"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.
It didn't take the Secret Service man long to locate the place he sought, and on the top floor he found a dark, swarthy individual bending over the complicated apparatus which operated a number of the electric signs throughout the city. Before the other knew it, Callahan was in the room—his back to the door and his automatic ready for action.
"Up with your hands!" snapped Callahan. "Higher! That's better. Now tell me where you got that information you flashed out to sea to-night by means of that phonograph sign up the street. Quick! I haven't any time to waste."
"Si, si, señor," stammered the man who faced him. "But I understand not the English very well."
"All right," countered Callahan. "Let's try it in Spanish," and he repeated his demands in that language.
Volubly the Spaniard—or Mexican, as he later turned out to be—maintained that he had received no information, nor had he transmitted any. He claimed his only duty was to watch the "drums" which operated the signs mechanically.
"No drum in the world could make that sign flash like it did to-night," Callahan cut in. "For more than fifteen minutes you sent a variation of the Morse code seaward. Come on—I'll give you just one minute to tell me, or I'll bend this gun over your head."
Before the minute had elapsed, the Mexican commenced his confession. He had been paid a hundred dollars a week, he claimed, to flash a certain series of signals every Saturday night, precisely at nine o'clock. The message itself—a series of dots and dashes which he produced from his pocket as evidence of his truthfulness—had reached him on Saturday morning for the two preceding weeks. He didn't know what it meant. All he did was to disconnect the drum which operated the sign and move the switch himself. Payment for each week's work, he stated, was inclosed with the next week's message. Where it came from he didn't know, but the envelope was postmarked Washington.
With his revolver concealed in his coat pocket, but with its muzzle in the small of the Mexican's back, Callahan marched his captive back to the hotel and up into his room. As he opened the door the telephone rang out, and, ordering the other to stand with his face to the wall in a corner—"and be damn sure not to make a move"—the government agent answered the call. As he expected, it was Thurber.