From twenty miles away stabbed the “atom-filtering” rays to Allen Baker in his cell in the death house.

The shrill voice of a woman stabbed the steady hum of the many machines in the great, semi-darkened laboratory. It was the onslaught of weak femininity against the ebony shadow of Jared, the silent negro servant of Professor Ramsey Burr. Not many people were able to get to the famous man against his wishes; Jared obeyed orders implicitly and was generally an efficient barrier.

“I will see him, I will,” screamed the middle-aged woman. “I’m Mrs. Mary Baker, and he--he--it’s his fault my son is going to die. His fault. Professor! Professor Burr!“

Jared was unable to keep her quiet.

Coming in from the sunlight, her eyes were not yet accustomed to the strange, subdued haze of the laboratory, an immense chamber crammed full of equipment, the vista of which seemed like an apartment in hell. Bizarre shapes stood out from the mass of impedimenta, great stills which rose full two stories in height, dynamos, immense tubes of colored liquids, a hundred puzzles to the inexpert eye.

The small, plump figure of Mrs. Baker was very out of place in this setting. Her voice was poignant, reedy. A look at her made it evident that she was a conventional, good woman. She had soft, cloudy golden eyes and a pathetic mouth, and she seemed on the point of tears.

“Madam, madam, de doctor is busy,” whispered Jared, endeavoring to shoo her out of the laboratory with his polite hands. He was respectful, but firm.

She refused to obey. She stopped when she was within a few feet of the activity in the laboratory, and stared with fear and horror at the center of the room, and at its occupant, Professor Burr, whom she had addressed during her flurried entrance.

The professor’s face, as he peered at her, seemed like a disembodied stare, for she could see only eyes behind a mask of lavender gray glass eyeholes, with its flapping ends of dirty, gray-white cloth.

She drew in a deep breath--and gasped, for the pungent fumes, acrid and penetrating, of sulphuric and nitric acids, stabbed her lungs. It was like the breath of hell, to fit the simile, and aptly Professor Burr seemed the devil himself, manipulating the infernal machines.

Acting swiftly, the tall figure stepped over and threw two switches in a single, sweeping movement. The vermillion light which had lived in a long row of tubes on a nearby bench abruptly ceased to writhe like so many tongues of flame, and the embers of hell died out.

Then the professor flooded the room in harsh gray-green light, and stopped the high-pitched, humming whine of his dynamos. A shadow picture writhing on the wall, projected from a lead-glass barrel, disappeared suddenly, the great color filters and other machines lost their semblance of horrible life, and a regretful sigh seemed to come from the metal creatures as they gave up the ghost.

To the woman, it had been entering the abode of fear. She could not restrain her shudders. But she bravely confronted the tall figure of Professor Burr, as he came forth to greet her.

He was extremely tall and attenuated, with a red, bony mask of a face pointed at the chin by a sharp little goatee. Feathery blond hair, silvered and awry, covered his great head.

“Madam,” said Burr in a gentle, disarmingly quiet voice, “your manner of entrance might have cost you your life. Luckily I was able to deflect the rays from your person, else you might not now be able to voice your complaint--for such seems to be your purpose in coming here.” He turned to Jared, who was standing close by. “Very well, Jared. You may go. After this, it will be as well to throw the bolts, though in this case I am quite willing to see the visitor.”

Jared slid away, leaving the plump little woman to confront the famous scientist.

For a moment, Mrs. Baker stared into the pale gray eyes, the pupils of which seemed black as coal by contrast. Some, his bitter enemies, claimed that Professor Ramsey Burr looked cold and bleak as an iceberg, others that he had a baleful glare. His mouth was grim and determined.

Yet, with her woman’s eyes, Mrs. Baker, looking at the professor’s bony mask of a face, with the high-bridged, intrepid nose, the passionless gray eyes, thought that Ramsey Burr would be handsome, if a little less cadaverous and more human.

“The experiment which you ruined by your untimely entrance,” continued the professor, “was not a safe one.”

His long white hand waved toward the bunched apparatus, but to her to the room seemed all glittering metal coils of snakelike wire, ruddy copper, dull lead, and tubes of all shapes. Hell cauldrons of unknown chemicals seethed and slowly bubbled, beetle-black bakelite fixtures reflected the hideous light.

“Oh,” she cried, clasping her hands as though she addressed him in prayer, “forget your science, Professor Burr, and be a man. Help me. Three days from now my boy, my son, whom I love above all the world, is to die.”

“Three days is a long time,” said Professor Burr calmly. “Do not lose hope: I have no intention of allowing your son, Allen Baker, to pay the price for a deed of mine. I freely confess it was I who was responsible for the death of--what was the person’s name?--Smith, I believe.”

“It was you who made Allen get poor Mr. Smith to agree to the experiments which killed him, and which the world blamed on my son,” she said. “They called it the deed of a scientific fiend, Professor Burr, and perhaps they are right. But Allen is innocent.”

“Be quiet,” ordered Burr, raising his hand. “Remember, madam, your son Allen is only a commonplace medical man, and while I taught him a little from my vast store of knowledge, he was ignorant and of much less value to science and humanity than myself. Do you not understand, can you not comprehend, also, that the man Smith was a martyr to science? He was no loss to mankind, and only sentimentalists could have blamed anyone for his death. I should have succeeded in the interchange of atoms which we were working on, and Smith would at this moment be hailed as the first man to travel through space in invisible form, projected on radio waves, had it not been for the fact that the alloy which conducts the three types of sinusoidal failed me and burned out. Yes, it was an error in calculation, and Smith would now be called the Lindbergh of the Atom but for that. Yet Smith has not died in vain, for I have finally corrected this error--science is but trial and correction of error--and all will be well.”

“But Allen--Allen must not die at all!” she cried. “For weeks he has been in the death house: it is killing me. The Governor refuses him a pardon, nor will he commute my son’s sentence. In three days he is to die in the electric chair, for a crime which you admit you alone are responsible for. Yet you remain in your laboratory, immersed in your experiments, and do nothing, nothing!”

The tears came now, and she sobbed hysterically. It seemed that she was making an appeal to someone in whom she had only a forlorn hope.

“Nothing?” repeated Burr, pursing his thin lips. “Nothing? Madam, I have done everything. I have, as I have told you, perfected the experiment. It is successful. Your son has not suffered in vain, and Smith’s name will go down with the rest of science’s martyrs as one who died for the sake of humanity. But if you wish to save your son, you must be calm. You must listen to what I have to say, and you must not fail to carry out my instructions to the letter. I am ready now.”

Light, the light of hope, sprang in the mother’s eyes. She grasped his arm and stared at him with shining face, through tear-dipped eyelashes.

“Do--do you mean it? Can you save him? After the Governor has refused me? What can you do? No influence will snatch Allen from the jaws of the law: the public is greatly excited and very hostile toward him.”

A quiet smile played at the corners of Burr’s thin lips.

“Come,” he said. “Place this cloak about you. Allen wore it when he assisted me.”

The professor replaced his own mask and conducted the woman into the interior of the laboratory.

“I will show you,” said Professor Burr.

She saw before her now, on long metal shelves which appeared to be delicately poised on fine scales whose balance was registered by hair-line indicators, two small metal cages.

Professor Burr stepped over to a row of common cages set along the wall. There was a small menagerie there, guinea pigs--the martyrs of the animal kingdom--rabbits, monkeys, and some cats.

The man of science reached in and dragged out a mewing cat, placing it in the right-hand cage on the strange table. He then obtained a small monkey and put this animal in the left-hand cage, beside the cat. The cat, on the right, squatted on its haunches, mewing in pique and looking up at its tormentor. The monkey, after a quick look around, began to investigate the upper reaches of its new cage.

Over each of the animals was suspended a fine, curious metallic armament. For several minutes, while the woman, puzzled at how this demonstration was to affect the rescue of her condemned son, waited impatiently, the professor deftly worked at the apparatus, connecting wires here and there.

“I am ready now,” said Burr. “Watch the two animals carefully.”

“Yes, yes,” she replied, faintly, for she was half afraid.

The great scientist was stooping over, looking at the balances of the indicators through microscopes.

She saw him reach for his switches, and then a brusk order caused her to turn her eyes back to the animals, the cat in the right-hand cage, the monkey at the left.

Both animals screamed in fear, and a sympathetic chorus sounded from the menagerie, as a long purple spark danced from one gray metal pole to the other, over the cages on the table.

At first, Mrs. Baker noticed no change. The spark had died, the professor’s voice, unhurried, grave, broke the silence.

“The first part of the experiment is over,” he said. “The ego--”

“Oh, heavens!” cried the woman. “You’ve driven the poor creatures mad!”

She indicated the cat. That animal was clawing at the top bars of its cage, uttering a bizarre, chattering sound, somewhat like a monkey. The cat hung from the bars, swinging itself back and forth as on a trapeze, then reached up and hung by its hind claws.

As for the monkey, it was squatting on the floor of its cage, and it made a strange sound in its throat, almost a mew, and it hissed several times at the professor.

“They are not mad,” said Burr. “As I was explaining to you, I have finished the first portion of the experiment. The ego, or personality of one animal has been taken out and put into the other.”

She was unable to speak. He had mentioned madness: was he, Professor Ramsey Burr, crazy? It was likely enough. Yet--yet the whole thing, in these surroundings, seemed plausible. As she hesitated about speaking, watching with fascinated eyes the out-of-character behavior of the two beasts, Burr went on.

“The second part follows at once. Now that the two egos have interchanged, I will shift the bodies. When it is completed, the monkey will have taken the place of the cat, and vice versa. Watch.”

He was busy for some time with his levers, and the smell of ozone reached Mrs. Baker’s nostrils as she stared with horrified eyes at the animals.

She blinked. The sparks crackled madly, the monkey mewed, the cat chattered.

Were her eyes going back on her? She could see neither animal distinctly: they seemed to be shaking in some cosmic disturbance, and were but blurs. This illusion--for to her, it seemed it must be optical--persisted, grew worse, until the quaking forms of the two unfortunate creatures were like so much ectoplasm in swift motion, ghosts whirling about in a dark room.

Yet she could see the cages quite distinctly, and the table and even the indicators of the scales. She closed her eyes for a moment. The acrid odors penetrated to her lungs, and she coughed, opening her eyes.

Now she could see clearly again. Yes, she could see a monkey, and it was climbing, quite naturally about its cage; it was excited, but a monkey. And the cat, while protesting mightily, acted like a cat.

Then she gasped. Had her mind, in the excitement, betrayed her? She looked at Professor Burr. On his lean face there was a smile of triumph, and he seemed to be awaiting her applause.

She looked again at the two cages. Surely, at first the cat had been in the right-hand cage, and the monkey in the left! And now, the monkey was in the place where the cat had been and the cat had been shifted to the left-hand cage.

“So it was with Smith, when the alloys burned out,” said Burr. “It is impossible to extract the ego or dissolve the atoms and translate them into radio waves unless there is a connection with some other ego and body, for in such a case the translated soul and body would have no place to go. Luckily, for you, madam, it was the man Smith who was killed when the alloys failed me. It might have been Allen, for he was the second pole of the connection.”

“But,” she began faintly, “how can this mad experiment have anything to do with saving my boy?”

He waved impatiently at her evident denseness. “Do you not understand? It is so I will save Allen, your son. I shall first switch our egos, or souls, as you say. Then switch the bodies. It must always take this sequence; why, I have not ascertained. But it always works thus.”

Mrs. Baker was terrified. What she had just seen, smacked of the blackest magic--yet a woman in her position must grasp at straws. The world blamed her son for the murder of Smith, a man Professor Burr had made use of as he might a guinea pig, and Allen must be snatched from the death house.

“Do--do you mean you can bring Allen from the prison here--just by throwing those switches?” she asked.

“That is it. But there is more to it than that, for it is not magic, madam; it is science, you understand, and there must be some physical connection. But with your help, that can easily be made.”

Professor Ramsey Burr, she knew, was the greatest electrical engineer the world had ever known. And he stood high as a physicist. Nothing hindered him in the pursuit of knowledge, they said. He knew no fear, and he lived on an intellectual promontory. He was so great that he almost lost sight of himself. To such a man, nothing was impossible. Hope, wild hope, sprang in Mary Baker’s heart, and she grasped the bony hand of the professor and kissed it.

“Oh, I believe, I believe,” she cried. “You can do it. You can save Allen. I will do anything, anything you tell me to.”

“Very well. You visit your son daily at the death house, do you not?”

She nodded; a shiver of remembrance of that dread spot passed through her.

“Then you will tell him the plan and let him agree to see me the night preceding the electrocution. I will give him final instructions as to the exchange of bodies. When my life spirit, or ego, is confined in your son’s body in the death house, Allen will be able to perform the feat of changing the bodies, and your son’s flesh will join his soul, which will have been temporarily inhabiting my own shell. Do you see? When they find me in the cell where they suppose your son to be, they will be unable to explain the phenomenon; they can do nothing but release me. Your son will go here, and can be whisked away to a safe place of concealment.”

“Yes, yes. What am I to do besides this?”

Professor Burr pulled out a drawer near at hand, and from it extracted a folded garment of thin, shiny material.

“This is metal cloth coated with the new alloy,” he said, in a matter of fact tone. He rummaged further, saying as he did so, “I expected you would be here to see me, and I have been getting ready for your visit. All is prepared, save a few odds and ends which I can easily clean up in the next two days. Here are four cups which Allen must place under each leg of his bed, and this delicate little director coil you must take especial pains with. It is to be slipped under your son’s tongue at the time appointed.”

She was staring at him still, half in fear, half in wonder, yet she could not feel any doubt of the man’s miraculous powers. Somehow, while he talked to her and rested those cold eyes upon her, she was under the spell of the great scientist. Her son, before the trouble into which he had been dragged by the professor, had often hinted at the abilities of Ramsey Burr, given her the idea that his employer was practically a necromancer, yet a magician whose advanced scientific knowledge was correct and explainable in the light of reason.

Yes, Allen had talked to her often when he was at home, resting from his labors with Professor Burr. He had spoken of the new electricity discovered by the famous man, and also told his mother that Burr had found a method of separating atoms and then transforming them into a form of radio-electricity so that they could be sent in radio waves, to designated points. And she now remembered--the swift trial and conviction of Allen on the charge of murder had occupied her so deeply that she had forgotten all else for the time being--that her son had informed her quite seriously that Professor Ramsey Burr would soon be able to transport human beings by radio.

“Neither of us will be injured in any way by the change,” said Burr calmly. “It is possible for me now to break up human flesh, send the atoms by radio-electricity, and reassemble them in their proper form by these special transformers and atom filters.”

Mrs. Baker took all the apparatus presented her by the professor. She ventured the thought that it might be better to perform the experiment at once, instead of waiting until the last minute, but this Professor Burr waved aside as impossible. He needed the extra time, he said, and there was no hurry.