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 phosphore.  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 quantities 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, God 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 passion, 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.”