in the water and "taxi" alongside her parent ship. Hence the necessity for a long and powerful derrick to swing the seaplane, with its broad expanse of wings, clear of the ship's side and deposit it carefully upon deck.

"Here he comes!" exclaimed Fuller, indicating a faint object in the eastern sky.

Rapidly it resolved itself into a large biplane with triple floats in place of the three landing wheels that form a necessary adjunct to army aeroplanes. Then the polished wood propeller, glinting in the oblique rays of the sun, could be discerned as it slowed down preparatory to the seaplane commencing a thousand feet glide.

With a succession of splashes the biplane took the water, "bringing up" with admirable judgment at a distance of less than fifty yards from the starboard quarter of the parent ship.

The seaplane carried a crew of two. The pilot pushing up a pair of goggles revealed a fresh-looking, clean-cut face that gave one the impression of a public school boy. Billy Barcroft was still in his teens. He had just another month to enter into his twentieth year. In height he was a fraction under five feet ten inches; weight—an important consideration from an airman's point of view—was "ten seven." Supple and active, he carried not an ounce of superfluous flesh. Standing up and lightly grasping a stay, he swayed naturally to the slight lift of the seaplane—the personification of that product of the Twentieth Century, the airman.

His companion, who had just completed the "winding in" of the trailing aerial, raised his head above the coaming surrounding the observer's seat. In appearance he resembled Barcroft so strongly-that the pair might have been taken for twin-brothers. But no relationship, save the ties of friendship and duty, existed betwixt Billy Barcroft and his observer, Bobby Kirkwood. The latter was an Assistant Paymaster, who, deserting the ship's office for the freedom of the air, had already mastered the intricacies of "wireless" and other qualifications necessary for the responsible duties of observer.

"You've been a jolly long time, you belated bird!" shouted Fuller in mock reproof. "What's the stunt?"

"Couldn't help it," replied Barcroft with a broad grin. "If you were in my place and saw a crowd of Hun Staff officers pushing along in motor-cars wouldn't your idea of courtesy lead you to pay them a little attention? Kirkwood gave 'em a couple of plums and a whole drum. Result—a slight increase in the Hun death-rate."

Barcroft had, in fact, gone well inland over the German batteries, on a sort of informal joy-ride. From a height of 5,000 feet the observer had spotted what appeared to be a motor convoy bowling along the road between Zeebrugge and Bruges. With a daring bordering on recklessness the pilot had vol-planed down to within two hundred feet, greatly to the consternation of the grey-cloaked German Staff officers, who, leaving the shelter of their steelroofed cars, scurried with loss of dignity for the safety that was denied most of them. For with admirable precision Kirkwood had dropped two bombs fairly into the line of cars, following up the attack by firing a whole drum of ammunition from the Lewis gun into the fleeing Huns.

Deftly the flexible steel wire from the outswung derrick engaged the lifting hooks of the seaplane. The machine was just clear of the water when the order came "Avast heaving." Simultaneously a bugle blared. It was the call for Flying Officers.

Leaping into the stern sheets of a boat in attendance, Barcroft and Kirkwood were taken to the side of the "Hippodrome," where they gained the deck of the ship. Already Fuller and the rest of the airmen had gone aft. Something was literally in the air.

The signal commander held up a leaf torn from a signal pad.

"A wireless has just come through," he announced in clear deliberate tones. "A hostile plane has made a raid over parts of Kent. She is now on her way back, apparently heading for Ostend. Machines from Eastchurch have started in pursuit, but the Hun has a useful lead. Now, gentlemen, a nod is as good as a wink to a blind horse: we are between the raider and his base."

The assembly dispersed like magic, the airmen hurriedly donning leather jackets and flying helmets and giving peremptory orders to the mechanics in attendance. In less than five minutes the first of the stowed seaplanes was ready to glide down the inclined platform to take to flight.

Yet, from a starting point of view Barcroft had a decided advantage. His seaplane was practically ready. There was enough petrol for a lengthy flight, and a good reserve of ammunition for the Lewis gun. Bombs there were none, nor were any likely to be required for the task in hand. The chances of a hit on a small and rapidly-moving target were very remote. It was by machine-gun fire that the attack upon the returning raider was to be made.

With the motor throbbing noisily and with clouds of oil-smelling smoke pouring from her exhaust, Barcroft's seaplane taxied away from the towering side of her ungainly parent. Then, so gracefully that it was impossible to determine the exact moment when the aircraft ceased to be waterborne, the seaplane rose swiftly and steadily in the air.

Climbing in steep spirals the machine quickly rose to a height of 5,000 feet. It was enough for all practical purposes, allowing a margin of superior altitude to that of the expected Boche.

"Good enough!" shouted the flight-sub through the speaking tube. "Aerials paid out? All ready?"

"All serene," replied Kirkwood, affixing a whole drum of ammunition to the upper side of the breech mechanism of the deadly machine gun. "By Jove, we've all been pretty slick this time. The fifth bird has just got away."

Barcroft leant over the side of the fuselage. Seven hundred feet below and speeding away to the nor'-west were a couple of the "Hippodrome's" seaplanes. Two more, at a lower altitude but still climbing, were heading in a south-easterly direction. Thus, when the formation was complete, Barcroft's machine would be in the centre of a far-flung line thrown out to form a barrier betwixt the solitary raider and his base.

The British airmen were at an atmospheric disadvantage. Straight in their face came the rays of the setting sun, while the calm sea beneath them was one blaze of reflected light. Against that blinding glare it was almost impossible to distinguish the mere black dot in the vast aerial expanse that represented the returning hostile aviator; while on the other hand the Hun, with the sun at his back, would be able to discern with comparative ease the glint of the seaplane's wings.

The characteristic tick of the wireless brought. Kirkwood to attention. With the receiver clamped to his ear he took down the message and passed it on to his companion.

"Our pigeon!" soliloquised Barcroft grimly. The information was to the effect that the "Hippodrome" had first sighted the approaching Hun machine by means of telescopes. The hostile craft had previously spotted two of the intercepting seaplanes, and her pilot, taking advantage of the light, decided to make a vol-plane to within a few hundred feet above the level of the sea. By so doing he was sacrificing his advantage of altitude, but there was a chance of slipping unobserved under the British aircraft. Once through the far-flung cordon he hoped to rely upon superior speed and climbing powers to elude pursuit.

By this time Barcroft had "picked up" his opponent. At first sight it seemed as if the Hun were executing a nose dive. Keenly on the alert the flight-sub depressed the ailerons with a quick yet decided movement. There was no trace of jerkiness in the pilot's actions. All were performed with that smooth dexterity and rapidity that comprised the essential qualifications of a successful airman.

At an aggregate speed of nearly two hundred miles an hour the rival aeroplanes converged. It seemed as if each pilot were bent upon ramming his opponent and sending the colliding craft to a common destruction.