Willie did so and joined the Secret Service man. The restaurant was just across Bowling Green, on the east side of Broadway. The two descended in the elevator, walked across the little park, and entering the restaurant, stood near the door. Willie watched the waitresses come and go, for there were still some people eating. Presently Willie touched the detective’s arm. “That’s the girl,” he said, and he pointed to a black-haired waitress just coming from the kitchen with a tray of food. The detective walked over to her table, followed by Willie. When she had distributed her food, the detective spoke to her quietly. “Did you ever see this lad before?” he asked. The waitress looked keenly at Willie. “Yes,” she said. “He’s been in here several times.” “When did you see him last?” “At dinner-time.” “Do you remember what he had to eat?” “I’m not sure, but I think he had coffee and a sandwich.” “How are you able to recall him?” The girl hesitated. “Maybe it’s because he’s so little, but I guess it’s because he’s so polite. Anyway, he’s different from most of the boys that come in here, and I like him. He often eats at my table.” “I’m obliged to you,” said the Secret Service man, and the two investigators went out. “So far so good,” said the Secret Service man. “Now let’s return to your office.” They walked back to the Custom-house. “How do you know it was twelve-fifteen when you got back?” asked the detective. “I looked at the clock, to see how long I could stay in the wireless room.” “Was anybody in the office then?” “Mr. King was. He sat at his desk, but his back was toward me and he was busy so that I am sure he did not notice me.” “What did you do next?” “I went directly into the wireless room.” “Let’s take a look at it.” They passed through one or two of the office rooms and then into a small inner room that had been made for a sort of storeroom, but was little used for any purpose. The Secret Service man looked around the room. “What did you do after you came here?” he demanded. “I shut the door, so I would not be interrupted. Then I sat down at my instrument and called my old chums at home.” “How long did you call them?” “I can’t say exactly. I called and called at frequent intervals, right up to the time I went back to the office. When I reached my desk, it was exactly one o’clock.” “Can you prove you were calling all that time?” “I’m afraid I can’t. I didn’t get a single answer. If I could find any other operator who heard me, I might be able to. But I don’t believe there’s much chance that I could find such a person.” “Why not? There are lots of operators talking and listening in all the time.” “Certainly. But mostly they use longer wave-lengths than I did. You know we amateur operators are limited to a low wave-length. There are hundreds of operators, no doubt, who were near enough to have heard me, but mostly they work in longer wave-lengths.”