The detective turned his keen eyes on his questioner and looked hard at him for a moment or two. "Tell me all about it, sir," he said. Burton hurriedly related all that had happened. "A cable to Ostend would be enough, wouldn’t it?" he asked in conclusion. "I’m afraid it would hardly do, sir," replied the detective. "Your description is too vague. Tall man about forty, bald, with a hand-bag--there may be dozens on the boat. It would be too risky. We have to be careful. I saw a notorious diamond thief go on board, but I couldn’t arrest him, not having a warrant, and nothing certain to go upon. You had better go to the police station, tell the superintendent all you know, and leave him to communicate with the Belgian police in due course." "And give the thief time to get rid of the stuff! If it once passes from his hands the secret will be lost to us, and any foreign Power may be able to fill its shells with Dr. Micklewright’s explosive. It’s too bad!" He looked with bitter disappointment at the steamer, now a mere speck on the surface of the sea. Suddenly he had an idea. "If I got to Ostend first," he said, "I could have the man arrested as he lands?" The detective smiled. "I don’t think the Belgian police would make an arrest on the strength of your story, sir," he said. "Why, you can’t even be sure your man is aboard. Arresting the wrong party might be precious awkward for you and everybody." "I’ll risk that," cried Burton. "It’s my funeral, any way." "That little machine of yours is safe, I suppose, sir? It won’t come down and bury you at sea?" "No fear!" said Burton with a smile. "Still, in case of accidents, here’s my card. All I ask is, don’t give anything away to newspaper men for a couple of days, at any rate. It’s to a newspaper man we owe the whole botheration." "All right, sir; I’ll give you a couple of days. I wish you luck." Burton hurried to one of the small boats lying for hire alongside the pier, and was put on board his own vessel. He started the motor, but in his haste he failed to pull the lever with just that knack that jerks the floats from the surface. At the second attempt he succeeded, and the water-plane rose into the air as smoothly as a gull. The steamer was now out of sight, but he had a general idea of her direction, and hoped by rising to a good altitude soon to get a glimpse of her. The wind had freshened, and time being of the utmost importance, Burton congratulated himself on the possession of a Clift compass, by means of which he could allow for drift, and avoid fatal error in setting his course. The steamer had nearly an hour’s start, but as he travelled at least twice as fast, he expected to overhaul her in about an hour if he did not mistake her direction.