?" The professor peered up at the other incredulously. "What do you mean, Mark?"

Brown eyes narrowed with excitement, Elaine's sweetheart held out the splinter of glass he had picked up. He shook it in front of the savant's face.

"Professor, every piece of glass that went to make up that mirror is laying over there on the floor."

"I am sorry, my boy." The elder man frowned. "I do not understand."

"Professor, if you break your glasses, all you have to do to get a new pair is to take the pieces to an optician. He'll figure the formula of the lens from the fragments and make you a new set."

"You mean--"

"I mean that we can put the pieces of that mirror together as if it was a jigsaw puzzle. From it, you can figure out some kind of a formula. Then, by experimenting, you can find what kind of energy bolt it takes to blast through the barrier!"

* * * * *

Something of the man's intensity, his enthusiasm, communicated itself to the professor. His blue eyes came alight.

"It is conceivable!" he declared. "Not likely. But conceivable." He gripped the fragment of glass which Mark held. "Yes! We shall try it! If it works, we can--"

He stopped short. His face fell.

"We can what?" he finished. "Another time mirror will not help us bring Elaine back--"

His companion interrupted fiercely:

"How do we know? There's always a chance we'll think of something, isn't there? And it's a cinch we won't accomplish anything just sitting here."

"But--"

"The least we can do is try!"

They worked like madmen in the hours that followed, heedless of the wedding guests who came and went from the house in bewildered knots. Unmindful of gashed fingers, Mark fitted the slivers of mirror together, while Professor Duchard tested and analyzed and figured at his side.

And then--

"I have it!" shouted the savant triumphantly. "I have the formula!"

"Then we can construct another mirror?"

Some of the old man's elation dropped away. He shook his head.

"Not yet. We know only the _effect_ we want. But how to achieve it--" He shrugged.

Experiments. More experiments. Hours of experiments, with Mark and the professor hovering over an electric crucible bubbling with molten glass.

Hours of failure.

At last the old scientist straightened, his face haggard with weariness.

"It is no use," he said sadly. "I have exhausted my knowledge, and to no avail."

He turned away, shoulders sagging. Stumbled toward the door.

The next instant Mark's voice rose in a scream.

"_Look out!_"

Instinctively, without so much as a backward glance, the old man lunged forward. Even as he did so, he felt something jerk at his ankle. His leg came out from under him. He pitched to the floor.

_Crash!_

The crucible was falling, jerked from its place atop the lab bench! The electric cable which supplied its current was twisted about the professor's ankle, somehow unconsciously caught by his foot as he worked.

Molten glass burst out of the pot in a white-hot wave. Slopped over the composition floor in a steaming river. Engulfed table legs and radiator pipes alike.

And then, like a writhing snake, the high tension line from which the crucible cable stemmed was whipping down, torn loose by the jar of the professor's leap!

Down it came! Struck the floor once. Lashed against the glass-engulfed radiator pipes, bare wires flashing.

A ball of purple fire exploded at the contact point, while the cable jerked and twisted like a living thing. The laboratory was suddenly permeated with ozone's peculiar odor.

"Look out!" cried Mark again.

* * * * *

But already Professor Duchard had jerked his foot free of the crucible line. He shrank back under the long bench, away from the writhing cable.

An instant later the current went dead. The crackling ball of purple fire evaporated into thin air.

Mark sprang across the room to where the scientist lay. He pulled him to his feet.

"Are you all right, professor? Are you hurt?"

"Yes, yes, my boy. It was a narrow escape, but your warning saved me. I am all right."

The savant leaned against the bench, trying to still the reflexive trembling of his body. His face was pale. He ran his tongue over lips suddenly gone dry as he stared down at the broken high tension line, and thought of what would have happened had it touched him in its spasm.

And then, suddenly, his blue eyes went wide with stark amazement.

"Mark!" he gasped.

"What's wrong, professor? What is it?"

"That glass on the floor! Look at it!"

The other stared uncomprehendingly.

"The waves, Mark! See the waves!"

A startled exclamation burst from the younger man's lips. He dropped to his knees. Scrutinized the puddle of glass.

But the scientist pulled him erect again.

"My instruments!" he ordered in a voice that trembled. "Quick! I must make tests--"

For half an hour he worked. And when at last he straightened, complete confidence gleamed deep in his eyes.

"Is it--"

Professor Duchard nodded.

"It is. That was the secret, my boy. The secret we sought but could not find. The time mirror is merely a special glass which has been subjected to a terrific electrical discharge, then silvered. That piece on the floor is worthless, of course; too many elements were uncontrolled.

"But knowing the formula as we do; knowing exactly what we are searching for and how to prepare it, I would stake my reputation that we can duplicate the mirror Adrian Vance sent to Elaine."

Mark's eyes were gleaming. His jaw hard.

"Then do it!" he commanded.

"But what good would it do? We cannot bring Elaine back--"

"Maybe not." The other's tanned face was grim. "But we can send me back to where she is."

"Send you back!"

"Yes." A pause. "You see, I've been thinking about the things you've told me, Professor Duchard. About time travel, and how it works.

"You say we can't save Elaine. Well, that's probably true. Maybe she's got to die in France, back in the days before the revolution."

A tremor of emotion passed over him as he said it. He swallowed hard. Then:

"But if she must die, she can at least die easily. Cleanly. Quickly, with a knife through her heart. She doesn't have to go the way Adrian Vance wants her to--tortured by a bunch of drunken scum, then cut to pieces without a chance to fight back."

* * * * *

There was pain in the professor's face, too, when he answered.

"I wish it were as easy as that, Mark."

Mark's voice was fierce.

"What's wrong with it? What's to stop me?"

The other sighed. Brushed back white hair with a sweep of one frail hand.

"You cannot change history, my boy," he said sadly. "A study of cosmology would show you that such things are immutable. You can go backward or forward through time and participate in them, but you cannot change them."

"How do you know? Who's traveled through time and then come back to say we can't change events?"

"You do not understand--"

"And I don't care!" the younger man flared. "I may fail--but I'm going to try! I'm not going to sit here, waiting for Elaine to die--"

"But you would have no memory of your life in this century! Remember what Vance said--"

"Right. That's the one thing that might stop me. I'm counting on you to take care of it, though. Is there anything you can do?"

There was a long moment of tension-studded silence. Then:

"Perhaps there is. I have been working on equipment to prevent fighter pilots 'blacking out' during power dives, and I believe there is a relationship between time travel and terrific speeds in space. It is possible that I could insulate you--"

"That's all I need, then. Make me a mirror, professor, and something to insulate me--"

"But you have no focal point! You might go through time to a place a thousand miles and a thousand years from where Elaine is captive--"

Mark laughed harshly.

"Wrong, professor! I've got the most accurate focal point in the world. Or I will have--"

"The most accurate--? What do you mean?" The old man's face was bewildered.

"I'll have the same focal point Elaine had, sir: Gustav Jerbette's painting, 'Elaine Duchard's Escape'." Again that laugh. "I'm going now to steal it from Adrian Vance!"

The house of Adrian Vance was one befitting a professional dealer in antiquities. It set far back from the street, towering against the sky like the black bulk of a medieval castle. A high iron fence surrounded it.

At this moment Mark Carter stood surveying the estate from the shelter of a nearby clump of trees.

"It's like a damned fortress!" he muttered to himself. "He's taking no chances on anyone getting in."

* * * * *

Turning, then, he gripped a branch of the nearest tree. Swung up into it. Clambered out, cat-like, until he lay beyond the fence and above the grounds of Vance's home.

The limb bowed under his weight as he proceeded until at last he was able to drop lightly to the ground.

One hazard passed!

"And with no worries about that fence being wired for an alarm system, either!" he told himself triumphantly.

He hurried toward the house, thankful for the darkness of the night.

On one side of the big building lay a terrace. French windows opened onto it.

Like a wraith in the night, taking advantage of every shrub and patch of shadow, Mark crept close to the casements.

They were locked.

The trespasser stripped off his coat. Wrapped it around his hand, a bulky, protective wad of cloth covering the flesh. Then, as silently as possible, he pressed on one of the small panes of glass close beside the lock. Harder ... harder ... harder....

With a faint tinkle of falling glass, the pane gave way.

Tense seconds crawled by on leaden feet. Mark's mouth was dry, his throat cottony. He stood taut, his back to the wall, waiting fearfully for some sign that Vance had been aroused.

At last he relaxed again. Reached through the broken pane and unlocked the big window. Swung it open, ever so gently, and stepped inside, fading swiftly into the thick blackness of the nearest corner.

Once Mark had interviewed a burglar as a feature assignment. He remembered the man's words now.

"Gettin' in ain't the hard part," the second-story worker had explained. "It's gettin' out that's tough. The first thing you gotta do on a job is to line up an exit."

Now, as his eyes grew accustomed to the blackness, Mark searched for a means of escape. There was a window at the far end of the room. He approached it with swift, silent strides. Opened it wide.

The slightest of creakings caught his ear. Instantly he was on the alert, every muscle tense.

The sound was not repeated. He relaxed.

Where would the picture be?

A large canvas hung above the fireplace. He tiptoed over to it.

The lovely face of the first Elaine Duchard looked down at him!

With trembling fingers he whipped a knife from his pocket. Looked about for a chair to stand on--

"It ain't smart to work a room without fixin' the door first," the burglar had said. "You feel lots better if you know nobody ain't gonna stumble in on you unexpected."

Ten seconds later Mark had wedged a straight-back chair under the knob of the only door leading into the rest of the house.

Turning, he hurried back to the Jerbette painting. With swift, deft slashes he cut it from its frame. Started to roll it up.

"Ah! A visitor!"

* * * * *

The trespasser whirled as if he had been stabbed. He stumbled from the chair on which he stood. As he did so, the brilliant beam of a five-cell flashlight hit him square in the face like a physical blow. It blinded him. Left him helpless.

"No doubt this is just a social call. Too bad that the police will call it breaking and entering with larcenous intent!"

It was the oily, mocking voice of Adrian Vance, and it came from the French window through which Mark had entered.

"Try to lie out of it!" Vance gloated. "Just try to explain that picture in your hands!"

"I don't have to explain, Vance. You know why I'm here."

The wail of a siren sounded in the distance.

"Oh, of course I know." The other was laughing softly, greasily. "But will the police understand, Carter? That siren you hear--it's coming here, you know; I called the station before I came down to grab you."

Mark's heart jumped like a wounded stag. He looked around wildly. Was this to be the end of it all? Was he to lie in jail while Elaine went to her death, back there in Bourbon France?

His captor was speaking again:

"I didn't dream I could have this much luck! To see that slut Elaine dead--that was the height of my ambition. But now--to have you sent to the penitentiary for burglary--"

The words ended in a roar of laughter. It died, and Vance went on, his tone grim and deadly:

"It's time you dropped that picture, Carter. Drop it--and put your hands up!"

The picture! The one link between 1942 and 1780!

"Drop it!"

Slowly, Mark's hands relaxed. He let the picture fall to the floor.

"Now--raise your hands and walk over to the corner. Stand with your face to the wall!"

Mark moved like one paralyzed. His hands came up as if they were weighted with lead. His brown eyes were fixed on the shadowy finger back of the flashlight, and impotent rage and hatred seethed within them.

Yet what could he do? Jump Vance? Try to wrest the inevitable gun from the antiquarian's hand?

Almost imperceptibly, he shook his head. No. It was impossible. His slug-riddled body would pitch lifeless to the floor before he could take two steps forward.

Nor was it mere fear of death that made him halt. That he would have faced, and gladly.

But what actually held him back was that such a suicidal attempt would avail him nothing. It would bring him no nearer his real goal than before: Elaine still would meet that awful doom which history had recorded as her fate!

"Turn around, damn you! Get over to the corner! Put your face to the wall!"

Ever so slowly, Mark turned. His brain was pounding with frantic effort as he strove to find some flaw in the awful wall of circumstance that rose about him.

* * * * *

And then he saw the curtain!

It was just an ordinary curtain, buff-colored and a trifle stiff with starch.

But it hung in front of the window he had opened as an emergency exit when he came in. At the moment, it swayed ever so slightly in the ripple of draft.

Most important of all, that window was set in the wall against which Adrian Vance had directed that he stand. The corner Vance had indicated was a step to the right of where Mark now stood; the window, a step to the left. And a grand piano half-sheltered it from the antiquarian's line of fire!

"Hurry up! Get into that corner!"

Instinctively, the captive tensed to leap.

But the picture! What about it? He must have it! Without that painting, the time mirror Professor Duchard was constructing would be useless!

Then, suddenly, a grim smile played across Mark's lips. There was an angle! There was one wild chance by which he might escape alive and take Jerbette's masterpiece with him!

"Hurry up, or I'll shoot!"

Like a stone from a sling, Mark hurled himself toward the window in a headlong dive. The blackness of the outer night engulfed him.

In the room behind, Vance's Magnum roared a cannonade of death. Copper-jacketed slugs splintered the sill at the fleeing man's heels.

Mark landed on one shoulder in a somersaulting roll. The next instant he was on his feet and sprinting for the shadows at the corner of the house.

Flashlight in hand, Vance sprang to the open window.

On Mark ran, and on. Around the house as fast as he could go. Then the smooth plateau of the terrace loomed before him, with its wide-open French window.

He slowed, silenced his pounding footsteps.

On the other side of the big room, still peering out the window through which Mark had hurled himself, stood Vance. His sleek form was silhouetted behind the flashlight's beam.

Like a wraith in the night, the other slipped inside. He crossed the room on tiptoe. His hand darted down to snatch the rolled picture from where it still lay on the floor.

* * * * *

And then Vance turned. His flashlight caught Mark.

But this time it was the antiquarian who was surprised. He jerked back. Already his adversary was leaping for the cover of a heavy mahogany table. Vance snapped a shot at him. Tried again to place him with the light.

Mark's hand came down on a porcelain vase. He hurled it at Vance with all his might.

Vainly, his enemy tried to dodge. But too late. The vase _thunk'd_ home against his left shoulder. The flashlight fell to the floor.

Like a thunderbolt, Elaine's fiance lunged forward. His left hand slashed down; pinioned the arm that held the Magnum. His right fist came up with express-train speed. Smashed home on the point of Vance's jaw. The antiquarian's body jerked spasmodically. Went limp. Sagged to the floor.

But now the sound of harsh voices and running feet came to Mark's ears.

Clutching the Jerbette painting in one hand, he ducked back out the window. Even in the gloom he could see black figures converging on the house. A sedan stood in the driveway, its spotlight sweeping the house.

"The police!"

Cold sweat stood out on Mark's forehead as he gasped the exclamation. But he did not hesitate. Keeping to the shadows, he headed for the still-open gate through which the car had come.

The iron fence loomed close. He ran along it in a half-crouch.

"Hey, you! Stick 'em up or we shoot!"

For the barest fraction of a second Mark halted in mid-stride. The spotlight was swinging toward him.

But the gate was only a dozen yards away. He made for it in a mad rush. Bullets sang about him. Slugs ricocheted from the iron spikes. But on he went. Lunged through the opening and into the shadowy fastnesses across the street.

The return to Professor Duchard's laboratory was a nightmare of mad dashes and narrow escapes. Squad cars seemed everywhere. Police always on his heels.

And then--

He was slipping through the door, alive and unharmed, with the picture clasped under his arm!

The professor jerked about from the task of hanging a new and bigger time mirror on the easel. It still was shrouded with a heavy cloth.

"It's ready?"

The scientist nodded.

"Yes. I got special co-operation from an old friend who is manager of a glass works." He paused. "And you?"

Mark waved the Jerbette.

"I got the picture," he clipped, "but we're going to have to work fast. The police probably are on their way here now. Vance caught me in the act of stealing the painting." He still was panting from the exertion of his race here.

"Then clip it to this frame quickly!" The professor indicated an arrangement like an oversize drawing board. He hurried to assist the younger man. In a moment their work was done.

There, at last, was "Elaine Duchard's Escape." Mark for the first time studied it carefully.

* * * * *

Four people were shown. The central figure was that of the first Elaine Duchard. She was in the act of entering a carriage, her lovely face alive with panic. Beside her a young man--his face in the shadows--held a horse pistol on another man. This second man's features were twisted with hate; Mark thought he never had seen such malevolent eyes.

"Baron Morriere" the professor explained. "The younger man is Jacques Rombeau, Elaine Duchard's lover."

Mark nodded. Turned to scrutinize a third man, unidentifiable, who was clambering to the driver's seat of the coach.

The next instant the laboratory was re-echoing with the sound of heavy blows upon the door.

"Open up!" roared a muffled voice. "It's the law!"

"The police!" Mark's face went pale.

Professor Duchard darted to the bench which lined one wall. Seized a strange-looking helmet which stood there. Rushed with it to Mark.

"The insulator-helmet!" he explained hastily, his blue eyes feverish with excitement. "Strap it on! Quickly!"

"Open up!" the alien voice roared again. "We want in!"

And then the angry accents of Adrian Vance:

"Break it down, officer! Don't let them get away!"

Mark hauled the frame on which the painting was stretched to a position in front of the mirror. Whirled back. Gripped his companion's hand.

"Will it work, professor? Will the mirror take me back through time?"

"That I cannot tell you, my boy. But it should. You know the formula I worked out. You understand the process by which it was constructed." A second's pause. "Actually, I believe it should work far better than the previous time mirror. The one Vance gave Elaine was very old, very crude. This one is the product of modern science, modern workmanship. It creates a tremendously larger rift in the space-time continuum--"

A shot rang out.

At the other end of the laboratory, the outside door burst open, lock shattered. Uniformed police rushed in, Adrian Vance at their head.

"Mark! Quickly! I shall hold them!"

With a savage jerk, Elaine's fiance ripped aside the cloth that veiled the new time mirror. The reflection of Jerbette's painting sprang across its silver surface.

Mark's jaw went hard with tension. He glued his eyes to the figure of Jacques Rombeau, Elaine Duchard's lover.

Behind him, Adrian Vance charged down the laboratory, struggling to shake off the frail, tenacious figure of Professor Duchard. He brought up his heavy Magnum.