"Perpetual motion sounds foolish, I'll admit. But, Professor Kennedy, this Creighton self-acting motor does things I can't explain."

Craig looked perplexed as he gazed from Adele Laidlaw, his young and very pretty client, to me. We had heard a great deal about the young lady, one of the wealthiest heiresses of the country. She paused a moment and looked at us, evidently thinking of the many schemes which people had devised to get her money away from her.

"Really," she went on, "I haven't a friend to whom I can go, except Mr. Tresham—no one on whom I can rely for advice in a case of this kind."

Several times, I recollected, there had been rumors that she was engaged to Leslie Tresham, who had been the lawyer for her father before his death. The rumors had always been denied, however, though I am sure it was not Tresham's fault.

"You see," she continued, as Craig still said nothing, "father was of a mechanical turn of mind; in fact so was the whole family, and I suppose I have inherited it. I'm just crazy over cars and boats. Anyhow, I was introduced to Mr. Creighton and he seemed so earnest and his work was so interesting that I bought a little of his stock. Now he needs more money to perfect his motor. Perhaps the thing is all right, but,—well, what do I really know about it?"

One could not help feeling a great deal of sympathy for her. She was not the type of woman who would be easily misled, yet I could imagine that she must constantly be on her guard against schemers of every sort lurking to take advantage of every whim.

"H'm," mused Kennedy, with a smile, eyeing our visitor keenly. "I've been consulted on about everything from pickpockets to the fountain of youth. Now it's perpetual motion. I must say, Miss Laidlaw, your case has a decided scientific interest for me, anyhow, as well as personal. I'd like to look at this wonderful machine, if you can arrange it."

"I can do that," she answered confidently with a glance of thanks to Kennedy for his help. "May I use your telephone?"

She had to wait some time for an answer to her call, but finally she got Creighton on the wire.

"He had just come in," she said, hanging up the receiver. "He'll be there if we come down right away."

Adele Laidlaw drove us downtown in her own high-powered car, which, true to her mechanical instincts, she handled herself. She drove it very well, too. In fact, I felt safer than with Kennedy, who, like many drivers, was inclined to take chances when he was at the wheel himself and could see what he was up against, though he balked severely when anyone else did it.

"How did you become interested in this perpetual motion machine, Miss Laidlaw?" he asked as we threaded our way through the dense traffic.

"Well, I suppose everyone knows that I'm interested in engines," she replied, as we waited for the signal from a policeman at a cross-street. "I've spent a good deal on them in speed-boats and in racing cars, too. An acquaintance, a friend of Mr. Creighton's, a Mrs. Barry,—Mr. Tresham knows her,—thought perhaps I might use the motor somehow and told me of it. I went down to see it and—I must confess that it fascinated me."

I had not yet quite got myself accustomed to a girl who was interested in such things, though, in these days, I must confess, saw no reason why she should not be. Kennedy was dividing his attention between the admirable manner in which she handled the car and her very expressive face. Was it really, I wondered, that Creighton, more than his motor, has fascinated her?

She drew up before the Consolidated Bank Building, a modern steel and concrete structure in the uptown business section.

"The laboratory is next door," she said, as she let the car slide ahead a few feet more. "Mr. Tresham's office is in the Bank Building. I've had to go there so often since father died that I stopped through force of habit, I suppose."

Mindful of Kennedy's admiration for Freud, his theory of forgetting occurred to me. Was there any significance in the mistake? Had the unconscious blunder betrayed something which perhaps she herself consciously did not realize? Was it Tresham, after all, whom she really admired and wanted to see?

Creighton's workshop was in an old two-story brick building, evidently awaiting only the development of the neighborhood before it was torn down. Meanwhile the two buildings were in marked contrast. Which of them typified Creighton? Was he hopelessly out of date, or really ahead of his time? I must confess to having had a lively curiosity to meet the inventor.

The entrance to the laboratory from the street was through a large door into a room in which was a carpenter's bench. On one side were some powerful winches and a large assortment of tools. In the back of the room a big door led to another room on the ground floor to the rear.

"Mr. Creighton's is upstairs," remarked Miss Laidlaw, turning past the locked door and going up a worn flight of steps.

"Whose shop is that?" asked Kennedy, indicating the door.

"I don't know who rents these rooms down here," she replied.

Up the stairway we went to the second floor. On the top landing stood some old machinery. In a little room on one side was a big desk, as well as books, instruments, and drawings of all sorts. Opposite this room was another little room, with many bits of expensive machinery on shelves and tables. Back of these two, and up a step, was a large room, the full width of the building, the workshop of the inventor, into which she led us.

"I've brought a couple of friends of mine who may be interested in the vibrodyne motor," Miss Laidlaw introduced us.

"Very pleased to meet you, gentlemen," Creighton returned. "Before we get through, I think you'll agree with me that you never dreamed of anything more wonderful than this motor of mine."

He was a large, powerfully built man, with a huge head, square jaw with heavy side whiskers, and eyes that moved restlessly under a shock of iron-gray hair. Whether it was the actual size of his head or his bushy hair, one got the impression that his cranium housed a superabundant supply of brains.

Every action was nervous and quick. Even his speech was rapid, as though his ideas outstripped his tongue. He impressed one as absorbed in this thing which he said frankly had been his life study, every nerve strained to make it succeed and convince people.

"Just what is this force you call vibrodyne?" asked Craig, gazing about at the curious litter of paraphernalia in the shop.

"Of course, I'm willing to admit," began Creighton quickly, in the tone of a man who was used to showing his machine to skeptical strangers but must be allowed to explain it in his own way, "that never before by any mechanical, electrical, thermal, or other means has a self-moving motor been made."

He paused apparently to let us grasp the significance of what he was about to say. "But, is it impossible, as some of the old scientists have proved to their own satisfaction it must be?" he went on, warming up to his subject. "May there not be molecular, atomic, even ionic forces of which we have not dreamed? You have only to go back a few years and study radioactivity, for instance, to see how ideas may change.

"Today," he added emphatically, "the conservation of energy, in the old sense at least, has been overthrown. Gentlemen, all the old laws must be modified by my discovery of vibrodyne. I loose new new forces—I create energy!"

I watched him narrowly as he proposed and rapidly answered his own questions. He was talking quite as much for Miss Laidlaw's benefit, I thought, as ours. In fact, it was evident that her interest in the machine and in himself pleased him greatly.

I knew already that though the search after perpetual motion through centuries had brought failure, still it captivated a certain type of inventive mind. I knew also that, just as the exact squaring of the circle and the transmutation of metals brought out some great mathematical discoveries and much of modern chemistry, so perpetual motion had brought out the greatest of all generalizations of physics—the conservation of energy.

Yet here was a man who questioned the infallibility of that generalization. Actually taking the ultra-modern view that matter is a form of energy, he was asserting that energy in some way might be created or destroyed, at least transformed in a manner that no one had ever understood before. To him, radioactivity which had overthrown or amplified many of the old ideas was only a beginning.

"Here is the machine," he pointed out at last, still talking, leading us proudly across the littered floor of his laboratory.

It seemed, at first glance, to consist of a circular iron frame, about a foot and a half in diameter, firmly bolted to the floor.

"I have it fastened down because, as you will see, it develops such a tremendous power," explained the inventor, adding, as he pointed above it, "That is all the power is developed from, too."

On a shelf was a Daniell battery of four cells. In the porous cup was bichromate of potash and in the outer vessel dilute sulphuric acid.

"Let me show you how I get two and a half horsepower out of three ounces of zinc for nine hours," went on Creighton proudly. "As you doubtless know, the usual thing is one horsepower per pound of zinc per hour. Ultimately, I expect to perfect the process until I get a thousand horsepower from an ounce in this vibrodyne motor."

He started the engine by attaching the wires from the comparatively weak Daniell cells. Slowly it began to move, gaining speed, until finally the very floor shook from the great power and the rapidity of the motion.

It seemed incredible that the small current from the battery should develop such apparent power and I looked at Kennedy in amazement.

"There's a carelessly—or purposely—ill-balanced flywheel, I suspect," whispered Craig to me surreptitiously.

"Yes, but the power," I persisted.

He shook his head. Evidently he was not convinced, but had no theory, yet.

Adele Laidlaw looked at Craig questioningly, as though to read what he thought of it. Before her he betrayed nothing. Now and then she would look earnestly at Creighton. It was evident that she admired him very much, yet there seemed to be something about him that she did not quite understand.

Just then the telephone rang. Creighton stopped his machine and left us for a moment to answer the call, while the engine slowed down and came to rest.

Quickly Kennedy pulled out his watch and pried the crystal off the face. He walked over to a basin and filled the crystal with a few drops of water. Then he set it down on the table.

I looked at it closely. As nearly as I could make out, there seemed to be a slight agitation on the surface of the thin film of water in the glass. Craig smiled quietly to himself and flicked the water into the sink, returning the crystal to his watch.

I did not understand just what it was that Craig was after, but I felt sure that there was some kind of vibration that he had discovered.

Meanwhile, we could hear Creighton telephoning and I noticed that Miss Laidlaw was alertly listening, too.

"Why, no," I heard him answer monosyllabically but in a tone that was carefully modulated, "not alone. Let me call you up—soon."

The conversation ended almost as abruptly as it had begun. Somehow, it seemed evident to me that Creighton had been talking to a woman. Though he apparently had not wanted to say anything before us, he could not disguise the fact. From his quick, nervous manner with us, I had concluded that no mere man could have commanded so deferential a tone from him.

A moment later he rejoined us, resuming his praises of his motor. By this time I had come to recognize that he was a master in the manipulation of fantastic terms, which I, at least, did not understand. Therein, perhaps, lay their potency, though I doubt whether Kennedy himself knew what Creighton meant when he talked of "polar sympathy," "inter-atomic ether," "molecular disintegration," and "orbitic chaos."

I saw that Adele Laidlaw was watching Creighton narrowly now. Was it on account of the telephone call? Who had it been? Perhaps, it occurred to me, it was Mrs. Barry. Was Creighton afraid of arousing the jealousy of Adele Laidlaw?

There seemed to be nothing more of importance that Craig could learn at present and we soon bade Creighton good-by, leaving with Miss Laidlaw. I noticed that he locked the door after us as we went out.

"I'd like to meet this Mrs. Barry," remarked Craig as we passed out of the building.

He said it evidently to see just how Miss Laidlaw would take it. "I think I can arrange that," replied Adele Laidlaw colorlessly. "I'll ask her to visit me this afternoon. You can call casually."

We accompanied her to her car, promising to report as soon as possible if we discovered anything new.

"I'm going in to call on Tresham," remarked Craig, turning into the Bank Building.