IF you have read "Beyond the Pole" by A. Hyatt Verrill, you will no doubt be interested in the present story by the some author. We have no hesitancy in recommending it, and at the same time stating that we believe it is one of the greatest stories on man-made invisibility which has ever appeared. In these latter days of science it would be rush to say that invisibility can not be produced. Already Dr. Jules Steam, of Alsace-Lorraine, has produced partial invisibility by injecting certain liquids into animal tissue, which makes the animal practically transparent when it is viewed in a certain light. The full details of his experiments were published in the February, 1921, issue of SCIENCE AND INVENTION. No experiments have been made on human beings as yet. There is no question but that sooner or later the problem of invisibility will be solved. Just what might happen when the secret is found is well related by the author of this story, which you will read not only with great interest but with much amusement as well.

THE MAN WHO COULD VANISH

PROLOGUE

ON the third day of last August the public was astounded by a story which appeared in every newspaper in the country. Extra editions of even the most staid and conservative papers appeared on the streets shortly after noon and, in screaming headlines, announced:

"HARTWELL BUILDING DISAPPEARS. TWENTY STORY STRUCTURE VANISHES IN BROAD DAYLIGHT AND REAPPEARS. MARVELOUS AND INEXPLICABLE ILLUSION WITNESSED BY CROWDS. BELIEVED TO BE A DEMONSTRATION BY SOME MASTER HYPNOTIST SEEKING PUBLICITY."

It is not necessary to quote the stories that occupied entire pages of the press, for while all agreed in the main essentials, no two were the same and all contained glaring errors and discrepancies. Moreover, the events must still be fresh in the minds of my readers. Suffice to say that each and every account stated that the new Hartwell Building, in process of construction on Nineteenth Street, had suddenly vanished from sight during the noon hour; that hundreds of citizens had packed the thoroughfare; that the police and fire departments had been called out, and that, for a space of several minutes, only a vacant lot and an immense excavation had been visible where the building had stood. Then, while the crowd looked on, the structure had reappeared as suddenly and mysteriously as it had vanished.

The story was so utterly incredible, that at first, many persons thought it merely a canard or some advertising or publicity scheme. But as, during the following days, the press was filled with accounts of the phenomenon as related by eyewitnesses, and as the police and ?re department officials confirmed the reports, and there could be no question regarding the authenticity of the story, innumerable theories and explanations were suggested, and so for days the crowds thronged the streets near the Hartwell Building and stood, gazing tioned certain phenomena of expectantly, in the hopes that it might repeat its mysterious behavior.

The concensus of opinion was that the astounding occurrence had been brought about by some hypnotist or fakir who, as the East Indian magicians are supposed to do, had hypnotisecl the onlookers, and that the disappearance of the building had been wholly an illusion. "No doubt," said the "Times," "the public will soon be informed that Signor So-and-So, the world's greatest hypnctist and illusionist, will appear at a certain theatre, with a further announcement of the fact that the Signor deluded hundreds of persons, and by his mesmeric powers, caused them to believe that a twenty-story building could vanish into thin arr."

But as time went on and no one came forward to claim the doubtful honor of being able to accomplish such a feat, by hypnotism or otherwise, the mystery deepened, and every conceivable theory—both natural and supernatural, was advanced to explain the wholly unaccountable phenomenon.

Up to the present time the truth has never been known, and only two men in the world are aware of the actual facts and the real solution of the mystery. One of these is Doctor Lemuel Unsinn, Professor of Physics at Stanforth University, and my life-time friend and college chum; the other is myself. As the time has now passsed when any harm can come from giving the true story to the world, and as the explanation is even more incredible and remarkable than any of the imaginary solutions put forth, we have agreed that the public should be made acquainted with the facts. Indeed, the authentic story would have been published some months ago had it not been essential to make certain arrangements to safeguard the secret, and whose making required much more time than had been anticipated.

In order to make clear just how the astounding occurrence took place, and to enable my readers to thoroughly understand my true if incredible story, it will he necessary to begin at the beginning and to recount every detail of the events which led to the final results. To many readers much of this matter will no doubt, prove rather dry, and, if I were writing fiction, l would omit all those portions of the tale which deal with the scientific side and the preliminaries. But both Dr. Unsinn and myself feel that to omit such matters would be a great mistake, and that as the story is of as much interest and importance to the scientific world as to the layman, nothing should be left untold. Moreover, we feel that unless such matters were included my story would be considered as purely fictitious. And at any rate the reader is at liberty to skip such portions of my narrative as the appreciative reader may find to be lacking in real and genuine interest.

CHAPTER I
Doctor Unsinn Propounds Some Theories

IT really began when I was visiting my old friend and chum, Dr. Lemuel Unsinn, soon after his return from an international conference of scientists. He had been telling me of the various new discoveries which had been announced by his fellows, and mentioned certain phenomena of light rays, which, hitherto unseen, had now been brought within the scope of human vision. Although l could not, as a layman, see the importance of the diacovery, my friend was most enthusiastic about the matter, and, among other statements, declared that it might yet be possible to render objects invisible.

I laughed. "That is utterly impossible," I declared.

"Nothing within the realms of Science is impossible," he retorted.

"Perhaps not," I admitted, "but there are many things which are so highly improbable that to all iptents and purposes they are beyond ossibilit or reason.

"Utter nonsense!" he ejaculated. Ignorance, lack of imagination, pig-headed conservatism. Every advance made by Science has been declared improbable or impossible, or both, until its feasibility has been proven. Railways, steamships, the telegraph and telephone, radio, airplanes/—all have been laughed at and declared impossibilities until thev became actualities. "Science." he went on, assuming his lecture-room manner, and looking at me over the rims of his glasses, "science does not acknowledge the existence of the words impossible and improbable. What seems a mere dream today may become an every-day affair tomorrow. The scientist—-"

"Oh, all right," I laughed. "Cut out the lccture. Granting that nothing is beyond Science. as represented by my old friend, Lemuel Unsinn, how do you propose going about it?"

"I presume you refer to the matter of rendering visible objects invisible," he smiled, leaning back in his chair and placing the tips of his fingers together.

I nodded.

"Hmm, I hardly care to divulge all my ideas, even to such an old friend as yourself," he chuckled. "But I am willing to suggest lines along which such investigations might be conducted. You state that it is preposterous to consider making visible, solid matter invisible. Is it any more preposterous than to make inaudible sounds audible, invisible things visible, or audible sounds inaudible?"

I shook my head. "No, I'd say one's as impossible as the other."

Lemuel grinned. "Which shows your monumental ignorance," he exclaimed. "My dear boy," he continued, "those feats are all accomplished facts and are so familiar to you that you do not realize they exist. The inaudible waves transmitted by radio are rendered audible in the receiving set; the audible waves which enter the microphone of the transmitting station are sent inaudibly through the ether; and heat, which is invisible under certain conditions is plainly visible under other conditions which occur every day."

"Yes," I granted rather grudgingly, "I'll admit the matter of sounds, but I'd like to know when and how heat can be seen. That is, unless you refer to the wavy effect seen above a pavement or sand on a hot day."

"No, there you have air," usually invisible, rendered visible by its motion," replied my friend. "But you have undoubtedly seen red~hot and white-hot metal. And there you have heat made visible. Heat, sound, light and probably scent also, are all caused by vibratory waves. Waves varying in length from the shortest X-rays and Gamma rays to the longest recorded waves; waves varying from less than a billionth part of a meter to over one-hundred-and fifty thousand meters in length. Unfortunately, however, the human system it not designed or attuned to register or recognize more than an infinitely small'proportion of these vibratory waves. Our eyes-can only record those which range between violet and red, but our nerves and ears can detect others which are invisible. For example, there are the heat waves which are too long for us to see. But if, by heating an object, we decrease the length of the waves until they come within the limits of our vision we see the heat waves as red. And by still heating the object the hotter waves appear to us as violet, white or yellow; white being, as you know, merely a mixture or combination of the various light waves. In other words, my dear boy, our eyes, our nerves, our ears, and in all probability our noses as well, are much like radio receiving sets. We can 'tune in' waves of light, sound, heat and scent within certain limits, and, like radio receiving sets, we often fail to 'tune out' interferences. Many sounds are far too high or too low for the human ear to detect, just as many light waves are too short or too long for us to see."

"All extremely interesting and educational." I said. "But what bearing does all this have on the matter under discussion—the rendering of various objet-ts—any object I believe you said,—invisible?"

"Let me reply by asking you a question," smiled my friend. "Why are objects—hurnan beings, houses, trees, anything we see,—visible? Merely because they reflect light," he continued without waiting for my answer. "Very well, then. We see an object because it reflects light; we see colors on that object because it has properties which cause it to absorb certain light rays and to reflect others—if red to us, it absorbs the violet, indigo, blue, green, yellow and orange rays. If it appears white it reflects all the rays. If black, it absorbs them. In other words we do not actually see the object at all. We merely see the light waves reflected from the object. And if means can be found to cause the object to absorb the light rays—"

"You'd have a black object instead of a colored one," I laughed.

"Exactly," agreed my friend quite unperturbed. "Provided the absorption was imperfect," he added. "But," he continued, "if the means were such as to cause perfect absorption, in other words to allow the light waves to pass through the object, then it would become invisible, just as clear glass is invisible, even though glass reflects certain waves of light which cannot be detected by the human eye."

I chuckled. The idea of transforming opaque objects to transparent objects seemed highly amusing. "Co to it," I laughed, "Why not begin with the ladies? Their clothes are pretty transparent now."

"If you are trying to be facetious there's no use in my attempting to explain my ideas and theories," commented Dr. Unsinn in an injured tone.

"I wasn't laughing at your theories," I assured him. "And I'm really interested, even if I don't see what you're getting at."

"If your sense of logic and your knowledge of science were as highly developed as your sense of humor and your knowledge of women's garments, you might more readily grasp what I am 'getting at' as you put it," he said dryly. "However," he continued, "I had no intention of conveying the idea that I believed visible objects could be rendered invisible by such means. But if, by altering the frequency or lengths of light waves reflected from an object, we could render such wavestoo short or too long for the human eye to register, then the object would become wholly invisible."

By this time I was really interested. My friend's arguments were, I knew, sound. If the frequency of one form of vibratory wave could be altered; if an oscillating wave could be changed to a direct wave or vice versa, if the inaudible radio waves could be made audible by the simplest of instruments, was there any scientific reason why light waves ordinarily visible might not be made invisible?

"And the man who succeeds in accomplishing such a feat will control the world," declared Dr. Unsinn interrupting my thoughts. "Imagine it! Think for a moment what it would mean! He could command anything, everything. He could amass millions, billions if he wished. He could control the destinies of nations! No treaties, no plots, no business deals could be secret. He could go anywhere, unknown, unsuspected, unseen. Why," he exclaimed, as he sprang from his chair and began excitedly pacing the room. "Think what it would mean to a nation! "Armies, battleships, invisible! And——"

"Think what it would mean to the crooks." I broke in. "Better not delve too far, Old Man. You might succeed and your secret might leak out. Well, I must he going. Good luck to you in your experiments. And"—wit'h a laugh, "Let's hope that the next time I see you I shan't see you at all."

CHAPTER II
An Amazing Demonstration

A FEW days after the foregoing conversation with my old friend, Doctor Unsinn. important business unexpectedly called me to South America.

Although his words often occurred to me on the long journey south, yet I gave them little serious consideration, for I knew that Lemuel, like so many scientific men, was prone to theorize and to argue most plausibly and convincingly in support of some theory, even if he had no real faith in it. And, amid new scenes and new friends, and with matters of much more pressing importance to occupy my attention, all thoughts of Dr. Unsinn's weird ideas were completely driven from my mind.

Not until several months later when I was homeward bound, did l again think of our last conversation. I had, to be sure, dropped him a postcard now and then, but I had received no reply and did not expect any. Lemuel was never one to write, and he considered it a waste of time to carry on a purposeless correspondence with anyone, although he would fill page after page with facts, figures and theories in letters to other scientists. Now, however, as I recalled our conversation, I found myself wondering if he had actually attempted to carry his theory to a test. Of course the idea was ridiculously bizarre and unattainable and yet, I felt sure that Dr. Unsinn had actually been in earnest and really believed that it was scientifically possible to produce invisibility in solid matter.

And the more I mentally reviewed his words and analyzed his statements, the more I felt that he might be right, at least theoretically. After all, was such a feat any more remarkable than the fact that the ship"s wireless operator was talking and listening to people thousands of miles distant and separated from our ship by countless leagues of sea and land? And yet the idea of any material object being invisible seemed so far-fetched and supernatural that I could not bring myself to believe that Lemuel would ever attempt to experiment along such lines. Nevertheless, I had thought so much on the subject that, at the first opportunity after my arrival, and reaching my apartment, I called Dr. Unsinn, by phone and, after the usual greetings, asked how he was succeeding in his black art. Perhaps he felt slightly piqued at my tone or my words, but instantly there was a change in his voice and he replied, rather shortly, that it was evident that I had not improved in my attitude towards science, but that, as an old chum and friend, he would be glad to have me call whenever I found it convenient.

Just why my curiosity had been aroused I cannot say, but curious I was nevertheless and within the hour I was at Lemuel's door. His Filipino servant Miguel, answered the bell and greeted me with a welcoming grin on his usually emotionless face.

"The Señor Doctor is in the laboratory," he announced as I entered. "He say you will please to await him in the library. He will arrive in one little moment."

I was somewhat surprised for, as a rule, I was welcome to enter Lemuel's holy of holies whenever I called, and never before had I been asked to await his pleasure like a perfect stranger. But no doubt, I thought, he was busy on some delicate experiment and did not wish to be interrupted. Entering the library I turned to a table littered with magazines and scientific reports and rather idly glanced through them. A sound, like the creacking of a foot~step on a loose board caused me to turn, but the door was open, the hallway was in plain view and no one was in sight. Once more I resumed my perusal of the periodicals and was becoming a bit interested in an article I ran across, when I was startled by a low chuckle. Instantly I wheeled about, surprised that I had not heard my friend's approach, only to find the room empty. Then, as I stood, rather foolishly gaping I fear, and puzzled to understand how my ears had deceived me, I fairly jumped. Out of the obviously empty room came Dr. Unsinn's unmistakable voice.

"Sorry to have kept you waiting," it said; you're looking exceedingly well after your trip."

For an instant a strange creepy sensation swept over me. Then I realized that this must be one of my friend's practical jokes. No doubt he had installed some sort of telephone or loud speaker arrangement in the apartment and was testing it out on me.

As nearly as I could judge, the words had come from the farther corner of the room where there was a large, deeply-upholstered chair. Taking a step nearer, I peered into the corner, trying to discover the hidden instrument. And as I gazed at the chair I rubbed my eyes and wondered if I were taking leave of my senses.

Slightly above the back of the chair and suspended in mid-air were a pair of spectacles. On the left side and a short distance below was a round metal disc and also seemingly floating in the atmosphere, were a number of buttons, a gold watch and a chain, two small ornamental silver buckles, some cuff links and a large signet ring. Just below these and suspended a few inches above the chair seat were several silver coins, while just above the floor four rows of small metal rings hung without any support whatsoever.

Even while I gazed, dumbfounded, utterly at a loss to account for this strange hallucination, that ghostly chuckle again issued from the corner, and I saw the various objects sway, the coins shift their position and thc ring move towards the spectacles which seemed to follow it. as though drawn by a magnet, as it again descended to its former position. Then, once again, the uncanny voice spoke.

"My dear boy, your expression is most remarkable," it said. "You really should see yourself. But it is most gratifying to me for it proves my test is a success. If I remember correctly, you remarked, when I last saw you, that you hoped the next time you saw me you would not see me at all. Well, your wish is granted, you are gazing— or rather I might say, gaping, at me without seeing me. But I do not wonder you are amazed and also incredulous——don"t deny it, I can see you think this some hoax. However——"

I had been gazing, gaping; jaw dropped, mouth open, eyes fairly popping, as the voice spoke, and fascinated, I saw the watch, the discs and the money slowly rise upward and come towards me. The next instant I fairly shriekcd and leaped back. An unseen ghostly hand had gripped my shoulder! A hearty peal of laughter rang through the apartment as, shaken, almost terror stricken, I shrank back against the old-fashioned mantel.

"Yes, my experiment is a complete success," announced the disembodied voice, "but there is no need to carry the test further. You see my 'black art' as you call it has worked, and the impossible has been made possible. But I feel you will be more at ease if I am visible. No doubt it will take time to accustom yourself to the phenomenon."

Hardly had the last word been issued when the watch, the discs and the coins vanished, and Dr. Unsinn stood before me, as solid, as substantial and as natural as ever.

I collapsed. It was almost as great a shock to my nerves to see my friend materialize from the air as it had been to hear his voice, to feel his grip when he had been invisible, yes, invisible, for no longer could I doubt that the scientist had succeeded in making the impossible possible.

"I think I have answered your query of this morning," exclaimed Dr. Unsiun triumphantly, as he scatcd himself in his favorite chair. "I felt quite sure of my success even before you arrived," he continued. "I could not be sure, however, for, strangely enough,—and quite surprising and as yet somewhat inexplicable to me, I can scc myself in a mirror even when invisible to others. But I tried it to a slight extent on Miguel, although I dared not put the fellow to a thorough test,—too superstitious and excitable you know. Might have died of fright or have bolted, if I had spoken, or if he had noticed anything such as my watch or buttons. Ah, you noticed such objects did you not?"

By this time I had regained a bit of my composure and enough breath to speak. "I'll say I did," I replied. "But why allow such objects to remain visible?"

"Hmm, that is my great difficulty," replied Lemuel regretfully. "It is obvious that the same treatment will not serve for all objects. I have learned how to render any organic substance invisible, but, as yet, I have not discovered how to accomplish the result with inorganic matter. My body, my clothing, my shoes, yes, even objects of wood are, by my method, easily rendered invisible, but metals—my watch, my suspender buttons, the coins in my pocket and the eyelets for my shoe strings resist, so far, all my efforts."

"But how," I interrupted, "do you do it?"

Dr. Unsinn smiled knowingly. "That is a secret I do not care to divulge," he replied. "But," he went on, "in a general way it is along the lines I suggested during our last conversation on the subject,-—by altering the frequency of light waves so that they become invisible to the human eye. As you, my friend, are deplorably ignorant of higher physics, I may perhaps better explain the process by comparing it with certain phenomena of radio with which you may be more or less familiar. Do you know the meaning of the term 'heterodyne?'"

I nodded.

"Good," continued Lemuel. "Then I can state that by my process I send out certain vibratory waves from my apparatus, and these, striking the light rays, reflect them back with a frequency which renders them invisible. In other words, the light rays which would, normally, strike a solid object, and, being reflected therefrom, would cause that object to become visible, are prevented from striking that object by my method, but strike an armor of an envelope of outgoing vibratory waves. Is that clear?"

"Perfectly,' I lied blithely, not in the least understanding the scientific side of the explanation, but deeply interested nevertheless. "But," I asked, "I don't understand why some objects remain visible while others vanish, and I didn't notice any apparatus for bringing on your astounding invisibility."

"I do not myself fully understand why organic objects should respond to my treatment and inorganic objects should resist it," admitted my friend. "But it is probably due to the fact that inorganic materials do not throw off my vibratory waves at the same frequency as organic materials. But I will solve the problem; I must solve it! As for your other query, the appliance which I employ is very compact and becomes invisible together with myself. At first the apparatus was cumbersome and clumsy, but I have now perfected it and have it so readily and perfectly under control that it is even more simple than tuning-in on a small radio receiving set. Indeed, the results may be brought about slowly and gradually, as I will demonstrate."

As Dr. Unsinn stood before me an incredibly weird change came over him. A thin haze seemed to envelop his body, and as I stared fascinated, the haze seemed slowly to clear away and to my indescribable amazement I saw the curtained doorway leading into the room whose portiére and parts of whose frame appeared through my friend's body and head. If ever there was a ghost Lemuel was one. And then, as if snuffed out, Lemuel completely vanished and only his spectacles, the fraternity button on his lapel, his watch and chain, his cuff-links, his belt and arm-garter buckles, his ring, watch and chain and the other metallic objects of his apparel remained to assure my reeling senses that Dr. Unsinn still stood before me.

I cannot begin to describe the sensation of thus seeing my companion vanish before my eyes, but it was nothing compared to the creepy, uncanny nerve-racking sensation which followed, as Lemuel's characteristic chuckle issued from the transparent air and he again spoke.

"For Heaven's sake!" I cried, "Don't do that. I'll have a nervous collapse if that disembodied voice of yours keeps on."

The voice laughed, but the next instant my friend was before me as substantial as ever.

"You'll get accustomed to the sensation," he declared, "but—"

"Never," I broke in. "No normal person could ever get accustomed to seeing a man vanish before his eyes or to hearing a voice talking from thin air."

"Hmm, I had rather expected something of this sort," admitted Lemuel. "No doubt it is a bit unnerving but you must accustom yourself to the phenomenon. Now, if you will follow my directions and, using a duplicate instrument, will render yourself invisible—"

"I will not!" I declared. "I have no desire to try the experiment. But even if I did I fail to see how that would render your disappearance any less uncanny."

"It is my belief," replied Dr. Unsinn, "that if you were treated by my waves I would still be visible to you and you to me. I am, as I informed you, quite visible to myself when I look in a mirror. This I assume is due to some effect which my apparatus exercises upon the optic nerves, thus enabling the eye to register the light-waves even when their frequency is accelerated. I am most anxious to test the matter and you will confer a great favor by acceding to my wishes."

"Not a bit of it," I declared. "You can monkey with such things all you wish, but I'm perfectly satisfied to remain visible."

Lemuel shook his head sadly. "You're a conservative imbecile," he informed me. "I had counted on your accompanying me, as I go about, in order to note the effect upon the public, and it would be most desirable that you should also be invisible."

"Look here," I said. "I know you can vanish; I know it's all a perfectly natural feat, but it's too devilishly creepy and uncanny for my nerves. And if you're going to keep on being snuffed out and talking from an invisible mouth I'll leave you to your own devices and not come near your place."

Dr. Unsinn grinned. "You forget that you couldn't prevent me from coming to see you," he reminded me. "I could enter your apartment unseen and unsuspected. I might be seated on one of your chairs or lying on a couch in the same room with you and you'd never suspect it."

"If I didn't see your confounded watch and other metallic articles," I assented. "But with all your darned scientific ardor I know you're not one to butt-in where you're not wanted,—even for the sake of an experiment."

"But all joking aside," said my friend, "I am sorry that your nerves should be upset by my demonstration. However, there is, I think, a means of overcoming all your objections and yet helping me with my most valuable and interesting experiments. I have, in fact, devised a little instrument which will enable you to see me even when I am invisible to others."

Rising, he opened a cabinet, and turning, handed me a small rectangular box slightly larger than a cigarette case. To one end of the box a fine braided cord was attached with the other cnd terminating in a pair of metalrirnmed, slightly tinted, eyeglasses.

"If you will place the detector case in your pocket and adjust the glasses on your nose, we will try an interesting test," announced Dr. Unsinn.

"Look here," I said. "Is this some darned trick to make me invisible?"

"I assure you it is not," he declared. "But if I am not vastly mistaken it will prevent me from becoming invisible to you."

Somewhat hesitatingly, and without the least faith in the apparently simple device, I slipped the case in my breast pocket and placed the glasses on my nose. As far as I could see all objects remained the same as before, though everything, including Lemuel's face, took on a peculiar pinkish tint, due, I supposed, to the color of the glasses.

"I presume you have no difficulty in seeing the various objects about the room, including myself," said my friend.

"Not a bit," I assured him.

"Then, if you will kindly press the lever on the case we will proceed."

Examining the case, I noticed a small lever or arm which fitted snuggly into a small groove on one edge of the affair.

"Lift the lever and move it forward—toward the cord, as far as it will go," said my friend.

A slight click followed by an almost inaudible whistling sound issued from the case as I obeyed his instructions. But, as far as I could see, there were no other results. Lemuel still sat in his chair, his legs crossed, his elbows on the chair-arms, the tips of his fingers together, and his mild blue eyes looking over the tops of his glasses.

"The confounded contraption's a dud," I exclaimed, "everything's just the same."

"Precisely," my friend agreed. "But just remove the glasses from your eyes for a moment."

As I complied with his request I uttered a cry of utter amazement. Dr. Unsinn was absolutely invisible!

"Now replace the glasses," said his disembodied voice.

Hardly knowing what to expect, absolutely dumbfounded, I again placed the glasses before my eyes and there sat my friend as before. I could not believe it. I could not believe that this "now you see him and now you don't" effect was produced by the glasses. No. I felt sure, it was a trick on I.cmuel's part. He must manage to vanish and to reappear coincidingly with my donning or removing the lenses. But he assured me,—quite heatedly and convincingly,—that he had remained in the invisible state throughout the experiment, and, moreover, he was so evidently highly elated at the success of his invention that at last I was forced to believe that the magic glasses actually rendered the invisible visible. But my brain was now in s complete chaos. My friend's power to render himself invisible, the fact that certain objects remained visible, the effect of the glasses rendering him visible to me while still invisible to ordinary eyes, were all unquestionable facts; but they were so weird, uncanny and downright supernatural, that I felt as if in a confused, preposterous dream, and I half expected to wake up at any moment.

"It's splendid," exclaimed Lemuel, interrupting my chaotic thoughts. "Even if I cannot overcome your absurd and unreasonable objections to becoming invisible it now matters little."

"Look here!" I ejaculated. "Just what are you planning to do? Are you going out to amass the millions you spoke of, to control the world? I'll admit there's no reason why you should not succeed,—possessing your secret, nothing is impossible of attainment, but if you plan taking me along you're mistaken. I'm not invisible and I donlt intend to be, and I can easily foresee where I'd be the goat for any counfounded ghostly acts you perpetrated."

Dr. Unsinn laughed heartily. "My dear boy!" he cried, controlling his merriment. "You appear to forget that I am a scientist and a respected member of the community with a reputation to uphold. I have not the least desire or intention to overstep the bounds of honesty, law, or proper behavior, even if invisible. If I were so minded I could, as you know, help myself to the world's treasures, could control the destinies of nations, could in fact place myself beyond the power of man or the law. But my sole idea is to use my discovery for the benefit of mankind, to perfect it and give it to the world, as so many great discoveries have been given. We men of science are never materialists.—"

"You're an idiot!" I exclaimed. "Benefit of mankind! Give it to the world! Why, if you gave your discovery to the world,—if you gave the secret to anyone,—it would be a curse to mankind; you'd be destroying law and order and the world!"

"Hmm, perhaps there is something in that," admitted Lemuel regretfully. "But at any rate, I must discover how to treat inorganic substances before any very extensive experiments can be conducted. It would hardly do for a crowd to see a watch and buttons wandering about without visible attachment or reason."

"You might leave your watch behind, and use bone or fibre buttons," I suggested.

"But, my dear man," objected my friend, "unless I can render all substances invisible I shall feel that my efforts have been in vain."

"And I sincerely hope you fail," I informed him. "I don't see what good it will do for the rest of the world, and if it leaks out, Heaven help us."

"Just what thousands of conservative hide-bound persons have said of every great discovery of the past," exclaimed Lemuel, as I rose to take my leave.

CHAPTER III
Dr. Unsinn Perfects His Invention

AS I walked towards my apartment, my mind was, of course, filled with thoughts of my friend's amazing discovery. And, among other matters, it came to me, as a rather curious and amusing fact, that Dr. Unsinn, who had dwelt so enthusiastically upon the material possibilities of invisibility, when he first discussed the matter, was now far more interested in proving his scientific theories than in profiting by his discovery. It was typical of the man, and is, I believe, of most scientists. But a more disturbing thought was that my friend was deplorably absent-minded,—a common trait of scientists also, especially when preoccupied with some experiment, and, being so inherently honest and frank himself, he was too prone to assume that his fellow-beings were the same. In this day, so I feared, a very grave danger. I remembered occasions in the past when, suddenly side-tracked by some new lead, he had completely forgotten formulae or calculations which had enabled him to succeed in some experiment, and had never been able to duplicate the results. Might he not, in endeavoring to perfect some feature of his own discovery, forget some important detail and find himself unable to restore himself to visible form? It was in fact this chance that had caused me to refuse to test his device upon myself. I could see where it might be most entertaining and advantageous to become invisible temporarily, but I had no desire to remain in that condition indefinitely, and any failure of Lemuel's device, any miscalculation, any accident or any sudden illness on his part might leave rne forever incapable of resuming my visible form. The risk to be sure might be small, but it was far too great for me to take. And finally, there was the chance that Dr. Unsinn might, in his ardor and enthusiasm, divulge his secret. Unquestionably he would wish to announce his discovery to his fellow scientists; if he did so some one would make the fact public and then, as I had said to Lemuel, Heaven help mankind. My head swam and I fairly trembled at thought of what would occur should my friend's secret fall into the hands of unprincipled men. Law, society, governments would be powerless. Possessing the power to become invisible, crooks could defy the world. They could loot banks, state treasuries, mints and all other sources of boarded millions, unseen, unhampered and leave no traces of their identity. Murder, robbery, rrapine, any and all crime could be committed without fear of detection or punishment. Even if caught unawares and thrown into prison an invisible man eould'walk out without being seen. No walls could hold him, no court try him, no punishment be dealt him. And even if the secret were known to all, it would make little difference, unless, as Lemuel had seemed to think, a person invisible himself could see others when under the effect of the apparatus. The next instant I laughed out so loudly that passers-by turned and stared at me. What a fool I had been! How ridiculous my worry over any such possibility! I had forgotten about the marvelous glasses! My friend's secret might become public property and yet be harmless, even in the hands of the most desperate criminals. Iust as there is an antidote for every poison, so Lemuel's magic glasses would safeguard the world from any evil that might result from his discovery. Moreover, there was always the chance that he would be unable to discover a means of rendering inorganic matter invisible, and if so, his invention would be of little value either to honest or dishonest men. At thought of the weird situations that might result, I chuckled. I could imagine a gunman, himself invisible holding up some citizen, and I could visualize the amazed expression of the victim as he saw a revolver suspended in mid-air and pointing at him, and heard a disembodied voice ordering him to throw up his hands. And it was amusing to picture' motor cars, apparently empty, threading their way through traffic and stopping and starting at the signals of a visible whistle blown by an invisible traffic officer. Yes, one's imagination could run riot and nothing imagined could equal the reality if my friend's invention came into general use. And, no doubt, I had greatly overestimated the dangers and the undesirable features of the discovery. In all probability the invention, once it became known, would create little more excitement or wonder than had followed the invention of the telephone, the radio or any other epochal thing. People would take it as a matter of course and no greater harm would come of it than had resulted from the discovery of the steam engine, electricity, or any other revolutionary invention, all of which had been looked upon as inimical to the world and to mankind when they had been ?rst announced.

At any rate, I could not afford to worry over Lemuel's affairs even if his marvelous achievement continually occupied my thoughts.

For several days I had not heard from Dr. Unsinn, and I was far too busy with my own work to visit him. No doubt he was deep in his experiments and I felt sure he would notify me when he had perfected anything new. And in this I was not mistaken. Answering my telephone, I was greeted by Lemuel's voice.

"I've got it!" he cried. "l've conquered inorganic matte; Everything is perfected! Can you come over at once.

As on my previous visit, Miguel admitted me, and, as before, he requested me to wait for my friend in the library. But this time I was prepared and had no intention of being either frightened or amazed at anything Dr. Unsinn might spring on me. At least, I thought I was; but I had underestimated my friend's abilities and the astounding possibilities of his perfected discovery.

Standing before the old-fashioned fireplace, and listening intently for the slightest sound which might betray the approach of an invisible being, I peered about the room half expecting to see Lemuel materialize or to hear his bodiless voice speaking to me.

As I did so a thin fog or mist seemed to cloud my vision. I can best describe the sensation as similar to a "blind headache" from which I had at times suffered. I could distinguish every object in the library, but everything appeared to be slightly out of focus. I rubbed my eyes and stared again. In the wall opposite where I stood a luminous spot appeared; other bright spots seemed to take form on the ceiling and the floor and on the other walls. Without doubt, I thought, I was in for a terrific headache, for such bright, luminous spots always appeared before my eyes when such an attack was coming on. And then a strange, a marvelous, an absolutely astounding and terrifying change took place. Floor, ceiling, walls; every object within the room melted away. It was exactly the effect that I had seen when a film or a lantern-slide is melted by the heat of the projection machine. One instant I was standing before the fireplace in Dr. Unsinn's library; the next instant I was in the centre of a blank, standing in a void. To the right, where a wall and two windows had been, was the broad, tree-shaded street with its electric lights and shadowy houses on the further side. Above me was space; below me intense, fathomless blackness. And yet, my feet rested on solid matter and as, too amazed and terrified even to cry out, I felt gropingly with my outstretched hands, my fingers touched the mantel and a nearby table with magazines that rustled at my touch. And then, instantly, I knew what had occurred. Incredible, utterly unbelievable as it seemed, I knew that Lemuel by his uncanny, his almost supernatural invention had amused himself and had demonstrated his powers by rendering the entire apartment invisible!

My fright gave way to absolute wonder. It was impossible but true, and feeling confident that I was right, I rather hesitatingly took a step forward. Never shall I forget the sensation. Surrounded by nothingiess, as far as my vision went, suspended in mid-air, yet I was walking as securely, as firmly and on as solid a floor as ever. Reassured, I turned towards the street that stretched before me and far beneath me. As if in a dream I walked forward with arm extended, and, the next moment, banged with uncomfortable force against a solid wall. And at my involuntary expletive, Lcmuel's hearty laughter came from behind me, and I staggered back as an invisible hand slapped my shoulders.

"It works!" exclaimed the voice. "It's the most wonderful discovery ever made by man!"

"And the most damnable way to wreck a man's nerves," I blurted out, as my hands came into contact with an invisible chair and I dropped weakly into it.

"Sorry I had to frighten you a bit," said my friend's voice. "But I wanted to test the matter thoroughly."

"If you want to keep my friendship, you'll turn off your confounded machine and get things back to normal," I replied testily.

"Oh, all right," agreed Lemuel, "but look here, old man, can't you wait a minute? I—"

"I'm looking here, there and everywhere," I exclaimed. "And there's nothing to see and I've had enough of this."

"Dash it all, then I was wrong after all," cried Dr. Unsinn. "I felt sure that while subject to the treatment one person could see another, and that while invisible a person could see objects invisible to others. Well, after all, it doesn't matter so much."

"You get things back to visibility again before you start lecturing," I commanded. "lt's worse than a nightmare."

Before I had finished speaking I found myself once more amid the familiar surroundings of my friend's library with Lemuel seated, grinning triumphantly, in his favorite chair.

"You didn't give me enough time to test my theories thoroughly," he complained. "I wished to try the glasses again.

"You tested it enough to suit me and more," I said. "I'll take the glasses on your say-so. In fact, from now on, I'll believe anything you say in regard to your discovery or invention or black magic or whatever it is. If you say you can make the entire universe invisible l'll not argue with you. But let me tell you it's lucky you didn't live a century or so ago. You'd be burned for a witch before now."

"You forget that it would be a difficult undertaking to burn an invisible being," he reminded me. "And just think how scared those witch-baiters would have been, if their stake and fire had suddenly vanished from before their eyes.

"And I'll wager that a lot of people will wish you had been executed before you made your devilish discovery," I told him.

"Not a bit of it!" he declared. "The world will welcome it and will acclaim me the greatest inventor and greatest benefactor of the human race."

"See here," I cried, all my old fears again possessing me, "won't you listen to reason and common sense? You're so carried away with your success that you havenlt stopped to think what it would mean, if you let the world know of your invention. No, don't interrupt me, I've worried over this ever since I was here last, and I'm going to have it out with you here and now. I'll admit you've succeeded better than I expected or hoped, for if you had failed to make inorganic substances invisible your invention might not have been so dangerous. As it is, the possibilities for destroying life, property, society and mankind are too tremendous to even think of. Can't you see what it would mean if crooks got hold of it? Can't you see what it would mean if it fell into the hands of Bolshevists, or revolutionists or governments? Why man, you'd upset the world, destroy civilization, wreak unspeakable woe and misery and terror."

"Piffle!" ejaculated Lemuel, "if everything and everybody was invisible the status of the world would remain unchanged. How could a criminal attack an invisible victim? Instead of facilitating crime it would deter crime. Instead of bringing on wars and destruction it would prevent such things. I-Iow could an army fight an invisible foe? How could a navy attack invisible ships? And invisible police and officers of law and order could apprehend criminals much more readily. Besides, you forget about my glasses. If the public or any part of the public possessed these, nothing would be invisible to the wearers."

"Idiotic reasoning," I declared. "Suppose someone stole or learned your secret? Suppose the agent of a hostile nation got hold of it? Or suppose some gang of criminals secured the invention by fair means or foul? Is it likely that they would let the world know of the glasses which counteract the process? No, every moment that you possess the apparatus for working your devilish trick, you're threatening your fellow men and civilization with annihilation. If you wish to benefit the world, destroy every calculation, every bit of apparatus, every trace of what you've done and never divulge a word of it."

"You're an old scare-head," said Lemuel, though I could see that my words had had their effect. "And," he continued, "I have no intention of following your advice. There is not the slightest danger of my discovery being found out unless you or I divulge it. I shall not,—for the present at least, and I know you will not. Moreover, even if it were known, no one could work it. The proceedure is known only to myself."

"Anything one man has done another can repeat," I reminded him.

"Possibly," he admitted. "but to proceed with my statement. I am free to grant that certain things you have said are not without foundation. I had, in the beginning, expected to make my invention public, for of course it is impossible to patent it. Anyone could pirate the patent, and, availing himself of his knowledge could render himself invisible and thus beyond reach of the law. But I may dccide not to give my discovery to the world at large. It all depends upon future experiments and tests. And, if you really feel as you say in regard to it, "you'll help me to carry out my tests. If, in my judgment and in yours, these experiments prove the invention actually a peril to society then, I assure you, it will never be revealed to the public. But if, on the other hand, you, as well as myself, are convinced that the discovery will be beneficial rather than inimical, I shall let the world know the secret."

"Hmm, well I suppose that's fair enough," I assented. "But before I agree I want to know what these experiments are which you have in mind."

"Certainly," said Lemuel. "I intend to go about while invisible, accompanied by you equipped with the glasses, and from personal observation determine just what will or might happen, and whether the power to become invisible would be beneficial or otherwise."

"I don't see anything to object to in that," I assured him, "and I'll agree to help you, provided you agree not to do anything which might result in my being held responsible. Remember, I will be visible and you will not, and I'd hardly care to stand up in a police court and claim that an invisible companion was responsible for certain acts of which I was accused. No, Lemuel, I have no desire to end my days in an insane asylum."

"But, my dear boy," chuckled my friend, "that would be a splendid test, and of course I could always materialize at the last moment. Just imagine the effect on a policeman or a magistrate!"

"Yes just imagine it," I replied drily. "And unless you're willing to agree to my terms you can imagine your experiments without my aid."

"You take me far too seriously," exclaimed Lemuel. "I have no intention of overstepping the bounds of the law and I shall certainly so conduct my experiments that no blame can be attached to you. But," he added regretfully, "it would be much better if you also would submit to the effect of my device."

"Well, I won't and that's an end to that," I declared positively. "And," I continued, "there's another matter. You'll have to promise me that you will not try the experiment of making things invisible by wholesale,—no vanishing of rooms, buildings or other structures while occupied. A terrible panic might and most certainly would result. And this includes trolley cars, railway trains, moving vehicles and similar things. A panic is the easiest thing in the world to start and the hardest to stop."

"I promise," assented my friend, "but I shall most assuredly try my invention on unoccupied structures and other objects."

"I don't care what you try it on provided you do not endanger life or property," I told him.

"Then we'll start our experiment tomorrow," exclaimed Lemuel. "We'll start from your apartment. If convenient to you, I'll call at ten tomorrow morning."

CHAPTER IV
Dr. Unsim-i's Experiment

I DO not know exactly what object Dr. Unsinn had in view, or what he hoped to accomplish by his "experiment." Certainly he had demonstrated his discovery and had proved it successful by his tests on myself. Possibly he fclt that human sight might vary, that some persons might find him invisible while to others he was visible, or again, he may have wished merely to gratify his own vanity, and enjoy the sensation of moving unseen among his fellows. He could not, in fact, clearly explain to me what he expected or why he was so insistent upon having me accompany him, when, as we had agreed, we set out from my apartment. But in view of the events which followed I feel sure that it was fate or predestination that led him to undertake his experiment.

Wearing the marvelous glasses, in order that I might not lose sight of my companion, who had rendered himself invisible, I hailed an approaching trolley car. But habit is a strong and persistent thing, and the human mind is greatly governed by the impressions it receives through the eyes, and, at the very outset of our venture I learned this to my chagrin. Boarding the car with Lemuel at my heels, I handed the conductor a dime and he returned a nickel in change. I was on the point of handing it back, and the word "two" was on the tip of my tongue when a nudge from Lemuel's elbow brought me to my senses. As my friend was plainly visible to me I had completely forgotten that he was invisible to the conductor, and I mentally vowed to watch my step more closely in the future. There were fcw passengers in the car and my companion seated himself in one corner while I took the seat beside him. And presently habit once again came to the fore and came near to getting me into a most embarrassing sittuation. Quite forgetting, momentarily, that my friend was invisible, I spoke to him, and he, quite in his ordinary manner, replied. In fact we were carrying on quite an animated conversation when I was suddenly brought to a realization of what we were doing by the behavior of the other passengers. Everyone was gazing at me. Some curiously, others half pityingly, as if thinking me either mad or intoxicated, while still others were grinning and thoroughly enjoying the spectacle of a man carrying on a conversation with himself. Even the conductor had entered the car and was staring at me, a strangely puzzled expression on his face, as if undecided whether I was a dangerous lunatic or a common drunk. Fortunately, my presence of mind came to my rescue, and, flushing, but forcing a smile, I turned to an intelligent appearing gentleman near me. "I must apologize for my absent-minded ness," I stammcred. "I was merely practising a bit of ventriloquism for my act, and inadvertently spoke aloud."

This lame explanation appeared to satisfy everyone. The passengers resumed their former occupations of staring vacantly out of the windows, reading their papers, or gazing absently at the advertising placards within the car, while the conductor, evidently relieved, betook himself again to the rear platform.

By now, however, the experiment was getting on my nerves. I had feared that my friend's absent-mindedness might lead him into trouble and yet, by my own thoughtless actions, I had twice within a few moments barely cscaped getting into deep water. And the fact that I could not speak my mind to my invisible companion, and that I had pledged myself to see the experiment through, only added to my irritation. As, inwardly fuming, I resolved to keep my mind constantly alert to avoid further embarrassment, the car came to at stop and a stout, pompous and overdresscd middle-aged woman entered. As the car started with a jerk she lurched forward, and, before I realized her intention, she plumped herself into the apparently vacant seat beside me. A grunt from my invisible friend, and a terrific shriek from the stout female instantly followed, and, as if bounced from a spring, she sprang up, her eyes blazing, her face white with indignation and fairly shouting a torrent of abuse as she shook her beringed fist in my face.

"Brute! Disreputable old rake!" she screamed, "I'll have you jailed! I'll have you imprisoned!"

Instantly the car was in an uproar. Passengers crowded forward; necks were craned; everyone talked at once, and the conductor pushed his burly figure between the irate female and myself.

"Hey, what's the game?" he demanded. "What did this guy do to yer, lady?"

"He obtruded himself beneath me,—the unspeakable fiend!" she shrieked. "He endeavored to embrace me and pinched me."

"I did nothing of the sort," I declared, fairly shouting to make myself heard. "—"

"Tell it to the judge," interrupted the conductor, stepping towards me.

Fortunately for me the gentleman to whom I had offered my ventriloquistic explanation, now intervened in my behalf.

"The lady is mistaken," he declared, rising and restraining the conductor. "I was observing her and this gentleman closely. She seated herself in the vacant seat and this gentleman did not move. Possibly—"

"Yeah, the old g-uy's right," chimed in a greasy mechanic opposite. "He never done nothin'. The dame's nutty. What guy'd want her to squat in his lap?"

Instantly the woman's wrath was turned on this new victim, but before violence could be done the conductor intervened. "Hey, quit this roughhouse stuff," he ordered. "If youse want to fight take it outside. Guess you're in wrong, lady. Sit down, or get off and call a cop."

Still glaring, and voicing her opinions of everyone, and especially of me, she again descended ponderously to Lemuel's seat.

An involuntary exclamation escaped my lips, but it was uncalled for. During the excitement, Dr. Unsinn had risen and had slipped unseen to the rear platform where he was beckoning to me wildly.

Only too glad to escape, I rose and joined him and, as the car came to a halt, we stepped off.

"Confound the woman!" he exclaimed the moment we were alone. "She very ncarly fractured my thighs. You would have gotten us into a nice fix if she had. How could a doctor set an invisible bone? And the apparatus in my pocket might have been ruined so that I could not have regained my visible form. You'll have to he more careful in future. Why didn't you stop her or warn me?"

For an instant I was too amazed at his outburst to speak. So he, too, was blaming me for all the trouble. This was too much.

"Look here!" I cried, "I've had enough of this. You're as well able to take care of yourself while invisible as when visible. If you're going to depend on me to keep you out of trouble I'll quit and you can go ahead with your damnable experiment alone. And you talk about getting into trouble! You're safe and l'm the goat every time. Think it's fun for me to be called names and threatened with arrest? I'd look nice trying to explain matters to the police or the judge, wouldn't I?"

"Lemuel chuckled. "Come, come," he exclaimed, placing his hand on my arm. "I didn't mean to have you take it that way, old man. But we'll both have to be a trifle more circumspect in future. And, really, it was most amusing. Now I propose taking a taxi hereafter. I am convinced that trolley cars are not suitable conveyances for me in conducting my tests. But the test was most conclusive after all."

By now the humor of the incident had outweighed the more serious side of the affair in my mind, and I laughed heartily with Lemuel as we waited at the corner for an empty taxi to approach.

Within the vehicle we could converse freely for the noise of the motor and the surrounding traffic prevented the driver from hearing our voices.

Lemuel, elated at the success of his experiments, was now becoming reckless and suggested that it would be most interesting and amusing to render the taxi and ourselves invisible. But I sternly forbade it. "You're an idiot," I declared, "we could be maimed or killed even if we were invisible. Don't you realize we'd be in a wreck within ten seconds? hlf you make any more such ciiazy"suggestions I'll see that you're place in a lunatic asylum.

"Easier said than done," he reminded me, "but, all joking aside, I must try the effect on something more than myself. Ah, I have it! Stop the cab, will you?"

As he had been speaking we had passed a huge office building in course of erection and as I paid the taxi driver, Lemuel was gazing appraisingly at the towering structure of steel and stone.

"A splendid opportunity!" he cried enthusiastically. "Possibly my pocket apparatus may not have sufficient power but—"

"Confound you!" I cried. "Didri't you promise me you wouldn't try your invention on any structure?"

"I did not," he declared decisively. "I merely agreed not to render invisible any structure containing human occupants. This building is vacant. A strike is in progress and the place is deserted.

"Well, you promised not to do anything which would cause a panic or trouble" I persisted.

"And I intend to keep my promise," he replied. "I shall defer my experiment until the noon hour when the streets will be practically deserted, and there can be no panic. And I fail to see how it can cause any trouble."

All arguments which I could offer were in vain, and, I must confess, l was rather fascinated by my friend's suggestion. To cause a towering steel and stone structure to vanish would, indeed, be a feat—if it could be done, and I was anxious to find what the effect on the public would be. But as it was still nearly two hours before noon we resumed our way, with Lemuel seeking new opportunities to test his discovery on the public.

The sidewalks were thronged with shoppers, and presently, as we pushed our way through the crowd, a terrified shriek pierced the hum and noises of the busy street, as my companion, either accidently or thoughtlessly, bumped into a passing woman. As she collapsed in a faint I sprang forward; but Dr. Unsinn was before me. Completely forgetting that he was invisible, he stooped down, raised the victim's head and then, lifting her in his arms, started for a nearby drug store. Instantly pandemonium broke loose. Screams, shouts, frightened cries rose from the crowd which had quickly gathered and awed, unable to beligve theig ey?, men, alyvomen ?lgti children shoved, crowde , and oug t to m e way or t e woman's form floating in air through their midst. For a moment my heart seemed to cease beating. All my fears appeared about to be justified. In an instant there would be a panic with crushed and trampled bodies and all the attendant horrors. But for once the impending catastrophe was stayed by the very panic and terror of the crowd. So intent were the people on the incredible sight which had terrified them that they stood as if turned to stone, petrified with amazement and fear.

And then a still more incredible thing happened. The woman's body suddenly vanished! Lemuel had bethought himself, and, undoubtedly confused at the conditions he had created, had tried to improve matters by rendering his victim invisible. And the seemingly supernatural occurrences had been witnessed by myself as well as by the crowd, for, in the melee the glasses had been wrenched from my nose and were hanging, dangling, useless and temporarily forgotten from my breast pocket. And as the woman's form vanished, a strange sound, half sigh, half groan, arose from the gaping multitude. Before hundreds of eyes the impossible had taken place. A woman had fainted, without reason or cause she had risen and had floated through the air and had utterly vanished in the midst of the crowd. For an instant they remained spellbound, awed into absolute silence. And in that instant Lemuel had entered the drug store with his burden and had deposited her gentlybut hurriedly upon a chair, where, as instantaneously as she had vanished, she again resumed her customary form. As every occupant of the shop had rushed to the doors and windows to see what was taking place on the street, nobody noticed the sudden reappearance of the woman. To me it was all nearly as surprising as to the public, but I had sense enough left to hastily don my glasses, as Lemuel slipped past the white-clad employees of the store, and, taking care not to collide with another bystander, rejoined me.

We had no desire to linger and see the results of the affair, and hurried from the crowd and turned into a nearby cross street. I could scarcely berate my friend for what had occurred, for it had been an unavoidable accident, but I did not hesitate to use it as an example of the dire results which might follow if he kept on with this experiment or made his secret public.

Lemuel was, however, far more excited and disturbed than I, and without even attempting to reply he rushed into a subway entrance. Without stopping to think he hurried to the change booth and thrust a quarter under the wicket. Without glancing up, the occupant shoved back five nickels, and my friend gathered thcm up. But as the coins slid from the wooden shelf and vanished without apparent reason, and with no human hand grasping them, the man peered from his cage. An expression of mortal terror swept across his stolid features, and, with an inarticulate, choking cry, he reeled backward from his stool. But Lemuel did not stop. The events of the past few minutes had completely upset him, and the scientific mind when upset often becomes panicky. For the moment he had, no doubt, completely forgotten that he was invisible, and, rushing forward, he boarded the train with me at his heels. Fortunately it was a dull hour for the subway-—my friend was not forced to jostle or push his way, which most assuredly would have resulted in further troublesiless than half a dozen passengers were within the car which we entered. Lemuel sat silent, evidently composing his thoughts, and fumbling in one of his pockets. The next moment a terrified shout reechoed through the car; a woman fainted; the guard appeared at the door; there was the hissing of released air, and the train came to a jolting, lurching stop. I had a premonition of what had occurred, and, snatching off the pink glasses, I found my worst fears more than fulfilled. The car and its occupants had completely disappeared! With eyes fairly popping from their sockets, mouth agape, and shaking as if with ague, the guard stood on the platform of the next car, staring, utterly aghast, at the void that stretched between him and the car ahead. Reason and instinct told him it was impossible, but his senses told him that a car had completely vanished while speeding at fifty miles an hour, and had taken its passengers along with it. So thoroughly frightened and flabbergasted was the guard that even Lemuel's voice, issuing from space, failed to attract his attention.

"Confound the thing!" exclaimed my companion, "I must have pressed the wrong button, or it may have been shifted when I carried that fainting woman. Likely as not it was injured when that miserable creature seated herself in my lap. Now—"

"My God, man! Can't you do something?" I cried, visions of the car and its occupants remaining forever invisible flashing through my mind.

Then, as instantaneously and unexpectedly as it had vanished, the car was once more in the train. it had all occurred in a few seconds, and the bewildered passengers stared about, rubbing their eyes as if awakening from a dream, while the guard, blinking and muttering, jerked the signal cord and the train again rumbled on.

Fortunately for all concerned, Dr. Unsinn had managed to get his devilish machine to function properly, and no harm had come of the incident, but I had had about enough of it all, and I feared that at any moment, the apparatus might fail entirely or might do the wrong thing. At the next step I left the train, forcing my friend along with me, and, dragging him into an obscure corner of the station platform where there was no chance of.bemg overheard, I expressed my view of his experiment in no gentle terms.

"You can't expect a delicate device to withstand two hundred and fifty pounds of feminine flesh and bone, can you?" he demanded. "I'm not surprised that it was temporarily disarranged. But it's entirely right now. If you don't believe it l'll demonstrate it right here.

"Don't you dare!" I exclaimed. "You'll resume your normal form as a demonstration, and we'll go to lunch. Then back to my apartments and no more of this experiment. You've caused enough trouble for one day and I'll have a nervous breakdown if this sort of thing continues."

"l'll agree on one condition," replied Lemuel with more readiness than I had expected. "I'm determined to try my experiment on that unfinished building. After that I'll cease my experiment for today."

In vain I argued. Lemuel could be as obstinate as a mule at times, and, at last, realizing that he was bound to carry out his desires and that if I left him he might bring about dire results when alone, I assented to his condition.

So, with Dr. Unsinn once more his usual self, we found a quiet restaurant where I was accustomed to dining. The waiter, having taken our order, handed me a copy of the latest edition of a paper, and, half fearfully, I glanced through it, expecting to find an account of one or more of the strange occurrences for which we had been responsible. But nothing had appeared, and I decided that, in all probability, the witnesses had not cared to report an experience which would expose them to ridicule and a suspicion of insanity.

Lemuel was in high spirits. To be sure, he'l1ad made one or two mistakes, but each case, as he put it, added to the value of his experiment and of his observations. And he could not resist crowing over me a bit when he called my attention to the fact that neither panic nor disasters had resulted.

"It is exactly as I foresaw," he declared. "The entirely new and unknown does not terrorize human beings. Wonder and amazement temporarily paralyze the muscles, and, as you should know, two opposed impressions cannot occupy the mind at the same time. Hence fear cannot have a place where wonder is predominant.

"No, my friend, your fears of my discovery creating a panic or causing terror and shock are absolutely unfounded."

"You forget about the woman who fainted, and the man in the subway," I reminded him.

"Utterly beside the question," he snorted. "In the case of the woman it was bodily contact which frightened her, and, in the other case, the fact that the money vanished. In neither case was it due to fright at my invisibility."

"ltls hopeless to argue with you," I said. "Indirectly, your invisibility was at the bottom of it, and Heaven alone knows what a panic might have resulted if that car had remained invisible long enough for the passengers of the other cars to have investigated the cause of the train stopping."

"I can and shall prove I am right," he declared. "Come, we'll have a try at that building and I'll wager no one will be terrified."

"For Heaven's sake, don't vanish here!" I cried, as I saw Lemuel reach towards an inner pocket. "Wait until we are alone. I'd suggest a telephone booth as the most convenient and safest spot."

A few moments later my friend entered a booth, and almost instantly emerged, visible only to myself. Hailing a taxi, we were soon in the vicinity of the partly completed Hartwell Building. It was the lunch hour and very few persons were on the street. Opposite the building a chauffeur dozed in his taxi, two fruit vendors argued in vociferous Italian on the corner, and a few pedestrians who had dined early were wandering about gazing into shop windows. Entering the main doorway of the building we found ourselves in the spacious rotunda with its litter of discarded building materials and abandoned scaffoldings.

"Ah, here we are!" exclaimed Lemuel gleefully. "Now, if my pocket apparatus can produce results on this edifice I shall feel that nothing is too great to be rendered invisible. Entire armies, navies, cities, yes——"

"Then I hope it doesn't work," I interrupted.

But my hopes were in vain. As Lemuel had been speaking, he had adjusted his instrument and scarcely had my last word been uttered, when the twenty stories of concrete, steel and stone dissolved about us, leaving us, invisible to others, standing in air above the yawning abyss of the foundation excavation.

For a brief instant no one within sight appeared to notice that the structure had vanished. Then the dozing chauffeur jerked upright, his jaw sagged, and with a wild yell he sat transfixed, pointing dramatically at the empty lot where the building had stood. At his cry everyone on the street turned. Shouts and exclamations drew occupants of stores and restaurants on the run. With screeching horns taxis came tearing into the street, and in almost no time Nineteenth Street was filled with a gaping, gesticulating, excited crowd.

"Didn't I tell you so?" cried Lemuel triumphantly. "No one is frightened. All—" His words were cut short by the clanging of a bell as a patrol wagon came dashing around a corner, while from the opposite direction, the screaming siren of a fire truck added to the uproar.

"Quick!" I cried, "Someone's called the police and turned in a fire alarm. In a minute they'll be here. They'll find us and there'll be the devil to pay!"

Lemuel roared with glee. "You forget we're invisible," he reminded me. "And it will be highly amusing to witmass the reactions of the police and firemen when they find solid walls where obviously there are none. And imagine thc results when those who succeed in entering vanish instantly."

"Turn off the damnable machine instantly," I commanded him, "this has gone far enough."

The police and firemen were advancing towards us, hesitatingly but determined, although what they expected to accomplish er why they imagined their services were required, is still a mystery to me. As I have said before, habit is one of the strongest of influences. Dr. Unsinn, being a great respector of law, and seeing the police approaching, succumbed to force of habit and almost involuntarily stopped his mechanism. Instantly the huge building once more towered above the street, and with a hoarse cry of warning and alarm, the crowd broke and fled, seeking refuge in doorways and stores ns if fearing the structure might crash thundering into the street. Even the police sprang back, but the firemen, to their credit be it said, stood their ground, and, thinking something was expected of them, turned half a dozen streams of water on the buildings. In the excitement Lemuel and I slipped unseen from a rear entrance and hurried from sight around a corner.

Despite all my experiences with my friend's discovery I was shaken and upset by this latest demonstration of his power, and even Lemuel was, I could see, in a highly excitable frame of mind. His device had exceeded even his most sanguine expectations and his experiment had, from his point of view, been a huge success.

Several times he started to speak, but each time I checked him, for the sidewalks were thronged with pedestrians and I had no desire to have attention turned towards us after our latest achievement.

We were now in a shopping district, and as we walked along, picking our way with care in order that Lemuel might not jostle some passer-by, I noticed a rough-looking, heavily-built fellow loitering near the edge of the sidewalk and furtively glancing at each woman who passed him. Suddenly he darted forward, snatched a handbag from a stylishly-dressed girl, and dashed up the street. Screaming that she had been robbed, the girl started after him. Cries of "Stop thief!" resoundcd from every side, and a score of persons turned and gave chase. Lemuel and I had been nearest to the fellow, and with one accord we were after him, quite forgetting that one of us was invisible. Dashing around the corner, the rascal entered an almost deserted side street with us at his heels and the howling mob half a block in the rear. In my youth I had been something of a runner, and Lemuel had, it flashed upon me, won the coveted "S" of our university as a sprinter. Rapidly we gained upon the fellow, and, as he turned to duck into an alleyway, Lemuel grasped him by the coat with a command to halt.

Instantly, and without stopping, the fellow half turned and dealt a vicious, back-handed blow with his doubled fist. It caught Lemuel full in the face, and with a gasping cry he staggered back into my arms with a two inch gash laying bare the cheek bone and blood gushing from the wound. But even at that moment, while supporting my injured comrade, my attention was focussed upon the ruffian who had struck him down. Feeling the impact of his fist upon a fellow-being's flesh, he had wheeled, and, the next moment, stood rooted to the spot.

Instead of a form stretched on the pavement or a battered man staggering back, not a living soul was near with the exception of myself. The fellow's eyes grew wide, his mouth opened, and the next moment he uttered a terrified scream, and dropping the hand-bag fell to his knees, covering his eyes with his hands, babbling incoherently, and shaking with mortal fear. Upon the flagging before me was a blotch of blood, and, from nowhere, drops of blood were slowly adding to the crimson pool. Lemuel might be invisible but the blood from his wound was not. To the cowering, superstitious wretch, the blood, slowly dripping from an unseen victim, must have been a most awful and terrifying sight.

The oncoming mob now was nearly upon us, and, a dozen fears swept through my confused brain. What if the blood stains on the pavement attracted attention and an explanation were demanded? What would happen to my invisible companion, as the mob, dashing onward, bore him down and trampled him under foot? And what if the cowering wretch before us blurted out the truth? But I need not have worried. So intent were the man-chasers upon their quarry that they gave no heed cvcn to me, and in a moment, the red blotch was completely obliterated by scores of feet, as the crowd surrounded us and seized the thief who offered no resistance. And almost by a miracle Dr. Unsinn escaped the fate I had feared. I sprang behind him as the mob reached us and thus partially shielded him, but despite this, the shouting, panting, perspiring crowd jostled and bumped him, tearing his coat half from his shoulders, knocking his spectacles into the street where they were instantly ground to bits underfoot, tearing his collar awry, knocking off his hat and, as I knew from his half-stifled grunts, exclamations and ejaculations, giving him many a painful jab and bump with elbows and shoulders. But in that hub-bub, the cries of any man were inaudible, and as everyone jostled and pushed his neighbor no one noticed that an invisible but solid human form was in their midst. Luckily the mob surged forward around the thief and left a fairly clear space through which I halfdragged, half-pushed my battered, bruised and dishevelled comrade.

Attracted by the commotion, half a dozen taxis had drawn up to the curb, their drivers craning their necks and peering into the milling crowd about the captive, and giving no heed to anything else. Quickly opening the door of the nearest, I bundled Lemuel inside, and, at last succeeding in gaining the chauffeur's attention, I ordered him to drive off. He turned with a half-uttered oath and refused to move, but noticing my own rumpled appearance, and realizing I had been in the thick of the trouble, his tone changed and he asked what it was all about. In a few words I explained that it was merely a purse-snatchcr, and that I had been knocked over in the meléc. For an instant he gazed suspiciously at me, for my bands were a bit smeared with Lemuel's blood, and for a brief instant I trembled for fear he would drive us to the nearest police station. But he had lost interest in the crowd and excitement, and as I suggestively showed him a ten dollar bill, he grinned knowingly, threw in the gears and with loudly honking horn headed uptown as I had directed.

Hastily bandaging Lemuel's face with my handkerchief to prevent any further complications arising over blood dripping on the taxi seat or floor, and half-supporting him, for he was still dazed and groggy and without his glasses was almost as blind as a bat, I fanned him with my hat.

Presently he showed signs of recovering. took several deep breaths of relief and ruefully felt of his various bumps. contusions and bruises. Then, with a groan, he remarked: "Whew, that fellow packed an awful punch!"

"Yes" I agreed, "and obviously the fact that you are' invisible does not prcvent you from getting hurt."

"Nor from suffering," mumbled my companion, "I'm positive my jaw is fractured."

"Don't try to talk," I said. "I'd take you to a hospital or a doctor's office, but you'd have to be visible and you're in no fit shape to materialize in public. You look like a butchery."

By the time we reached my apartments Lemuel was near a collapse and was, I knew, suffering intensely. But he was still game, and with but little assistance walked up the steps and into my rooms where he instantly dropped upon a couch.

"Now, if you're able to, and the confounded thing isn't out of order, get back to your normal state," I commanded him. "I'll have my doctor here in a moment, but you've got to be visible first."

I was greatly worried for fcar that Lemuel might faint or lose consciousness before he could restore himself to visibility, and I was so perturbed and excited that it never occurred to me that, even if he remained invisible, I could give the glasses to the physician and thus enable him to attend to my fricnd's injuries. However, to my relief, Lemuel fumbled with his mechanism, and presently was once more visible to unaided human eyes. And not an instant too soon. He had exhausted his last strength in operating the device which dropped to the floor as unsciousness left him.

Fortunately, my doctor lived less than a block distant, and, still more fortunately, he was in his office. Within five minutes he was bending over Dr. Unsinn, and, being as all doctors should be, a most discreet man, he forbore to make embarrassing inquiries as to the manner in which Lemuel had received the wounds.

To my intense relief he assured me that there was no fracture and no injuries more serious than the one deep gash and severe contusions.

Lemuel regained consciousness as the doctor was bandaging the wound, but he made no attempt to speak, and, for that matter, his face was too swollen and painful to permit him to utter an intelligible word for the next twentyfour hours.

In the meantime we eagerly bought and read the papers which were filled with accounts of the Hartwell Building mystery, and I could see by Lemuel's expression, even through his bandages, that he was immensely pleased at the attention his feat had attracted. There were also items regarding our, or rather Lemuel's other exploits. A score of persons had reported the incident of the fainting woman; the man in the subway station had related his experience, but not a word appeared in print regarding the sudden vanishing of the car. No doubt the guard hesitated to mention or report the matter fearing that his superiors might, quite reasonably, feel that a guard subject to such hallucinations was unfit for his position. And, in all probability, the passengers who had been present and who, the chances were, had spoken to the guard after our departure, were convinced that they had been subjected to some optical illusion.

And of course there was no reference to the thief-chase or Lemuel's injuries, for the thief alone had seen anything out of the ordinary.

And of course no one had suspected our connection with all the phenomena, for which I was extremely thankful, although it did not please Lemuel, who declared, somewhat peevishly that he had received no credit for his astounding discovery.

"Credit!" I exclaimed, "If the police knew you were at the bottom of these things you'd very probably be in jail by now."

"And," I continued, "I hope this last experience of yours has convinced you that 1 was right and that your discovery is a menace. If you take my advice you'Il destroy every one of your formulae and every confounded contraption that has to do with the invention."

A wry grin twisted Dr. ynsinn's plastered and bandaged face. No, he declared, I shall destroy nothing. But I must admit that I have found my discovery is not so beneficial to the individual or the public at large as I had hoped. It is, I fear, too vast in its possibilities to be given to the world as I had planned. But I still am positive that it is a most important discovery 'and, if properly eruployed, will be of incalculable benefit to the world. N0, instead of destroying it as youdsuggeslt, I shall present it to our government wit t e un erstan ing that it hall remain a secret until needed to avert some national calamity."

I breathed a sigh of deep relief. "In that case," I replied, "your invention is as good as destroyed."

THE END