"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."

All the intense hatred that she had felt for that other woman in