After circling round the spot for another few minutes to speak with the Commodore of the fleet of mine-sweepers, Dastral turned the hornet's head once again towards the enemy's coast, and the captain of the tramp steamer dipped his pennant and gave a long blast on the siren, as a token of gratitude for the service rendered. The aviators were well pleased with themselves for the part they had taken in the little adventure, which had not been without its thrills, and a spice of danger. They were now almost in mid-Channel, and could see both shores. There were the white cliffs of Old Albion behind them, while in front, a little on their left, Cape Grisnez rose out of the water. Below them several liners, transports and colliers, could be seen making either up or down Channel, or for one of the ports on the English or French coasts. Turning round to Fisker, the pilot shouted through the speaking tube:-- "Sorry it wasn't a German submarine, old fellow. There'll be no D.S.O. for us for picking up a string of floating mines." "Ah, well. Better luck next time," called back the observer. "The place is too well patrolled now for the Huns' submarines to show themselves about here. Gemini! but I'd give my brevet and six months' pay to spot one this journey. It would be some find." The observer did not reply immediately. He was keenly searching the opposite shore to find the breakwater at the entrance to Boulogne harbour. "Can you see it yet?" called the pilot, noting an anxious look on Jock's face. "Yes," replied the latter. "Better give her another two points south, and then we shall just about hit the canal below the town. Our instructions were to follow it to the main aerodrome." "Aye, aye," answered the pilot, altering the controls slightly, and bringing her head round upon a more southerly course. Shortly after this, the town and harbour of Boulogne came into full view to the naked eye. Their intention was to leave it a little on their left, and, then making a landfall of a certain railhead and canal, take a short cross-country flight to the big aerodrome behind the British lines. They now began to regard themselves as nearly at the end of their journey, and had no expectation of a still greater adventure before them--an adventure which would prevent them reaching their destination, at any rate, that day. Only some five or six miles of sea now lay between them and the land, and they were right over the track of the transports, which made a continuous line of traffic between the two shores, when Fisker, who had taken up his glasses again in order to watch a batch of troopships, escorted by a couple of destroyers, suddenly turned them on to a large four tunnelled hospital ship, which, coming out of the harbour, crowded with wounded and war-worn men, was ploughing its solitary way towards Old Blighty, without any other escort or protector than the Red Cross flag.