“When was this—­this photograph taken?” asked the Tracer quietly.

“The day after I arrived in New York.  I was here, alone, smoking my pipe and glancing over the evening paper just before dressing for dinner.  It was growing rather dark in the room; I had not turned on the electric light.  My camera lay on the table—­there it is!—­that kodak.  I had taken a few snapshots on shipboard; there was one film left.”

He leaned more heavily on his elbow, eyes fixed upon the picture.

“It was almost dark,” he repeated.  “I laid aside the evening paper and stood up, thinking about dressing for dinner, when my eyes happened to fall on the camera.  It occurred to me that I might as well unload it, let the unused film go, and send the roll to be developed and printed; and I picked up the camera—­”

“Yes,” said the Tracer softly.

“I picked it up and was starting toward the window where there remained enough daylight to see by—­”

The Tracer nodded gently.

“Then I saw her!” said Harren under his breath.

“Where?”

“There—­standing by that window.  You can see the window and curtain in the photograph.”

The Tracer gazed intently at the picture.

“She looked at me,” said Harren, steadying his voice.  “She was as real as you are, and she stood there, smiling faintly, her dark, lovely eyes meeting mine.”

“Did you speak?”

“No.”

“How long did she remain there?”

“I don’t know—­time seemed to stop—­the world—­everything grew still. . . .  Then, little by little, something began to stir under my stunned senses—­that germ of misgiving, that dreadful doubt of my own sanity. . . .  I scarcely knew what I was doing when I took the photograph; besides, it had grown quite dark, and I could scarcely see her.”  He drew himself erect with a nervous movement.  “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—­”