He opened a secret drawer in his desk, inserted his forefinger and, apparently, pressed a button. The doors of the bookcase flew open as if by magic, and, at the same time, a bell inside the bookcase rang sharply. Miss Dana watched each motion of her employer intently. “That is all done by electricity,” said he. “But it does something else--opens the apple.” He reached up and lifted the cover. Then he removed something from the apple and placed it in Miss Dana's hand. “Oh, how lovely!” she exclaimed. It was a ring made of the finest gold and containing an immense ruby. “That,” said her employer, “I call the Isburn Ruby. It belonged to my mother, and it is precious to me, both on account of its great intrinsic value, and as an heirloom.” He dropped it into the brass apple, replaced the cover, and shut the doors of the bookcase. “That cover can only be removed when the bookcase doors are open; they can only be opened by touching the button in the secret drawer in my desk, and, even then, a notice of the opening is given by the electric bell. I think the ruby is well protected, but if anybody steals it I shall call upon you to find the thief.” Miss Dana said, laughingly, that she feared she would never have a chance to distinguish herself in that direction. About a fortnight later, Mr. Isburn sat at his desk one morning opening his mail. He was so preoccupied with an interesting letter containing an account of the very mysterious disappearance of a young woman, that he was not aware, for some time, of the presence of a person who stood beside his desk. He looked up, suddenly, and saw a pretty girl, dressed in picturesque Italian costume, holding a basket filled with roses, pinks, and other cut flowers. Mr. Isburn was passionately fond of flowers and kept a vase filled with them upon his desk. He selected a large bunch of flowers made up of the different kinds. At that moment the door was opened and a clerk appeared: “Mr. Isburn, there is a call for you on the long distance telephone.” “I will be back in a moment,” he said to the flower girl, as he went into an adjoining room. The telephone bell was being rung continuously, and he called “Hello” several times before the tintinnabulation ceased. The call was from a town some fifty miles away. The operator informed him that No. 42 wished her to tell him that she had a valuable clue in case T 697 and would not return for several days. Mr. Isburn knew that No. 42 was Miss Dana.