"always said she was a mule, sir," exclaimed the driver. "either she won't fire or else she back-fires when you don't expect it. did you cop it, sir?"

derek, with the jagged ends of a compound fractured bone threatening to push through the skin, was compelled to admit that he had.

apart from the acute pain, it was galling to realize that, after coming through a beautiful crash and spending the best part of the day and night under machine-gun fire in a shell-hole with nothing worse than a slight flesh-wound in the forehead, it was his very hard luck to be crocked up by a mere back-fire, especially as he had been careless enough to grasp the handle in the wrong way.

"rotten night's work," grumbled the driver, as he liberally dosed his wound with iodine. "where's that there corporal, sir? good lord, he's copped it, too!"

he bent over the unfortunate n.c.o.

"dead as mutton," he announced nonchalantly. there was no surprise in his tone. three years of living cheek by jowl with sudden death in all sorts of terrible forms had blunted his feelings. "poor bloke! and it might have been a blighty for him, too—same as me. 'ere, mate!"

a man bending under the weight of a coil of wire was slouching past. at the hail he threw his burden down, glad of the opportunity to ease his aching shoulders.

"what's up?" he asked.

the driver explained.

"fat lot you knows about an engine," remarked the new-corner. "that's why they put you in the m.t. and i've been driving motor-lorries all over yorkshire and lancashire these ten years. there's not a blinking motor that i can't master, and yet they shove me in the bloomin', foot-slogging infantry. chronic, i calls it."

"don't want to hear about your qualifications," broke in the driver with acerbity. "what i want is a practical demonstration."

then realizing that it was hardly the style to adopt when a favour was required he added:

"'course it was rough luck on you, mate; but i can't help it, can i? now be a sport and get the old mule a-going, and i think i can find a whole packet of fags in my greatcoat pocket. crikey! that was a near 'un," he ejaculated, as a shell burst about a hundred yards away and slightly to the left of the road. "jerry's putting a lot of stuff over tonight."

"sure you've got the fags?" enquired the newcomer cautiously. the prospect of getting hold of a packet of cigarettes interested him far more than did the boche shells. like the poor, german shells were always present; cigarettes were not.

"feel in my pockets," said the driver. "they're yours as soon as you get the blessed engine to fire."

the man was about to do so when in the reflected glare of a star-shell he caught sight of the driver's hastily-applied bandage.

"by gum, you've been hit, lad!" he exclaimed. "why didn't you say so, instead of offering me fags? reckon as you'll want 'em more'n me, so here goes."

a deft manipulation of throttle and spark, a short rapid jerk of the hitherto refractory cranking-handle, and the engine began throbbing with renewed activity.

before the driver could hand over the promised guerdon his benefactor settled matters by lifting him easily and gently into the seat. derek, feeling sick and giddy with the pain of his broken arm, took his seat beside the driver, while the tommy, slinging his bundle across his shoulders, ambled off into the darkness.

to derek the journey was a nightmare. racked with pain, hungry, thirsty, and dead tired, he was hardly conscious of the jolting, swaying vehicle, of the crump of heavy shells that were constantly searching the lines of communication, of the numerous halts owing to the congestion of traffic. whether it was five miles, or fifty, he had not the remotest idea. all he did was to wedge the shoulder of his unwounded arm into the angle formed by the tilt and the front of the tender, and trust that he would not be flung from his seat by the terrific bumps as the battle-scarred vehicle literally bounded over the uneven road.

he was practically unconscious when deft arms assisted him from the car. he could hear voices sounding dim and far-away. then he was faintly aware that he was in an underground retreat of vast size that smelt of iodine and ether; a lot of—to him—unnecessary man-handling, a struggle for breath, and then merciful oblivion.

upon recovering consciousness derek found himself at a base hospital. his arm had been set in splints, while his forehead was swathed in surgical bandages. it was the second stage of his journey to blighty.

three days later he was placed on board a hospital ship at boulogne. his arm was making very satisfactory progress, and he was able to walk up the gangway unassisted; but, shortly after arriving on the other side, he made his first acquaintance with hospital red tape.

a short train journey brought him to minterton station, the nearest place by rail to tollerby military hospital.

greatly to derek's surprise he found a nurse, several orderlies, and an ambulance waiting for him.

"but i can walk quite all right," protested the patient.

"no doubt," was the reply, "but you must go in the ambulance; it's routine."

nor did "routine" end there, for on arriving at the hospital daventry was peremptorily ordered to go to bed at five in the evening.

"it's routine," explained the nurse. "the doctor will have to take your temperature."

"surely he can do that without sending me to bed," said derek resentfully.

the nurse shrugged her shoulders.

"i didn't frame the regulations," she replied. "i'm afraid there's no help for it; to bed you must go."

followed a not altogether congenial fortnight. the compound fracture healed rapidly; no complications ensued; yet derek had to exist under restraint, and subjected to the too rigorous rules and regulations of the hospital.

there were eleven other wounded officers in the ward, all bored stiff with things in general, and the hospital in particular. the only diversion, and one that they thoroughly enjoyed, was listening to the lurid and incoherent remarks of their fellow patients whenever they were "coming to" after an operation. it was one of those few occasions when a patient could "speak his mind", even though he were in a semi-conscious state, and invariably the hospital staff came in for a considerable amount of "strafing", to the huge delight of the rest of the ward.

then came derek's "medical board". he rather welcomed the examination, fully convinced that he would be granted sick leave, and then be ordered to rejoin his squadron. the result was almost equivalent to a knock-out blow between the eyes.

the medicos had no fault to find with the young pilot's arm, but they persisted in harping upon subjects apparently irrelevant to the case, until derek began to wonder what on earth they were trying to discover.

he found out soon afterwards. his medical history sheet was endorsed "unfit for flying". absolutely unaware of the fact, his strenuous flights on the western front had resulted in an insidious nervous attack. although he felt perfectly fit for aerial work, the doctors knew better. henceforth he was no longer free to soar aloft; the exhilaration of handling the joy-stick of a 'bus was no longer his.

"won't i be able to fly again?" he asked one of the doctors.

"possibly you may get another pair of wings some day," replied the r.a.m.c. officer grimly.

"then i suppose i'm booked for the infantry," continued derek. "anyway, that's better than nothing. i want to have a look-in at the finish."

"not in your present category, my young fire-eater!" replied the doctor. "aren't there any ground jobs going in the r.a.f.: equipment officer, for example?"

derek was not enthusiastic. like gallio, he cared for none of these things.

"what you want," continued the doctor, "is a job afloat. nothing like it for fellows off colour after a crash. do you know anything about the sea?"

"i've knocked about in small yachts," replied derek. "nothing in the deep-sea line, unfortunately."

"there are hundreds of amateur yachtsmen doing jolly good work in the r.n.v.r., as you know. 'harry tate's navy' they used to call them; but, by jove, the way those fellows played the game at zeebrugge was an eye-opener! i suppose you know that the r.a.f. is starting a new stunt—a marine branch?"

"haven't heard yet," replied derek. "it sounds promising."

"i've a young brother in it," said the doctor. "if you like, i'll write and get particulars. the show's only been running a month, i believe. sableridge is the name of the place; it's somewhere on the south coast."

directly derek received particulars he wrote off to the air ministry, stating his qualifications and requesting to be transferred to the marine section, r.a.f. promptly came a reply acknowledging his communication, and requesting him to call at room number so-and-so at the palatial hotel in use as the head-quarters of the r.a.f.

without any preliminaries, derek was subjected to a brief yet searching examination. what did he know about navigation? could he box a compass, set a course, read a chart, understand the rule of the road and the use of a lead-line? could he semaphore and morse? could he handle a motorboat in a roughish sea?

"very well," concluded his examiner. "go home, and if you don't hear from me in a week's time, come up again."

the week passed slowly, for derek was now keenly interested in what he hoped was to be his new r?le. a great feature was that he would still be in the r.a.f. he really didn't want to hear within the week, for the chances were that his services might not be required. the uncertainty of the whole performance was exasperating; he couldn't understand why his fate couldn't be decided on the spot.

on the morning of the 7th, just as derek was about to proceed to the railway station to journey to town, a letter came, with the words, "air ministry" printed on the envelope.

it was brief, and to the point. lieutenant derek daventry was to report for duty at the marine training depot, sableridge, on the 19th instant. whether he had to appear in khaki or in the new air force blue, whether he was to take his field kit, or whether he was to have furnished quarters were points on which he was left entirely in the dark.

"good enough, though!" he exclaimed. "this sea-service business is some stunt."