the small space they had left for him between the pushed-out hanging and the wall.  An exclamation from the Curator, who had only waited for his coming to take his first look, added zest to his own scrutiny.  It would take something more than the sight of a well-known door to give it such a tone of astonished discovery.  What?  Even he, with the accumulated surprises of years to give wings to his imagination, did not succeed in guessing.  But when his eyes, once accustomed to the semi-darkness of the narrow space which Correy had thus opened out before him, saw not the door but what lay within its recess, he acknowledged to himself that he should have guessed—­and that a dozen years before, he certainly would have done so.

It was a bow—­not like the one hanging high in the Apache exhibit, but yet a bow strong of make and strung for use.

* * * * *

Here was a discovery as important as it was unexpected, eliminating Mrs. Taylor at once from the case and raising it into a mystery of the first order.  By dint of long custom, Mr. Gryce succeeded in hiding his extreme satisfaction, but not the perplexity into which he was thrown by this complete change of base.  The Curator appeared to be impressed in much the same way, and shook his head in a doubtful fashion when Correy asked him if he recognized the bow as belonging to the museum.

“I should have to see it nearer to answer that question with any sort of confidence,” he demurred.  “From such glimpses as I can get of it from here I should say that it has not been taken from any of our exhibits.”

“I am sure it has not,” muttered Correy.  Then with a side glance at Mr. Gryce, he added:  “Shall I slip in behind and get it?”

The detective, thus appealed to, hesitated a moment; then with an irrelevance perhaps natural to the occasion, he inquired where this door so conveniently hidden from the general view led to.  It was the Curator who answered.

“To a twisting, breakneck staircase opening directly into my office.  But this door has not been used in years.  See!  Here is the key to it on my own ring.  There is no other.  I lost the mate to it myself not long after my installation here.”

The detective, working his way back around the pedestal, cast another glance up and down the gallery and over into the court.  Still no spying eye, save that of the officer opposite.

“We will leave that bow where it is for the present,” he decided, “a secret between us three.”  And motioning for Correy to let the tapestry fall, he stood watching it settle into place, till it hung quite straight again, with its one edge close to the wall and the other sweeping the floor.  Had its weight been great enough to push the bow back again into its former place close against the door?  Yes.  No eye, however trained, would, from any bulge in the heavy tapestry, detect its presence there.  He could leave the spot without fear; their secret would remain theirs until such time as they chose to disclose it.