“Good heavens almighty!” exclaimed the soldier, mixing his words in his unfeigned surprise.

“Quite so,” pursued the other calmly; “for in so doing I think we can release it from the purpose that binds it, restore it to its normal condition of latent fire, and also”—­he lowered his voice perceptibly —­“also discover the face and form of the Being that ensouls it.”

“The man behind the gun!” cried the Colonel, beginning to understand something, and leaning forward so as not to miss a single syllable.

“I mean that in the last resort, before it returns to the womb of potential fire, it will probably assume the face and figure of its Director, of the man of magical knowledge who originally bound it with his incantations and sent it forth upon its mission of centuries.”

The soldier sat down and gasped openly in his face, breathing hard; but it was a very subdued voice that framed the question.

“And how do you propose to make it visible?  How capture and confine it?  What d’ye mean, Dr. John Silence?”

“By furnishing it with the materials for a form.  By the process of materialisation simply.  Once limited by dimensions, it will become slow, heavy, visible.  We can then dissipate it.  Invisible fire, you see, is dangerous and incalculable; locked up in a form we can perhaps manage it.  We must betray it—­to its death.”

“And this material?” we asked in the same breath, although I think I had already guessed.

“Not pleasant, but effective,” came the quiet reply; “the exhalations of freshly spilled blood.”

“Not human blood!” cried Colonel Wragge, starting up from his chair with a voice like an explosion.  I thought his eyes would start from their sockets.

The face of Dr. Silence relaxed in spite of himself, and his spontaneous little laugh brought a welcome though momentary relief.

“The days of human sacrifice, I hope, will never come again,” he explained.  “Animal blood will answer the purpose, and we can make the experiment as pleasant as possible.  Only, the blood must be freshly spilled and strong with the vital emanations that attract this peculiar class of elemental creature.  Perhaps—­perhaps if some pig on the estate is ready for the market—­”

He turned to hide a smile; but the passing touch of comedy found no echo in the mind of our host, who did not understand how to change quickly from one emotion to another.  Clearly he was debating many things laboriously in his honest brain.  But, in the end, the earnestness and scientific disinterestedness of the doctor, whose influence over him was already very great, won the day, and he presently looked up more calmly, and observed shortly that he thought perhaps the matter could be arranged.