"How on earth could I have obtained that photograph of her in the darkness ?" he demanded.
"N-rays," said the Tracer coolly.

"It has been done in France." "Yes, from living people, but--" "What the N-ray is in living organisms, we must call, for lack of a better term, the subaura in the phantom." They bent over the photograph together.

Presently the Tracer said: "She is very, very beautiful ?" Harren's dry lips unclosed, but he uttered no sound.
"She is beautiful, is she not ?" repeated the Tracer, turning to look at the young man.
"Can you not see she is ?" he asked impatiently.
"No," said the Tracer.
Harren stared at him.
"Captain Harren," continued the Tracer, "I can see nothing upon this bit of paper that resembles in the remotest degree a human face or figure." Harren turned white.
"Not that I doubt that _you_ can see it," pursued the Tracer calmly.

"I simply repeat that I see absolutely nothing on this paper except a part of a curtain, a window pane, and--and--" "What! for God's sake!" cried Harren hoarsely.
"I don't know yet.

Wait; let me study it." "Can you not see her face, her eyes?
_Don't_ you see that exquisite slim figure standing there by the curtain ?" demanded Harren, laying his shaking finger on the photograph.