The flight-sub had completed his preparations. Two letters, one to his parents and one to Betty Deringhame, had been written, sealed and handed to the fleet-paymaster to be forwarded in the event of the writer's death. This unpleasant but necessary business performed, Barcroft dismissed the matter from his mind and concentrated his thoughts and energies on the work in hand. "All correct, Jones?" he asked, addressing the air-mechanic who was putting the finishing touches to the seaplane that was to carry Barcroft and Kirkwood on their adventurous flight. "All correct, sir," was the reply. "I've advanced the spark a trifle, sir she ought to simply buzz; but perhaps you'll see that everything's to your satisfaction." Carefully Billy tested his controls, examined unions, contact breaker, and automatic lubricators. Success depended upon motor efficiency almost as much as upon the skill and courage of the pilot. The slightest hitch might spell disaster. "There's the permission to part company," announced Kirkwood as a signal, made in response to a display of bunting from the yard-arms of the respective seaplane-carriers, was hoisted from the naval signal station. "Wonder if I'll see Old England again," he added in an undertone. Already the cruisers were steaming out of harbour; not in the pomp of pre-war days with guards drawn up on the quarter-deck and bands playing as each vessel passed the flagship. Silent and grim, huge emblems of seapower, they glided past the harbour batteries and, increasing speed to twenty-two knots, were soon out of sight. With destroyers preceding and following, the four seaplane-carriers were next to leave. On gaining the open sea they formed line abreast, surrounded by their vigilant escort; the light cruisers, reducing speed to that of the convoy, taking up station two miles astern. In this formation the flotilla reeled off knot after knot without incident, until late in the evening, when two of the destroyers on the "Hippodrome's" starboard beam began a rapid fire that lasted nearly five minutes, breaking station and circling in a fashion that recalled the preliminary manoeuvres of a pair of cautious boxers. "U-boat, somewhere over there," commented Fuller, who with Barcroft and the A.P. was on deck in preference to the somewhat boisterous ward-room. "I don't think they've got her. Wonder if she's dived and avoided the cordon. If so we'll have to look out." "Hope she won't bag us at this stage of the proceedings," said Kirkwood. "At any rate, our quick-fires are manned, and it will be dark in another half-hour." The two destroyers had resumed station, having signalled to the effect that no definite result was observed but it was believed that the U-boat's periscopes had been smashed by gun-fire.