ious fact that the doctor was clearly upon the trail of
discovery. In his mind at that moment, I believe, he had already solved
the nature of this perplexing psychical problem. His face was like a
mask, and he employed the absolute minimum of gesture and words. All his
energies were directed inwards, and by those incalculable methods and
processes he had mastered with such infinite patience and study, I felt
sure he was already in touch with the forces behind these singular
phenomena and laying his deep plans for bringing them into the open, and
then effectively dealing with them.

Colonel Wragge meanwhile grew more and more fidgety. From time to time
he turned towards my companion, as though about to speak, yet always
changing his mind at the last moment. Once he went over and opened the
door suddenly, apparently to see if any one were listening at the
keyhole, for he disappeared a moment between the two doors, and I then
heard him open the outer one. He stood there for some seconds and made a
noise as though he were sniffing the air like a dog. Then he closed both
doors cautiously and came back to the fireplace. A strange excitement
seemed growing upon him. Evidently he was trying to make up his mind to
say something that he found it difficult to say. And John Silence, as I
rightly judged, was waiting patiently for him to choose his own
opportunity and his own way of saying it. At last he turned and faced
us, squaring his great shoulders, and stiffening perceptibly.

Dr. Silence looked up sympathetically.

"Your own experiences help me most," he observed quietly.

"The fact is," the Colonel said, speaking very low, "this past week
there have been outbreaks of fire in the house itself. Three separate
outbreaks--and all--in my sister's room."

"Yes," the doctor said, as if this was just what he had expected to
hear.

"Utterly unaccountable--all of them," added the other, and then sat
down. I began to understand something of the reason of his excitement.
He was realising at last that the "natural" explanation he had held to
all along was becoming impossible, and he hated it. It made him angry.

"Fortunately," he went on, "she was out each time and does not know. But
I have made her sleep now in a room on the ground floor."

"A wise precaution," the doctor said simply. He asked one or two
questions. The fires had started in the curtains--once by the window and
once by the bed. The third time smoke had been discove