The Mystery of the Hasty Arrow

The hour of noon had just struck, and the few visitors still lingering among the curiosities of the great museum were suddenly startled by the sight of one of the attendants running down the broad, central staircase, loudly shouting: "Close the doors! Let no one out! An accident has occurred, and nobody's to leave the building." There was but one person near either of the doors, and as he chanced to be a man closely connected with the museum, -being, in fact, one of its most active directors, -he immediately turned about and in obedience to a gesture made by the attendant, ran up the marble steps, followed by some dozen others.
At the top they all turned, as by common consent, toward the left-hand gallery, where in the section marked II, a tableau greeted them which few of them will ever forget...