The Thinking Machine rose and went to Miss Winthrop's desk. "Here is an extension telephone with the receiver on the hook. It happens that the little silver box which you gave Miss Winthrop is just tall enough to lift this receiver clear of the hook, and the minute the receiver is off the hook the line is open. When you were at your desk and she was here, you couldn't see this telephone; therefore it was a simple matter for her to lift the receiver, and place the silver box underneath, thus holding the line open permanently. That being true, the sound of the typewriter—the striking of the keys—would go over the open wire to whoever was listening at the other end. Then, if the striking of the keys typed out your letters and, by their frequency and pauses, simultaneously tapped out telegraphic code, an outside operator could read your letters at the same moment they were being written. That is all. It required extreme concentration on Miss Winthrop's part to type accurately in Morse rhythms."
"Oh, I see!" exclaimed Grayson.
"When I knew that the leak in your office was not in the usual way," continued The Thinking Machine, "I looked for the unusual. There is nothing very mysterious about it now—it was merely clever."
"Clever!" repeated Grayson, and his jaws snapped. "It is more than that. Why, it's criminal! She should be prosecuted."
"I shouldn't advise that, Mr. Grayson," returned the scientist coldly. "If it is honest—merely business—to juggle stocks as you told me you did, this is no more dishonest. And besides, remember that Miss Winthrop is backed by the people who have made millions out of you, and—well, I wouldn't prosecute. It is betrayal of trust, certainly; but—" He rose as if that were all, and started toward the door. "I would advise you, however, to discharge the person who operates your switchboard."
"Was she in the scheme, too?" demanded Grayson. He rushed out of the private office into the main office. At the door he met a clerk coming in.
"Where is Miss Mitchell?" demanded the financier hotly.
"I was just coming to tell you that she went out with Miss Winthrop just now without giving any explanation," replied the clerk.
"Good day, Mr. Grayson," said The Thinking Machine.
The financier nodded his thanks, then stalked back into his room.