training under war-time conditions must necessarily be as brief as possible, consistent with a certain degree of efficiency; and the period of instruction at sableridge was no exception. as quickly as raw material could be fashioned into fairly competent motor-boatmen, drafts were sent away and recruits brought in to fill their places, in order that the r.a.f. marine might relieve the royal navy of a certain branch of its work—namely, attending upon sea-planes and coastal airships.

as far as an officer under instruction was concerned, the test was a simple, and at the same time a drastic one. he might be sent at a few hours' notice to bring a motor-boat round from, say, great yarmouth to sableridge, a distance of between two and three hundred miles. he had to use his discretion—to remain in port should the weather look threatening, or the atmospheric conditions point to fog or mist. nevertheless, it was no light task to navigate a half-decked motor-craft in the depth of winter, when short days and dark nights added to the difficulties of making a passage.

it was of no use for an officer to attempt to live on his reputation. he had to be prepared to execute orders rationally and efficiently. there was one second-lieutenant who boasted that in pre-war days he had navigated his own yacht from blackpool to the isle of man. shortly after he had reported for duty at the depot an officer was required to bring a motor-launch round from harwich.

"why not send ruby, sir?" suggested the major, as he and the colonel were debating as to who should be deputed for the task. "he has taken a boat across to the isle of man."

so second-lieutenant ruby received his sailing orders, and for the next few days he walked about like a man in a trance. the magnitude of his task appalled him. finally he went to the major and declared that he was not equal to navigating the boat. from that moment he ceased to be a motor-boat officer, and was given a tedious but safe shore-billet.

it was towards the end of the first week in november that derek daventry received his orders for his first trip as an independent command. his instructions were to take two 35-footers and proceed to wagshot air station, where he was to receive a sea-plane and tow her back to sableridge. the double distance amounted to nearly seventy miles, of which half was open sea work. the sea-plane was an obsolete machine, the engines of which had been removed, and was required merely for the purpose of practising how to take this kind of aircraft in tow.

all the previous day derek was exceptionally busy. on him rested the responsibility of the voyage. he had to see that the boats' equipment was in order, that the tanks were filled with petrol, that there was plenty of lubricating oil on board, that the men had drawn their rations and blankets, and that charts and navigating instruments were on board.

before sunset the two boats were moored alongside the pier. the start was timed for six in the morning. hardly ever had derek studied the barometer so frequently and so carefully. twice during the night he rose from his camp-bed, donned trench-coat and sea-boots, and walked down to the pier, in order to satisfy himself that the boats were riding properly in the tide-way, and that their securing-rope had sufficient slack to allow for the rise and fall of the tide.

at 5 a.m., just as he was enjoying a sound slumber, he was awakened by his batman.

"what sort of morning is it?" he asked.

"cold, sir, and fine," replied the man. "bright moonlight, and hardly any wind."

quickly derek tumbled out of bed and began to dress. experience had taught him that to be warmly clad in a boat is as necessary as when flying. over his khaki breeches he wore a pair of thick flannel trousers. on his feet he had a pair of socks, a pair of woollen stockings, and a voluminous pair of india-rubber sea-boots. walking even a short distance in loosely-fitting boots inevitably resulted in the total destruction of the heels of the socks, but on the other hand it would be a fairly simple matter to kick off the boots in the event of derek finding himself "in the ditch". sea-boots that fit tightly, and cannot be taken off quickly in an emergency, are nothing short of death-traps.

he discarded his tunic, wearing in its place two thick sweaters. the next items were his oilskin trousers and coat, while the only outward and visible sign that he held his majesty's commission in the r.a.f. was his cap, with the distinctive badge of the crown, eagle, and wings.

by the time he had completed dressing breakfast was served. he ate his meal in solitary state in the electrically-lighted mess-room. there was no question of the excellence of the food at sableridge, even in war-time. hot scotch porridge, with treacle, eggs and bacon, toast, real butter, marmalade and jam—a square meal to fortify the young officer's inner man for the coming ordeal of a sea-voyage. feeling rather like an arctic explorer, for across his shoulders he now carried a well-filled haversack and a pair of binoculars, derek descended the steps of the officers' mess and walked down to the pier.

the batman was right. it was a cold morning. every bush was festooned with hoar-frost that glistened in the moonlight. the planks of the pier were slippery with ice, while there was a biting coldness in the air that gave a zest to life, even at six o'clock on a november morning.

the crews of the two boats were already at the pier-head, black oilskinned figures, looking like ghostly familiars in the grey light. both craft had their engines running, the fumes from the exhausts rising strongly in the cold air. from the stern of each boat flew the white ensign, while as a distinguishing pennant each displayed the "international f" from the short iron mast abaft the fore-deck.

then came a grim reminder that there were war risks even on a coastal voyage. before embarking every man had to give his name to the signalman on the pier-head, in order that their next-of-kin should be promptly informed if the boats met with disaster and the crews failed to return.

"all ready?"

"all ready, sir!"

"cast off!"

with a slight jerk, as the clutch was slipped in, the 35-footer gathered way, her white ensign temporarily enveloped in the bluish haze of the exhaust. a slight touch on the wheel steadied her on her helm, and soon the white signal-house on sableridge pier was a misty wraith in the darkness.

half a cable's length astern followed the second boat, her sergeant-coxwain, unused to the science of navigation, although he knew how to handle a small craft, keeping station with the utmost fidelity. at that distance she was a mere indistinct grey wedge, her position chiefly indicated by the "bone in her teeth", otherwise the creamy froth leaping from her knife-like bows and thrown wide on either side by her pronounced flare.

ahead the bar buoy winked its friendly greeting. no other light was visible in that quarter, and steering for that particular light was "not good enough", when on either hand of the narrow channel were dangerous sandbanks, on the fringes of which the surf was pounding heavily.

it was on this account that derek kept looking astern. over the bobbing canopy and beyond the fluttering ensign were two white lights, one several feet higher than the other, and actually four hundred yards apart. these were the only lights ashore, and were permitted when the exhibition of any other illuminant would result in a fine not exceeding ￡500. in short, they were the harbour leading lights, and as long as a mariner kept them in line, either when entering or leaving the fairway, he could carry on in absolute confidence, scorning the hidden dangers on either hand.

the bar buoy at last! giving the boat starboard helm derek swung her round until her head pointed due east. already his cap and oilskins were running with moisture, and the salt spray was stinging his face and making his eyes smart despite the scanty protection afforded by the "dodger".

"hardly so comfortable as my old 'bus," thought daventry; "but it's jolly exhilarating. now then, old lady, let's see how you take that one!"

"that one" referred to a crested "comber" that was bearing down towards the swiftly-moving boat. a slight touch on the helm and the fine bows swung round to take the advancing mass of water line on. administrating a vicious slap to the wave the motor-boat lifted to the crested billow. spray came hissing aft in solid sheets, pattering on the canvas canopy with a sound similar to that of peas being shaken in a wooden box. she was through, but immediately beyond was another wall of water.

right down until her fore-deck ventilators were hidden plunged the boat. for a moment derek thought she would never recover herself. the engine faltered. in a second the alert engineer was at the throttle and the "spark".

"water on the mag, sir," he shouted. "i'll have to ease her."

"and about time," thought derek. "wonder if it's like this all the blinking way?"

but soon the boat entered smoother water. the breakers were on the weather side of the bar. beyond was easier going.

winking the moisture from his eyes, derek glanced astern. the other boat was making fairly good weather of it, although she looked to be nothing more than a double wing of white foam.

"good enough," declared derek, and, calling to one of the deck-hands, he gave the wheel over into his care, admonishing him to report immediately thorbury head became visible.

"now for a smoke!" he exclaimed, and, pulling out his favourite pipe, he carefully loaded up.

curiosity prompted him to see what the rest of the crew were doing. grasping the life-lines on the canopy he made his way aft, his sole foothold being the narrow, slippery water-ways.

under the awning were the rest of the crew, lying helpless on top of a nondescript heap of blankets and oilskins, together with the disintegrated rations—fresh beef, "bully", and loaves. in the throes of sea-sickness the hapless "george robey's marines" hardly cared whether they were on or in the sea.

clearly nothing could be done to help the luckless victims of mal de mer, so derek made his way back to the steering-well, and, standing behind the coxswain, surveyed the outlook.

there was very little to be seen, only a limited expanse of white-crested water, bounded by darkness that was even now struggling for mastery with the first faint tints of a grey dawn. land, somewhere within three miles, was invisible. all that the helmsman had to depend upon was a small and untested compass fixed in a rather inaccessible and unhandy spot, and within three feet of the mass of metal comprising the six-cylinder motor.

there was also the danger of bumping on a drifting mine. derek realized the peril. fortunately perhaps for them, the men were in ignorance of the fact that mines had been reported within thirty miles of fisherton harbour, and, with an onshore wind and the indraught of the tide, thirty miles was a very small distance for one of these instruments of destruction to drift in forty-eight hours.

added to this there was the possibility of being fired upon by the batteries at churst and fort edward, guarding the narrow channel leading to the tidal estuary on the banks of which wagshot air station stands. although the forts had been warned that the two r.a.f. motor-boats were passing, there was always a chance that a highly-strung battery-commander might mistake the two grey hulls for the conning-towers of a pair of u-boats and give the order to open fire. such a thing had been done before, with disastrous results.

suddenly derek's reveries were broken by the coxswain shouting:

"there it is, sir; a couple of points on the port bow!"

unable to comprehend the nature of the intelligence, derek peered ahead in the direction indicated, quite expecting to see a horned mine a few yards from the bows. then he heaved a sigh of relief, for looming faintly through the mist was the unmistakable outline of thorbury head.