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.

His mind was busy as he flew. He had to admit the force of what the detective had said. It would almost certainly be difficult to induce the Belgian police to act on such slight information as he could give them; and in the bustle of landing, the criminal, of whose identity he could not be sure, might easily get away. Burton was beginning to feel that he had started on a wild-goose chase when, catching sight of the smoke of the vessel some miles ahead, he suddenly, without conscious reasoning, determined on his line of action. Such flashes sometimes occur at critical moments.

Waiting for a few minutes to make sure that the distant vessel was that in which he was interested, he bore away to the east, instead of following directly the track of the steamer. It was scarcely probable that the flying-boat had already been noticed from the deck. He described a half-circle of many miles, so calculated that when he approached the vessel it was from the east, at an angle with her course.

He was still at a considerable height, and as he passed over the vessel his view of the deck was obscured by the cloud of black smoke from her funnels. In a few seconds he wheeled as if to return on his track; but soon after recrossing the steamer he wheeled again, and making a steep volplané, alighted on the sea about half a mile ahead. Then with his handkerchief he began to make signals of distress. There was a considerable swell on the surface, and it might well have seemed to those on board the steamer who did not distinguish the flying-boat from an aeroplane that the frail vessel was in imminent danger.