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.

She glanced about the room, and her eye took in the giant switches of copper with their black handles; there were others of a gray-green metal she did not recognize. Many dials and meters, strange to her, confronted the little woman. These things, she felt with a rush of gratitude toward the inanimate objects, would help to save her son, so they interested her and she began to feel kindly toward the great machines.

Would Professor Burr be able to save Allen as he claimed? Yes, she thought, he could. She would make Allen consent to the trial of it, even though her son had cursed the scientist and cried he would never speak to Ramsey Burr again.

She was escorted from the home of the professor by Jared, and going out into the bright, sunlit street, blinked as her eyes adjusted themselves to the daylight after the queer light of the laboratory. In a bundle she had a strange suit and the cups; her purse held the tiny coil, wrapped in cotton.

How could she get the authorities to consent to her son having the suit? The cups and the coil she might slip to him herself. She decided that a mother would be allowed to give her son new underwear. Yes, she would say it was that.

She started at once for the prison. Professor Burr's laboratory was but twenty miles from the cell where her son was incarcerated.

As she rode on the train, seeing people in everyday attire, commonplace occurrences going on about her, the spell of Professor Burr faded, and cold reason stared her in the face. Was it nonsense, this idea of transporting bodies through the air, in invisible waves? Yet, she was old-fashioned; the age of miracles had not passed for her. Radio, in which pictures and voices could be sent on wireless waves, was unexplainable to her. Perhaps—

She sighed, and shook her head. It was hard to believe. It was also hard to believe that her son was in deadly peril, condemned to death as a "scientific fiend."

Here was her station. A taxi took her to the prison, and after a talk with the warden, finally she stood there, before the screen through which she could talk to Allen, her son.

"Mother!"

Her heart lifted, melted within her. It was always thus when he spoke. "Allen," she whispered softly.

They were allowed to talk undisturbed.

"Professor Burr wishes to help you," she said, in a low voice.

Her son, Allen Baker, M. D., turned eyes of misery upon her. His ruddy hair was awry. This young man was imaginative and could therefore suffer deeply. He had the gift of turning platitudes into puzzles, and his hazel eyes were lit with an elfin quality, which, if possible, endeared him the more to his mother. All his life he had been the greatest thing in the world to this woman. To see him in such straits tore her very heart. When he had been a little boy, she had been able to make joy appear in those eyes by a word and a pat; now that he was a man, the matter was more difficult, but she had always done her best.

"I cannot allow Professor Burr to do anything for me," he said dully. "It is his fault that I am here."

"But Allen, you must listen, listen carefully. Professor Burr can save you. He says it was all a mistake, the alloy was wrong. He has not come forward before, because he knew he would be able to iron out the trouble if he had time, and thus snatch you from this terrible place."

She put as much confidence into her voice as she could. She must, to enhearten her son. Anything to replace that look of suffering with one of hope. She would believe, she did believe. The bars, the great masses of stone which enclosed her son would be as nothing. He would pass through them, unseen, unheard.

For a time, Allen spoke bitterly of Ramsey Burr, but his mother pleaded with him, telling him it was his only chance, and that the deviltry Allen suspected was imaginary.

"He—he killed Smith in such an experiment," said Allen. "I took the blame, as you know, though I only followed his instructions. But you say he claims to have found the correct alloys?"

"Yes. And this suit, you must put it on. But Professor Burr himself will be here to see you day after to-morrow, the day preceding the—the—" She bit her lip, and got out the dreaded word, "the electrocution. But there won't be any electrocution, Allen; no, there cannot be. You will be safe, safe in my arms." She had to fight now to hold her belief in the miracle which Burr had promised. The solid steel and stone dismayed her brain.

The new alloy seemed to interest Allen Baker. His mother told him of the exchange of the monkey and the cat, and he nodded excitedly, growing more and more restive, and his eyes began to shine with hope and curiosity.

"I have told the warden about the suit, saying it was something I made for you myself," she said, in a low voice. "You must pretend the coil and the cups are things you desire for your own amusement. You know, they have allowed you a great deal of latitude, since you are educated and need diversion."

"Yes, yes. There may be some difficulty, but I will overcome that. Tell Burr to come. I'll talk with him and he can instruct me in the final details. It is better than waiting here like a rat in a trap. I have been afraid of going mad, mother, but this buoys me up."

He smiled at her, and her heart sang in the joy of relief.

How did the intervening days pass? Mrs. Baker could not sleep, could scarcely eat, she could do nothing but wait, wait, wait. She watched the meeting of her son and Ramsey Burr, on the day preceding the date set for the execution.

"Well, Baker," said Burr nonchalantly, nodding to his former assistant. "How are you?"

"You see how I am," said Allen, coldly.

"Yes, yes. Well, listen to what I have to say and note it carefully. There must be no slip. You have the suit, the cups and the director coil? You must keep the suit on, the cups go under the legs of the cot you lie on. The director under your tongue."

The professor spoke further with Allen, instructing him in scientific terms which the woman scarcely comprehended.

"To-night, then at eleven-thirty," said Burr, finally. "Be ready."

Allen nodded. Mrs. Baker accompanied Burr from the prison.

"You—you will let me be with you?" she begged.

"It is hardly necessary," said the professor.

"But I must. I must see Allen the moment he is free, to make sure he is all right. Then, I want to be able to take him away. I have a place in which we can hide, and as soon as he is rescued he must be taken out of sight."

"Very well," said Burr, shrugging. "It is immaterial to me, so long as you do not interfere with the course of the experiment. You must sit perfectly still, you must not speak until Allen stands before you and addresses you."

"Yes, I will obey you," she promised.

Mrs. Baker watched Professor Ramsey Burr eat his supper. Burr himself was not in the least perturbed; it was wonderful, she thought, that he could be so calm. To her, it was the great moment, the moment when her son would be saved from the jaws of death.

Jared carried a comfortable chair into the laboratory and she sat in it, quiet as a mouse, in one corner of the room.

It was nine o'clock, and Professor Burr was busy with his preparations. She knew he had been working steadily for the past few days. She gripped the arms of her chair, and her heart burned within her.

The professor was making sure of his apparatus. He tested this bulb and that, and carefully inspected the curious oscillating platform, over which was suspended a thickly bunched group of gray-green wire, which was seemingly an antenna. The numerous indicators and implements seemed to be satisfactory, for at quarter after eleven Burr gave an exclamation of pleasure and nodded to himself.

Burr seemed to have forgotten the woman. He spoke aloud occasionally, but not to her, as he drew forth a suit made of the same metal cloth as Allen must have on at this moment.

The tension was terrific, terrific for the mother, who was awaiting the culmination of the experiment which would rescue her son from the electric chair—or would it fail? She shuddered. What if Burr were mad?

But look at him, she was sure he was sane, as sane as she was.

"He will succeed," she murmured, digging her nails into the palms of her hands. "I know he will."

She pushed aside the picture of what would happen on the morrow, but a few hours distant, when Allen, her son, was due to be led to a legal death in the electric chair.

Professor Burr placed the shiny suit upon his lank form, and she saw him put a duplicate coil, the same sort of small machine which Allen possessed, under his tongue.

The Mephistophelian figure consulted a matter-of-fact watch; at that moment, Mrs. Baker heard, above the hum of the myriad machines in the laboratory, the slow chiming of a clock. It was the moment set for the deed.

Then, she feared the professor was insane, for he suddenly leaped to the high bench of the table on which stood one of the oscillating platforms.

Wires led out from this, and Burr sat gently upon it, a strange figure in the subdued light.

Professor Burr, however, she soon saw, was not insane. No, this was part of it. He was reaching for switches near at hand, and bulbs began to glow with unpleasant light, needles on indicators swung madly, and at last, Professor Burr kicked over a giant switch, which seemed to be the final movement.

For several seconds the professor did not move. Then his body grew rigid, and he twisted a few times. His face, though not drawn in pain, yet twitched galvanically, as though actuated by slight jabs of electricity.

The many tubes fluoresced, flared up in pulsing waves of violet and pink: there were gray bars of invisibility or areas of air in which nothing visible showed. There came the faint, crackling hum of machinery rather like a swarm of wasps in anger. Blue and gray thread of fire spat across the antenna. The odor of ozone came to Mrs. Baker's nostrils, and the acid odors burned her lungs.

She was staring at him, staring at the professor's face. She half rose from her chair, and uttered a little cry.

The eyes had changed, no longer were they cold, impersonal, the eyes of a man who prided himself on the fact that he kept his arteries soft and his heart hard; they were loving, soft eyes.

"Allen," she cried.

Yes, without doubt, the eyes of her son were looking at her out of the body of Professor Ramsey Burr.

"Mother," he said gently. "Don't be alarmed. It is successful. I am here, in Professor Burr's body."

"Yes," she cried, hysterically. It was too weird to believe. It seemed dim to her, unearthly.

"Are you all right, darling?" she asked timidly.

"Yes. I felt nothing beyond a momentary giddy spell, a bit of nausea and mental stiffness. It was strange, and I have a slight headache. However, all is well."

He grinned at her, laughed with the voice which was not his, yet which she recognized as directed by her son's spirit. The laugh was cracked and unlike Allen's whole-hearted mirth, yet she smiled in sympathy.

"Yes, the first part is a success," said the man. "Our egos have interchanged. Soon, our bodies will undergo the transformation, and then I must keep under cover. I dislike Burr—yet he is a great man. He has saved me. I suppose the slight headache which I feel is one bequeathed me by Burr. I hope he inherits my shivers and terrors and the neuralgia for the time being, so he will get some idea of what I have undergone."

He had got down from the oscillating platform, the spirit of her son in Ramsey's body.

"What—what are you doing now?" she asked.

"I must carry out the rest of it myself," he said. "Burr directed me when we talked yesterday. It is more difficult when one subject is out of the laboratory, and the tubes must be checked."

He went carefully about his work, and she saw him replacing four of the tubes with others, new ones, which were ready at hand. Though it was the body of Ramsey Burr, the movements were different from the slow, precise work of the professor, and more and more, she realized that her son inhabited the shell before her.

For a moment, the mother thought of attempting to dissuade her son from making the final change; was it not better thus, than to chance the disintegration of the bodies? Suppose something went wrong, and the exchange did not take place, and her son, that is, his spirit, went back to the death house?

Midnight struck as he worked feverishly at the apparatus, the long face corrugated as he checked the dials and tubes. He worked swiftly, but evidently was following a procedure which he had committed to memory, for he was forced to pause often to make sure of himself.

"Everything is O. K.," said the strange voice at last. He consulted his watch. "Twelve-thirty," he said.

She bit her lip in terror, as he cried, "Now!" and sprang to the table to take his place on the metallic platform, which oscillated to and fro under his weight. The delicate grayish metal antenna, which, she knew, would form a glittering halo of blue and gray threads of fire, rested quiescent above his head.

"This is the last thing," he said calmly, as he reached for the big ebony handled switch. "I'll be myself in a few minutes, mother."

"Yes, son, yes."

The switch connected, and Allen Baker, in the form of Ramsey Burr, suddenly cried out in pain. His mother leaped up to run to his side, but he waved her away. She stood, wringing her hands, as he began to twist and turn, as though torn by some invisible force. Eery screams came from the throat of the man on the platform, and Mrs. Baker's cries of sympathy mingled with them.

The mighty motors hummed in a high-pitched, unnatural whine, and suddenly Mrs. Baker saw the tortured face before her grow dim. The countenance of the professor seemed to melt, and then there came a dull, muffled thud, a burst of white-blue flame, the odor of burning rubber and the tinkle of broken glass.

Back to the face came the clarity of outline, and still it was Professor Ramsey Burr's body she stared at.

Her son, in the professor's shape, climbed from the platform, and looked about him as though dazed. An acrid smoke filled the room, and burning insulation assailed the nostrils.

Desperately, without looking at her, his lips set in a determined line, the man went hurriedly over the apparatus again.

"Have I forgotten, did I do anything wrong?" she heard his anguished cry.

Two tubes were burned out, and these he replaced as swiftly as possible. But he was forced to go all over the wiring, and cut out whatever had been short-circuited so that it could be hooked up anew with uninjured wire.

Before he was ready to resume his seat on the platform, after half an hour of feverish haste, a knock came on the door.

The person outside was imperative, and Mrs. Baker ran over and opened the portal. Jared, the whites of his eyes shining in the dim light, stood there. "De professah—tell him dat de wahden wishes to talk with him. It is very important, ma'am."

The body of Burr, inhabited by Allen's soul, pushed by her, and she followed falteringly, wringing her hands. She saw the tall figure snatch at the receiver and listen.

"Oh, God," he cried.

At last, he put the receiver back on the hook, automatically, and sank down in a chair, his face in his hands.

Mrs. Baker went to him quickly. "What is it, Allen?" she cried.

"Mother," he said hoarsely, "it was the warden of the prison. He told me that Allen Baker had gone temporarily insane, and claimed to be Professor Ramsey Burr in my body."

"But—but what is the matter?" she asked. "Cannot you finish the experiment, Allen? Can't you change the two bodies now?"

He shook his head. "Mother—they electrocuted Ramsey Burr in my body at twelve forty-five to-night!"

She screamed. She was faint, but she controlled herself with a great effort.

"But the electrocution was not to be until morning," she said.

Allen shook his head. "They are allowed a certain latitude, about twelve hours," he said. "Burr protested up to the last moment, and begged for time."

"Then—then they must have come for him and dragged him forth to die in the electric chair while you were attempting the second part of the change," she said.

"Yes. That was why it failed. That's why the tubes and wires burned out and why we couldn't exchange bodies. It began to succeed, then I could feel something terrible had happened. It was impossible to complete the Beta circuit, which short-circuited. They took him from the cell, do you see, while I was starting the exchange of the atoms."

For a time, the mother and her boy sat staring at one another. She saw the tall, eccentric figure of Ramsey Burr before her, yet she saw also the soul of her son within that form. The eyes were Allen's, the voice was soft and loving, and his spirit was with her.

"Come, Allen, my son," she said softly.

"Burr paid the price," said Allen, shaking his head. "He became a martyr to science."

The world has wondered why Professor Ramsey Burr, so much in the headlines as a great scientist, suddenly gave up all his experiments and took up the practice of medicine.

Now that the public furor and indignation over the death of the man Smith has died down, sentimentalists believe that Ramsey Burr has reformed and changed his icy nature, for he manifests great affection and care for Mrs. Mary Baker, the mother of the electrocuted man who had been his assistant.