* * * * *

“Thank you very much, Professor.  I will send a messenger to Miss Inwood with a copy of the inscription.  Good-by.”

He hung up the receiver, turned thoughtfully, opened the door again, and walked into the sunlit living room.

“Look here!” cried the Captain in a high state of excitement.  “I’ve got a lot of numbers out of it already.”

“Wonderful!” murmured the Tracer, looking over the young man’s broad shoulders at a sheet of paper bearing these numbers: 

9—­14—­5—­22—­5&m
dash;­18—­19—­1—­23—­25—­15—­21—­2—­21—­20—­15—­14—­3—­5—­ 9—­12—­15—­22—­5&mda
sh;­25—­15—­21—­5—­4—­9—­20—­8—­9—­14—­23—­15—­15—­4.

“Marvelous!” repeated the Tracer, smiling.  “Now what do you suppose those numbers can stand for?”

“Letters!” announced the Captain triumphantly.  “Take the number nine, for example.  The ninth letter in the alphabet is I!  Mr. Keen, suppose we try writing down the letters according to that system!”

“Suppose we do,” agreed the Tracer gravely.

So, counting under his breath, the young man set down the letters in the following order, not attempting to group them into words: 

INEVERSAWYOUBUTONCEILOVEYOUEDITHINWOOD.

Then he leaned back, excited, triumphant.

“There you are!” he said; “only, of course, it makes no sense.”  He examined it in silence, and gradually a hopeless expression effaced the animation.  “How the deuce am I going to separate that mass of letters into words?” he muttered.

“This way,” said the Tracer, smilingly taking the pencil from his fingers, and he wrote:  I—­NEVER—­SAW—­YOU—­BUT—­ONCE.  I—­LOVE—­YOU.  EDITH INWOOD.

Then he laid the pencil on the table and walked to the window.

Once or twice he fancied that he heard incoherent sounds behind him.  And after a while he turned, retracing his steps leisurely.  Captain Harren, extremely pink, stood tugging at his short mustache and studying the papers on the desk.

“Well?” inquired the Tracer, amused.

The young man pointed to the translation with unsteady finger.  “W-what on earth does that mean?” he demanded shakily.  “Who is Edith Inwood?  W-what on earth does that cryptogram mean on the window pane in the photograph?  How did it come there?  It isn’t on my window pane, you see!”

The Tracer said quietly:  “That is not a photograph of your window.”

“What!”

“No, Captain.  Here!  Look at it closely through this glass.  There are sixteen small panes in that sash; now count the panes in your window—­eight!  Besides, look at that curtain.  It is made of some figured stuff like chintz.  Now, look at your own curtain yonder!  It is of plain velour.”

“But—­but I took that photograph!  She stood there—­there by that very window!”

The Tracer leaned over the photograph, examining it through the glass.  And, studying it, he said:  “Do you still see her in this photograph, Captain Harren?”