She thought before answering. “I believe about one hundred miles, but I am not certain. Miss Porter and I generally used the instrument to receive messages.” “But you have sent messages?” “Yes, occasionally.” “To whom did you send a message last night, Miss Deane?” Dorothy’s reply was prompt. “To no one.” Mitchell smiled, not unkindly. “I’m afraid denial won’t do any good. I saw you and Miss Porter in the attic at the Porter mansion last night.” “You saw us?” Dorothy’s surprise was unmistakable, and Mitchell chuckled. “Where were you?” “In Dr. Thorne’s dining-room, the window of which overlooks that side of the Porter mansion.” There was a brief pause, and then Mitchell repeated his former question. “To whom did you send a message last night?” “I sent no wireless message last night,” reiterated Dorothy. “Oh, so it was Miss Porter.” A self-satisfied smile crossed the detective’s lips, and Dorothy’s heart sank as she racked her brain in an effort to puzzle out the meaning of his questioning her on such a subject. What had the wireless to do with his investigation of the mystery surrounding Bruce Brainard’s death? She sat forward in her chair as Mitchell commenced speaking again. “I saw you both in the attic earlier in the evening, as you did not pull down the shades. About midnight I saw one of you return, but as only a candle was burning near the window at that time, I could not be certain whether it was you or Miss Porter.” He paused and looked inquiringly at Dorothy. “You say it was about midnight? Are you quite certain, Mr. Mitchell, that you did not fall asleep and dream all this?” “I did not,” answered Mitchell shortly, ruffled by her manner of receiving his news. “In proof of it the Arlington Radio Station caught Miss Porter’s message, but not the name of the person she was sending it to.” “Ah, indeed?” skeptically. “And what was the message?” “‘Peace and tranquillity.’” Dorothy’s reception of his answer startled the detective--she burst into peal on peal of laughter. “Excuse me,” she stammered as soon as she could speak. “You were so serious and--and--” Again she laughed whole-heartedly. “You have unearthed a mare’s nest, Mr. Mitchell.” Mitchell’s rising color testified to his displeasure. “Kindly tell me the meaning of those three words, Miss Deane,” he demanded. “They bear the customary meaning attributed to them,” retorted Dorothy, her eyes still twinkling. “The phrase you quoted is frequently used by Miss Porter and myself for practice work in sending messages.” The detective watched her in angry silence, then started to address her just as the door was pushed quietly open and Hugh Wyndham stopped on the threshold. Neither man observed him as they faced Dorothy, their backs turned to the entrance. “Your explanation is very pat, Miss Deane,” said Mitchell. “Perhaps you can also explain what it was Miss Millicent Porter threw into an unused well late yesterday afternoon.”