Kennedy had placed himself directly before her, listening intently to her ravings. Suddenly he managed to fix her eye, as if by a sort of hypnotic influence.

"Agnes!" he called in a sharp tone.

The name seemed to arrest her fugitive attention. Before she could escape from his mental grasp again he added: "Your date-book is full.

Aren't you going to the Novella this morning?"

The change in her was something wonderful to see. It was as though she had come out of a trance. She sat up in bed and gazed about blankly.

"Yes, yes, I must go," she cried as if it were the most natural thing in the world. Then she realised the strange surroundings and faces.

"Where is my hat--wh-where am I? What has happened?"

"You are all right," soothed Kennedy gently. "Now rest. Try to forget everything for a little while, and you will be all right. You are among friends."

As Kennedy led us out she fell back, now physically exhausted, on the pillow.

"I told you, Barron," he whispered, "that there was more to this case than you imagined. Unwittingly you brought me a very important contribution to a case of which the papers are full this morning, the case of the murdered actress, Blanche Blaisdell."

IV

THE BEAUTY SHOP

It was only after a few hours that Kennedy thought it wise to try to question the poor girl at the hospital. Her story was simple enough in itself, but it certainly complicated matters considerably without throwing much light on the case. She had been busy because her day was full, and she had yet to dress the hair of Miss Blaisdell for her play that night. Several times she had been interrupted by impatient messages from the actress in her little dressing-booth, and one of the girls had already demolished the previous hair-dressing in order to save time. Once Agnes had run down for a few seconds to rea.s.sure her that she would be through in time.

She had found the actress reading a newspaper, and when Kennedy questioned her she remembered seeing a note lying on the dresser.

"Agnes," Miss Blaisdell had said, "will you go into the writing-room and bring me some paper, a pen, and ink? I don't want to go in there this way. There's a dear good girl." Agnes had gone, though it was decidedly no part of her duty as one of the highest paid employes of the Novella. But they all envied the popular actress, and were ready to do anything for her. The next thing she remembered was finishing the coiffure she was working on and going to Miss Blaisdell. There lay the beautiful actress. The light in the corridor had not been lighted yet, and it was dark. Her lips and mouth seemed literally to shine. Agnes called her, but she did not move; she touched her, but she was cold.

Then she screamed and fled. That was the last she remembered.

"The little writing-room," reasoned Kennedy as we left the poor little hair-dresser quite exhausted by her narrative, "was next to the sanctum of Millefleur, where they found that bottle of ether phosph.o.r.e and the oil of turpentine. Some one who knew of that note or perhaps wrote it must have reasoned that an answer would be written immediately. That person figured that the note would be the next thing written and that the top envelope of the pile would be used. That person knew of the deadly qualities of too much phosphorised ether, and painted the gummed flap of the envelope with several grains of it. The reasoning held good, for Agnes took the top envelope with its poisoned flap to Miss Blaisdell. No, there was no chance about that. It was all clever, quick reasoning."

"But," I objected, "how about the oil of turpentine?"

"Simply to remove the traces of the poison. I think you will see why that was attempted before we get through."

Kennedy would say no more, but I was content because I could see that he was now ready to put his theories, whatever they were, to the final test. He spent the rest of the day working at the hospital with Dr.

Barron, adjusting a very delicate piece of apparatus down in a special room, in the bas.e.m.e.nt. I saw it, but I had no idea what it was or what its use might be.

Close to the wall was a stereopticon which shot a beam of light through a tube to which I heard them refer as a galvanometer, about three feet distant. In front of this beam whirled a five-spindled wheel, governed by a chronometer which erred only a second a day. Between the poles of the galvanometer was stretched a slender thread of fused quartz plated with silver, only one one-thousandth of a millimetre in diameter, so tenuous that it could not be seen except in a bright light. It was a thread so slender that it might have been spun by a microscopic spider.

Three feet farther away was a camera with a moving film of sensitised material, the turning of which was regulated by a little flywheel. The beam of light focused on the thread in the galvanometer pa.s.sed to the photographic film, intercepted only by the five spindles of the wheel, which turned once a second, thus marking the picture off into exact fifths of a second. The vibrations of the microscopic quartz thread were enormously magnified on the sensitive film by a lens and resulted in producing a long zig-zag, wavy line. The whole was shielded by a wooden hood which permitted no light, except the slender ray, to strike it. The film revolved slowly across the field, its speed regulated by the flywheel, and all moved by an electric motor.

I was quite surprised, then, when Kennedy told me that the final tests which he was arranging were not to be held at the hospital at all, but in his laboratory, the scene of so many of his scientific triumphs over the cleverest of criminals.

While he and Dr. Barren were still fussing with the machine he despatched me on the rather ticklish errand of gathering together all those who had been at the Novella at the time and might possibly prove important in the case.

My first visit was to Hugh Dayton, whom I found in his bachelor apartment on Madison Avenue, apparently waiting for me. One of O'Connor's men had already warned him that any attempt to evade putting in an appearance when he was wanted would be of no avail. He had been shadowed from the moment that it was learned that he was a patient of Millefleur's and had been at the Novella that fatal afternoon. He seemed to realise that escape was impossible. Dayton was one of those typical young fellows, tall, with sloping shoulders and a carefully acquired English manner, whom one sees in scores on Fifth Avenue late in the afternoon. His face, which on the stage was forceful and attractive, was not prepossessing at close range. Indeed it showed too evident marks of excesses, both physical and moral, and his hand was none too steady. Still, he was an interesting personality, if not engaging.

I was also charged with delivering a note to Burke Collins at his office. The purport of it was, I knew, a request couched in language that veiled a summons that Mrs. Collins was of great importance in getting at the truth, and that if he needed an excuse himself for being present it was suggested that he appear as protecting his wife's interests as a lawyer. Kennedy had added that I might tell him orally that he would pa.s.s over the scandal as lightly as possible and spare the feelings of both as much as he could. I was rather relieved when this mission was accomplished, for I had expected Collins to demur violently.

Those who gathered that night, sitting expectantly in the little armchairs which Kennedy's students used during his lectures, included nearly every one who could cast any light on what had happened at the Novella. Professor and Madame Millefleur were brought up from the house of detention, to which both O'Connor and Dr. Leslie had insisted that they be sent. Millefleur was still bewailing the fate of the Novella, and Madame had begun to show evidences of lack of the constant beautification which she was always preaching as of the utmost importance to her patrons. Agnes was so far recovered as to be able to be present, though I noticed that she avoided the Millefleurs and sat as far from them as possible.

Burke Collins and Mrs. Collins arrived together. I had expected that there would be an icy coolness if not positive enmity between them.

They were not exactly cordial, though somehow I seemed to feel that now that the cause of estrangement was removed a tactful mutual friend might have brought about a reconciliation. Hugh Dayton swaggered in, his nervousness gone or at least controlled. I pa.s.sed behind him once, and the odour that smote my olfactory sense told me too plainly that he had fortified himself with a stimulant on his way from the apartment to the laboratory. Of course O'Connor and Dr. Leslie were there, though in the background.

It was a silent gathering, and Kennedy did not attempt to relieve the tension even by small talk as he wrapped the forearms of each of us with cloths steeped in a solution of salt. Upon these cloths he placed little plates of German silver to which were attached wires which led back of a screen. At last he was ready to begin.

"The long history of science," he began as he emerged from behind the screen, "is filled with instances of phenomena, noted at first only for their beauty or mystery, which have been later proved to be of great practical value to mankind. A new example is the striking phenomenon of luminescence. Phosphorus, discovered centuries ago, was first merely a curiosity. Now it is used for many practical things, and one of the latest uses is as a medicine. It is a const.i.tuent of the body, and many doctors believe that the lack of it causes, and that its presence will cure, many ills. But it is a virulent and toxic drug, and no physician except one who knows his business thoroughly should presume to handle it. Whoever made a practice of using it at the Novella did not know his business, or he would have used it in pills instead of in the nauseous liquid. It is not with phosphorised ether as a medicine that we have to deal in this case. It is with the stuff as a poison, a poison administered by a demon."

Craig shot the word out so that it had its full effect on his little audience. Then he paused, lowered his voice, and resumed on a new subject.

"Up in the Washington Heights Hospital," he went on, "is an apparatus which records the secrets of the human heart. That is no figure of speech, but a cold scientific fact. This machine records every variation of the pulsations of the heart with such exquisite accuracy that it gives Dr. Barron, who is up there now, not merely a diagram of the throbbing organ of each of you seated here in my laboratory a mile away, but a sort of moving-picture of the emotions by which each heart here is swayed. Not only can Dr. Barron diagnose disease, but he can detect love, hate, fear, joy, anger, and remorse. This machine is known as the Einthoven 'string galvanometer,' invented by that famous Dutch physiologist of Leyden."

There was a perceptible movement in our little audience at the thought that the little wires that ran back of the screen from the arms of each were connected with this uncanny instrument so far away.

"It is all done by the electric current that the heart itself generates," pursued Kennedy, hammering home the new and startling idea.

"That current is one of the feeblest known to science, for the dynamo that generates it is no ponderous thing of copper wire and steel castings. It is just the heart itself. The heart sends over the wire its own telltale record to the machine which registers it. The thing takes us all the way back to Galvani, who was the first to observe and study animal electricity. The heart makes only one three-thousandth of a volt of electricity at each beat. It would take over two hundred thousand men to light one of these incandescent lamps, two million or more to run a trolley-car. Yet just that slight little current is enough to sway the gossamer strand of quartz fibre up there at what we call the 'heart station.' So fine is this machine that the pulse-tracings produced by the sphygmograph, which I have used in other cases up to this time, are clumsy and inexact."

Again he paused as if to let the fear of discovery sink deep into the minds of all of us.

"This current, as I have said, pa.s.ses from each one of you in turn over a wire and vibrates a fine quartz fibre up there in unison with each heart here. It is one of the most delicate bits of mechanism ever made, beside which the hairspring of a watch is coa.r.s.e. Each of you in turn, is being subjected to this test. More than that, the record up there shows not only the beats of the heart but the successive waves of emotion that vary the form of those beats. Every normal individual gives what we call an 'electro-cardiogram,' which follows a certain type. The photographic film on which this is being recorded is ruled so that at the heart station Dr. Barron can read it. There are five waves to each heart-beat, which he letters P, Q, R, S, and T, two below and three above a base line on the film. They have all been found to represent a contraction of a certain portion of the heart. Any change of the height, width, or time of any one of those lines shows that there is some defect or change in the contraction of that part of the heart. Thus Dr. Barron, who has studied this thing carefully, can tell infallibly not only disease but emotion."

It seemed as if no one dared look at his neighbour, as if all were trying vainly to control the beating of their own hearts.

"Now," concluded Kennedy solemnly as if to force the last secret from the wildly beating heart of some one in the room, "it is my belief that the person who had access to the operating-room of the Novella was a person whose nerves were run down, and in addition to any other treatment that person was familiar with the ether phosph.o.r.e. This person knew Miss Blaisdell well, saw her there, knew she was there for the purpose of frustrating that person's own dearest hopes. That person wrote her the note, and knowing that she would ask for paper and an envelope in order to answer it, poisoned the flap of the envelope.

Phosphorus is a remedy for hysteria, vexatious emotions, want of sympathy, disappointed and concealed affections--but not in the quant.i.ties that this person lavished on that flap. Whoever it was, not life, but death, and a ghastly death, was uppermost in that person's thoughts."

Agnes screamed. "I saw him take something and rub it on her lips, and the brightness went away. I--I didn't mean to tell, but, G.o.d help me, I must."

"Saw whom?" demanded Kennedy, fixing her eye as he had when he had called her back from aphasia.

"Him--Millefleur--Miller," she sobbed, shrinking back as if the very confession appalled her.

"Yes," added Kennedy coolly, "Miller did try to remove the traces of the poison after he discovered it, in order to protect himself and the reputation of the Novella."

The telephone bell tinkled. Craig seized the receiver.

"Yes, Barron, this is Kennedy. You received the impulses all right?

Good. And have you had time to study the records? Yes? What's that?

Number seven? All right. I'll see you very soon and go over the records again with you. Good-bye."

"One word more," he continued, now facing us. "The normal heart traces its throbs in regular rhythm. The diseased or overwrought heart throbs in degrees of irregularity that vary according to the trouble that affects it, both organic and emotional. The expert like Barron can tell what each wave means, just as he can tell what the lines in a spectrum mean. He can see the invisible, hear the inaudible, feel the intangible, with mathematical precision. Barron has now read the electro-cardiograms. Each is a picture of the beating of the heart that made it, and each smallest variation has a meaning to him. Every pa.s.sion, every emotion, every disease, is recorded with inexorable truth. The person with murder in his heart cannot hide it from the string galvanometer, nor can that person who wrote the false note in which the very lines of the letters betray a diseased heart hide that disease. The doctor tells me that that person was number--"

Mrs. Collins had risen wildly and was standing before us with blazing eyes. "Yes," she cried, pressing her hands on her breast as if it were about to burst and tell the secret before her lips could frame the words, "yes, I killed her, and I would follow her to the end of the earth if I had not succeeded. She was there, the woman who had stolen from me what was more than life itself. Yes, I wrote the note, I poisoned the envelope. I killed her."

All the intense hatred that she had felt for that other woman in the days that she had vainly striven to equal her in beauty and win back her husband's love broke forth. She was wonderful, magnificent, in her fury. She was pa.s.sion personified; she was fate, retribution.