ARTS OF THE OPERATIVES The Midnight Camera—The Way of a Man and a Maid and a Dictagraph—Secret Inks and Codes—Stories of the Trail—How Evidence Was Secured. It already has been stated that the American Protective League had no governmental or legal status, though strong as Gibraltar in governmental and legal sanction. The mails are supposed to be sacred—the Postmaster General has sworn they always shall be sacred. They are sacred. But let us call the A. P. L. sometimes almost clairvoyant as to letters done by suspects. Sometimes it clairvoyantly found the proofs it sought! It is supposed that breaking and entering a man’s home or office place without warrant is burglary. Granted. But the League has done that thousands of times and has never been detected! It is entirely naïve and frank about that. It did not harm or unsettle any innocent man. It was after the guilty alone, and it was no time to mince matters or to pass fine phrases when the land was full of dangerous enemies in disguise. The League broke some little laws and precedents? Perhaps. But it upheld the great law under the great need of an unprecedented hour. A man’s private correspondence is supposed to be safe in his office files or vault. You suppose yours never was seen? Was it? Perhaps. It certainly was, if you were known as a loyal citizen—a true-blood American. But the League examined all of the personal and business correspondence of thousands of men who never were the wiser. How could that be done? Simply, as we shall see. Suppose there was a man, ostensibly a good business man, apparently a good citizen and a good American, but who at heart still was a good German—as hundreds of thousands of such men living in America are this very day. This man has a big office in a down-town skyscraper. He is what the A. P. L. calls a “suspect.” Let us call him Biedermacher. About midnight or later, after all the tenants have gone home, you and I, who chance to be lieutenants and operatives in the League, just chance in at the corridor of that building as we pass. We just chance to find there the agent of the building—who just chances also to wear the concealed badge of the A. P. L. You say to the agent of the building, “I want to go through the papers of Biedermacher, Room 1117, in your building.” “John,” the agent says to the janitor, “give me your keys, I’ve forgotten mine, and I want to go to my office a while with these gentlemen.” We three, openly, in fact, do go to Biedermacher’s office. His desk is opened, his vault if need be—it has been done a thousand times in every city of America. Certain letters or documents are found. They would be missed if taken away. What shall be done? The operative takes from his pocket a curious little boxlike instrument which he sets up on the table. He unscrews a light bulb, screws in the plug at the end of his long insulated wire. He has a perfectly effective electric camera.