Gazing out over the lights of the city, scarcely aware that he saw them, his subconscious mind had been following for the past three minutes something apparently usual, but in reality entirely out of the ordinary. "By George!" he muttered, "I wonder...." Then, taking his watch from his pocket, his eyes alternated between a point several blocks distant--a point over the roofs of the houses--and the second hand of his timepiece. Less than a minute elapsed before he reached for a pencil and commenced to jot down dots and dashes on the back of an envelope. When, a quarter of an hour later, he found that the dashes had become monotonous--as he expected they would--he reached for the telephone and asked to be connected with the private wire of the Navy Department in Washington. "Let me speak to Mr. Thurber at once," he directed. "Operative Callahan, S. S., speaking.... Hello! that you, Thurber?... This is Callahan. I'm in Norfolk and I want to know whether you can read this code. You can figure it out if anybody can. Ready?... Dash, dash, dash, dot, dash, dash, dot--" and he continued until he had repeated the entire series of symbols that he had plucked out of the night. "Sounds like a variation of the International Morse," came the comment from the other end of the wire--from Thurber, librarian of the Navy Department and one of the leading American authorities on code and ciphers. "May take a little time to figure it out, but it doesn't look difficult. Where can I reach you?" "I'm at the Monticello--name of Robert P. Oliver. Put in a call for me as soon as you see the light on it. I've got something important to do right now," and he hung up without another word. A quick grab for his hat, a pat under his arm, to make sure that the holster holding the automatic was in place, and Callahan was on his way downstairs. Once in the street, he quickened his pace and was soon gazing skyward at the corner of two deserted thoroughfares not many blocks from the Monticello. A few minutes' consultation with his watch confirmed his impression that everything was right again and he commenced his search for the night watchman. "Who," he inquired of that individual, "has charge of the operation of that phonograph sign on the roof?" "Doan know fuh certain, suh, but Ah think it's operated by a man down the street a piece. He's got charge of a bunch of them sort o' things. Mighty funny kinder way to earn a livin', Ah calls it--flashing on an' off all night long...." "But where's he work from?" interrupted Callahan, fearful that the negro's garrulousness might delay him unduly. "Straight down this street three blocks, suh. Then turn one block to yo' left and yo' cain't miss the place. Electrical Advertisin' Headquarters they calls it. Thank you, suh," and Callahan was gone almost before the watchman could grasp the fact that he held a five-dollar bill instead of a dollar, as he thought.