“F—­F—­F,” the fan was calling insistently.

And then the answer came.  It took the unexpectedly prosaic form of a violent sneeze, a vociferous outburst on a bench directly behind Mr. Grimm.  Senorita Rodriguez jumped, then laughed nervously.

“It startled me,” she explained.

“I think there must be a draft from the conservatory,” said a man’s voice apologetically.  “Do you ladies feel it?  No?  Well, if you’ll excuse me—?”

Mr. Grimm glanced back languidly.  The speaker was Charles Winthrop Rankin, a brilliant young American lawyer who was attached to the German embassy in an advisory capacity.  Among other things he was a Heidelberg man, having spent some dozen years of his life in Germany, where he established influential connections.  Mr. Grimm knew him only by sight.

And now the rhythmical tapping of Miss Thorne’s fan underwent a change.  There was a flutter of gaiety in her voice the while the ivory fan tapped steadily.

“Dot-dot-dot!  Dash!  Dash-dash-dash!  Dot-dot-dash!  Dash!”

“S—­t—­5—­u—­t,” Mr. Grimm read in Morse.  He laughed pleasantly at some remark of his companion.

“Dash-dash!  Dot-dash!  Dash-dot!” said the fan.

“M—­a—­n,” Mr. Grimm spelled it out, the while his listless eyes roved aimlessly over the throng.  “S—­t—­5—­u—­t m—­a—­n!” Was it meant for “stout man?” Mr. Grimm wondered.

“Dot-dash-dot!  Dot!  Dash-dot-dot!”

“F—­e—­d,” that was.

“Dot-dot-dash-dot!  Dot-dash!  Dash-dot-dash-dot!  Dot!”

“Q—­a—­j—­e!” Mr. Grimm was puzzled a little now, but there was not a wrinkle, nor the tiniest indication of perplexity in his face.  Instead he began talking of Raphael’s cherubs, the remark being called into life by the high complexion of a young man who was passing.  Miss Thorne glanced at him once keenly, her splendid eyes fairly aglow, and the fan rattled on in the code.

“Dash-dot!  Dot!  Dot-dash!  Dot-dash-dot!”

“N—­e—­a—­f.”  Mr. Grimm was still spelling it out.

Then came a perfect jumble.  Mr. Grimm followed it with difficulty, a difficulty utterly belied by the quizzical lines about his mouth.  As he caught it, it was like this:  “J—­5—­n—­s—­e—­f—­v—­a—­t—­5—­f,” followed by an arbitrary signal which is not in the Morse code:  “Dash-dot-dash-dash!”

Mr. Grimm carefully stored that jumble away in some recess of his brain, along with the unknown signal.

“D—­5—­5—­f,” he read, and then, on to the end:  “B—­f—­i—­n—­g 5—­v—­e—­f w—­h—­e—­n g g—­5—­e—­s.”

That was all, apparently.  The soft clatter of the fan against the arm of the chair ran on meaninglessly after that.

“May I bring you an ice?” Mr. Grimm asked at last.

“If you will, please,” responded the senorita, “and when you come back I’ll reward you by presenting you to Miss Thorne.  You’ll find her charming; and Mr. Cadwallader has monopolized her long enough.”