THE

SECRET BATTLEPLANE

BY

PERCY F. WESTERMAN

AUTHOR OF

"THE RIVAL SUBMARINES," "A SUB. OF THE R.N.R.," ETC., ETC.






S. W. PARTRIDGE & Co.
4, 5 & 6 SOHO SQUARE, LONDON, W.1.

Contents

CHAPTER I

SNOWED UP

"That rotter of a garage fellow!" exclaimed Athol Hawke explosively. "He hasn't done a thing to the wheel; and, what is more, he rushed me sixpence for garaging the bike, the young swindler."

"Didn't you go for him?" enquired his chum, Dick Tracey.

"He wasn't there to go for," replied Athol. "He was away on some job, and left the explanations to a youngster. But, my word, it is snowing! Think she'll stick it with that groggy wheel?"

The scene was the Market Square, Shrewsbury. The time, nine o'clock on a Saturday morning, March, 1916. It was, as Athol remarked, snowing. A week or more of intermittent blizzards had culminated in a steady fall of large, crisp flakes, and judging by the direction of the wind, the heavy, dull-grey clouds and an erratic barometer, the worst was yet to come.

Athol Hawke was a lad of seventeen, although he looked several years older. He was tall, lightly yet firmly built, of bronzed complexion, grey eyes and with dark hair. The fact that he was wearing waterproof overalls, leggings and fur gloves tended to conceal his build.

His companion, who was similarly attired, was Athol's junior by the short space of three days. In height he was five feet seven—four inches less than that of his chum; build, thick-set; complexion might have been fair but exposure to wintry conditions had resulted in his face being burnt to a reddish colour. His hair was light brown, with a tendency to crispness; his eyes blue. By disposition he was remarkably bright and cheerful, characteristics that served as a foil to Hawke's almost invariable staidness.

The two chums were riding a motor-bicycle and side-car. They had "been on the road" nearly a week. What possessed them to select a time of blizzard and equinoctial gales to go tearing across England; why they were apparently "joy-riding" in wartime; why they chose a district that was most decidedly within the region of activity of hostile air-craft—all this will have to be explained in due course.

At eleven o'clock on the previous day they had ridden into the quaint and picturesque old town of Shrewsbury, having left Chester shortly after daybreak. During the run they had made the disconcerting discovery that several of the spokes of the side-car wheel had worked loose, possibly owing to the drag of the snow and the atrocious "pot-holes" and setts of Lancashire. The wheel might last out till the end of their tour—and it might not. Dick suggested risking it, but the ever-cautious Athol demurred. They would remain at Shrewsbury, he declared, until the following day and get the damage made good.

A motor mechanic had promised faithfully to carry out the job, and had let them down badly.

"Well, what's the programme?" asked Athol. "We may be able to push on, but I guess it's pretty thick over the hills. Already there's a good two inches of snow—and it's still tumbling down."

Dick surveyed his surroundings in his customary optimistic manner. The cobbled square was already hidden by a dazzling white mantle. The roofs of the old buildings and the detached pillared market-house were covered with fallen flakes. A weather-worn statue, poised stolidly upon a lofty pedestal, was fast resembling the time-honoured character of Father Christmas.

Save for a few belated lady-clerks of the Army Pay Department, who cast curious glances at the two snow-flaked motor-cyclists as they hastened to their daily toil, the square was deserted. At the corner of an adjacent street two recruiting sergeants stood in meditative silence, regarding with a set purpose the pair of strapping youths.

"More of 'em, by Jove!" exclaimed Dick, as his eyes caught those of one of the representatives of His Majesty's Army. "Here they come, old man. Stand by to give 'em five rounds rapid."

"Nothin' doing, sergeant," announced Athol as the foremost non-com., beaming affably, vouchsafed some remark about the weather as a preliminary feeler to a more important topic. His companion had diplomatically "frozen on" to Dick.

With a dexterity acquired by much practice each lad unbuttoned his mackintosh coat and from the inner breast pocket of his coat produced a formidable-looking document.

"Bless my soul!" ejaculated the first sergeant. "Who'd a' thought it? Very good, sir; we can't touch you—at least, not yet. You never know."

"You speak words of wisdom, sergeant," rejoined Athol, as he replaced his paper. "Now, to get back to more immediate surroundings, what do you think of our chances of getting to Ludlow to-day?"

"On that thing?" asked the sergeant. "Not much. It's as thick as can be over Wenlock Edge. This is nothing to what's it's like up there. You'd never get through."

The word "never" put Dick on his mettle.

"We'll have a jolly good shot at it, anyway," he said. "Come along, Athol, old man. Hop in and we'll have a shot at this Excelsior business."

Athol Hawke would like to have lodged a protest. He was anxious concerning the groggy side-car wheel, but almost before he knew where he was, Dick Tracey had started the engine and the motor was swishing through the crisp, powdery snow.

Down the steep Wyle Cop and across the narrow English Bridge they went, then turning shook the snow of Shrewsbury from the wheels, since it was literally impossible to shake the dust from their feet.

Mile after mile they reeled off, the road rising steadily the while. Tearing through the snow flakes was really exhilarating. The air was keen and bracing; the scenery fairy-like in the garb of glittering white.

"Glad we pushed on," exclaimed Dick. "We're doing it on our heads, don't you know. The little beast of an engine is pulling splendidly."

The words were hardly out of his mouth when there was a perceptible slowing down of the three-wheeled vehicle, although the motor throbbed with increasing rapidity.

"Belt slipping," declared Athol laconically.

"It's the leather one," said his companion as he stopped the engine and dismounted.

"We'll shove the rubber one on. Leather always is rotten stuff to slip in the wet, and yet there's a proverb, 'There's nothing like leather.'"

"Doubt whether the other one will do any better," remarked Hawke. "See, the lowermost part of the belt rim has been ploughing through the snow. This is the thickest we've had so far."

"It is," assented Dick. "But we'll push on. It is a pity to turn back. We can't be so very far from Church Stretton now. From there it's downhill almost all the rest of the way."

The change of belts was effected and the journey resumed. For the next quarter of a mile progress was good, although great care had to be exercised to avoid the snow-banks on either side of the road.

Presently the road dipped with considerable steepness, and bending to the right crossed a small bridge. Beyond, it again rose and with increased gradient, and appeared to plunge directly between two lofty hills. The rising ground was thickly covered with pine trees, each branch bending under the weight of virgin snow.

"Looks like a bit of Switzerland," observed Dick. "Hanged if I can see why people want to go abroad to see scenery when there are places like this at home. But, my word, we've a stiff bit of road to tackle! Wonder if she'll do it?"

"She's got to," said Athol grimly. He was one of those fellows who embark upon an undertaking with evident misgivings, but when fairly in the thick of it warm to their task and are undaunted in spite of difficulties and rebuffs.

But there are limitations even to the capabilities of a three and a half horse power motor. Right nobly the engine did its work, but once again the belt slipped with exasperating loss of power. So deep was the snow at this point that the lower framework of the side-car was ploughing through it, while the heated crank case coming in direct contact with the snow was throwing off vapour like a high pressure steam engine. To add to the difficulty an accumulation of compressed snow had choked the front mudguard.

"All alight here!" shouted Dick. "By Jove, we'll have to jolly well push up this hill."

With the engine still running on low gear the lads literally put their shoulders to the wheel. It was hard work. In spite of the lowness of the temperature they were glowing with exertion, as, under their united efforts, they advanced at the rate of a mile an hour.

"Jolly long way to the top," panted Dick. "Hope we don't get snowed up. I say, that looks cheerful."

He pointed to a derelict motor car, almost hidden in a drift by the side of the road, where the bank of snow had risen to at least seven feet in height.

"Can't be much farther to Church Stretton," said Athol encouragingly. "Buck up, old man."

For another fifty feet they struggled manfully, until Tracey switched off the motor and brought the bike to a standstill.

"Spell-oh!" he announced, shaking the powdered snow from his cap. "I've had enough for a bit."

"If we stop we—like the drunken man—'goes over,'" declared Athol. "Every minute things are getting worse."

"Can't help it," rejoined Dick breathlessly. "Like the engine, I'm badly overheated."

For some moments the two chums stood still, taking in as much of the scenery as the snowstorm permitted, for so thick was the air with falling flakes that they could form no idea of the height of the hills on either hand.

Presently a horseman appeared, his mount floundering through the snow. So narrow was the track that in order to pass the bike and side-car he had to plunge into the drift.

"Pretty thick," remarked Athol.

"Ay, that it is," replied the man. "An' it's worse up yonder."

"Any village about here?" asked Dick.

"Not for some miles," was the reply. "And not a house, if it comes to that."

The man rode on. He seemed loth to waste time in conversation.

"We've struck the worst part of Wenlock Edge, it seems," said Athol consulting his road map. "It would have paid us to have stuck to the Severn valley, only we both wanted to see Ludlow and its castle. Well, ready?"

Dick nodded assent, and restarted the engine. Although the belt slipped frantically the slight friction of the pulley aided the bodily efforts of the lads. By dint of much exertion another hundred yards were covered; then despite their efforts they came to a dead stop.

"How about turning back?" suggested Dick.

"No good," decided Athol. "We might get to the bottom of the hill—might not. It's a moral cert we could not get up the rise on the other side of the bridge."

"And we can't leave the bike here," added his companion. "It would completely block the road."

"The road is blocked already, I fancy. The plain fact is this: we're snowed up, and what's more the side-car wheel has gone to pot at last."

CHAPTER II

A MYSTERIOUS BENEFACTOR

"Get the luggage out, old man," said Dick. "We'll pad the hoof and see if we can find a cottage. We might, with luck, get a fellow with a horse to pull the bike to the top of the hill."

"I guess the job's beyond the powers of a gee-gee," remarked Athol, who, ankle-deep in snow, was unstrapping the luggage from the carrier. "We'll have a shot at hiking the show into the drift. It seems fairly firm snow on this side."

By dint of strenuous efforts the two lads succeeded in lifting the heavy side-car to the fringe of the road, leaving a space of less than six feet between the wheel of the car and the snow-bank on the opposite face of the track. Then, shouldering their belongings, the weather-bound travellers trudged stolidly up the hilly road.

"Here's a jamboree!" exclaimed Dick after a long silence. He was regaining his breath and with it his exuberant spirits. "We'll have something to remember. By Jove, isn't this a ripping country?"

"It's all very fine," said Athol guardedly, "but, remember, we may be held up for a fortnight. This stuff takes a jolly lot of thawing, you know. Hulloa! There's someone hammering."

"The child is correct," declared Dick with a laugh. "And hammering metal work. I believe our friend the horseman was a little out in his statements. There must be a human habitation of sorts, and, judging by the direction of the sounds—unless the acoustic properties of a snowstorm are erratic—the fellow is tinkering away on that hill on our right. Yes, old man, here's a gap in the hedge. It looks remarkably like a carriage drive."

For the last hundred yards the road was bounded by a raised bank surmounted by a thick laurel hedge. The gap that was just beginning to become visible resolved itself into a pathway barred by a tall gate tipped with a row of formidable spikes.

"Wonder there isn't an array of notice-boards of the 'Trespassers will be prosecuted' order," remarked Athol. "It seems to me that no one has used this path since it started snowing. However, it must lead somewhere, so let's investigate."

Lifting the rusty latch the two lads pushed hard against the gate. They had to force the bottom bars through eighteen inches of snow before they could open it.

The hammering noise was still maintained with hardly a break. The workman, whoever he might be, was certainly industrious.

For fifty yards the path ran straight up a steep ascent and then bore abruptly to the left. Here Athol and his chum were confronted by another gate which, unlike the outer one, was secured by a stout padlock and chain. On either side ran a laurel hedge almost as tall as the one separating the grounds from the highway. To the right hand gate-post was attached a socket supporting a large bell, the clapper being worked by means of a chain.

"I say, looks a bit fishy, eh?" remarked Dick, regarding the barrier with interest. "P'raps we've struck a private asylum."

"Don't know. Suppose if the owner wants to keep tramps and stranded wayfarers out, he's quite at liberty to do so," replied Athol. "However, necessity knows no law, so let's agitate the piece of sounding brass."

He jerked the chain. The bell rang out with startling loudness, the vibrations echoing and re-echoing between the pine clumps. The hammering ceased abruptly.

An old man, supporting himself by means of a stick, ambled through the snow, appearing from behind the hedge on the left of the gate. He was apparently about eighty years of age, wizened featured and white haired.

"What do you want?" he asked in a quavery voice. "My master sees no one except by appointment. If you have one, well and good; if you haven't, 'tisn't any use your stopping here."

As he spoke he made a snapping sound with his fingers and, in answer to the signal, two enormous bull-terriers lolled sullenly to the old man's side, and with the precision of a pair of music-hall twins, each bared his formidable teeth and growled menacingly.

Athol stood his ground. The chilliness of his reception had "set his back up."

"Look here, my man," he said with asperity. "You've done your duty by warning us, now go and tell your master that he is wanted—and look sharp about it."

Then, seeing the old fellow hesitate, he added,

"Sharp about it, I said. I'm not used to giving the same order twice."

"And I am not used to having my servants ordered about by strangers," exclaimed a deep, well-modulated voice. "Since your business seems urgent perhaps you will kindly state it."

The speaker was a tall, finely built man of about forty years of age. His features were clear cut, his brow lofty, and his jaw massive. He was clean shaven, revealing a pair of tightly pursed lips. His complexion was pale, his eyes of a deep blue colour and set rather wide apart beneath a pair of bushy, overhanging brows. Across his forehead was a horizontal scar of old standing, showing white even in contrast to his greyish complexion. His hair was dark brown tinged with grey and growing high upon his temples.

"We called to ask for assistance," began Athol. "Our motor-bike——"

"Mechanical breakdown?" asked the occupier of the premises.

"No; we're snowed up, and the side-car wheel has given out," announced the lad.

"H'm; well, I'm glad it isn't an engine fault," remarked the stranger. "Had it been you would have had no sympathy from me. A fellow who cannot tackle a refractory engine ought not to be allowed in charge of one on the road. Where's your bike?"

"About a hundred yards down the hill and in a snow-drift," replied Athol. "We did our level best but the snow was too much for us. We thought, perhaps, that we might find someone who has a horse——"

"Horse," repeated the man. "It will want something better than a horse, I'm thinking. Open those gates, Harvey, and look sharp about it. Come in, both of you. I'll be with you in a couple of minutes."

He gave the lads an approving smile as they both walked past the bulldogs without the faintest hesitation. Then he disappeared up the path, while the gatekeeper, having opened and unfastened the massive portal, vanished between the laurel hedges.

"We've struck a rummy show, old man," whispered Dick. "The old chap isn't a bad sort, though. Wonder what he is going to bring out? A traction engine?"

Tracey's curiosity was speedily set at rest by the reappearance of the stranger, dragging behind him a sleigh. The contrivance had no runners; it consisted merely of a rectangular sheet of metal curled at the foremost end. On it were thrown a couple of fir planks, about six feet in length, and nine inches in breadth.

"It's quite easy, thanks," said the stranger, declining the lads' offer to assist in dragging the sleigh. "It's made of aluminium. You will have to bear a hand when we get the bike on it. Best foot forward. I have a lot of work to finish before lunch, you know."

"Threaded?"

"Yes, we cut the threads before we left."

"Good men!" exclaimed their benefactor approvingly. "You both seem of a mechanical turn of mind. Well, you can set to work. If there's anything you require ring that bell. Lunch will be ready in an hour and twenty minutes. If you haven't finished by that time there's four hours between that and teatime. Excuse me, I must be off."

The shed was well lighted and warmed by means of hot water pipes. In one corner was a portable forge, in front of one window an up-to-date lathe. Engineer's tools, all in excellent condition, occupied racks on the walls, while on the beams overhead were bundles of white metal rods and stacks of aluminium sheeting.

"We've fallen on our feet, old man," remarked Dick. "Lunch, too, by Jove! I'm hungry. Our scrumptious repast at Shrewsbury is but a pleasant memory. I could do a jolly good tuck-in now."

"Nothing like work to while away the time," asserted Athol, casting off his motor-overalls and coat and rolling up his sleeves; "Buck up, old fellow, and rip that tyre off."

Soon the two young tourists were hard at it, and none was more surprised than they were when the door of the shed was opened and their host exclaimed,

"Spell-oh! Down tools, lads. Why, you have made a show. You'll find some cleaning stuff in that tin. I'll take you to the bathroom in the house."

"'Fraid we're in a jolly pickle," said Athol apologetically.

"I'm used to that," rejoined the stranger, as he led the way to a substantially-built stone-house standing in an open space between the pine-trees. "If you like to take off your boots—they look pretty saturated—I'll lend you some slippers."

Having washed, the lads were ushered into a long dining-room. The table was laid with covers for three. An old manservant, who might have been a brother to the gatekeeper, waited until the diners' wants had been attended to; then having thrown a couple of logs upon the already briskly glowing fire, he went out.

"Now to business," exclaimed their host. "First let me introduce myself. My name is Desmond Blake. My age—an important consideration in these strenuous days—is forty-two; my profession, an engineer who has been cold-shouldered by a—but that can wait. Now, tell me, what are your names? And what brings you in these parts?"

CHAPTER III

THE WONDERS OF THE SECRET BATTLEPLANE

"It's a long story," began Athol, having first given their questioner their names. "We don't want to bore you, Mr. Blake."

"Not at all," the host hastened to assert. "I am all attention."

"Suppose I ought to go back to the early stages of the war," said Athol. "You see, one yarn does for both of us, since we share and share alike. Fifteen months ago we were at a boarding-school in the south of England. It was only a small affair. We were prefects and all that sort of thing, and had practically finished our education before entering an engineering college. Dick's father is a major serving in Mesopotamia, my governor is a lieutenant-colonel and a prisoner of war at Meseritz. We have no relatives left in England. After a time we ran away from school and enlisted. You see, we are fairly big fellows and somehow we couldn't hang back. The training part wasn't half bad, although we had a couple of gypsies, an ex-convict, and a solicitor as billet-mates. Then we did five months in France, and got on jolly well until we were both offered commissions. That put the hat on the show."

"How was that?" asked Mr. Blake.

"The colonel sent us back to the regimental depot, and while our papers were under consideration the War Office made us produce our birth certificates. Then they found out that we were both under eighteen, so they pushed us out of the army—worse luck."

"Wouldn't even give us a chance to go back to the ranks," added Dick. "And we were having quite a good time. We'd stuck it through the best part of the winter, and the warmer weather was coming; but it was no use. They turned us down."

"And so we thought we'd have a fling before we settle down to engineering," continued Athol. "We both have a little money. We bought the motor-bike and side-car—got it dirt cheap from a fellow who was going to join up. We started off through the Midlands, were in the thick of the last Zepp raid in Northampton, went on through Newark, York, Halifax, and Lancashire, and then to Cheshire. From thence to Shrewsbury and here we are."

"What regiment were you in?" enquired their host.

The lads produced the documents that had effectually floored the recruiting sergeants at Shrewsbury. They were their discharges from the Loyal North Lancashires.

"Wonder, with your mechanical turn of mind, that you hadn't tried for the Royal Engineers or the Flying Corps," remarked Mr. Blake.

"We did have a shot at the R.F.C., but there were no vacancies at that moment," explained Athol. "We were rather cut up about it. But we did see some flying out there. Once we saw our monoplanes bring down a couple of Taubes one after the other; but sometimes we saw what we didn't want to see—our machines outclassed by those Fokkers. The brutes have the advantage, you know. They climb much more quickly than ours. It's not that they are more powerfully engined. It's the design. Our fellows are frightfully keen, but they are handicapped."

"You seem keen on aviation?"

"Rather," replied Athol, enthusiastically.

"Then, perhaps, my modest workshop may interest you," remarked Desmond Blake. "Pon' my word I don't know why I should allow you to inspect my work; I have kept it a strict secret so far, even dispensing with a staff of assistants in order to be untrammeled by the unwelcome visits of more or less incompetent factory inspectors."

He paused, pondering over in his mind some debatable point.

"By Jove!" he exclaimed, noticing his guests' empty soup plates. "We're supposed to be at lunch, and I had forgotten the fact."

In answer to a summons on a bell the old servant reappeared, deftly removed the plates and served the second course. This done, he went out.

"Since you have given me a résumé of your career," said Mr. Blake, "perhaps you might like to hear mine, at all events since the momentous day, the fourth of August, 1914.

"At the outbreak of hostilities I was in South America, doing remarkably well in mining engineering. A particular hobby of mine was flying, and having made three or four successful experimental machines, embodying features not previously known to aviation, I naturally thought that my experience would be welcome to the War Office.

"Accordingly I settled my affairs out there with the utmost dispatch and hurried home. My first interview with the authorities at Whitehall was decidedly frigid. They were awfully polite, but somehow they failed to come to any practical decision. Wanted a scale model, as if that would serve the same purpose as the actual machine I proposed to submit. I offered to have a battleplane complete, including engines, for inspection and test within fifteen days, but I was informed that this was unnecessary until the plans had been inspected by a sub-committee.

"Altogether half a dozen sub-committees tried their hands with my plans and specifications. Afterwards I discovered that hardly a single member knew anything about practical flying. Some of them hardly knew the difference between an airship and an aeroplane—asked questions on a par with those of the Yankee senator at the 'Titanic' enquiry.

"Without going into details I may say that my offer to the War Office was finally declined with thanks. I had no better luck with the Admiralty, for directly they learnt that the War Office had 'turned me down' I was metaphorically shown the door.

"I warrant that if I were a renegade and had taken my plans to Berlin the German government would have snapped them up, either by fair means or foul. As it is, their agents have been giving me a deal of trouble.

"However, foiled in my patriotic efforts I determined to erect a private factory, build a really formidable battleplane and give a practical demonstration over the heads of the War Office. My first trouble was to find a suitable site. It had to be in a remote district, far from a prohibited military area, yet fairly accessible from the important industrial centres. I lighted upon this place, and found it answered my purpose.

"Everything I have to do single-handed. I dare not run the risk of getting mechanics to help, partly, as I said before, owing to the Factory Act restrictions, but more especially from a fear lest my ideas should be filched.

"And now the finished article lies in my grounds, ready for instant flight, except for one drawback——"

"The snow, I suppose," hazarded Dick.

"Does not affect it to any appreciable extent," rejoined Desmond Blake. "My battleplane does not require hard, level ground for a 'take-off.' It will rise almost perpendicularly. No, it is not the climatic elements. To be concise I need a couple of capable and willing helpers, and judging by what you have already told me, I think you fellows have sufficient patriotism to volunteer your services in that direction. Am I right?"

Dick gave his chum an enquiring glance. Athol, naturally cautious, knew that Dick would have jumped at the offer.

"Your tempting invitation needs thinking over," replied Athol. "We should——"

"Of course," agreed Desmond Blake. "Of course. Suppose you defer your decision until you have inspected my invention? You will, I feel sure, treat the subject as one of a highly confidential nature."

"Rather," agreed both lads simultaneously.

"I knew you would," continued their host. "In any case you will be here a week at least, for the snow lies about a long time, and the roads will be simply impassable for motor traffic during the thaw. That is, if you decide to continue your journey by motor. There is always a means of getting to Church Stretton on foot and taking train from there. On the other hand, if you decide to remain, my house is at your disposal."

"You are awfully kind," said Athol.

"With an ulterior motive," added Desmond Blake. "You are the very fellows I was looking for. I want to 'rope you in.' That's speaking bluntly. I believe in saying what I mean without beating about the bush."

"You mentioned that you had trouble with the German agents," remarked Dick.

"I have reason to believe so," replied Blake. "I have no conclusive proofs. I can only infer that spies are at the bottom of the trouble. On three occasions my grounds were broken into. My gatekeeper, Harvey, a tough old chap in spite of his years, was able to thwart two attempts to break into my workshop. On the third instance I scared the intruder pretty badly by means of a shock with a high tension wire. At the same time the automatic shutter of a camera was released in the hope of getting the likeness of the gentleman in question. Unfortunately the magnesium flashlight failed to explode at the same moment as the exposure of the lens. What I ought to have done was to leave the lens uncovered. I shall know better next time."

"Wouldn't the plate become fogged?" asked Dick, who was a successful amateur photographer.

"Oh no; you must remember the attempt was made at night. The sudden flash of the magnesium acts much the same as the brief exposure of the plate in daylight."

The meal proceeded slowly, while conversation flowed briskly. Desmond Blake knew the value of a good lunch as an incentive to amiability, and had played his cards well. "Now for the hangar," he said, at the end of the meal. "You smoke? No, good; I'm glad to hear it. It's an expensive habit, although I have a great weakness in that direction. In fact, I sometimes find myself on the point of smoking a pipe in the petrol store."

"We've seen fellows in the Royal Flying Corps drop the glowing ends of their cigarettes in petrol just for sheer mischief," said Dick. "Nothing happened."

"But it might have," rejoined their host. "'Fraid it doesn't speak for the good quality of the petrol or the common sense of the men who fool about with it. It isn't the liquid petrol that is dangerous, but the vapour it gives off. I've been experimenting in that direction, trying to get a spirit that is non-inflammable under normal atmospheric pressure and only exploded when under compression."

"Have you been successful?" asked Athol.

"To a certain extent; that is to say, I have treated petrol so as to make it unresponsive at ordinary pressure except to a very hot spark."

Still conversing Desmond Blake led the way from the house, through a dense belt of pine trees, to a small clearing. The greater part of this space was occupied by a galvanised iron shed, at one end of which were large double doors. Between the threshold and the nearmost trees there was a distance of roughly ninety feet, the trees themselves exceeding a hundred and twenty feet in height.

"Here's the hangar," announced their guide, indicating the shed.

"Curious situation, if you don't mind my saying so," observed Athol. "You'll have to cut down more of those trees before the biplane is able to take flight."

"On the contrary there is more 'taking-off' space than is absolutely necessary, and, I might add, the machine is not a biplane. It is fashioned, as far as possible, on the principle of a bird, and unless my memory plays me false, I know of no bird possessing more than two wings. But here we are."

Desmond Blake rolled back one of the doors of the shed. The other, actuated by means of a flexible wire running over pulleys, slid back too.

"Merely a labour-saving device," said Blake. "I based my calculations upon a one-man show. But what do you think of her?"

In the dazzling reflected light from the snow the battleplane stood revealed to the lads' eager gaze. At first sight it hardly resembled a flying machine. It was more like a huge cigar raised at an angle of forty-five degrees and supported by a pair of trellis girders each of which in turn terminated in a couple of pneumatic-tyred wheels. The planes were folded against the fuselage; there were no signs of aerilons, horizontal or vertical rudders and other contrivances common to aeroplanes. This creation had the appearance of a gaunt, featherless bird standing erect on a pair of spidery legs.

"What propels it?" asked Dick. "Where is the propeller? And the planes? You said it was not a biplane. To me it looks like a nonplane. Hope I am not asking too many questions," he added apologetically.

"Fire away; as many as you like," rejoined Desmond Blake. "In the first place there is no propeller, that is, if you mean a rotary one. To go back to the simile of birds; they don't cleave through the air under the action of a two-bladed propeller. That, after all, is a tacit admission by aeronautical engineers that they are unable to copy nature; so they make a substitute that fails to perform the relative task that a bird's wings do with seemingly little effort. I have dispensed with a propeller and substituted mechanical planes that approximate very clearly the natural method of flying. Before I explain further we must get aboard; I'll show you the way. One could make use of a pair of steps, but they would be awkward things to carry about, especially at the Front."

With remarkable agility the inventor swarmed up a light aluminium ladder built into the girder-legs of the battleplane. Thirty feet up he disappeared from view through an aperture in the underside of the fuselage.

In a trice Dick followed, Athol ascending with more deliberation. The latter was puzzled at the great rigidity of the aluminium girders. Evidently Desmond Blake had solved the task of making the metal as tough as steel without any marked increase of weight. Another thing Athol noticed was that all the cross sections of the latticed girder were pear-shaped, the blunt end facing the direction of flight, the tapering end being aft. This was expressly for the purpose of reducing the friction of the air.

Squeezing through the trap door the lads found themselves on the floor of the chassis, which was composed of a succession of broad steps on inclined planes in order to afford a firmer footing when the battleplane was at rest. Between the floor and the curved roof or deck there was sufficient space for a tall man to stand upright. Against the concave sides were folded cots, in which those of the crew "off duty" could sleep during prolonged flights, while at approximately one-third of the length of the fuselage from the blunt nose was the motor room, a veritable nest of intricate, lightly-built and powerful machinery.

"Do you work the battleplane entirely from under cover?" asked Athol.

"Oh no," replied Desmond Blake. "It is essential to have a wide field of outlook. Here is the pilot's seat. Get in and see what it is like."

He indicated a circular seat perched about a foot beneath the deck, from which an oval-shaped opening provided with a raised coaming had been cut. Overhead was a light metal canopy which, when required, could be lowered flush with the top part of the chassis. To gain the seat from the floor of the fuselage it was necessary to make use of a metal ladder.

"Steady yourself by that horizontal bar," cautioned the inventor, indicating a short rod on the fore side of the coaming.

The warning was necessary, for, as Athol slid into the seat, the seat slid from him. It was only by hanging on to the bar and allowing his feet to dangle in the air that the lad saved himself from falling four or five feet to the floor.

"Don't say that I didn't give you fair warning," exclaimed Desmond Blake, while Dick laughed at his friend's predicament. "Now, have another shot at it. Lift yourself fairly into the seat. That's it."

"What's the idea?" enquired Athol.

"There are four seats like that, and each one is gimballed. That is, it is suspended in a similar manner to a compass on board ship, so that in spite of the motion the sitter is always 'right side up.' No matter how the battleplane banks, nose-dives, or even 'loops the loop,' the crew, seated in their allotted stations, are always in a natural position."

"That I can see," said Dick. "But how is a fellow to see where's he going when the plane is upside down? In that event his head and shoulders are inside the fuselage."

"Only for a few moments," replied the inventor. "The plane is self-righting, provided, of course, there is 'air-room.' Just give a glance at your friend's feet. No, there's nothing wrong with them. That's not what I meant. His feet are resting on a step, behind the step is a sheet of burnished metal inclined at an angle of forty-five. Now, in the event of the 'plane turning over on its major axis that mirror would project below the inverted deck of the chassis, and thus the pilot would still be able to 'look ahead.'"

Facing the pilot's seat were a few indicators and levers, whereby the altitude and speed of the plane could be determined and the aircraft steered on her course. A voice-tube communicated with the motor-mechanic who occupied the third seat. The second and fourth seats were raised slightly above the others, and were intended for the machine-gunners.

"The offensive armament is not yet on board," explained the inventor. "I have turned out a couple of automatic weapons firing eight hundred shots a minute. Here is one of the cartridges," he continued, drawing a metal cylinder from his pocket. "The calibre is 303, the same as that of the small arms of the British Army, but you must observe that the bullet is longer and different in other respects."

"It certainly is longer," agreed Dick, as he handled the cartridge. "But beyond that I see no difference."

"Do you notice a minute line round the bullet?" asked Blake. "The projectile is made in two parts. On leaving the muzzle the parts fly apart, but are held together by a length of flexible wire. Thus each bullet resembles a miniature chain-shot of the days of the old wooden walls. A hostile plane would stand little chance if under the fire of a hail of these bullets. There would be no clean holes in the fabric; struts and tension wires would be severed and the whole contraption would fall like a stone."

"Then what propels the plane?" asked Dick, his interest in the motors claiming precedence above all other constructional details.

"This pair of engines, each of two hundred horse-power," was the reply. "See, I actuate this lever and the wings—I prefer to call them wings rather than planes—unfold."

Swiftly, yet with an even movement, wings, hitherto lying snugly against the chassis, were outspread. Taking into consideration the length of the battleplane from nose to tail—barely fifty feet—the space from tip to tip of the wings looked disproportionately small. Each wing projected fifteen feet from the side, and curved backwards like that of a bird. The fabric from which the wings were made was composed of thin, specially-treated aluminium, in plates overlapping each other like tiles on the roof of a house.

"Now, Tracey," continued Desmond Blake, "see if you can coax the motors to start. If you can manage a car-engine you will be able to get them to fire. There's no danger of the bird taking flight. She's pinned down to the floor securely. At the same time I don't think I would run the motors all out, if I were you."

Deftly Dick set to work turning on the petrol and flooding the carburettor.

"Is it necessary to prime the motors?" he asked.

"They ought to fire without," replied the inventor. "There's the self-starter—that lever on your right."

At the first attempt the engines fired easily. In spite of being in a confined space there was very little noise, thanks to the efficient silencer. It was doubtful whether the purr of the motors could be heard beyond the limits of the grounds.

Yet, although the fabric of the battleplane trembled under the pulsations of the motors, the wings remained motionless save for the vibration imparted to the whole contrivance. Seeing Dick's look of enquiry the inventor pointed to a lever close to the lad's right hand.

"Gently with it," he cautioned. Depressing the lever Dick was aware of a terrific air-current rushing overhead. Dead leaves and pieces of aluminium sheeting that were lying on the floor of the shed were whisked up and flung about with great velocity. Peering over the edge of the coaming Dick could see that both wings were now beating the air with terrific violence, being actuated by a number of rods working on concealed cams. Supplementary rods imparted a second motion to the wings, the innermost and rearmost edges of which moved up and down independently of the primary movement of the fore part.

Stretching out his hand the inventor cut off the electric current, and the motors came to a standstill.

"Cannot afford to waste petrol in these hard times," he said with a smile. "You've seen enough to form an idea of how the plane flies. The mere up and down flap of the wings is insufficient; it is the peculiar twist of the after part that does the trick—something after the principle of a man sculling a boat by means of a single oar working over the transom. If he were to waggle the blades of the oar to and fro without giving a dexterous twist nothing would result except a see-saw motion of the boat. It certainly would not move ahead through the water, except for the tortuous movement of the oar."

"I should have thought that the wings were far too small," observed Athol.

"On the contrary they are just the right proportion compared with the weight and power of the motors," replied Desmond Blake. "I have not modelled my invention on the lines of an albatross, whose spread of wings is enormous. I had the lark in my mind's eye. That little bird, as you know, soars almost perpendicularly, yet the wings are small in proportion to the size and weight of its body. Now you have had a general idea of the secret battleplane. To return to the attack: are you fellows willing to sign on as crew?"

"Rather!" replied both lads without hesitation.

CHAPTER IV

A TRIAL TRIP

"A willing heart goes a long way," declared Desmond Blake. "On the other hand there's a verse:—

"We'll risk that," rejoined Dick.

"In that case we'll compromise matters," said the inventor. "Since you have offered yourselves in all good faith, we'll run in joint harness for the next fortnight. I'll show you the ropes, and if at the end of that time you wish to dissociate yourselves with the enterprise you may. In a fortnight's time I hope to be ready for an experimental flight to London just to show the authorities what my invention can do."

"Hope the weather will be warmer," said Athol. "It must be cold work flying on a day like this."

"Not in a covered-in artificially-heated chassis," corrected Desmond Blake. "Even the pilot's and observer's heads are protected by transparent screens."

"I should have thought that the snow driving against the screen would obscure it," remarked Dick.

"Then we'll put your theory to the test," declared the inventor briskly. "No time like the present. I'll open the doors to their widest capacity and fill up the tanks with fuel. You might also fix the two automatic guns to their pedestals; it's as well to have a trial flight with the normal weights on board."

The hose communicating with a powerful suction pump was coupled on to the tanks, and fifty gallons of fuel taken on board.

"I've doctored the petrol," explained the inventor. "I introduce a quantity of benzine in tabloid form. The result is—I am judging by results obtained on a car—that I can get fifty per cent. more power out of the motors. Now hold tight for the take off."

The floor of the shed being slightly on the down grade the vibration of the engines was sufficient to set the battleplane in motion until it reached the open space in front of the doors.

It was now snowing heavily. The tops of the pine trees were almost hidden in the blurr of falling flakes.

"Pull that slide over the rearmost seat, Dick," ordered the inventor. "It won't be needed this trip. That is good. Now, stand by with the ignition lever. That will be your only job for a while."

Desmond Blake had climbed into the pilot's seat, and had raised a hinged wind screen fitted with side wings and overhead covering. Athol followed his example, taking his place at the second, or machine gunner's seat.

The snow laden air reeked with petrol fumes and the smoke from the exhaust, but the noise of the motors was hardly audible without. The throbbing sound seemed to be confined to the interior of the fuselage.

Both lads, agog with excitement, held on tightly. For some seconds nothing appeared to happen; then with a sudden, powerful jerk the battleplane seemed to stand on end. Kept in a natural sitting position by a delicately-balanced seat, the two chums were forcibly aware of a pain in their necks, as if they had banged their heads violently against a door-post. The sudden starting or stopping of a lift was nothing to the jerk, for the battleplane had to clear the tree-tops with little lateral space to spare.

For the present they could see nothing except the whirring tips of the wings and the streaks of white as the machine soared against the falling snow. Already the manometer registered a height of four hundred feet and the needle was still moving rapidly round the dial.

Presently the fuselage assumed a horizontal position. The movement was now regular and free from vibration, for the direction of flight was no longer in an inclined motion.

"Easier than I thought," remarked the inventor.

Without raising his voice he could comfortably communicate with the rest of the crew, since the rush of air did not disturb the interior of the fuselage. Nor did the snow accumulate upon the wind-screens as Dick had surmised, for the nature of the transparent substance caused the impinging flakes to disperse without any suspicion of moisture being deposited upon the glass.

Owing to the design of the wing-screens it was now possible for the lads to learn and observe the ground almost immediately below them. Eight hundred feet beneath was a blurr of white, across which were traced several winding dark lines, for the battleplane had run out of the falling snow and was now heading southwards.

"Not much of a day for observation purposes," said Blake, who had relinquished his grip on the levers and was now trusting solely to the "stabilisers" or automatic devices for maintaining a straight course. "We are now over Ludlow. That patch is the ruins of the castle. You can just discern the town."

"I thought Ludlow was built on the side of a steep hill," remarked Athol.

"It is," assented the inventor. "That street is almost as steep as a roof of a house. Altitude tends to impart an appearance of flatness to the landscape, especially in the snow. We'll turn now, and follow the Shrewsbury railway. I don't like getting too far afield on an experimental run when so many landmarks are obliterated. Now, Athol, make your way for'ard and I'll show you how to manoeuvre the plane. Dick will have his turn later. It is essential that every man of the crew should know how to handle the steering and elevating gear."

For half an hour Desmond Blake kept his understudy hard at it, showing him how to make the battleplane bank almost horizontally, and how to change the speed gear to enable the wings to overcome the force of gravity during the vertical flight.

"You'll do," declared the inventor admiringly. "Now back to your perch. We are going to have a shot at looping the loop."

Desmond Blake waited until Athol had regained the gimballed seat, then, depressing a lever that had the double effect of lowering the gearing of the engine and elevating the "aerilons," or wing-tips, he caused the battleplane to soar almost vertically upwards.

The lads wondered why the terrifically acute angle of ascent did not cause the fuel to flow to the rearmost of the four connected tanks, and thus affect the aircraft's lateral stability. The inventor, glancing over his shoulder, must have read their thoughts.

"Climbing to get a better chance in case she jibs," he called out. "No need to worry about the petrol. Each tank has a reserve valve that only operates when the angle of inclination exceeds fifteen degrees."

The arrangement of the tanks was another instance of Blake's forethought. At normal flying positions the petrol in each tank was practically at the same level in order to ensure constant trim of the machine. But directly the tilt of the battleplane tended to allow the volatile spirit to flow to the lowermost tank, automatic valves in the connecting pipes came into action, thus causing each tank to retain approximately the same weight of liquid fuel.

For three minutes the battleplane climbed steeply and at a high speed that had never yet been approached by the most daring aviator. Then, following a hasty caution from the pilot, the aeroplane began to describe a circle in a vertical plane. Although the seats retained their normal positions, the centrifugal force tended to throw Athol and Dick off their balance. The next moment their heads were within a few feet of the up-turned floor of the fuselage, while their feet were dangling in the space enclosed by the wind-screens. Five seconds later the battleplane had regained its normal position, having described a complete loop of a radius of less than a hundred feet.

"That's good!" exclaimed the inventor with pardonable pride. "Now look out to enjoy the sunshine."

To the lads' surprise the battleplane was bathed in bright wintry sunshine. The aeroplane had emerged above the bank of snow clouds and was cleaving her way through the clear air. Away to the south-west the sun was low in the heavens, for it was now within an hour of sunset.

"Time to get back," declared Blake briskly. "We've got to drop through the snow-clouds beneath, and trust to luck to pick up our bearings. 'Fraid I've overstepped the bounds of discretion, but it was jolly well worth it."

Actuating a lever he "locked" the wings. Like a giant seagull swooping down from a lofty cliff the aeroplane began a steady volplane towards the bank of clouds a thousand feet below.

At a speed of well over a hundred and fifty miles an hour the battleplane cleft the bank of suspended vapour. Almost pitch darkness succeeded the clear sunshine of the upper air. The sudden transition temporarily blinded the three aviators.

Desmond Blake spoke not a word. With his eyes fixed upon the dials of the manometer he gauged the earthward flight. At five hundred and fifty feet, an altitude well above that of the highest hills on the Welsh border, he checked the descent. Although the gloom was now less it was still impossible to discern anything of the country beneath. Evidently the battleplane was encountering a snowstorm heavier than she had previously experienced.

Standing by, ready to "flatten out" at the first sign of terra firma, the inventor allowed the machine to continue its downward flight, although at a greatly retarded velocity.

Suddenly he thrust the vertical rudders hard over, at the same time unlocking the wing mechanism. As he did so he had a momentary glimpse of a tall slender spire within fifty feet of the tip of the left wing. Immediately afterwards the battleplane almost skimmed a lofty pinnacle that resolved itself into another snow-outlined spire.

"By Jove!" ejaculated Blake as he set the battleplane to climb above the danger area. "We're slightly out of our bearings."

"Where are we, then?" asked Dick, who had also seen the fleeting vision.

"Over Coventry," replied the inventor. "We've narrowly escaped colliding with two of the city's three famous spires. Take her, Athol, and keep her as she is while I look at the map. It will be a compass course back, with a good deal of guesswork thrown in."

A hurried consultation told Blake that, allowing for the almost cross-set of the northerly wind, half an hour's flight in a north-westerly direction ought to bring them within recognisable distance of home.

"Birmingham's beneath us," observed Blake after a few moments' interval. "Fine city, Birmingham, but a nasty place if one has to make an involuntary landing."

He had hardly uttered the words when with a disconcerting jerk the motors faltered, picked up for a few pulsations, and then ceased firing.

The battleplane began to drop towards the labyrinth of buildings that, hidden by the thickly-falling flakes, lay less than three thousand feet below.

CHAPTER V

SO NEAR AND YET SO FAR

Not for one moment did Desmond Blake's presence of mind desert him. Quickly locking the wings in position to enable the battleplane to maintain a maximum glide he turned her "down wind." Volplaning in the teeth of the stiff northerly breeze would, he knew, result in a cross-country gain of, perhaps, a mile or two; whereas, gliding with the following wind there was more than a sporting chance of covering sufficient distance to get clear of the thickly populated outskirts of the Metropolis of the Midlands.

Following the stoppage of the motors Dick slipped from his seat and made his way along the floor of the fuselage till he came to the silent machinery. Switching on an electric torch, for it was now dark within the "hull" of the battleplane, and with the failure of the motors the dynamo-run lamps had gone out, Dick made a hasty examination.

"Ignition," he reported. "Magneto, I fancy."

"Guessed so," rejoined the inventor, laconically. "See if you can rectify matters. I'll keep her steady as long as I can."

Volplaning at fifty miles an hour does not give one much time for effecting adjustments. Before the lad had been able to verify his suspicions a peculiar motion warned him that the battleplane was describing a semi-circular swoop. Ten seconds later, with hardly a perceptible jar she came to earth, or rather, landed in a deep snow-drift.

"Had to risk it," declared Blake cheerily. "This will do for the present. Night's coming on apace. Fortunately there are plenty of emergency rations on board."

"Where are we?" asked Athol.

"Goodness only knows," said the inventor. "All I know is that we just skimmed the tops of a tall building. It wouldn't be a bad idea to land and have a look round. Nothing like fixing one's bearings in case we have to clear out in a hurry."

Although the fuselage when at rest had a normal inclination of about forty-five degrees it now barely exceeded fifteen. On alighting the airmen discovered that the battleplane was resting in the snow on a shelving slope. Twenty feet from her bows was a stone wall in a ruinous condition. Only the drag of the snow drift had prevented the battleplane from hurling itself "nose-on" against the formidable obstruction.

Already the twilight was falling, the dim light rendered still fainter by the steady drive of heavy flakes. Away to the right a dim outline, silhouetted against the afterglow, denoted the position of the building against which the battleplane had so narrowly escaped being hurled.

"A ruined castle," exclaimed Athol.

"And, to me, a familiar spot," rejoined the inventor. "We couldn't have lighted upon a better place. This is Kenilworth. There is little fear of interruption, it is late in the day, and people would not be tempted to wade through the snow drifts even if the grounds are not closed. Yes; we'll do here very nicely. There's plenty of room for a 'take off.' Now for a meal, then we'll tackle the repairs. I don't propose making a fresh start until just before daybreak."

Returning to the battleplane the three aviators "battened" down to guard against the possibility of any stray ray of light betraying their presence. Two battery-charged electric lamps gave quite a brilliant illumination. The meal, though frugal, was heartily appreciated, while thanks to the amount of heat still retained by the radiators fed by the exhaust the temperature bordered upon sixty degrees.

"One must be ready to profit by slight misfortunes," remarked Blake during the the meal. "I have an idea. I'll have separate magnetos to each engine."

"Will that help us?" asked Dick. "If one engine fails one of the wings will cease beating and the other will go on flapping. The battleplane would be like a duck wounded in one wing."

"So she would," admitted the inventor dubiously.

"Separate magnetos by all means," continued Dick, "but it would be well to fit a free wheel sprocket on the main shaft of each engine, and arrange it so that each motor actuates both wings. Then if one engine falters or stops the other will continue to propel the battleplane. Of course you would only have half the power, but that would be sufficient to keep her in the air."

Desmond Blake thought deeply for a few minutes.

"By smoke, Dick!" he exclaimed. "You've solved a knotty point. We'll make the necessary alterations directly we return. You are quite right about the power of each motor. Each possesses one and a half times the lifting power necessary for the battleplane."

By nine o'clock in the evening the adjustments to the magneto were satisfactorily carried out, and the battleplane's wings having been folded to escape an accumulation of snow, the airmen turned in for the night.

As Blake had surmised the night passed without interruption. Little did the inhabitants of the picturesque village of Kenilworth suspect that the most ingenious flying machine that the world had yet possessed was resting quietly in the snow-covered courtyard of the famous mediaeval ruin.

So soundly did the two lads sleep in their comfortable bunks that the first intimation they had of the arrival of another day was Desmond Blake's voice exclaiming,

"Now, then, you fellows. Five o'clock and a fine morning."

A cup of hot coffee and some biscuits having been served out, the airmen prepared to resume their flight. It was still twilight. Snowflakes were falling, although not with the violence that characterised yesterday's storm. From a not far distant farmyard cocks were lustily heralding the dawn.

Silently, under the guidance of the masterhand, the huge mechanical bird left its roosting place on the snow covered ground and soared swiftly upwards until it attained a height of two thousand feet.

Suddenly a huge, ill-defined shape lurched past the battleplane, passing less than two hundred feet underneath. In spite of the terrific speed, for the two objects were moving in the opposite direction and at an aggregate rate of one hundred and eighty miles an hour, both lads recognised the shape as that of a Zeppelin.

Desmond Blake saw it, too, and acted promptly. In a few seconds the battleplane had made a semi-circular motion and, "all out," was following the night-raider.

Athol sprang to the machine-gun but the pilot waved his hand to indicate that the weapon was not to be used. Already the Zeppelin, having gained a great distance during the change of direction on the part of the battleplane, was out of sight.

"No use," he exclaimed hurriedly. "Only dummy cartridges. Must blame the Defence of the Realm Act for that."

Seven minutes later the Zeppelin was again sighted. Apparently she had been engaged in a raid over the Midlands and had lost her way. She was moving jerkily, and was down by the stern. Whether that was owing to injury from anti-aircraft guns or merely through the accumulation of snow on the upper part of her envelope the lads could not decide.

Unperceived by the crew of the Zeppelin the battleplane soared majestically overhead until a vertical distance of less than a hundred feet separated the gas-bag from her winged rival.

"If we had ammunition we should have her at our mercy," remarked the inventor.

"Take charge for a few minutes, Athol. I want to give her a little reminder of our meeting."

The lad gripped the steering levers. So strong was his faith in the masterpiece of the inventor that he handled the swiftly-moving battleplane as faultlessly as if his acquaintance with the mechanical bird had been of two years' duration rather than of a few hours.

Meanwhile, Blake descended to the interior of the fuselage, returning presently with a long steel marline-spike. Through the hole in the rounded end he threaded a string of red, white and blue ribbons for the joint purpose of steadying the improvised dart in its flight and in order to leave no doubt in the minds of the Huns of the origin of nationality of the weapon.

Then, clambering into the seat vacated by the deputy pilot, Blake lowered one of the wing-screens and poised the marline-spike over the side.

"Faster," he ordered.

Dick touched the lever actuating the sparking-gear. Perceptibly the battleplane increased her speed until she overlapped the unsuspecting Zeppelin by almost two-thirds of the latter's length.

Blake released his grip of the rough and ready dart. For a couple of seconds it seemed to fall well in front of the swiftly-moving Zeppelin, then, its course describing a gradually increasing curve, it was observed to be making for the huge target.

With a thud it struck the flattened part of the upperside of the envelope about fifty feet from the tail. Completely perforating the aluminium sheeting it vanished, leaving a few fragments of streamers to mark the palpable hit.

"There'll be some gas lost there, I'm thinking," remarked Blake grimly. "Up helm, Athol. We have no more missiles at our disposal. One thing, we've had practice at bomb-dropping."

In a few seconds the errant Zeppelin was lost to sight in the snow-laden atmosphere, as the battleplane was steadied on a course that was to bring her back to her hangar.

"There is our base," announced the pilot, pointing to a clump of snow-laden pines almost hiding a lofty conical hill. "Make sure of your bearings, lads; you never know when the knowledge will come in handy. Now, stand by."

Skilfully Desmond Blake brought the battleplane to a standstill with her nose within five feet of the doors of the shed.

"Now for a proper breakfast," he exclaimed cheerfully as the crew alighted. "It won't take long to house the little beauty, then——"

He stopped abruptly, his hands gripping the half-open doors.

"The deuce!" he ejaculated.

CHAPTER VI

THE INTERRUPTED VIGIL

"What's wrong?" enquired both lads anxiously, for the worried expression on the usually calm features of the inventor told its own tale.

In his agitation Blake failed to make reply. He dashed into the shed, followed by his two assistants. Everywhere there were signs of disorder as if some intruder had hastily overhauled the secrets of the jealously guarded spot. The high tension wire that had previously baulked a nefarious attempt had been severed by means of a pair of insulated wire-cutters. The lens of the tell-tale camera had been smashed and the dark slide removed and exposed to the light.

A safe, cunningly built into a concrete pier of the shed, had been forced open and its contents removed.

"The spy has secured the plans; that's pretty evident," he declared. "We can do no good here at present. What I want to find out is how the fellow forced his way into the grounds."

Accompanied by Athol and Dick, the inventor left the shed and hurried across the snow-covered ground. Already the footprints of the intruder had been obliterated by the falling flakes. He could not have chosen a better time for his successful attempt.

Along the path through the shrubbery the crew of the battleplane hurried. At the inner gate the first sight that met their eyes was the body of one of the bull-terriers half buried in the snow. The other animal was discovered dead in the bushes, whither it had crawled before expiring. Both animals had been poisoned.

In the little lodge was the unconscious form of the aged porter. Evidently he had put up a stiff fight, for there was blood upon the floor, and a revolver with two chambers discharged was still grasped in his right hand.

Blake bent over his devoted servant.

"He's alive," he announced. "I can find no trace of an injury. He must have been tackled by two men. He's been chloroformed."

The inventor's first task was to restore the unconscious man. His anxiety on the porter's behalf seemed to banish all other thoughts from his mind. The loss of the almost invaluable plans were as naught compared with the state of his faithful retainer.

"Shall I go for a doctor?" asked Athol.

Blake shook his head.

"I'm used to a land where doctors are few and far between," he replied. "That makes every man there more or less of a medico. You might start that fire again, Athol, and get a kettle on."

Having waited until the patient had recovered consciousness, Desmond Blake and Dick left the lodge, Athol having volunteered to remain with the victim of the outrage.

Letting himself in by means of a sidedoor the inventor soon found that the house had not been an object of the spies' investigations. The old butler was still asleep, ignorant of the attempt upon his brother the porter.

"This little business has upset my plans, Luck," remarked Blake. "Or, rather, it will force my hand. It's no use trying to track the thieves. For one thing we have no clues; for another we simply haven't the time to waste. In the likely event of those plans reaching Germany, another month will result in the appearance of hostile battleplanes built to my specifications. So our task is to convince the War Office of the outstanding nature of my invention, and get the Royal Aircraft Factory people to set to work as hard as they can."

"You will have to make another set of working plans, I suppose?" remarked Dick.

"No, fortunately. As it happens I have both duplicate and triplicate tracings deposited at a London bank. However, that is not our immediate concern. What I propose doing is this. I'll motor into Church Stretton this morning and take old Harvey to the cottage hospital. Athol and you might make up arrears of sleep. This afternoon we'll tackle that little job you mentioned in connection with the dual drive. There are also a few adjustments necessary, which I noticed during our trial trip—not important, but certainly desirable. While I am in Church Stretton I'll engage a man and his wife as caretakers of the house while we're away. One never knows when we may be back. To-morrow at nine o'clock I intend starting on our flight to London."

Desmond Blake's plans worked smoothly. During the afternoon the suggested alterations to the driving transmission gear were satisfactorily carried out, and everything made ready for the momentous flight.

"I'm sending something of the nature of an ultimatum to the War Office," he remarked during the course of the evening. "You see we have to announce our arrival, otherwise the anti-aircraft guns might favour us with their unwelcome attentions. On the other hand it's worse than useless asking formal permission from the authorities to fly over the Metropolis. The application would drift to and fro between a dozen or more departments. Every little tinpot in office would have some remarks to make—I know them of old. The chances are that I would get an evasive reply in about a fortnight. Good heavens! If we had an Admiralty and a War Office purged of the somnolent civil element the war would be over by this time. So I've just cut in with a bald announcement. I've left a telegram to be dispatched at nine to-morrow—the time we start—stating that the Desmond Blake battleplane will manoeuvre over the Horse Guards Parade at 10 a.m. But we'll turn in now. It's getting late, and we've a full programme in front of us tomorrow."

"Do you mind if we sleep on board the battleplane?" asked Athol.

"Mind? No, of course not. But what's the object?"

"We've been talking it over," said Athol. "We thought that perhaps those spy Johnnies might pay us another visit."

"Hardly likely," replied Blake grimly. "They've collared the plans, and those will keep them quiet."

"I don't know so much about that," rejoined Dick. "They might think that that is our opinion, and consider it a favourable chance of returning and doing damage to the battleplane. That would give them a tremendous start."

"Perhaps you're right," declared the inventor. "Now I come to think of it there is a possibility that the rascals will attempt to culminate their efforts. We'll all sleep on board, and take turns at keeping watch. I haven't bothered to fix up that high tension wire again. 'Fraid they know too much. We'll arm ourselves and be ready to give them a warm reception."

"By the by," remarked Dick, "whilst we were repairing the side-car wheel I noticed a 'buzzer' in the workshop."

"Yes," replied Blake. "I bought it to practise Morse signalling. Found myself awfully testy, by the by. But why do you ask?"

"We could fix it up on board, muffle the sound and connect the battery with a push on the door of the shed," said Dick. "We could arrange it that as soon as the door opens wide enough to admit a man a circuit would be complete."

"Might try it," admitted Blake. "But you must remember these fellows are prepared for all sorts of dodges. Well, we'll adjourn at five minutes' intervals. The great thing is to get on board without being seen, for ten to one if these rascals intend paying us another visit they will be keeping a sharp look-out on the house."

With a loaded revolver reposing in the side pocket of his coat, Athol was the first to make for the shed where the battleplane was housed. Slipping quietly through an open window in the rear of the house he crept stealthily through the snow, keeping well under the cover of the pinetrees. As an additional precaution he walked backwards, so that should the spies subsequently examine the ground they would find that the footprints led away from the shed.

It seemed a long five minutes waiting for Dick to rejoin him. The eerie shape of the battleplane, looming faintly through the darkness, and the possibility that even now some miscreant might be hidden in the hangar, gave the lad an unpleasant sensation that he had not experienced since his first night on sentry in the first-line trenches of Flanders.

At length Dick arrived. Not a word was spoken. They stood motionless until Blake joined them. Still in silence they ascended the aluminium ladder and gained the interior of the fuselage. Already it had been arranged that Athol was to have the first watch—from nine to midnight. Blake had insisted upon keeping the next three hours. He knew what the mental strain of that watch meant, when a man's diurnal vitality is supposed to reach its lowest ebb. Out of consideration for his young and efficient helpers he knew that by taking the middle watch each lad would have six hours' continuous rest, unless something unforeseen occurred.

Lying at full length upon the floor of the fuselage Athol could command a considerable extent of the shed, for the aperture by which the crew had gained the interior of the battleplane had purposely been left wide open. The double doors of the building had been locked and the key removed, while Dick's contrivance had been fixed up, the "buzzer" lying within a foot of the watcher's ear.

The lad had no idea of the time. Already it seemed as though he had been for hours at his post. The silence, broken only by the moan of the wind in the pines, and the occasional thud of a heap of accumulated snow from the roof of the hangar, was oppressive.

"What's that, I wonder?" thought the lad as, after a seemingly interminable lapse of time, a faint hissing, bubbling noise caught his ear. For some seconds he listened intently. Then came the unmistakable odour of the fumes of a powerful acid, mingled with the spluttering of the drifting flakes as they came in contact with the hot metal.

The miscreant, whoever he might be, had fought shy of the task of picking the lock, and was employing either sulphuric or nitric acid.

Athol knelt up, gripping the coaming of the aperture and straining his ears. Then, just as he was about to steal softly to his companions, he felt a hand laid lightly upon his shoulder.

Desmond Blake had also detected the signs of the miscreant's attempt.

Without trusting himself even to whisper, Blake began to apply a series of light touches to his assistant's arm. Athol, quick to grasp the significance, understood. The inventor was employing the Morse system of communication.

"No action till I give the word," he tapped out. "Wake Dick."

Although his chum was sound asleep Athol succeeded in rousing him in silence, and the three airmen gathered round the aperture of the fuselage, awaiting developments.

Quite half an hour passed; then came the rending of the chemically-treated corrugated metal sheeting. A muffled exclamation of pain followed by a guttural oath plainly indicated that the fellow had burnt himself with the powerful corrosive.

Crawling through the opening the intruder hung a great coat over the hole, to trap any rays of light from passing without, and switched on an electric torch. For some seconds he stood gazing at the mechanical marvel he meant to destroy. His scientific curiosity made him temporarily set aside his purpose, for still holding the torch he began to swing himself up the girder-ladder communicating with the interior of the apparently untenanted battleplane.

The reflected glare of the upturned torch made it easy for the lads to follow the inventor's unspoken directions. Cautiously they backed until they had placed the motor space between them and the aperture towards which the fellow was climbing.

The man seemed in no hurry, for some minutes elapsed before his head and shoulders appeared in view. Then came another pause as, sitting on the coaming with his feet resting on the topmost rung of the ladder, he flashed his light around the interior of the mechanical bird.

The miscreant had little of the accepted appearance of a spy. He was slight of build, although his head seemed out of all proportion to his body. His features were round and florid, his eyes—as far as the glare of the torch permitted them to be seen—large and exhibiting a docile expression like that of a well-cared-for household cat. Encountered under ordinary circumstances one would without hesitation set him down as an easy-going, babyish man devoid both of mental and bodily power.

Judging him from a physical point of view Athol formed a rapid conclusion that either he or Dick could tackle him with one hand.

Still Blake gave no sign. He was too old a campaigner to throw away his advantage by premature action. He resolved to wait until the fellow had moved sufficiently far from the aperture to be unable to make a quick dive for safety.

Presently the German crept forward, still flashing his torch. Evidently there was something that attracted his attention to a greater: extent than did the motors and wing-actuating mechanism.

"Hands up!" exclaimed Desmond Blake sternly, at the same time flooding the interior of the fuselage with the dazzling rays of his electric lamp.

"Sorry—my mistake," replied the fellow coolly. "Mistook this place for a barn, 'pon my word, I did. Beastly awkward mistake, don't you know. Then, seeing what I took to be a novel sort of agricultural implement I was curious——"

"Are you putting your hands up?" enquired the inventor briskly.

A pistol shot rang out. The spy, grasping the still-smoking weapon, threw himself flat upon the floor to await the result of his shot. Dazzled by the glare he had been unable to see his challenger; nor was he cognisant of the fact that the two lads were present. The result of previous investigations led him to believe that the inventor was the only able-bodied man about the place, and, now that the dogs had been disposed of, the odds were level.

Greatly to the consternation of Athol and his chum, Blake began to emit blood-curdling, hollow groans. They were on the point of replying to the rascal's shot when Blake signed to them to keep under cover, punctuating his groans by a series of winks that showed plainly that there was plenty of "kick" left in him yet.

The spy showed no immediate haste to follow up what he considered to be first blood. The powerful rays of the lamp irritated him. Until the brilliant light was put out movements would be too risky. He looked about for something bullet-proof and portable that might serve as a mantlet to cover his progress towards the lamp.

Close at hand was a small teak box containing sand. Blake had placed it on board in case of fire. It was certainly proof against a revolver bullet—perhaps even sufficient to stop a rifle-bullet.

Stretching out his arm the spy grasped the edge of the box and began to draw it towards him. The act was his undoing, for a keen knife whistled through the air with unerring aim, and the next instant the German's left hand was transfixed and securely pinned to the hard teak.

"Drop that pistol and put your right hand up," ordered Blake, when the fellow's cries for mercy had subsided sufficiently for the inventor to make himself heard.

The German obeyed. The excruciating pain had overcome all his cunning and spirit of resistance.

"That's reasonable," declared Blake, possessing himself of the surrendered weapon. "Now, lads, lash his ankles. Hang it all! What possessed the idiot to start blazing away? Goodness only knows what damage he's done to the intricate mechanism. And he expected I'd begin to pump nickel through my invention in the hope of plugging him."

"I thought you were hit," remarked Athol.

"Hit? No fear," replied the inventor. "I wanted that fellow to think he had given me a souvenir. It was a jolly good thing I learnt that South American trick of throwing a knife. Didn't think much of it at the time, but, by Jove! it served its purpose."

Having removed the knife and dressed the German's hand, the airmen moved their prisoner aft, securing him to a ring-bolt in the floor. Then bidding Dick mount guard over the captive, Blake, accompanied by Athol, searched the shed and its immediate surroundings.

"There is only one of them this time," declared Blake. "Here are his footprints. This looks cheerful, too."

He stooped and picked up a couple of detonators and a coil of fuse. The spy had set these on the ground at the foot of the tree, apparently with the intention of fixing them up when he had satisfied his curiosity concerning the battleplane.

"It's most fortunate that you fellows suggested spending the night on board," declared Blake fervently. "The battleplane would have been blown sky high before morning if I hadn't listened to your advice. Now I think I'll subject our Hun to a little cross-examination."

CHAPTER VII

THE BATTLEPLANE'S OFFICIAL DEBUT

Without speaking a word Desmond Blake approached his prisoner and regarded him intently. For a full minute he kept his eyes fixed upon the German, who at first seemed indifferent to the attention paid him.

Presently the spy began to shift uneasily under the searching scrutiny. Try as he would to avoid the penetrating look he found himself unable to withstand the seemingly mesmeric influence. His whole attitude was that of a dog cowed solely by the severity of its master's gaze.

"What is your name?" demanded Blake, breaking the strained silence.

"Sigismund Selighoffer," replied the spy in a strangely subdued voice.

"A native of Germany?"

"Of Halle."

"A spy?"

"Yes." The answer was given with considerable hesitation. It was the man speaking in spite of his inclination to maintain silence and discretion.

"You stole my plans. Where are they?"

"It was my employer, Karl von Secker, who took the plans. We were here last night. He went away yesterday, taking the plans with him; but before he went he gave me orders to destroy this machine."

"You know where he is?"

"On my honour, no. He could not tell me. Perhaps he will make his way back to Germany. It is easy for him to do so."

Blake asked several more questions, not once shifting his eyes from the thoroughly cowed Hun.

"Very good," he concluded. "In a few hours' time you will be handed over to the authorities for trial. If it be any satisfaction to you I might add that you will be the first German—and I hope the last—to set foot on this battleplane."

He turned and went for'ard. Directly his back was turned the spy broke into a torrent of oaths, defying his captors and reviling himself for having given away so much information.

Blake merely shrugged his shoulders.

"Simply the triumph of a strong mind over a weak one," he explained to the lads. "Herr Selighoffer is merely a pawn in the game—a tool of the more dangerous von Secker. Had we no other and more urgent work in hand it would be a delightful task to run von Secker to earth. Man-hunting is, from my personal knowledge, one of the greatest thrills a criminologist can experience. Once I had to track a Brazilian desperado across miles of country—but that story can wait. We must trust the recovery of the plans to the authorities. Now, lads, the pair of you had better turn in again. I'll keep watch, although I don't anticipate any further trouble from prowling Huns. It would be just as well to keep an eye upon that slippery customer, Sigismund."

The rest of the night passed without interruption. At seven the lads arose, bathed and had breakfast; by eight-thirty the battleplane was ready for her flight to London.

"Better thirty minutes too early than thirty seconds too late," remarked Dick.

"H'm! perhaps in this case," rejoined Athol. "Do you remember that morning in the trenches facing the Menin road? We were both a little tardy in turning out to breakfast."

"And what happened?" asked Blake.

"Nothing as far as we were concerned," replied Dick. "Except that we had no breakfast that morning. A shell had landed close to the stew pot and the men with their rations were blown to bits. It was a case of Nah Pooh with them."

Without a hitch the battleplane was brought from the hangar, her wings extended and the motors set running. It had now ceased snowing, and although the ground was still covered with a mantle of white, there seemed every prospect of a fine day.

Making a splendid ascent the machine quickly attained an altitude of twelve thousand feet, and a compass course was shaped to due east. Blake had a definite object in flying high. The air was sufficiently clear to distinguish prominent landmarks, but at that altitude there was hardly any possibility of the battleplane being seen from the earth. He wanted to make his arrival as dramatic and sudden as possible.

"We're touching one hundred and eighty miles an hour now," announced the inventor. "Could do another twenty with ease if we wished. We'll romp there hands down."

"Why this easterly course?" asked Dick, who, having for the time being finished with the motors, had taken his place close to the pilot. "This will land us somewhere in Norfolk if we carry on."

"Only till we pick up the North-Western main line," replied Blake. "There's nothing like a railway to help you to fix a position. In conjunction with a good map a railway lets you know where you are almost to a mile."

Forty-seven minutes from the time the battleplane left the ground a dull haze upon the horizon indicated that the metropolis was in sight. Quickly the intervening distance was covered, until at a height of two thousand feet the airmen were immediately over the Thames.

"Good enough!" declared Blake, at the same time locking the wings. Although the motors were still running they were acting merely as "free engines," ready to be coupled up to the wings in a case of emergency. For the rest of the distance the battleplane was to glide under the attraction of gravity.

Unerringly Blake brought the battleplane towards the gravelled expanse of the Horse Guards Parade. Save for a few persons hurrying across the place was almost deserted. Evidently there was no sign that the aviators were expected. Either the telegram had been delayed or the War Office officials had considered it a hoax.

Suddenly Blake coupled up the wing-mechanism. The beating of the wings caused several of the pedestrians to look skywards. For a second or so they seemed hardly able to credit their senses. Aeroplanes they knew, but the huge mechanical bird astonished them. Right and left they scattered, leaving the parade as deserted as a Siberian plain.

Making a faultless landing the battleplane came to rest. Blake, throwing back the wind screen, awaited developments.

In less than five minutes the machine was surrounded by thousands of curious spectators. It took all the efforts of a strong force of police and soldiers to keep the crowd back.

A way having been cleared through the press a group of military staff officers came up. Amongst them Blake recognised a tall, alert figure in the uniform of a major-general.

"Good morning, Sir Henry!" he exclaimed. "You see I have carried out my promise. Come on board, if you please."

Agilely Sir Henry swarmed up the ladder.

"A top-hole fellow," said Blake to his companions during the officer's progress. "One of the few who were at least sympathetic when I first submitted my plans."

"By Jove, Blake!" exclaimed the newcomer, as, slightly breathless, he gained the interior of the fuselage. "This is rather unexpected."

"I warned you," replied the inventor.

"You did, but, pardon my saying so, I was sceptical."

"But not to the extent of some of your colleagues," added Blake with a tinge of irony. "However, that's done with. Here is the battleplane. I formally offer her to the Government. But before we go farther. Do you know that there is a German spy here—actually within the precincts of the War Office?"

"Good heavens, no!" replied Sir Henry in astonishment. "How do you know that?"

"Optical proof," replied Blake. "If you'll come aft I'll show you."

Briefly the circumstances under which Sigismund Selighoffer was captured were stated, and in a very few minutes the spy was taken from the battleplane and marched off under escort.

"Now as far as I am concerned I hope I'll hear no more about that fellow," commented Blake. "My time is too precious to waste in attending courts-martial. All the same I should be particularly pleased to hear that von Secker, the spy's accomplice—or rather, employer—is run to earth. These fellows pay considerably more attention to outside inventions than does the British Government, I'm sorry to say. But let me show you round. Oh, yes, there's room for a few more," he added as three or four staff officers shouted out for permission to come on board.

With them was one of the civil staff of the War Office. Blake eyed him with a grim smile, for he was the man who had been so prominent in cold-shouldering the inventor but a few months previously.

"Yes, we should like to witness a flight," replied Sir Henry in answer to Blake's proposition. "This ability to ascend almost perpendicularly must be a unique, I might say, rather ingenious property. No, I don't think I will accompany you this trip... another time, perhaps."

One by one the staff officers filed through the aperture in the floor of the fuselage and descended to the ground, amidst the plaudits of the crowd. The civilian official was the last to leave, when Blake touched him on the shoulder.

"You remember me?" he asked.

"Of course, of course I do," replied the man pompously. "I never forget faces. You will doubtless recollect that during our former interview I expressed my opinion——"

"That an ounce of fact is worth a pound of theory," rejoined Blake. "In the circumstances the remark was uncalled for."

"But in my position one has to look for results," stammered the man nervously, for Blake had fixed him with that disconcerting look that had so effectually cowed the spy.

"The result is here," declared the inventor. "You are now going to accompany us for a spin. You are not afraid?"

If he were afraid the official was doubly afraid to admit it. He nodded his head.

"Good!" exclaimed Blake approvingly, as he closed the hatchway at his feet. "Start her up, Dick. Open the exhaust full out. A little noise will shift the crowd."

Dick obeyed, using the "cut-out." Instead of the engines purring almost noiselessly they roared like the concentrated discharge of a battery of mitrailleuses. Then, with a mighty sweep of her wings the battleplane appeared to stand on end. The next instant she was soaring swiftly above the dirty grey stone work of the buildings of the Horse Guards.

The passenger seated in the balanced chair, and seeing the body of the machine turning apparently around a fixed axis, was too astonished even to ejaculate. At length, encouraged by the cool demeanour of Dick and his chum, the official plucked up courage, and, the battleplane having settled down to a steady position, peered over the edge of the coaming.

It was his first sight of London from a height of three thousand feet. He was beginning to enjoy the sensation.

Up and down, describing erratic curves, nose-diving, volplaning and side-slipping with deliberate intent, Desmond Blake carried out his spectacular and demonstrative programme. At one moment it seemed as if the battleplane was diving under the Admiralty Arch; at almost the next it was skimming the aerials on the twin domes of the headquarters of the British Navy. Spinning round, almost on the tip of one wing, the tractable machine circled Nelson's Monument, as if to pay homage to the memory of the one-armed little man whose traditions the Navy of to-day so gallantly uphold. Then, at a rate equal to double that of an express train, the battleplane disappeared from view, to circle over the Nore at a height far beyond the range of the most efficient anti-aircraft guns that the Medway Defences possessed.

Fifteen minutes later the battleplane again came to rest on the Horse Guards Parade. Her passenger, almost speechless with unbounded admiration, did not hesitate to make his amends.

Nor was Sir Henry less enthusiastic.

Gripping Blake's hand as the inventor descended from the battleplane he exclaimed, "Bravo! my dear sir; your aeroplane is simply great. But why the deuce did you make such a show with it? By to-night all the world will know about it."

Desmond Blake shrugged his shoulders.

"It was the only way," he replied. "Nothing else would have attracted the attention of the War Office."

"You certainly have now," said Sir Henry with a smile. "Suppose we adjourn to my office. I'll summon my colleagues and we can discuss terms."

"There are no terms to discuss," objected the inventor. "The battleplane belongs to the Empire unconditionally."

CHAPTER VIII

A CROSS-CHANNEL FLIGHT

"I am off to France to-day, lads," announced Desmond Blake on returning to the battleplane after the conclusion of the conference. "It's sharp work, but now these gentlemen have warmed up they are like high pressure blast-furnaces. I suggested handing the plane over to one of the Flying Corps camps and remaining until a military crew had been trained to its use. They weren't keen on that exactly, so they made me promise to fly the machine across to the Front. I have been given a commission as captain in the R.F.C., so the poor neglected inventor blossoms out into a warrior of the aerial blue. Well, lads, the best of friends must part——"

"No, fear," declared Dick stoutly, and Athol backed him up in his protest. "It's not fair."

"On the contrary, it is perfectly fair," said Blake. "You have rendered me great service, and I deeply appreciate it. But when the battleplane goes abroad our implied contract is automatically broken."

"I don't see it," objected Athol bluntly. "We agreed to bear a hand for a definite period. Locality didn't enter into the conditions. Haven't we been entirely satisfactory?"

"Entirely."

"Then why are we to be pushed out of it? We are frightfully keen on the job."

"That I don't doubt," replied Blake. "It isn't that I don't want to take you. It's the official regulations coupled with a desire on my part not to run you into danger. You were turned back from the Front once before, remember."

"Hardly," replied Dick. "We were all right out there. It was coming home that did us in as far as the Army was concerned. The rotten part about the whole business is that the authorities insist upon a cast iron rule concerning a fellow's age. The number of years that a fellow has lived surely ought to be no criterion. A fellow might be absolutely fit for active service at sixteen or seventeen; another a physical wreck at thirty. It's jolly hard lines."

"A youngster of sixteen or seventeen might think he's fit," remarked Blake. "His heart is in his work and all that sort of thing, but his constitution is not properly developed. He crumples up under the strain, and additional and preventable work is thrown upon the medical authorities. That's the Army view of the case, I believe, and it's a sound view to take."

"Yet we maintain that each individual case should be tried on its merits," declared Athol. "To put the question bluntly: have you any objection to our going?"

"None whatever," replied the inventor.

"Then let us make an application. If you back us up there'll be no difficulty. You have the whip hand over this battleplane business."

"I'll see," replied Blake, loth to commit himself. Secretly he was pleased at the lads' determination and patriotism. Already he knew that they were capable. Their previous record at the Front proved that they were physically fit; and they had been strongly recommended for commissions by the commanding officer of their regiment.

"All right," he continued. "Come with me."

Leaving a gang of men at work painting distinctive red, white and blue circles on various conspicuous parts of the battleplane, Blake set off to find Sir Henry. In the record time of less than half an hour, so strongly did he set forth the charms of his youthful assistants, Athol Hawke and Dick Tracey were gazetted second lieutenants in the finest corps of airmen in the world.

The next step was to undo the mischief Blake had practically been forced to do by giving a public display of the marvellous capabilities of the battleplane. Accordingly it was announced, with all semblance of a confidential secret, that the machine had developed serious defects, and had been rejected by the authorities. Experience proved that by giving out the news in this manner it would spread as quickly or even more rapidly than if it had been proclaimed from the house-tops. No doubt there were scores of German agents mingled with the throng on the Horse Guards Parade, and in spite of all precautions a fairly detailed description of the battleplane, and particulars of her destination, would speedily be transmitted to Berlin.

At two o'clock in the afternoon the battleplane started on her cross-Channel flight. She rose awkwardly, side-slipping and missing fire badly, thanks to Blake's elaborate deception, and heading in a nor'-westerly direction was soon lost to sight.

Still climbing Blake kept her on a course diametrically opposite to her next landing-place until the battleplane attained the dizzy height of sixteen thousand feet. At that altitude, favoured by a slight haze, she was totally invisible from the ground. Then swinging round she retraced her course, flying at a rate of one hundred and eighty miles an hour towards the French coast.

Forty minutes later the battleplane planed down. As she swooped down out of a bank of clouds the lads could see what appeared to be a comparatively narrow stretch of silvery plain that expanded almost indefinitely in either direction north-east and sou'-west. It was the English Channel in the neighbourhood of the Straits of Dover. Ahead were the chalky masses of Cape Grisnez, the frowning promontory "flattened" out of all recognition by reason of the immense altitude of the observers.

"Do you remember the first time we crossed Channel?" asked Dick of his chum. "Sixteen solid hours of physical discomfort between Southampton and Havre. We were jolly bad."

"A submarine alarm would not have spurred us to energy," agreed Athol. "Four hundred and fifty men who had been singing 'Rule Britannia' at the top of their voices were lying on their backs, and bewailing the fact that the lady with the trident didn't rule the waves straighter. And now we are crossing the ditch in absolute comfort."

"Put on your flying helmets, lads, and lower the wind-screens," ordered Blake. "Nothing like getting used to Service conditions. Be careful as you lower away."

The warning was most necessary, for when the struts supporting the wind-screens were removed, it took practically all the strength at the lads' command to resist the fearful pressure of the wind upon the transparent panes.

Speaking, save by means of the voice-tubes, was now an impossibility. The furious air-currents, whirling past the airmen's heads, sounded like the continual roar of a mountainous sea breaking upon a rock-bound shore. The keenness of the wind cut the lads' faces; its violence almost took their breath away. For the first time they fully realised the sensation of speed through space.

Suddenly Blake, leaning outwards, pointed at something almost immediately beneath the fuselage. Following the direction of his outstretched hand, the lads could see a small glistening speck seemingly but a few feet above the sea. It was a monoplane.

Bringing their glasses to bear upon the machine the lads could distinguish it clearly. It was a British aircraft also making for the French coast, although owing to the relative difference of speed it looked as if it were flying stern foremost in the opposite direction. It was staggering in the teeth of a strong north-easterly gale, the effect of which was hardly noticeable in the upper air. The use of the binoculars also revealed for the first time that there was quite a mountainous sea running, while a patch of swirling foam betokened the presence of the dreaded Goodwin Sands.

Blake raised his wind-screen. His companions followed his example with alacrity. Peace reigned within the body of the battleplane, and conversation could be resumed.

"Plucky fellow, that airman," remarked Blake. "It wants a bit of nerve to set out across Channel on a day like this. Yet it is an everyday occurrence, and mishaps are few and far between. Contrast what that flying mail has to encounter with the conditions under which Blériot flew from Grisnez to Dover. The Frenchman's achievement was the talk of the world; probably only half a dozen people know of that fellow's flight. Of course I don't want to detract anything from Blériot's splendid feat, but—hulloa! what's that?"

Instead of the rhythmical purr of the motors came the unmistakable "cough" that precedes the stoppage of the engines through carburation troubles. In a trice Dick slid from his seat and made a hasty examination. As he did so the motors ceased firing.

"We're out of petrol," he reported. "Nonsense!" exclaimed Blake incredulously. "The tanks were refilled when we started from London."

"They're empty now, at any rate," added Dick. "Yes, I see what it is, the pet-cock on the draining pipe is open."

"Some of our visitors must have knocked it accidentally," declared the inventor. "Be as sharp as you can, Dick. There are some spare tins in the after compartment. One will save her. We're volplaning rapidly and against the wind we won't be able to fetch the land."

With her wings rigidly extended the battleplane was descending at an angle of thirty degrees to the horizontal. In ordinary circumstances she ought to be able to cover a distance of ten or twelve miles—more than sufficient to land her in French territory—but owing to the force of the hard wind her relative speed over the "ground"—which happened to be a raging sea—would be less than a couple of miles.

While Athol unscrewed the cap of the tank Dick crawled for'ard with a two-gallon tin of spirit. Recklessly he poured in the precious fuel, "tickled" the still warm carburettor and swung the engine. Without hesitation the motors began purring in their normal and businesslike manner.

"Hurrah!" exclaimed Blake. "You were just in time. We were only fifty feet up when she fired. Carry on with the other cans. There'll be just enough to get us home."

Dick was now painfully aware, as he carried can after can of petrol from the store compartment, that the battleplane was in the grip of the storm fiend. In her downward glide she had passed from the region of comparatively uniform wind pressure to a stratum in which vicious erratic currents assailed her on every side. In spite of the lad's utmost caution he was continually hurled violently against the side of the fuselage, while it was a matter of greatest difficulty to keep his footing upon the heavy floor of the steeply-inclined machine.

"Enough," ordered Blake. "Stand by. We're nearly there. I spot an aerodrome. It may be a British one. At any rate, we'll land."

Dimly wondering how the pilot would bring the huge battleplane to earth in that howling wind, the lads "stood by." Their confidence in Blake was unbounded.

Head to wind the machine planed earthwards. The whole expanse of the aerodrome seemed as if it were rising to greet the unique mechanical bird. Men, to whom the almost hourly arrival and return of flying machines caused little or no comment, emerged from their huts to witness the landing of the weirdest battleplane they had ever seen.

With almost an imperceptible jerk the landing wheels struck the sandy soil. Simultaneously Blake "switched off" the motors and thrust a lever hard down. The wings folding without a hitch no longer offered resistance to the wind, and the battleplane, pinned down to the earth by its own compact weight, rested firmly on the soil of France.

"So you have arrived," was the Wing Commander's greeting. "We were expecting you. Had a fair passage?"

"Fairly," replied Blake. "A slight mishap over the Channel well-nigh landed us into the ditch. It was blowing very hard at the time." "Seen anything of a monoplane on your way over?" enquired the flying officer. "We had information that one of our latest type of machine had left Newhaven a couple of hours ago."

"Yes," was the reply. "We passed her about half-way across. She was flying low and apparently making slow progress against the gale."

"A tough task for a new hand," commented the Wing Commander. "The youngster took his certificate only a fortnight ago, and this is his first cross-Channel flight."

"He would have done better if he had kept eight or ten thousand feet up," hazarded Blake.

"Possibly," rejoined his new chief drily. "Only it happens that our new pilots are specially warned to fly low when making for the French coast."

"I had no such instructions," declared Blake.

"Therefore it would not have been a great surprise to me if you had carried on right over our lines and dropped gently on one of the Germans' aviation grounds. We have already had one or two cases like that. Our new pilots, not being sufficiently acquainted with the locality, have overshot the mark. Deplorable of course, but the fact remains."

"Here comes the expected monoplane, sir," reported a young flight-lieutenant.

Still flying low and rocking under the influence of the eddying air currents the monoplane battled towards the aerodrome. At that altitude there was no mistaking the nationality of the men awaiting the aviator's arrival. Two mechanics, detaching themselves from their comrades, made ready to steady the planes when the machine touched ground.

With admirable precision the airman "flattened out." So well timed was his descent that it was almost impossible to determine the precise moment when the monoplane was air-borne and when it was supported by its landing wheels.

Rolling over the ground for nearly fifty feet the monoplane stopped head to wind. The pilot descended, removed his goggles and flying helmet, revealing the boyish, clear-cut features of a man barely out of his teens.

Numbed by the cold he walked unsteadily, rubbing his hands as he did so in order to restore the circulation.

"A bit nippy," he remarked casually, after he had formally reported his arrival. "She did it jolly well, though. By the bye, I see you've got here ahead of me," he added, addressing Blake and nodding in the direction of the securely held battleplane.

"I didn't imagine that you saw us; we were ten thousand feet up when we overtook you," said Blake.

"Neither did I," admitted the flight-lieutenant.

"Then how——" began the battleplane's inventor, surprised at the confession and at a loss to understand why the pilot of the monoplane was able to report on the former's progress.

"I'll let you into a secret," rejoined the young lieutenant laughing. "Last Friday at a quarter to nine in the morning that weird-looking 'bus," and he nodded in the direction of the battleplane, "ascended from a shed at a spot roughly twelve miles south of Shrewsbury, and proceeded in a south-westerly direction. Quite a short flight, out and home. Now, am I not correct?"

Almost dumfounded, Blake had to admit that the airman's information was correct.

"How did you know that?" he asked.

"Simply that instead of your being ten thousand feet above me I was that height above you," was the astonishing reply. "The Intelligence Department is not so sleepy as some people would have it believe. We had orders to try to locate a mysterious battleplane that was propelled by means of movable wings. I happened to be the lucky one to spot you, so you see we are not exactly strangers."

"And let us hope," added Desmond Blake, extending his hand, "that we shall be pals."

CHAPTER IX

A FIGHT TO A FINISH

For the next three days the crew of the battleplane were kept busily employed in getting ready for active service against the Huns. With the utmost expediency thousands of bullets made to Desmond Blake's specification had been turned out in one of the British ammunition factories and dispatched across to the aerodrome. Here they were taken in hand by mechanics attached to the R.F.C. and fitted into ordinary Service rifle cartridges for use with the automatic guns.

Both Athol and Dick had to undergo a brief but efficient machine gun course, and were instructed in the art of aiming at rapidly-moving targets from an equally mobile platform. Several branches of the flying officers' art they were not at present to touch. Blake's battleplane was to be used for purely offensive purposes, so that there was no occasion for the lads to be instructed in registering, observation and reconnaissance work. Nor was there time to study wireless. An apparatus had, however, been installed, and to work it a fourth member of the crew was appointed—Sergeant Michael O'Rafferty.

O'Rafferty was an Irishman by birth, name and characteristics. He was a light-weight of eight stone seven pounds, as agile in body as he was mercurial in temperament. Already he had two Hun biplanes to his credit, and was one of the most reckless flying men of that particular squadron.

Amongst other alterations to the battleplane on becoming a Service machine a regulation bomb-dropping device had been fitted in the floor of the fuselage. Eighteen powerful bombs were to be carried, and, when occasion arose, released by the application of the pilot's foot upon a pedal, while for offence against bodies of troops boxes of "flêches" or steel arrows were stowed on board.

The arrival from London of their uniforms completed the lads' preparations, and fully equipped they eagerly awaited an opportunity of meeting the Hun airmen.

The chance came sooner than they expected, for late one evening, when most of the reconnaissance machines had returned to their hangars, four enemy battleplanes were observed to be approaching. They were flying high to avoid the anti-aircraft guns in the rear of the third line of trenches.

Enemy air-raids had been few of late. The Hun aviators for the most part contented themselves by merely patrolling behind their lines on swift Fokkers, swooping down upon the equally daring but under-powered aeroplanes employed by the British for observation purposes. On this occasion it was evident that a raid upon the aerodrome was in contemplation.

Instantly there was a rush to man the British aircraft. Three got away before Desmond Blake could collect his crew and drag the battleplane from her shed; but once the huge mechanical bird drew clear of the ground her marked superiority in climbing became apparent.

Athol stood by the foremost quickfirer; O'Rafferty was at the after one; Dick had perforce to tend to the motors since the slightest hitch might result in victory to their opponents. Blake, cool and collected, though it was the first time that he was opposed to a hostile airman's fire, piloted the swift battleplane, manoeuvring to gain the equivalent to the old time "weather-gage"—a superior altitude.

Observing the novel type of aircraft rising to meet them, two of the Fokkers circled and prepared to dart down upon their opponent. Either they misjudged the speed and power of the British battleplane or else they deprecated the skill of her crew until it was too late.

With her engines all out the battleplane darted across and far beneath the downward course of the two German aircraft. A sharp burst of machine gun fire from the Huns was futile, for under-estimating the speed of their antagonist they made insufficient allowance in their aim. Harmlessly a sheaf of several hundred bullets whizzed astern of the secret battleplane.

Round swung the Fokkers in pursuit. For the first time they realised that in a climbing contest they were hopelessly beaten. In twenty seconds Blake had secured an undisputable gain. He was nearly a thousand feet above his opponents, and almost immediately overhead.

In that position the British battleplane was immune from her opponent's fire. The machine guns of the Fokkers were mounted so that they could fire ahead between the blades of the swiftly-moving propellers—less than five per cent. of the bullets being deflected in their path through the arc of revolution. The guns could also be swung round to fire on either side, but training of the weapons in a vertical plane was considerably restricted. It was impossible to fire at any target that was anything like overhead; a contingency that the Huns had not provided for, since their hitherto superior speed enabled them to decide their own conditions of fighting.

"Stand by, Athol!" shouted Blake.

Considering that Athol had been "standing by" during the whole of the flight the order seemed unnecessary until the lad grasped the significance of his superior officer's bidding.

Like a kestrel the battleplane dived towards the nearmost of her opponents. The pilot of the Fokker saw the danger. Discharging a large smoke-bomb he strove to escape under cover of the dense pall of vapour. For a few seconds it seemed as if the manoeuvre would prove successful, until Blake turned his craft and brought her on a parallel course to the escaping Hun.

The Fokker could now use her machine guns, although aiming was a matter of extreme difficulty. A hail of bullets clipping neat little holes in the tips of the battleplane's wings showed how close the shots were to securing telling hits.

Athol and Sergeant O'Rafferty opened fire simultaneously, since both machine guns could be brought to bear upon the German aircraft. Caught by the stinging hail of bullets the Fokker's struts and tension wires seemed to fly into fragments. Her shattered planes tilted upwards as she commenced to fall earthwards. Then, bursting into flames, the Hun machine crashed to the ground two thousand feet below.

A peculiar and disconcerting ping close to Athol's head warned him that the fight was not yet over. The second Fokker, finding that the mysterious aeroplane was directing its attention upon Hun No 1, had manoeuvred for its favourite position, and owing to the battleplane describing a circle the relative distance was now considerably decreased.

In a trice Blake banked steeply. As he did so O'Rafferty let loose a couple of dozen rounds. The Hun, hit more than once, turned and fled.

Giving a hasty glance round Blake took in the situation. The remaining Fokkers had been disposed of by the British biplanes, but not before one of the latter had to make an involuntary landing with its petrol tank perforated like a sieve and its observer badly wounded. There was now a fair chance of matching Blake's battleplane against the vaunted and possibly overrated Fokker.

The latter, with clouds of smoke pouring from her exhaust, was making off towards her own lines. Before gaining shelter she would have to pass over the British trenches less than thirty miles from the encounter, even if she were successful in throwing off pursuit.

Blake was equally determined to smash his opponent long before the latter came within sight of the German trenches. It was essential that in this early stage the secret battleplane should not show herself to the Huns over their own lines. The systematic disappearance of the "star" enemy airmen, without any hint of the nature of their destruction, would have a telling effect upon the morale of their flying men. It was a parallel case to the steady and unannounced decrease in the number of German submarines, scores of which left port never to return, and leaving no record of their disappearance save that known and jealously guarded by the British Admiralty.

"Now see what you can do, Athol," exclaimed Blake, as the battleplane, gaining upon her antagonist hand over fist, was in a favourable position to open fire.

Glancing along the sights Athol pressed the thumbpiece of the firing-mechanism. Some of the shots took effect, for the Fokker, in spite of the frantic efforts of the pilot to keep it under control, began to dive.

Athol ceased firing. The hostile aircraft was done for. Humanity urged him to let the Hun crew save themselves if it were possible to avoid being dashed to pieces upon the ground.

Erratically swaying, lurching and side-slipping, with one of the wings twisted like a broken reed, the German aircraft fell through a thousand feet of space before the pilot was able to check its descent. For ten seconds it seemed on the point of recovering itself, then the headlong flight was resumed.

Well in its wake followed the British battleplane. Blake was resolved to watch developments. He was curious to know the fate of the Hun crew.

Retarding the battleplane's flight the pilot kept her well under control, circling around the path of his defeated antagonist. Just as the Fokker was on the point of landing with an appalling crash the machine tilted acutely, then making a tail-dive alighted heavily upon the ground, throwing both pilot and observer from their seats.

In an instant the redoubtable Hun pilot regained his feet. Although fully expectant to be greeted by a discharge from the battleplane's machine-gun he staggered towards the wreckage and dragged his unconscious comrade further from the pile of tangled and twisted metal and canvas. Then striking a match and igniting his celluloid map he threw the blazing fabric into the petrol-soaked wreckage.

Bringing the battleplane to earth within twenty-five yards to windward of the burning aeroplane Blake descended, followed by Athol and the sergeant.

The Hun, revolver in hand, stood on the defensive, although no escape was possible, for already soldiers were hurrying up from their billets in a neighbouring hamlet. The Hun, not knowing what treatment he would be accorded, was evidently under the impression that no quarter would be given.

"Hands up!" ordered Blake.

"You no shoot, me no shoot," replied the German aviator, still brandishing his pistol. "Spare my life and surrender I will make."

"We respect a brave foe," exclaimed Blake. "But you are our prisoner."

The German dropped his revolver and folded his arms. Blake advanced with outstretched hands to compliment his opponent on his bravery, but as he did so the aviator reeled and fell senseless to the ground.

"They'll both pull through, I should imagine," declared an army doctor who with others had hurried to the spot. "They look a pair of tough birds. But, by Jove! what type of aircraft have you here?"

"Just an experiment," replied Blake modestly. "We haven't done so badly for a first attempt. Hop in, Athol, night's coming on apace, and I'd rather tackle half a dozen Huns than risk a landing in the dark."

CHAPTER X

TRICKED

"Mornin', Blake," remarked the Wing Commander. "Feel like an out-and-home flight? Thought so. Well, give a glance at this map."

Three weeks had elapsed since the secret battleplane had worsted the two Fokkers—three weeks of strenuous activity. The battleplane bore many honourable scars, souvenirs of aerial combats. But as yet her rôle had been a purely defensive one; she had never gone over the German trenches, hostile anti-aircraft had not as yet sent their shrapnel shells bursting all around her. Already the Huns had learnt of the presence of a super-powerful aircraft of unique design, and with feelings akin to dismay they realised that risky as it had been to fly over the British lines it was no longer practicable anywhere within the radius of action of the mysterious mechanical bird.

"Look here," continued the Wing Commander, placing a long, slender finger on the unfolded map that lay on the trestle table, "that's Olhelt, a village or rather hamlet not far from Hasselt, and within ten miles of the Netherland Frontier.

"We've received information that the Bosches have a secret Zeppelin base there, and that their new airships that are to be employed solely for raids over England are finally tested there before passing to active service. The place is strongly protected by Archibalds, and there are a dozen planes constantly on duty. Now, I want you to make a reconnaissance. If possible, bomb the Zeppelins to blazes. Would you prefer to undertake the job alone or shall I send a supporting squadron of swift battleplanes?"

"We'll tackle it alone, sir, I think," replied Blake. "Our silent motors are a decided factor in our favour, which would be thrown away if we were accompanied by any biplanes."

"So I thought, but I felt that I ought to give you the option," rejoined the Wing Commander. "Now, there is another point. We have a Belgian officer here, a man furnished with the highest credentials from the Belgian headquarters. He's a Limburger, and knows the district around Olhelt remarkably well. His name, let me see,"—the officer referred to a docket—"yes, his name is Etienne Fauvart, a lieutenant of the 21st Regiment of the Line. This man, for patriotic and personal motives—it was he who first reported the Zeppelin base; had the information from a relative living near Hasselt—wishes particularly to take part in the raid. According to his story he has a heavy account to settle with the Bosches near his home. It occurred to me that he might be useful for pointing out the various landmarks. From all accounts the place is rather puzzling for a strange airman to find."

"Whether he is to come with us or otherwise is for you to decide, sir," said Blake.

"Personally I am inclined to favour the suggestion," continued the Wing Commander. "Since you are so good as to leave the matter in my hands, I think you'd better take Lieutenant Fauvart. I'll have him brought in."

He touched a bell. An orderly appeared in the doorway.

"Bring the Belgian officer here," ordered the Wing Commander.

Lieutenant Etienne Fauvart was a loose-limbed man of about thirty. He was of average height, broad of shoulder and dark-featured. Although he clicked his heels as he saluted he lacked the alertness of the typical British officer.

"I am honoured to make your acquaintance, sir," he said in English with a good accent when Desmond Blake and he were introduced. "Also I esteem it an honour to go with you in your magnificent invention. I hope that we are able to blow the Zeppelins to pieces. Ciel! I look to the hour."

"Certainly an enthusiast," thought Blake as the Belgian discussed with his British confrères the plan of attack.

It was eventually decided that the secret battleplane was to leave the flying ground at an hour before sunset, soar to a great altitude and arrive over her objective shortly after sunset. Elaborate arrangements were made for her return, the aerodrome to be brilliantly lighted on receipt of a wireless message from the returning battleplane. In view of the possibility of a failure of the wireless a red and a blue star rockets were to be fired by the airmen.

The Belgian officer formed a supernumerary member of the crew, since Blake was loth to leave either of his three airmen behind. Accordingly Fauvart was placed at the post usually occupied by Dick when his duty with the motors had for the time been accomplished. Young Tracey accepted the situation with the utmost good-nature. Although reluctant to miss the visual part of the fun he realised that it was "some" luck to be able to participate in the great raid.

For the rest of the day the airmen were busily engaged in overhauling the mechanism, studying maps and otherwise preparing for the task. Etienne Fauvart, evincing great interest in the battleplane, had taken a deep fancy to Dick, and followed him with keen zest, asking innumerable questions.

"The fellow bores me stiff," soliloquised the lad. "He seems a decent sort, but he does ask awkward questions. He looks too cute to be stuffed, and I don't like choking him off. The only thing I can suggest is to refer him to Blake."

The Belgian took the hint quite good-naturedly. He refrained from asking any further technical questions, but Dick noticed that he made no attempt to "freeze on" to the imperturbable inventor.

At length, at the appointed hour, the battleplane started on her adventurous flight, her crew being sent-off with the hearty good wishes of their brother airmen—wishes for the most part expressed in that bantering, happy-go-lucky style that characterises men who have more than a nodding acquaintance with death.

The thin air literally shook under the concussion of hundreds of heavy guns as the battleplane swung high over the opposing lines. A big "affair" was in progress—one of those furious exchanges of strafing that are airily referred to in the official reports as "an activity of some magnitude." Two mines had just been sprung, their positions marked by huge clouds of smoke and dust. But of the actual fighting none was visible to the crew of the battleplane. A dense haze hid the khaki and grey fighting men from view, although rifle firing and the rattle of machine-guns could be distinctly heard as the see-saw struggle for the possession of the newly-made craters continued with the utmost desperation.

So intense were the undulations of the atmosphere over the terrific cannonade that the battleplane rocked violently. Her wings, beating the disturbed air with tremendous speed, seemed hardly able to support the main fabric. While the flight over the scene of the fighting lasted the mechanical bird was plunging and banking like a ship in a heavy following gale. So severe was the strain that had any of the metal-work been the least defective the weakness would have shown itself with dire results. Even Blake gave vent to an exclamation of relief as the machine drew safely away from the disturbed area.

"The spires of Hasselt," declared Lieutenant Fauvart, when, half an hour later, one of many of the numerous Belgian towns appeared in view, showing up clearly in the slanting rays of the setting sun. "You see those forests to the north? Beyond them lies Olhelt. It is in a valley, with trees all around. Already the valley is in shadow. The time for vengeance is at hand."

Evidently vengeance was the uppermost thought in the man's mind. Both lads had been curious to know the reason for the Belgian's oft reiterated words, but with their typical English reticence had refrained from asking him for enlightenment.

"I am cold," exclaimed Fauvart a moment later. "A man who is cold cannot do his work well. I go and get my heavy coat."

"And he wouldn't take my advice before we started," thought Athol, as the Belgian slipped from his seat and disappeared within the fuselage.

"We are in sight of Olhelt," announced Fauvart to Dick, who was sitting on the floor by the side of the motors.

"Are we?" replied the lad. "Think I'll have a look out."

He made his way to the Belgian's vacated post, and, leaning over, took in the expanse of country far beneath. Blake was circling the battleplane, since it was yet too early to volplane to the work of destruction. At that immense height, and thanks to the almost total absence of sound, the battleplane was safe from observation from the earth.

"I feel like a stoker in a naval engagement," thought Dick as he returned to his post. "Nothing to see, and all up if anything goes wrong. Another ten minutes will see the job through."

It seemed an interminable time before an acceleration of the motors announced that Blake had disconnected the wing mechanism and had locked the wings for a spiral volplane.

Dick promptly throttled down, and stood ready at the first sign to open the motors all out. As he did so he became aware of a peculiar smell. It was something like but not the same as that of burning oil. Then with disconcerting suddenness the motors ceased firing.

"Engine failure," reported the lad.

"Hang it all!" ejaculated Blake. "Couldn't have occurred at a worse time."

The Belgian started and whipped out a revolver.

"For me there is no surrender," he exclaimed dramatically. "I shoot myself rather than be a prisoner of war to the Bosches."

"Stop it!" exclaimed Blake, releasing his hold of the controls and gripping the Belgian's arm. "We are not done in yet. Far from it. Put that thing away and be reasonable. Look out and see if you recognise a good landing-place."

Fauvart, rallied by Blake's manner, did as he was told. By this time the battleplane was less than two thousand feet up. Somewhat to the airmen's surprise no shells came from the invisible anti-aircraft guns known to be somewhere in the vicinity.

"There!" exclaimed the Belgian, indicating a clearing in the woods, where even in the twilight the grass showed distinctly against the darker green of the treetops. "It may be safe to land there. If the Bosches have not already seen us we may escape detection."

"Any luck yet, Dick?" called out the pilot anxiously.

"No, sir," replied the lad, still deftly juggling with the magnetos, where apparently the fault lay.

With his customary skill Desmond Blake brought the battleplane to earth in the clearing pointed out by the Belgian lieutenant. His first act after landing was to fix a detonator and time fuse in position. Rather than allow the machine to fall into the hands of the enemy Blake had resolved to blow her to fragments.

"Be ready to slip it when I give you warning," he cautioned. "Stick it, Dick, but don't stop a moment after I give the word."

Some minutes passed but there was no sign of outside interruption. Athol, Sergeant O'Rafferty and the Belgian alighted, leaving Blake in the pilot's seat and Dick toiling at the motors, since the lad preferred to work alone in the confined space between the engines. The Belgian, having seemingly recovered his self-composure, began to stroll towards the edge of the clearing, carrying a large can.

"Where are you off to, Monsieur Fauvart?" asked Athol.

The lieutenant half turned his head and put his finger to his lips. Then signing to the lad to follow, he hastened his footsteps, although treading as softly as before.

O'Rafferty was about to accompany Athol when Blake called him back to bear a hand at slewing the battleplane round head to wind.

"They've gone to get some water for the radiator," said the pilot reassuringly. "Fauvart knows of a spring close handy. Getting on all right, Dick?"

"I'm doing my best," answered the lad guardedly.

The sergeant, lighting a cigarette, paced to and fro, with eyes and ears alert to catch the first sight or sound of anything of a suspicious nature.

Suddenly, to Blake's intense satisfaction, the motors began to purr smoothly.

"You've found out what was wrong, then," he said, at the same time motioning to the sergeant to take his place on board. "What was it?"

Before Dick could reply a revolver shot rang out. Then came the sounds of several men crashing through the brushwood. An instant later twenty or more grey-coated figures appeared in sight, led by the supposed Belgian officer.

"Surrender instantly!" he shouted. "Lieutenant Hawke is our prisoner. Do further damage to the battleplane and no quarter will be given. Hands up and you will receive honourable treatment."

CHAPTER XI

THE FATE OF A SPY

"All out, Dick," shouted Blake, at the same time coupling up the wing mechanism. Sergeant O'Rafferty, springing to the after machine-gun, swung the weapon upon the nearmost of the German troops. As he did so a ragged volley greeted him, the bullets either passing through the aluminium covering of the chassis or else whizzing harmlessly overhead.

With her wings beating the air with tremendous force the battleplane drew clear of Mother Earth. Four or five Germans, rushing forward, clung desperately to the framework of the landing wheels, amongst them the Hun who had so successfully posed as a Belgian officer.

Unfortunately for them they had totally under-estimated the lifting power of the mechanical bird. Blinded by the cloud of dust thrown up by the flapping of the huge wings and deafened by the roar of the exhaust—for Dick had opened the cut-out in order to give the motors full play—the Germans were unable to realise that their efforts to keep the battleplane pinned to the ground were unavailing.

Although the machine rose rapidly it lacked the speed that it usually attained. Powerfully engined as she was the battleplane could not ignore the additional weight of five burly Brandenburgers.

"Motors running well, Dick?" asked Blake, shouting to make himself heard above the terrific din.

"Splendidly now," replied the lad.

"Then see what's dragging her," continued the pilot, whose whole attention had to be centred upon the steering of the machine.

Dick made his way to the still open hatchway in the floor of the fuselage. He was hardly prepared for the sight that met his gaze.

Three Germans were astraddle of the horizontal girders supporting the legs of the landing-wheels. Another had thrown arms and legs round an upright and was bellowing lustily. The treacherous Hun who, under the name of Etienne Fauvart, had all but succeeded in capturing the secret battleplane, was clambering up the lattice work, with his revolver hanging from his teeth by means of the lanyard. Dick promptly shut the sliding hatch and made his way to his superior officer.

"We've a fine crew of Huns hanging on," he reported. "Five of them, and that skunk Fauvart in addition. I'd like to get hold of him and find out what's happened to Athol."

"In that case we should have to make a prisoner of him," replied Blake grimly. "No; he'll pay for his treachery now. I don't believe in prolonging the agony. Pass the word to Sergeant O'Rafferty to hold on tightly. And, please, muffle the exhaust. We'll alarm every Bosch within ten miles of us."

Directly the motors were silenced a deafening concussion was heard close to the underside of the chassis. A shrapnell shell, one of many, had just exploded. Some of the bullets perforated the wings or pinged harmlessly against the armoured plating of the fuselage. Two of the Huns, struck by flying fragments of metal, relaxed their grip and fell through space on their long journey to the ground three thousand feet below.

"All ready?" shouted Blake warningly.

The battleplane tilted abruptly and made a complete loop. In five seconds she had regained her normal flying trim, but without the treacherous German and his compatriots. They, unable to retain their hold under the sudden change of direction, were hurtling earthwards, their despairing screams still ringing in the ears of the horrified Dick.

But other work was on hand to distract the lad's mind from the act of retribution. Desmond Blake's searching glance had discerned the roofs of four large sheds almost hidden between the trees, the roofs being mottled so as to resemble as closely as possible the characteristics of the surrounding verdure.

Rising to such a height that there was little danger from a direct hit from the "Archibalds," the battleplane hovered over her objective, spiralling in sharp curves so that the limit of her flight brought her well within the perpendicular distance of her quarry.

At the order Sergeant O'Rafferty dropped two bombs in quick succession. The first, striking the ground close to the edge of the clearing, exploded with terrific violence, felling huge trees like ninepins and literally pulverising the nearmost shed. Almost simultaneously the second bomb alighted fairly in the centre of another Zeppelin house. A stupendous explosion followed, a blast of lurid flame leaping skywards, and rending the gloom of twilight like the concentrated flash of a dozen fifteen-inch guns. The roar of the detonation was appalling. The battleplane, under the influence of the far-reaching up-blast, shook like an aspen leaf, and fell vertically through a distance of nearly five hundred feet before the resistance of the wings restored her equilibrium.

The appalling nature of the work of destruction so overwhelmed the men at the anti-aircraft guns that they ceased firing. Undisturbed the battleplane continued circling, although at a much lower altitude, her crew examining the results of the bombs with studied leisure.

When most of the smoke had cleared away, although portions of the wreckage still burned furiously, it was seen that there was no necessity to drop more bombs. Not a single shed was left standing. Gaunt skeletons of destroyed Zeppelins reared their bent and twisted aluminium ribs betwixt the gaping metal sheets that a few minutes previously had concealed some of the latest types of the Kaiser's air-raiders.

"Shall we give them another, just for luck, sir?" asked Sergeant O'Rafferty.

"Not necessary," replied Blake, as he turned the battleplane in the direction of a faint yellowish path of light upon the horizon—the last vestige of declining day. "Lock the bomb-dropping gear, sergeant."

O'Rafferty hastened to obey, but by pure accident his foot slipped and came in contact with the disengaging pedal. Eleven seconds later came the crash of the exploding bomb.

"Sorry, sir," exclaimed the sergeant apologetically.

"Let's hope it isn't wasted," rejoined Blake, ordering the motors to be run "all out."

In the darkness the battleplane passed high above the opposing lines of trenches, their outlines rendered distinctly visible by the flashes of rapid rifle and machine gun fire, and the occasional glare of star-shells, punctuated by the high-explosive projectiles.

"Give them a call up, sergeant," ordered the pilot.

O'Rafferty brought the wireless into use, unwinding eighty feet of "aerial" that trailed behind the swiftly-moving battleplane. In answer to the message a blaze of electric arc lamps appeared upon the flying-ground.

Almost before the sergeant had wound in the aerial the battleplane was ready for her earthward glide. Flattening out to a nicety she landed within twenty feet of the door of the hangar, and was immediately surrounded by a throng of eager flying men.

"Instructions have been carried out, sir," reported Blake to the Wing Commander. "Three, possibly four, Zepps have been destroyed."

"Any casualties?" asked the commander.

"Mr. Hawke missing, and believed a prisoner, sir. We had to make an involuntary landing, and were rushed by a German patrol. In the circumstances no attempt at rescue was possible."

"And where is Lieutenant Fauvart?" continued the Wing Commander.

Desmond Blake smiled grimly.

"You palmed off a dud on us, sir," he reported, "so we dropped him. I don't think he crashed more than a couple of thousand feet, but it was quite enough to cause the German Intelligence Staff to lose one of their pet stars."

CHAPTER XII

SERGEANT O'RAFFERTY'S LUCKY BOMB

Captain Desmond Blake had hit the mark when he described the soi-disant Belgian lieutenant as a star. Subsequent enquiries revealed the fact that the real lieutenant Etienne Fauvart had been captured by the Germans in an affair of outposts near Dixmude. Armed with the papers found in the prisoner's possession and clad in a Belgian uniform a German staff officer had so successfully impersonated Lieutenant Fauvart that he had deceived the British staff officers. With the express purpose of luring the secret battleplane he had offered his services, and had made a true statement as to the position of the German Zeppelin sheds. Therein lay the secret of his ruse, for the British Intelligence Division already had some knowledge of the Zeppelin base, and finding that the supposed Belgian officer's description tallied with their reports, their suspicions, if any existed, were disarmed. If on the other hand the spy had indicated a Zeppelin station that had an existence only in his imagination he knew that he ran a grave risk of having his information challenged and himself arrested, court-martialled and shot.

Confident in his belief that the British secret battleplane would be rendered incapable of getting within effective distance of the Zeppelin sheds of Olhelt, he did not hesitate to indicate their exact position.

Once he succeeded in getting taken as one of the battleplane's crew he had no difficulty in compelling the machine to make a forced landing. Taking advantage of the excuse to fetch his coat, he had, during Dick's temporary absence, contrived to spray the high tension wire with a powerful corrosive. The wire, it must be explained, led from the magneto in a single length, afterwards branching into a number of subsidiary wires to the respective sparking plugs of the cylinders. By spraying the electric current conductor between the junction and the magneto the whole of the firing was put out of action simultaneously, after the acid had taken time to eat through the guttapercha insulating cover.

When Dick discovered the failure, but was unable at the time to ascertain the cause, he fortunately removed the high tension wires and replaced them with a spare set, which Blake, with commendable forethought, had made in case of emergency.

It will now be necessary to follow Athol Hawke's movements from the time when he followed the unsuspected spy into the wood.

Keeping close to the supposed Fauvart's heels the lad moved rapidly and cautiously, carefully avoiding treading upon dry twigs that littered the ground.

At intervals the lieutenant turned to reassure himself that the British airman was following, making signs to him to keep close. Proceeding thus they covered about two hundred yards, when suddenly the spy turned and grappled Athol by throwing both arms round the lad's body and pinning his arms to his sides. At the same time Athol saw numbers of German troops emerging from behind the trees.

Like a flash of lightning the lad realised that Fauvart was a spy. With a sudden wrench he freed his right arm, and drew his revolver, and fired at his captor. Only by adroitly ducking his head did Fauvart escape the bullet. As it was his forehead and hair were singed by the blast from the muzzle.

With a muttered curse the spy hurled the lad violently against the trunk of a tree, at the same time ordering some of the soldiers to secure the prisoner. Since Athol's shot had given the alarm, the question of an effective surprise no longer held good. Led by the officer in Belgian uniform the Germans, who had quite prepared for the contingency, rushed through the wood towards the British battleplane.

Bruised and shaken by his fall, Athol found himself roughly pulled upon his feet. With a burly Prussian on either side and a sergeant following, holding a revolver—Athol's own—against the prisoner's head, the lad was forced onwards, further and further away from his comrades.

Then came the sharp reports of a dozen rifle-shots followed by the well-known sound of the battleplane's motors running "all out," and the angry shouts of the foiled Huns.

Soon Athol and his guards were overtaken by the soldiers who had hoped to capture the British aircraft. Knowing the German language tolerably well, the lad overheard their conversation, although the disappointed mien of the Huns would have been sufficient to tell him that their efforts had been foiled.

To the accompaniment of the firing of the anti-aircraft guns Athol was hurried along. Presently the party arrived at another clearing. Here the Huns halted, looking skywards to see if the battleplane was still in sight. Athol followed their example.

What they saw did not help the Huns' good temper, for even as they watched they saw the battleplane loop the loop in the misty twilight, shedding several dark forms as she did so. Two of the bodies of the luckless Germans fell with a sickening crash within fifty yards of their watching comrades, while to Athol's intense satisfaction, notwithstanding the horror of the scene, he saw the Belgian-uniformed spy dashed to the ground almost at the feet of the men he had so treacherously summoned to seize the secret battleplane.

"Himmel!" ejaculated one of the Prussians. "They'll be dropping bombs on us soon. Let us hasten."

Still gripping their prisoner the men hurried off into the depths of the woods, where under the trees it was hardly possible to see one's hand before one's face. Stumbling over exposed roots, cannoning into tree trunks, the Huns continued their way. Athol overheard one of them say that the Zeppelin sheds were not a safe place for them, and that they had better make off in a different direction until the English aircraft had disappeared.

Even as he spoke a lurid flash threw a vivid glare over the sky, the gleam even penetrating the thick foliage. The crash that followed shook the ground, and sent a shower of leaves and twigs whirling from the trees. The Huns broke into a run, still retaining their hold upon their captive.

Another and yet another deafening detonation followed. The heavens glowered with the blood-red flames from the blazing Zeppelin sheds. Débris hurtled through the air all around the lad and his guards, although the scene of the explosion was at least half a mile away. The atmosphere reeked of the smoke of burning oil.

Presently the Huns, well-nigh breathless, came to a halt.

"It's all over now, Fritz," said one. "No more bombs have fallen. And Herr Major would have us believe that the English airmen were no good."

"It is all very well for Herr Major," retorted the other. "He, no doubt, is safe in his bomb-proof cellar. I, for one, should not be sorry if an English bomb blew him sky high. He makes our existence a misery. It is far worse than at——"

A dazzling flash seemed to leap from the ground almost at Athol's feet. He was dimly conscious of being hurled backwards, deafened by the noise of the detonation.

For quite a minute he lay still, not daring to move, and dimly wondering whether he were yet alive. Then he opened his eyes.

Some fifty yards off a fire was burning. In the centre of a circle of up-torn trees flames were bursting from a mass of débris, and throwing a ruddy glare upon the surrounding scene. The flames were spreading in the direction where he lay. He tried to rise. At first his efforts were unavailing. Something heavy was pinning him down: that something turning out to be the unconscious form of one of his guards. The other, huddled against an uprooted tree, was groaning dismally.

A sharp, burning pain on his right leg just above the knee warned Athol forcibly of his peril. An ember from the conflagration had settled on the limb and had burnt through his uniform trousers. Giving a tremendous heave the lad freed himself of his encumbrance and rose unsteadily to his feet.

"I'll have to drag those beggars out of it," he muttered, as he contemplated the helpless forms of his former captors. "They'll be burnt to cinders if I don't."

Suiting the action to the words he seized one of the Huns under the shoulders. It was as much as he could do, strong as he was, to drag the sixteen stone of listless humanity even a few yards.

Suddenly he became aware that men were hurrying through the wood. For the first time the realisation that there was a possibility of escape flashed across his mind. Pausing only to recover his revolver and ammunition he withdrew, intent upon putting a safe distance between him and the approaching Huns before coming to any definite plan of a bid for safety.

"Jolly near shave," he soliloquised. "I reckon Desmond Blake didn't know how close that last bomb came to blowing me sky-high."

He had yet to learn that Sergeant O'Rafferty's awkwardness had been instrumental in freeing him, temporarily at least, from the clutches of the Huns.

CHAPTER XIII

THE FRONTIER

Night had fallen when Athol emerged from the dense wood. Overhead the stars were shining brightly, although occasionally obscured by drifts of pungent smoke from the still burning Zeppelin sheds. In front lay an expanse of open fields, dotted here and there by isolated farm buildings, while in the distance, and thrown into strong relief by the flames, were the spires and roofs of a fairly large town.

"The Dutch frontier: that's my objective," decided Athol. "It's not more than ten miles away. North-west is the bearing, and I have about seven hours of darkness before me. None too much time, if I have to go cautiously."

Fixing his direction by means of the North Star the lad set out, treading softly and straining his ears to catch the faintest suspicious sound. As he proceeded other problems confronted him. He knew from report that the frontier was guarded and that a barbed wire fence formed a formidable barrier. More, the fence had a live wire of high voltage running through it, contact with which meant death to the human being or animal that incautiously attempted to pass from one frontier to another.

Also, in the event of success in the matter of gaining Dutch territory there was the almost certainty of being interned unless he could discard his uniform and procure civilian clothes. Much, then, had to be done before dawn.

Although by order of the German authorities the Belgians in the occupied territory were obliged to be within doors at sunset, the roads were far from being unfrequented. Motor-cars, bearing excited and furious German staff officers, rushed to and fro, for the destruction of the Zeppelin sheds was a severe blow to the Teutonic organisation. There was no rest that night for the Huns at Limburg.

It was unsafe for Athol to keep to the highway. For hours he pressed on, stopping frequently to take shelter while parties of Germans hurried along the tree-lined roads. It was not half so dark as the lad would have liked, and now that his eyes were accustomed to the starlit night he found he could see with tolerable clearness for a distance of several hundred yards. Conversely it was equally possible for a German sentry to spot him from a like distance. Vainly he hoped that it would rain, or that heavy clouds would obscure the star-spangled sky.

He was becoming very hungry. His latest meal was but a reminiscence. Water, of which he found plenty, assuaged his thirst, but it was a sorry substitute for the wholesome fare to which he was accustomed.

Three times he had to make a detour to avoid various compact hamlets. Once a dog began barking, rousing all the other canines in the neighbourhood, with the result that the lad had to retrace his steps, throw himself down and lie perfectly still until the clamour had subsided—a loss of half an hour's precious time.

"I can't be so very far off the frontier now," thought Athol. "Now comes the crucial test."

He found himself on the point of crossing a fairly broad highway, unfenced but lined with gaunt trees. Almost before he was aware of the fact he nearly collided with two German officers.

Fortunately for Athol their backs were turned to him. They were standing on the edge of the road close to a large tree that had effectually prevented the lad from noticing their presence. They were muffled in long cloaks through which the hilts of their swords protruded. Their spurs shone dully in the starlight as they impatiently shuffled their feet. In silence they stood, their gaze fixed intently down the highway.

With his heart in his mouth Athol backed with the utmost caution. As he did so his foot broke a dry twig. He dropped lying face downwards in the dewy grass, not daring to stir hand or foot until the Huns moved away. They were officers, he knew, and not sentries. Consequently there was no reason why they should stop there indefinitely. At the same time Athol felt curious to know why a couple of cloaked cavalry officers should be standing mutely on the highway at the hour of midnight.

Athol's fingers closed on the butt of his Webley. For the first time he realised the companionship of his Service revolver. Without it his whole attention would have been getting away unperceived; thanks to the knowledge that he had a reliable weapon at his command he could run the risk with comparative equanimity of tackling the pair of Huns. But only should occasion arise. For the present he was content to keep watch upon the mysterious inaction of the silent twain.

"Wish they'd get a move on," muttered Athol, after keeping in a prone position for nearly twenty minutes. The night was bitterly cold. His limbs were beginning to feel stiff and cramped in contact with the damp ground.

A sharp tug at his leather leggings almost caused the lad to utter an exclamation of alarm. For the minute he imagined that he was again in the grip of the Hun, until, turning his head, he saw a huge rat scampering off. The officers heard the sound, too, for they both looked intently in the direction of the startled rodent. Then one moved a few paces towards the centre of the road.

"They are coming, von Bohmer," he remarked.

"And about time," grumbled the other. "And, even now, we do not know whether von Secker will venture. If ever a man blunders through excessive caution it is friend Karl."

Von Secker—Karl. The names seemed familiar to the listening British subaltern. Yes, by Jove he had it: Karl von Secker, the spy and employer of the luckless Sigismund Selighoffer, and the fellow who had made off with Desmond Blake's plans of the secret battleplane.

Athol, with his ear almost in contact with the ground, could now distinctly hear the rumble of cart wheels and the sharp clatter of a horse's hoofs. A little later the vehicle pulled up, and a man dressed as a Dutch peasant threw the reins across the animal's neck and got down.

"What, alone, Herr Stein!" exclaimed von Bohmer. "Von Secker, then, has failed us. Has he sent any papers?"

"He says it is not safe to leave Dutch territory," replied the new-comer, "or, rather it is unsafe to enter it again from this side He is nervous—just imagine our von Secker being nervous."

The man addressed as Stein laughed uproariously. It was obvious that he was a German officer in disguise, otherwise he would not have dared to express his mirth in the presence of the haughty von Bohmer and his companion.

"But the documents, man!" exclaimed the latter impatiently.

"He says they are too bulky to send without risk of detection by the customs at the frontier. He assured me that the search is strict on the part of the Dutchmen; far more so than by the Englanders at Harwich."

"Then in Thor's name, how are we to get them?" asked von Bohmer. "Here they are, within five miles of German territory, and von Secker is frightened."

"I think that it is a question of payment," suggested Herr Stein. "However, the plans are at his lodgings at the Sign of the Golden Key in Weert. He says that early to-morrow morning he will photograph them, so that should they be seized we will still have something to work upon. And, I believe in consideration of a sum of gold in advance, he will then hand the plans over to me."

"Where can we get gold at this hour?" grumbled von Bohmer's companion. "I can understand von Secker's anxiety to secure photographs of the plans, since he is to be paid by actual results. It would be well to call upon him to-morrow, and let him know distinctly that it is the will of the General Staff that the plans should be delivered to them forthwith. Is not that so, von Bohmer?"

The officer addressed grunted in assent.

"We must be off," he said. "To-morrow, Herr Stein, we hope to offer you hospitality at the mess."

The officers turned and walked rapidly down the road in the direction of Hasselt, but before they had gone very far two orderlies leading their horses slipped from under the cover of a tree. Although they were less than a hundred yards from the spot where Athol lay, neither he nor they had the faintest suspicion of their respective presence.

As for the disguised German von Stein, he clambered into the cart, and, setting the horse at a leisurely pace, drove off in the direction of Weert, a town lying a few miles within the Dutch frontier.

Athol waited until von Bohmer and his companion had disappeared, then, keeping close to the line of trees, broke into a steady run, his boots making hardly any noise on the soft ground by the side of the pavé. It was not long before he came in sight of the lumbering vehicle, which, although proceeding slowly, made a loud clatter as the ironshod wheels rolled over the rough stones.

Unheard the lad overtook the cart and clambered softly on the tail-board. Stein was sitting on a board resting on the side of the cart, with his head on his hands and his elbows supported by his knees. In this hunched-up position he looked half asleep, while the horse, left to its own devices, walked stolidly along the centre of the highway.

Presently the road ascended a slight rise, which for this part of the country might be considered as a hill. Athol could discern the formidable line of barbed wire marking, the frontier boundary. Apparently there were no troops guarding this particular section, Already the majority of the Landsturm soldiers had been withdrawn from the policing of the frontier and had been sent to fill up appalling gaps in the German first-line trenches.

"Sorry, my man," soliloquised the lad, "but needs must."

He brought the butt end of his revolver smartly down upon Herr Stein's head. Without a sound the Hun dropped senseless to the floor of the cart.

Leaping to the ground Athol stopped the horse. Then he listened intently. Everything seemed quiet, although he knew it was quite possible that a sentry, his suspicions aroused by the stopping of the rattling vehicle, might appear upon the scene.

Still keeping his ears and eyes keenly on the alert, Athol quickly stripped the unconscious German of his coat, blouse, trousers and wooden shoes, slipping the garments over his uniform. His boots he was obliged to discard in favour of the ungainly "klompen."

His next step was to release the horse from the shafts and to set the animal adrift, after having removed the bit. This done Athol pushed the cart to the edge of the road and on the grass. From this point the ground shelved with comparative steepness to the barbed wire fencing.

"Wonder if it's heavy enough for the job?" thought the lad.

He caught sight of a pile of large stones, the remains of a demolished building. Working desperately he quickly transferred a number of stones to the floor of the cart. Then he paused for a well-earned breather.

Giving a final glance at the luckless Herr Stein, who was now breathing stertorously, Athol lifted the shafts and backed the cart down the incline. Gathering way the now heavily laden vehicle dashed towards the fence. Not until the back of the cart was within a yard of the barrier did Athol relinquish his grasp of the shafts.

Charging the wire fence fairly and squarely the novel battering ram bore all before it, sweeping an expanse of nearly ten yards of obstruction from its supports. The live wire, short-circuiting and emitting a series of vivid blue sparks, was writhing like a snake.

Using the wreckage of the overturned cart as a bridge Athol crossed the once formidable barrier and gained Dutch territory.

"So well, so good," he exclaimed thankfully. Then seized with an inspiration, he added, "And why shouldn't I pay von Secker a visit at the Sign of the Golden Key?"

CHAPTER XIV

ATHOL TACKLES VON SECKER

Making a long detour Athol eventually rejoined the road leading to Weert, this time quite two miles from the frontier custom-house. By his watch, which fortunately had escaped the unwelcome attentions of his former captors, it was now half past three. Already the stars were beginning to pale before the first blush of dawn. Ahead he could discern the quaint gabled roofs of the little town where the spy Secker had taken up his temporary abode.

Crawling into a dry ditch, the now drowsy lad propped his back against the sloping side and dosed fitfully. Once he was awakened by the measured tread of armed men. It was now broad daylight. The soldiers were Dutch troops going to relieve the frontier guards.

Lying at full length in the ditch he was unnoticed by the soldiers. Discovery at that early stage of the proceedings, although his personal liberty was not likely to be interfered with except for a short duration of investigation, was most undesirable. He had before him a fixed purpose, far more important to the welfare of his country than was his own freedom.

"Enough sleep for the present," he exclaimed. "Why, it's close on six o'clock, and, by Jove, I do feel peckish! Wonder what friend Stein has in his voluminous pockets."

A search provided nothing in the victualling department. There were a bundle of papers, including a Dutch passport and a permit for Jan van Wyck to cross the frontier; a purse containing fifteen gulden, some German marks and a few copper and iron coins—the latter having been issued in Germany to replace the withdrawn copper currency; and, what was particularly handy, a large scale map of the district.

Practically unnoticed by the throng of country-folk, for it happened to be market day, Athol entered the town. A cup of coffee and two hot rolls, purchased from a very deaf old Dutchwoman at a stall, served to stave off the pangs of hunger, and the lad felt fit for the furtherance of his daring venture.

It was as yet too early to pay a call at the Golden Key. On the other hand it was not advisable to defer the visit until the hour mentioned by Herr Stein, for by that time the spy might have been warned of the fate that had overtaken his intermediary. Waiting, Athol found, was the most tedious part of the whole business. Thanks to his disguise he attracted hardly any attention in the crowded market-place; nor did his ignorance of the Dutch language cause him any inconvenience, for the town was full of Germans, intent upon buying market produce at fabulously high prices.

Paper money, the lad noticed, passed freely, although at a low rate of exchange. The astute Dutchmen had learnt to profit by the fall of the mark, receiving payment in paper money and afterwards returning the notes to Germany, where they were, by Imperial decree, to be accepted at their face value. Judging by the conversation of the German customers, whose tongues wagged with a freedom unknown across the frontier, the civilian element was chafing under the shortage of food and abnormal prices, and one and all seemed sick of the war, which showed no signs of ending, and certainly not with the dazzling success which the Kaiser had promised.

Half-past seven was chiming as Athol ascended the flight of stone steps leading to the door of the Golden Key. In answer to his knock a short and very fat elderly woman appeared, and curtly demanded the lad's business. Although the question was put in Dutch Athol guessed its purport, and, replying in German, asked if Mynheer Jan van Wyck lodged there?

"Didn't you call upon him last night?" demanded the Dutchwoman sharply.

Athol was temporarily taken aback. He was priding himself upon his diplomacy in asking for the spy under his Dutch nom-de-guerre, when the woman's question "shook the wind out of his sails."

Producing a couple of gulden Athol slipped the coins into the woman's hand, and solemnly winked his left eye. The result surpassed his wildest expectations, for standing aside, the vrouw motioned for him to enter.

"Second door to the right on the first floor," she announced as she pocketed the money, and without paying further attention to Jan van Wyck's visitor she disappeared towards the back of the house.

Ascending the worn oak stairs Athol, making certain that his revolver was ready to hand, tapped very softly upon the door. Receiving no answer he rapped again. Then he heard a key turn in the lock and the door was opened for a space of about four inches.

The spy had only just got out of bed. He looked but half awake. That was, possibly, why he failed to distinguish between the genuine Herr Stein and his impersonator, the appropriated clothes being a sufficient disguise.

"Come in," he growled. "You are much too early. Why didn't you give the sign, or did you think I would not open if you did?"

Still grumbling, and with his face averted, von Secker shuffled across the room to a table on which were spread several sheets of drawing paper and tracing cloth.

"You are still too early," he continued. "I suppose you are here again concerning the plans?"

"I am, Karl von Secker," said Athol sternly, at the same time covering the spy with his revolver.

The effect of the words, spoken in English, was electrical. In an instant the German's lassitude dropped from him like a shedded garment. Seizing a lead paper-weight from the table he poised it to hurl at the lad's head.

Athol hesitated. Not that he was lost, but because he was confronted with a tricky problem. Setting aside the compunction he felt at shooting down a man, even though he were a dangerous spy, he realised that the house would be alarmed at the report of the weapon. He was out to regain possession of the battleplane's plans, not to get himself arrested by the Dutch authorities on a charge of murder.

It was as if von Secker read his thoughts, for the spy, scowling and grinding his teeth, made no further attempt to hurl the lump of metal. He, too, did not wish to be embroiled with the officials of a neutral government, although here was a good chance of making his escape across the frontier.

Athol lowered his revolver. Von Secker replaced the paper weight, although he still kept his fingers in contact with it.

"You have come on a fool's errand, young man," snarled the spy.

Athol, regretting that he had not discarded his clumsy wooden shoes, looked his antagonist straight in the face.

"We shall see," he retorted, then dropping his revolver on the floor, he leapt upon the Hun.

Too late von Secker grasped the paper weight. The next instant both antagonists were locked in mortal combat, Athol endeavouring to pin his opponent's arms to his sides, while von Secker did his level best to free his hands and employ the truly Hunnish trick of twisting his fingers in the other's hair and clawing at his eyes with his thumbs.

As if by tacit consent they struggled in comparative silence, rolling over and over on the massive oaken floor. It was a test of British brawn and endurance against German trickery and bodily weight, Athol striving to deal the spy a stunning blow with his fist.

Once von Secker all but succeeded in blinding his antagonist. His podgy fingers were entwined in the British lad's short hair, and his long thumb nails were scratching their way over Athol's forehead when the young subaltern butted violently. At the loss of a considerable amount of hair Athol succeeded in dealing the German a terrific blow at the chin with the top of his head.

Uttering a subdued yell of pain the spy relaxed his grip, then clutched blindly at the lad's throat. Over and over they rolled again, until in the course of the deadly struggle a charcoal stove was overturned.

The glowing embers spreading across the floor emitted suffocating fumes in the already ill-ventilated room, until it became evident that the result of the combat would depend upon which of the twain could longest withstand the asphyxiating smoke.

Momentarily labouring under increasing shortness of breath, Athol perceived that the effects of the fumes upon the Hun were telling far more than they did upon him. The German's furious efforts showed signs of slackening. His yellow features grew livid. Great beads of perspiration oozed from his receding forehead.

Wrenching himself clear Athol regained his feet.

"Do you give in?" he demanded.

Von Secker's reply was to draw up one leg and lash out as hard as he could. Although barefooted he could kick with the force of an experienced Continental boxer. Struck heavily in the side Athol reeled half-way across the room, while his antagonist, quick to reap the advantage, staggered to his feet. His strength was not equal to his will power. His knees gave way under him as he lurched towards the lad.

Well-nigh maddened with the pain, the English lad saw an opening. Breaking through the German's guard he planted his left with terrific violence on the point of the Hun's chin. The fight was over.

Far from showing elation over his victory Athol locked the door, threw open the casement and sat down in a chair. The fact that none of the rest of the household had appeared upon the scene puzzled him. Perhaps, he argued, they were accustomed to brawls.

Recovering his breath he set to work to stamp out the still smoking charcoal. This done he dragged the unconscious von Secker on to the bed and covered him with the clothes. Only a close examination would reveal the fact that he was not asleep.

The plans he folded into a small compass, applying pressure to make them lie flat, and stowed them away under his uniform. The rest of the documents, including the spy's code and maps he thrust into the stove and set fire to them. Without the slightest compunction he examined the contents of von Secker's pockets, taking his money, hotel coupons, a ticket on the Dutch State railways and a return between the Hook of Holland and Harwich.

Unlocking the door the lad listened. Everything seemed normal. Somewhere from a remote part of the house came the sounds of pots and kettles being vigorously scoured.

Passing out and locking the door on the senseless spy, the lad crept downstairs as silently as his wooden shoes would permit. The outer door was now ajar. Unseen he gained the open street, which fortunately was in an unfrequented quarter. As he did so he heard the old Dutch woman who kept the Golden Key shouting a farewell. In spite of his precautions she had heard his footsteps.

"The worst of doing things by stealth," thought Athol. "She will be suspicious." "What time does the public coach leave for the frontier?" he asked, bestowing another tip. It was, he reminded himself, some of von Secker's money.

"At half-past eight, from the Market Hall." she replied.

Athol set off in the opposite direction to the one he intended taking. It heightened the deception that he was making for the frontier. Not until he had mingled with the throng in the market square did he set of by a circuitous route, striking the Eindhoven road.

At that town, he found out by consulting the map, he could take train to Bois-le-Duc, and thence through Utrecht to the Hook.

"It won't be my fault if I am not home again within thirty-six hours," he soliloquised. "So here goes. I wonder what von Secker will say when he wakes up?"

CHAPTER XV

GAME TO THE LAST

Having covered a considerable distance Athol sat down behind a tree and made a hearty meal of some meat pies which he had taken the precaution to buy in Weert. By this time the excitement and lack of sufficient sleep were beginning to tell very forcibly. Even as he ate he felt himself nodding drowsily.

It was growing very warm as the sun rose higher in the heavens. The air was close and oppressive. Away to the southward, dark copper-coloured clouds were working up against the light breeze. There was every indication of a thunderstorm breaking at no distant time.

Presently a dull intermittent buzzing sound fell upon the lad's ears.

"An aeroplane," he muttered drowsily, hardly able to evince any interest in the familiar noise, until by the erratic sound of the engine he knew that something was amiss.

"Another Aviatik out of its bearings, I suppose," he said to himself. Then he looked upwards, trying to detect the plane against the dazzling light overhead.

The sound of the motor increased in volume. Chagrined at his failure to locate the source of the noise, Athol's interest deepened. He scanned the sky until he perceived the hitherto elusive machine.

It was a monoplane, flying fairly low, and proceeding in a westerly direction with a decided tendency to describe a right-handed curve. Although not immediately overhead, it was sufficiently close for the lad to distinguish the marking on the wings, fuselage, and vertical rudder.

Greatly to his surprise the monoplane bore the familiar red, white and blue concentric rings that denoted it to be a British machine.

"Whatever is that fellow doing over here?" wondered the lad. "He's placed the whole of Belgium between him and our lines. By Jove, if he starts dropping bombs about here there'll be trouble!"

But the airman made no attempt to let fall his cargo of explosives. Still describing a long erratic curve and decreasing his altitude as he did so he was soon almost invisible from the place where Athol stood—merely a shimmer of silvery-grey against the dark sky.

"Wish the fellow, whoever he is, had stopped to give me a lift," said the foot-sore subaltern as he resumed his dusty journey. "It's jolly rotten having to pad the hoof after one has been used to a hundred miles an hour or more through the air."

A few minutes later he noticed that the monoplane had swung round and was almost retracing its former course, and heading toward the east—in the direction of Germany.

"Perhaps he's trying to find Essen," thought Athol. "Krupp's place can't be much more than sixty miles away. Evidently he's lost his bearings and has just picked up a landmark. Yet it's strange that he's flying alone and right over a neutral country."

It was not long before the lad was forced to admit that his theory was at fault, for the monoplane suddenly executed a sharp turn and making a nose-dive was within an ace of crashing violently to the ground. Only in the nick of time did the machine "flatten out," alighting at a distance of almost two miles from the now highly-interested lad.

To see whether the pilot had effected a safe landing, or otherwise, Athol was at that time unable to determine, owing to the slight irregularity of the ground. He took to his heels along the highway in the direction of the settled monoplane.

Hitherto the road had been little frequented that morning, beyond a few market carts and knots of country-folk making their way to town. But now people appeared as if by magic. Every field seemed to disgorge two or three, every house half a dozen or more, including a large proportion of children—all intent on hurrying to see the foreign aircraft.

In less than twelve minutes Athol arrived upon the scene. The monoplane was apparently undamaged save for a buckled landing-wheel, until closer inspection revealed the fact that the 'plane was honeycombed with bullet-holes. Jagged holes, too, were visible in the fuselage, as well as the splaying marks of bullets that had failed to penetrate the light steel armour.

The pilot, a boyish-looking lieutenant, was behaving in a most eccentric fashion. He had alighted and had discarded his yellow leather coat and helmet. Across his forehead was a dark streak of dried blood. With one hand in his trousers pocket he was walking rapidly round and round the stranded monoplane, wildly waving his disengaged hand and shouting in unmistakable and forcible English for someone to oblige him with a match.

As he walked he tottered slightly. More than once he collided with the tips of the wings and brushed awkwardly against the rudder. The crowd, keeping a discreet distance, watched with amazement; giving back whenever a collision with the eccentric Englishman appeared imminent.

"Come on, you fellows!" he appealed. "Who'll oblige with a match? Quickly, before those strafed Bosches come on the scene! A match. Does no one understand?"

To his intense satisfaction Athol saw that there were no soldiers or civil guards amongst the throng, although at any moment the Dutch military officials might appear upon the scene. The spectators were for the most part men and women of the agricultural class.

"Can I bear a hand?" asked the lad, elbowing his way through the crowd.

"Thank God, a British voice!" exclaimed the airman, coming to an abrupt halt, and holding out his hand—not towards Athol but towards a man some feet to his left.

In a flash Athol understood. The luckless pilot of the monoplane was almost blind. He grasped the airman's hand, and drew him back from the crowd.

"You are in Holland," he said. "I saw you descend, and I guessed something was wrong. You've been hit pretty badly, I fear?"

"Got it properly in the neck this time," declared the lieutenant grimly. "Across the forehead—one eye gone, worse luck, and the other almost bunged up. Much as I could do to see the land. Couldn't do it now, by Jove! I've a chunk of one of their strafed Iron Crosses in my thigh, too. It's not much, but mighty unpleasant. Wanted to burn the machine, but found my matches had gone. Pocket of my coat shot clean away. But who are you?"

The flying man spoke in quick jerky sentences. His wounds were giving him acute pain. Already he was bordering upon delirium, his injuries aggravated by his inability, as he imagined, to prevent his machine falling into the hands of he enemy.

"Yes, you are in Dutch territory," Athol reassured him. Then, seized with an inspiration he asked, "Is the plane all right?"

"Far as I know," was the reply. "Why?"

"Because I belong to the R.F.C.," announced Athol. "Came a cropper near Hasselt yesterday and managed to get clear. If you can hold out for a couple of hours we'll fetch our lines, barring accidents. I'll take her when we're properly up, but it's the take-off and the landing part that are beyond me."

"Come along, then," exclaimed the other, his injuries forgotten in the prospect of saving his machine. "She's only a single-seater, so you'll have to perch up behind me."

Athol had to assist him to his seat. Deftly the almost sightless man tested the controls, and put the self-starter into operation. Without a hitch the propeller began to revolve, the crowd giving back at the first explosions.

"Hurry, man, hurry!" exclaimed Athol. "There are Dutch troops coming along the road."

"No internment for me, if I can help it," shouted the other, in order to make himself heard above the roar of the propeller. "So here goes."

Accelerating the engine, the lieutenant set the monoplane in motion, Athol shouting directions into his ear to enable him to avoid various obstructions in the way. For nearly two hundred yards the machine rolled over the ground, wobbling under the erratic revolutions of the buckled landing-wheel, until gaining sufficient momentum it rose steadily in the air.

"Now take her," exclaimed the pilot in a strong voice that surprised his companion by the volume of sound. "Let me know when your aerodrome is in sight. You'll find it easier than you would mine, and after all it doesn't much matter so long as it is a British one."

At a mean altitude of five thousand feet Athol steered the monoplane on a compass course. The wounded pilot had changed places with the lad, and was resting one hand lightly on the latter's shoulder. Beyond the few sentences he had spoken on relinquishing the steering-wheel the lieutenant maintained silence.

The monoplane proved a veritable flier, for in a little more than half the time Athol had estimated it was over the lines of the opposing armies.

Far beneath them a squadron of British aeroplanes was actively engaged, for the British guns were strafing the Huns with terrible violence. Not a single German aircraft appeared to join in combat with the intruders over their lines, for the British machines were doing good work by registering the results of the heavy shells.

"The flying ground is in sight," reported Athol. "Will you take her now?"

"Right-o," replied the lieutenant. "Tell me when to flatten out."

He depressed the aerilons. The monoplane's tail rose as it swept landwards at terrific speed. Athol, holding the pilot's binoculars, brought the glasses to bear upon the landscape.

"Wind's dead against us," he announced.

"That's good," rejoined the wounded man. "It will save us making a turn. Say when."

The ground seemed to be rising to meet them. Objects, a few seconds before hardly discernible, resolved themselves into buildings of various sizes, most of them roofless owing to the effects of repeated bombardments. Little mud-coloured specks developed into khaki-clad figures. And—a cheering sight indeed—there was the secret battleplane just folding her wings before returning to her hangar. In his imagination Athol felt certain that he could distinguish Blake and Dick superintending the labours of half a dozen men as they guided the huge bird into its nest.

There was no time to use the binoculars. The ground seemed perilously close.

"Now," exclaimed Athol.

With a perceptible jerk the direction of downward flight was checked. Then, giving a decided bump as the buckled landing-wheel touched the ground, the monoplane "taxied" for full fifty yards, and halted within ten feet of a group of officers, who scattered right and left as the machine bounded awkwardly towards them.

Athol, kneeling on the deck of the fuselage, touched his companion in order to guide him to the ground. The pilot, still holding the steering-wheel, made no effort to move.

"Do you want me to give you a hand?" he asked, touching him again, Still no response.

"What's wrong with your pilot?" enquired one of the officers anxiously.

Athol crawled forward and looked into his companion's face. The lieutenant's blood-rimmed eyes were wide open and staring fixedly in front of him, but they were the eyes of a corpse. The gallant pilot's mind had triumphed over his physical injuries up to the very moment that he had brought the monoplane safely to earth. He had gained at least one desire: he had brought his machine back to the British lines.

"Never expected to see you so soon, old man," was Dick's candid greeting to his chum.

"Nor did I," admitted Athol. "For that matter I wasn't at all sure that you got away all right. I heard the bombs drop, so I knew that the battleplane had set to work. In fact the last bomb you dropped nearly settled my hash. Instead it did me a good turn."

"And I went for Sergeant O'Rafferty for being such a clumsy blighter," said Blake. "By Jove, Athol, you seem to have had a run of luck. Sorry I can't say the same for the poor fellow who brought you back."

"Most remarkable case that," remarked an Army Medical Corps officer. "Not only was his sight injured, he had received a piece of shrapnel in his groin and a bullet lodged in his body in the region of his heart. All the while he was piloting that machine back he was bleeding to death internally. No wonder, with men of that stamp, that we hold the individual mastery of the air."

CHAPTER XVI

À BERLIN

Having, through Athol's instrumentality, recovered the battleplane's plans, Desmond Blake resolved to run no more risks in that direction. In spite of the most stringent precautions German spies were found to be active behind the British lines. Confidential documents disappeared almost under the noses of the authorities. So, rather than run a chance of having the plans stolen a second time, he destroyed them.

"The details of one battleplane may be kept a secret, with reasonable care," he remarked. "With a dozen in the making the odds are against it, and since the authorities have told me pretty plainly that I am of more use here than superintending the construction of other machines at home, I am content. I have an idea that they've a pretty stiff job for us to tackle before very long."

Blake's surmise was correct, for a few days later he was ordered to report himself at the Staff Office.

"By Jove!" he exclaimed, taking Athol and Dick aside. "We're going to put the wind up the Bosches this time. Half a dozen of our fastest machines are detailed to make a raid—guess where?"

The lads hazarded the names of several places, but without success.

"Berlin," declared Blake. "Our people have been keen on the idea for a long time, but the authorities at home have, for some unearthly reason, deprecated the idea. Sickly sentimentality I call it. They shrink from reprisals, although they know perfectly well that that is the only way to bring the Hun to his senses. Events prove it. He was the first to use gas shells; now he squirms and whines when we give him a dose of his own poison. He gloated over the torpedoing of our merchant ships, and squeals out piffling protests to neutrals when our submarines tackle his trading vessels in the Baltic. The German papers were full of bombastic rejoicing over the Zeppelin visits to our undefended towns; the Kaiser weeps copious crocodile tears when the Allied airmen knock his beloved Karlsruhe about a bit. I'd go a jolly sight farther than the precept laid down in the old Mosaic Law. 'An eye for an eye; a tooth for a tooth.' By Jove! Three British shells for every German one, and a ton of high explosive for every kilogramme of T.N.T."

"When do we start?" asked Dick eagerly.

"At three to-morrow morning," replied Blake.

"It's blowing half a gale from the west'ard," said Athol, "and the glass is falling rapidly. It's all right for the outward journey, but we'll have a job to get back. Not that I am at all anxious about the battleplane's capabilities," he hastened to add.

"There will be no coming back," declared Blake. "At least, not at present. We've been waiting for this westerly gale. With it the squadron ought to do at least a hundred and sixty over the ground. When we arrive over the German capital, by turning head to wind we can keep almost stationary over any part we choose until all the machines have dropped their bombs. Strict orders have been issued to avoid hitting, as far as possible, the residential parts of the city. Then, after that particular business is completed the machines are to resume the westerly, or north-westerly course, and alight on Russian soil, somewhere in the neighbourhood of Riga."

"And then?" asked Dick.

"Make ourselves useful until we get a fair wind back," replied Blake. "But be careful," he added, "not to mention this business to anyone. Even after the raid no communication will be made; the official bulletins will ignore it. And, I fancy, the Germans won't care to admit it, since they've boasted time after time that Berlin is absolutely immune from air attacks. We'll see how far their boast holds good."

For the rest of the day preparations for the long flight were diligently carried out. Blake and Dick overhauled the motors, oiled and tested the wing-operating mechanism, and carefully examined the controls lest any of the wires had developed designs of chafing. The petrol tanks were replenished under Dick's supervision, while in addition twenty cans of spirit were taken on board. Ammunition and stores were also placed in readiness for the flight, Athol and Sergeant O'Rafferty being responsible for the quantity and the correct weight, since a lot depended upon the flying trim of the mechanical bird.

Similar scenes of activity were witnessed in other parts of the aerodrome, while the individual units of the squadron detailed for the raid were being prepared for the most extensive aerial operation of the war. By nine o'clock everything was in readiness. The airmen retired for a well-earned and necessary rest, while sentries were posted at the door of each hangar to prevent any possibility of the machines being tampered with.

At two in the morning the pilots repaired to the Wing Commander's quarters to receive final instructions. The machines were to proceed in two columns, each biplane starting at two minute intervals, the columns to be roughly three miles apart. Blake's battleplane was to act as covering escort, flying at three thousand feet above the others. No attention had to be paid to hostile aircraft unless unavoidable. If the enemy should attack, half the squadron, assisted by the secret battleplane, was to engage, while the rest pushed on towards their objective.

As soon as the German capital was sighted, a wireless message was to be sent to the British headquarters; and then, and only then, was the Russian General Staff to be informed of the projected visit of the raiding aircraft.

Punctually at the appointed time the first of the biplanes left the aerodrome, followed at stated intervals by the rest. In spite of the howling wind the ascents were carried out without a hitch.

The secret battleplane was the last to leave. Almost silently as compared with her consorts she rose evenly and swiftly from the ground, and headed off in the direction the others had taken.

In the pale morning light the far-flung double line of British machines could hardly be distinguished against the angry red glow on the eastern horizon, although in the upper regions the deep bass hum of their exhausts could be distinctly heard.

As they neared the lines of opposing trenches three or four Fokkers rose with the evident intention of intercepting the raiding machines; but thinking better of it, they volplaned earthwards.

At length, far above the storm-driven clouds that hid every detail of the country from their sight, the raiders pursued an even and uninterrupted flight, piloted on a compass course by the flight commander in the leading biplane of the right column. With the wind almost dead aft navigation was a fairly simple matter. There was no need to trouble about "side-drifts." All that had to be done was to fly continuously in a straight line until it was judged that the machines were approaching their objective and then descend below the clouds and verify their position by reference to a map and a recognition of conspicuous landmarks.

The "maps" had been especially supplied for the raiding airmen's use by the French government, and were the result of careful aeronautical observation work in pre-war days. In a strict sense they could not be called maps, as they consisted of an elaborate series of enlarged photographic views taken from an altitude of about eight hundred metres, and embraced practically every mile of country between the Franco-German frontier and the environs of Berlin. Their compilation was the direct result of the memorable visit of a Zeppelin to Nancy, where, owing to an accident the gas-bag had been compelled to come to earth. An examination proved conclusively that the airship had been taking aerial reconnaissance of the French fortresses. The French government did not protest: it merely retaliated by making the series of photographic maps that were in the present struggle to play such an important part.

At a quarter to five the leading biplane of the right column began a volplane, the rest of the machines following its example. It was a test in order to verify their position.

For full five minutes each was lost to sight of the other as the air-squadron dipped swiftly through the dense, rain-laden clouds. While it lasted the ordeal was a nerve-racking one, for not only was there the danger of collision in the event of any of the biplanes swinging out of position, but the air was filled with "pockets"—partial vacuum of insufficient density to offer resistance to the planes—into which the airmen fell like stones until the machines "picked up" in the buoyant air beyond. Vicious and erratic currents and eddies, too, added to the pilots' difficulties, while in the midst of the layer of clouds it was almost as dark as midnight.

As the battleplane emerged from the underside of the clouds the lads could discern an extensive town through which flowed a broad river. Viewed from the height of seven thousand feet the town, with the numerous railways radiating from it, resembled a gigantic spider lurking in the centre of its web.

Already the leading biplanes were far beyond the maze of buildings, so it was evident that the city was not Berlin.

Blake noticed the look of enquiry on Athol's face.

"Magdeburg," he announced laconically. "Know the place well. We're fairly on the right road now—Brandenburg, Potsdam and then Berlin. Another quarter of an hour."

Up into the clouds climbed the raiding aircraft. The now furious gale was completely in their favour, for it was impossible for the Germans to send aloft any of their numerous captive balloons that formed a part of the aerial defences of the capital. The wind was beginning to rend the bank of clouds. Brilliant shafts of sunshine shot through the rifts. Over the ground the shadows chased each other with a speed that gave the aviators a knowledge of the strength of the gale.

Blake, holding the steering wheel, spoke hardly a word. His whole attention seemed to be centred upon the task of "keeping station" with the rest of the squadron. His left hand was almost continuously upon the timing lever of the motors, checking the speed of the battleplane whenever, as frequently happened, she showed a tendency to overhaul the biplanes.

Far below lay an extensive and irregularly shaped lake with at least two considerable towns on its banks. Surrounding the lake was a dense forest, of which a large part had been but recently cleared, for newly-felled trees were plentifully in evidence.

"Potsdam," announced Blake. "If we imitated the methods of the Kultured Huns we should drop a few bombs on Kaiser Wilhelm's palace. That lake is the Havel. They've cleared a lot of the Spandau and Potsdam forests, I see. Not that they are hard up for timber. I suppose it is chiefly for wheat growing, in anticipation of the day when the German frontiers are most considerably restricted. But stand by—the leading machines are turning head to wind."

The attack had been magnificently planned. One division of the biplanes had flown over the southern environs of Berlin; the other over the northern; now both were turning inwards and just holding their own against the wind. They had the city at their mercy.

Before the utterly surprised artillerymen manning the anti-aircraft guns were fully aware of the presence of the British raiders, powerful bombs were hurtling through the air, each missile aimed with deliberate intent upon a specified objective and not dropped haphazard under cover of darkness as in the case of the Zeppelin raids over England. The railway stations and other public buildings of military importance were carefully singled out by the airmen, in spite of the now furious but erratic fire of the German guns, particular attention being given to the official buildings in the Wilhelmstrasse, not omitting No. 13—the headquarters of the Imperial Admiralty.

It was by no means a one-sided engagement, for shrapnel shells were bursting heavily all around the British machines. As far as Athol and Dick were concerned they rather welcomed the warm attentions of the enemy. It was far better to run a fighting risk than to hover deliberately over a defenceless town and hail projectiles upon a populace unable to raise a little finger in self-protection.

Already fierce fires were raging in a dozen different quarters of the German capital. The air trembled with the terrific detonations of exploding bombs. The dense columns of smoke, beaten almost flat with the strong wind, prevented the airmen from making definite and accurate observations of the result of their work, but on the other hand the vapour hid the attacking aircraft from the artillerymen. Nevertheless two British biplanes were hit. One, taking fire, streamed earthwards, leaving a trail of smoke and flame in its wake. The other, its engine disabled, contrived to land in Thiergarten, where the pilot and observer were made prisoners.

The secret battleplane had dropped her last bomb and was preparing to resume her north-eastward flight when a shell burst almost immediately above her. A hail of bullets rattled against her proofed sides. One ripped a hole through Blake's airman's helmet, fortunately without doing further injury. The wings were perforated in fifty places, although the damage had little effect upon the speed of the machine. The battleplane literally reeled with the concussion, recovered herself, and then began to wobble alarmingly in spite of the efforts on the part of the pilot to keep her on a straight course.

One of the actuating rods of the left wing, bent by the violent impact of the base of the shell, was thrown out of action. Sooner or later the machine would be obliged to descend upon hostile soil, almost in the very centre of the German Empire.

CHAPTER XVII

DISABLED

It was indeed well that the battleplane was already flying "down the wind." Locking the wings, and trimming them at the furthermost limit of the bent actuating rod, Blake made the comforting discovery that the planes were in the best possible position for a prolonged glide. Aided by the following gale, the velocity of which was not far short of seventy miles an hour, the battleplane ought to cover a distance of from fifty to sixty miles before alighting. In that case he hoped to effect a landing in the bleak and sparsely-populated district drained by the sluggish River Warthe.

Nursing the volplaning craft with the utmost care, Desmond Blake was getting every possible foot of space out of the involuntary glide. Perfectly calm and collected he bade Athol find a particular section of the map of Prussia and Posen and fix it in the celluloid holder in front of him.

Dick, having shut down the motors, since they were no longer of service, clambered into his seat, and made good use of his binoculars; while Sergeant O'Rafferty deliberately fixed a time fuse under the row of crank-cases so that in the likely event of the presence of German troops, the battleplane would never fall into their hands except as a twisted and tangled mass of metal.

Fortunately the clouds of smoke issuing from the burning buildings had prevented the Huns from observing the result of their chance shot; and now the battleplane was at frequent intervals hidden in the masses of scudding clouds.

Apart from that there was little in her favour, for it was now two hours before midday. The twilight that had afforded protection on the occasion of the raid upon the Zeppelin sheds at Olhelt was denied her.

The manometer now registered a thousand feet. No longer the clouds afforded protection. The country had the aspect of being fiat, and almost destitute of trees; nor were there any signs of human habitation. On the distant eastern horizon could be discerned the smoking chimneys of a manufacturing town. To prolong the flight much further would be literally throwing away the chances that the airmen already held.

"We'll descend here," announced Blake, turning the battleplane head to wind. "Stand by to jump for it if the wind threatens to capsize her on landing."

The warning was necessary, for, owing to the jamming of the wing mechanism, the wings could not be folded immediately upon contact with the ground. The now rigid expanse of planes would have to withstand the full force of the gale, and everything depended upon the angle of inclination—whether it was sufficiently small to enable the weight of the machine to pin it to the ground.

Down planed the mechanical bird at a tremendous rate. Although it cleft the air at nearly seventy miles an hour its progress over the ground and against the wind was practically nil. In point of fact the battleplane was dropping vertically earthwards at a rate of fifteen feet per second.

Quickly the almost uniform motion gave place to a series of erratic jerks. The falling machine was in the influence of the rebound of the wind from the irregular surface of the ground. The motion reminded the lads of a small boat encountering the "wash" of a huge steamer.

With a double bump the battleplane struck the ground, reared until her landing-wheels were three feet in the air, and bumped again. Then rocking violently she showed every inclination to capsize, until Athol and the sergeant, sliding to terra firma at the risk of life and limb, clung tenaciously to the partly-tilted wings.

"Good men!" shouted Blake encouragingly, as he depressed the aerilons to counteract as much as possible the lifting tendency of the wind upon the wings. "A spanner there, Dick: shift those two nuts as sharp as you can."

Dick swarmed over the side, and clinging with one arm and both feet to one of the vibrating trellis girders, set desperately to work on the nuts and bolts securing the bent rod to the underside of the left wing. With the removal of the metal bar the wings were folded, and for the time being all danger of the battleplane being overturned by the gale was at an end.

"No signs of our friends the enemy," said Blake, standing erect upon the deck of the fuselage and sweeping the treeless plain with his binoculars. "There's a small village about three miles away. I can see the church spire and the roofs of the houses; the place lies in a hollow. Beyond that there are no signs of human habitation."

"Don't you think, sir," asked Sergeant O'Rafferty, "that if we pushed the machine a couple of hundred yards in that direction there would be more shelter in that dip in the ground? It's not deep enough to hide the battleplane entirely, but it may help things a bit."

"Certainly, sergeant," agreed Blake. "Every little helps, and we'll be less exposed to the wind in the hollow."

It was a strenuous task pushing the machine dead in the eye of the wind, but on gaining the spot that the sergeant had pointed out, the airmen found that there was almost complete shelter from the full force of the gale, while the highest part of the crippled machine showed only a couple of feet above the high ground surrounding the natural hollow.

Heavy rain was now falling. The stranded aviators faced the discomfort with rising spirits, for they knew that should the downpour continue the ground would quickly become a quagmire, and that the rain would keep the villagers within doors. Nevertheless all precautions were taken against surprises, since it was quite possible that workers in the fields had noticed the battleplane's descent, and had set off to warn the military.

Enveloped in their weather-proof coats, Athol and Sergeant O'Rafferty mounted guard, taking care to avoid the sky-line. From their respective posts they could command a vast tract of the neighbouring countryside, so that, unless the battleplane was stalked by practical scouts the danger of a surprise was completely obviated.

Meanwhile Blake and Dick were hard at work removing the bent rod. Upon examination the metal showed no sign of fracture, but it was essential that it should be straightened before the wing-mechanism could again be operated.

"We've a tough job here, Dick," observed the inventor as he gazed upon his damaged handiwork. "Now, if we were at home or at the flying ground it would be a simple matter. A forge and a blacksmith's anvil would enable us to rectify the injury in less than an hour."

In vain they applied pressure to the bent rod. They jumped on it, battered it with the heaviest spanners they possessed. The tough metal sturdily refused to respond to the treatment. For the first time since Dick had made Desmond Blake's acquaintance the inventor showed signs of despair.

"I have an idea!" suddenly exclaimed Dick. "It may work; it may not. In either case there can't be much harm done."

"Well, what is it?" enquired Blake hopefully. He had already good cause to appreciate the intelligence of his young assistant, and a ray of hope flashed across his mind at the lad's words.

"Suppose I take the rod into the village and get them to straighten it out," began Dick.

Blake frowned. He was on the point of telling the lad not to be idiotic, when Dick, reading his thoughts, hastened to explain.

"I can speak German well," he continued. "You see, I was three years at school in Mecklenburg—jolly rotten time I had, too!" he remarked in parenthesis. "In this great coat and flying helmet I don't suppose the simple villagers would guess that I was anything but a Hun aviator. I could try the Kopenick hoax over again. You see, we are bound to be captured if we can't get the job done, so it's all the same in the long run."

"There may be soldiers quartered in the village," objected Blake.

"Hardly likely," said Dick. "It is not on a railway line, and consequently troops are not likely to be stationed there. There might be some of the Landwehr or Landsturm. If so, they are Prussians. By passing myself off as a Saxon or a Badener I think that would account for my slight difference in accent."

"I'll go with you," said Athol.

"No, you don't," objected Dick with a laugh. "This is my show. You had your time the other day. If I pull it off all right, well and good; if not, well, we'll most likely have the pleasure of one another's society in a German prison camp."

"Very well, carry on," said Blake cordially. "And jolly good luck to you."

The already torrential rain was in itself an excuse for Dick to wear his aviator's coat buttoned tightly from his neck downwards, while his padded helmet pulled down over his face left little of his features exposed. As a precautionary measure he carried his revolver in its holster conspicuously displayed outside his coat.

Shouldering the bent bar, which, although remarkably tough, weighed less than seven pounds, Dick bade his comrades "au revoir," and set off on his three-mile tramp to the village.

It was slow progress. There was no beaten path. The coarse grass-land was ankle-deep in tenacious mud. The rain blotted out everything beyond a distance of two hundred yards. Not only was there the risk of missing the little hamlet, but the more serious danger of losing touch with the stranded battleplane, which at a distance of a hundred yards was an almost inconspicuous "hump" in the midst of a monotonous terrain devoid of anything in the nature of "bearings."

Trudging with his back to the gale Dick held on doggedly. Unless the wind veered or backed he could be fairly certain of his direction. With a change of wind, coupled with the fact that the sun was completely overcast, there would be no means of finding his way.

Before he had covered a mile and a half the lad encountered the first inhabitant of that dreary district. An old peasant, his bent form enveloped in a tattered cloak, was tending swine. Dick made no effort to avoid him. This man's attitude towards him might be taken as a specimen of the reception he would be likely to receive in the village. On approaching, the peasant regarded the flying officer with the undisguised curiosity that dwellers in rural districts invariably bestow upon strangers; until, realising that the newcomer was one of the military "caste," the old fellow bared his head, standing stock still in the downpour until Dick, who curtly acknowledged the act of homage, had walked past.

A little further on the lad struck a lane, so deep in slime that it was of no use as a means of progression. Worn several feet below the surface of the adjoining ground it resembled a stagnant ditch of liquid mud. However, guessing that it must lead to the village, Dick struggled gamely on, keeping to the slightly firmer ground by the side of the primitive by-way.

In another quarter of an hour he descried the misty outlines of the little village looming up through the mirk.

With a quickening pulse the lad pressed on, and gained the outskirts of the straggling hamlet. The road, even in the village, was little better than the quagmire without. At first there were no signs of human beings. A few ducks revelled in the slush and rain. A gaunt pig wallowed in the mud, nosing amidst the garbage in search of food. Peat-reeking smoke was issuing from some of the chimneys, and, beaten down by the rain, was driving over the saturated ground in eddying wisps.

Dick hastened onwards in the direction of the church, the only building with a pretence of importance in the squalid village. At the same time he kept his eyes and ears on the alert in the hope of finding some sort of a place where he could get the important work carried out. There was almost a total absence of shops in this particular quarter. Commercial intercourse, if any, must be carried on in a very meagre fashion, he argued.

Presently the lad's quick ear distinguished the clang of a blacksmith's hammer—not the quick, merry ring that characterises the smith's activity in Merry England, but the slow, listless hammering of a toiler whose heart is not in his work.

Guided by the sounds Dick turned down a narrow street until he came to a low stone and plaster building, through the two glazeless windows of which bluish smoke was issuing. Over the open door was a sign, setting forth that Johannes Müller was a skilled worker in iron-work, especially in connection with agricultural implements.

Striding pompously to the door as well as the slippery nature of the ground permitted, Dick entered the low smithy. Within were two men, neither of whom, owing to the hiss of the bellows-fanned flames, had heard him approach. The elder of the twain was a short, thick-set man in a grey shirt open at the neck, a pair of trousers reaching but a few inches below his knees, a pair of rusty boots and a paper cap. His hairy chest and gnarled arms betokened great strength, although his lower limbs were ill-developed, and seemed scarcely able to support the weight of his body. His features were coarse and brutal, the sinister effect being heightened by his soot-stained face and yellow protruding eyes. He had just set aside a light hammer and was resting upon the heavy "striker," while his assistant coaxed a mass of iron into a state of white heat.

The second man's features were hard to judge, for the lower part of his gaunt face was hidden by a bushy, unkempt beard of a light brown colour. His clothing consisted of a ragged shirt and trousers; his toes, innocent of socks, peeped through rents in an odd pair of boots that in England would look out of place anywhere except on a rubbish heap. His movements were listless and dejected, and as, for the first time, he caught sight of Dick, he shot a glance of mingled hatred and contempt. He made no attempt to attract the smith's attention to the new-comer, and it was not until the young officer stamped imperiously upon the cobbled stone floor that the old fellow was aware of the presence of his uniformed visitor.

The conscript habits of by-gone years were still latent in the smith's mind. Dropping his hammer, he brought his heels together, drew himself up as far as his bent frame would allow, and saluted smartly in the Prussian style.

"I want this straightened out instantly, smith," said Dick, returning the salute. "It is work of imperial importance."

"Certainly, herr leutnant," replied the man, relieving Dick of his burden. "A part of one of our incomparable flying machines? An accident has taken place?"

"Yes," replied Dick, then, realising that he would have to account for the fact that an officer had to perform the menial work of bringing the rod to the smithy, he added, "and my sergeant has broken his leg—the idiot.... So I must needs fetch and carry. ...And not a single peasant did I meet to relieve me of this weight. The mud and rain, too, are vile."

"There are few men left here," said the smith. "We are even obliged to——. But how is this to go, herr leutnant? Are the two slotted ends to remain in line or across each other, so?"

He traced a rough diagram upon a board by means of a piece of chalk, at the same time signing to his assistant to get to work with the bellows.

The man, his face working with anger, merely folded his arms. Again the smith motioned to him. Dick began to think the assistant was deaf and dumb, or, perhaps, of weak intellect.

Still meeting with refusal the smith grasped a round bar of iron. The other, stepping back to the wall snatched up a formidable pair of tongs.

"Hanged if I do a stroke of work to the job!" exclaimed the man in unmistakable English. "Let the Bosche do a bit. It will do him good. Nothin' doing here, old sport."

CHAPTER XVIII

TURNING THE TABLES

For a few seconds Dick stood dumfounded. The smith, full of apologies for the deliberate insolence of his assistant towards a German officer, hurriedly explained.

"The swine is an English prisoner," he said. "He was lent to me from a camp at Meseritz. If the rest of these Englishmen give so much trouble as this one I feel sorry for the good Germans to whom they are hired out. I pay this rascal a mark a week and feed him, and only by threatening to send him back to camp for punishment could I get him to work at all. But I was beginning to think I had broken his spirit, and now he goes back to his old ways."

"Let me see if I can cow him, smith," said Dick. "You cannot speak the English tongue, I suppose? No; well, I can, although it is a barbarous language, hardly fit for good Germans to use. I will frighten him. He will know what it means to refuse to work at the orders of a Saxon officer."

"The matter is in your hands, herr leutnant," replied the smith, obsequiously.

"It's all right, my man," began Dick, addressing his luckless fellow countryman. "Don't look astonished. I'm supposed to be jawing you. Look as sullen as you can. That's better. This is part of a British machine. We're stranded three miles out. Set to work as hard as you can, without giving the show away, and I'll do my level best to get you away. We're in a bit of a hole ourselves, but with this job set right we can make another start."

"Thought something was fishy, sir," replied the man. "Hun flying officers don't sport 'wings'; leastways, I've never seed 'em. Yours puzzled me a bit, but I'm getting past being astonished at anything."

"It's lucky for me that this old smith isn't as cute as you are," rejoined Dick. "Now I'll tell him I've made you promise to slog in. I'll let him know that you are to carry the rod back to the battleplane. I'll order him, and he daren't refuse."

"His bad fit is soon over this time, her leutnant," remarked the smith, as the prisoner resumed his post at the bellows. "And this is peculiar metal—so light. Do I temper it in water or oil?"

"Oil," replied Dick promptly, not that he was sure of it, but because it was unwise to profess ignorance.

Half an hour later the smith, puffing and blowing like a grampus, completed the task, apologising for the roughness of the finish.

"It will be as strong as ever it was," he declared. "The roughness is to be regretted, but after all, the makeshift job will last until you return. Is it to the Russian front, herr leutnant?"

"No, to the Bulgarian," replied Dick. "Only this terrific gale blew us out of our course. We were indeed lucky to land at all, except as a crew of corpses. Now, how much is your charge?"

The smith named quite a small sum. Experience had taught him the folly of demanding anything more of a German officer.

Dick paid him by means of the mark notes that Athol had taken from the spy, Karl von Secker, and with which his chum had thoughtfully provided him before setting off for the village.

"And now," he continued. "I must have your English prisoner to carry the thing back. I will make him return within three hours."

"He may take it into his head to escape, herr leutnant," objected the smith. "You will understand that I am responsible."

"I order you," said Dick sternly.

"In which case I must obey," replied the German. "But if your excellency will permit me, I will go with him. It will ease my mind of a lot of worry, and in these times one has quite enough trouble what with war taxes and food tickets."

"It is forbidden to criticise the actions of the government," said Dick sternly.

"True, true, herr leutnant. I deeply apologise. I trust it will go no further," said the smith tremblingly. "But it is permissible that I go with the man?"

"You seem fonder of the man than I do," grumbled the pseudo-Saxon. "Does it always pour like this in Posen? Come along, then, we must hasten."

The English prisoner shot an enquiring glance at Dick as the smith began to don a heavy coat.

"It's all right," said the lad reassuringly. "The old fool insists upon coming. We'll deal with him all right later on."

With no additional protection from the driving rain, which was now full in their faces, the thinly clad British Tommy shouldered the repaired rod and followed Dick into the street. The smith brought up the rear, cursing to himself as his weakly legs sank into the mud, that he had to dance attendance on an officer and a Saxon. There was one consolation, he argued. His patron might have been a Prussian, in which case kicks, not paper-money, might have been his reward.

Upon clearing the outskirts of the village Dick struck the sunken lane, keeping, as before, on the higher ground by the side, although by this time the deluge had left little to choose in the matter of a firm footing. He kept steadily onwards, striving the while to locate the place where he had to turn of across the trackless waste. The British Tommy, he knew, would stick closer than a brother; whether the smith would persist in forcing his company upon him troubled him but little. Even if the fellow was shrewd enough to discover that the battleplane was not a German one not much harm was likely to result, unless the smith proved particularly obstreperous.

Dick had already gained the comforting information that there were no troops within twenty or thirty miles, and that the village was practically devoid of able-bodied men; so that, in the event of missing the spot where Blake and his comrades were, the lad would have no hesitation in firing a revolver to attract their attention. For the present, however, he refrained from using the weapon. For one thing he was rather anxious to return unaided; for another the direction and force of the wind rendered futile all sound signals until he was very much closer to the stranded battleplane.

At long intervals Dick glanced over his shoulder. The now drenched soldier was trudging stolidly along; the smith was making heavy going, and showing visible signs of distress. Had Dick wished he could have outstripped the man without difficulty.

"Can't be far off now," he soliloquised. "Seems to me I've tramped nearly five miles."

He stopped and scanned the surrounding countryside. As far as the driving rain permitted the land presented a flat appearance without any outstanding characteristics—a treeless expanse of mud.

The smith must have guessed the lad's perplexity, for a curious look overspread his coarse features.

"Herr leutnant has lost his way?" enquired he. "Or, perhaps, the machine has flown off?"

"Silence!" exclaimed Dick fiercely. This time there was no need to impersonate the irate officer: he was genuinely furious with the fellow.

"Some one signalling, sir, on our right," declared the Tommy, whereat the smith, either surprised at the Englishman's audacity or anxious to vent his spleen upon the luckless prisoner, stooped, picked up a handful of mud and hurled it at him.

"They are our friends," exclaimed Dick joyously. "Keep yourself under control a few minutes longer. We mustn't let this low-down rascal smell a rat until we're ready for action again. May as well make him useful."

"Stop there till I tell you," ordered the lad, addressing the German. "You can keep a sharp eye on your assistant from where you are standing."

Then, bidding the Tommy follow, he hurried across the intervening hundred yards that separated him from his comrades. Unbeknown to all, Dick had actually passed within almost hailing distance of the battleplane without seeing it or being seen by Athol and the sergeant, until the hollow in which the machine rested was well on his right hand.

"Whom have you here?" asked Blake.

"A British soldier, hired out as a sort of slave to the village blacksmith," explained Dick. "We'll have to keep up the deceit until we set the rod in position; then it will be a huge joke to enlighten the rascally Hun on certain points."

Having given a rapid report on what had taken place, Dick assisted the inventor in replacing the actuating rod. In twenty minutes the work was completed, although on testing the machine Blake discovered that owing to some slight and almost imperceptible curve in the metal the rod was nearly a quarter of an inch shorter than before.

"May make a slight difference to our trim," said Blake. "However, flight alone will prove that. You see we haven't been idle. We have been repairing the larger rents in the wings. Now, all aboard. Dick, show your protégé the way. We'll give him a dry suit and some hot grub. Poor beggar, he's half dead with hunger and exposure."

"'Arf a mo', sir," protested the man. "Before I go can I have a word with yon chap?" And he indicated the still waiting smith, who was now heartily sick of the whole business, and was wishing that he had taken his chances in letting his assistant go alone.

"Very good," agreed Blake, thinking that the Tommy wished particularly to say something to the Hun.

The man plodded stolidly towards the smith until he got within a couple of yards.

"Put your dooks up, old sport," he exclaimed, at the same time "squaring up" to the astonished German.

Having no longer an iron bar with which to assert his authority, the smith showed no great eagerness to accept the challenge. If he expected the officers to intervene he was grievously mistaken.

At length in desperation, for the Tommy was edging nearer, with grim anticipation written on his gaunt features, the Hun threw himself into a defensive position. That was all his former assistant required; for the next moment the bully was sprawling on his back in a foot of liquid mud.

Apparently the British soldier considered that old scores were wiped out, for with the utmost magnanimity he hauled the helpless smith out of the mire and set him upon his feet. This done he unconcernedly strolled back to the battleplane.

"Couldn't help it, sir," he explained apologetically. "Had to get it off my chest. Let bygones be bygones, they used to drill into my head at school. I reckon that proverb ought to be wiped off the slate after what our chaps have gone through out yonder. Penal servitude ain't in it: it's slaving with starvation chucked in."

"Let's hope your troubles are now over, my man," quoth Blake as he took his seat at the helm. "All ready, Dick?... Hold on a minute."

The smith, finding that his assistant was on the point of being spirited away in the huge flying machine, came floundering towards them. Much as he feared being left alone with the pugnacious Englishman he dreaded having to report his loss to the commandant of the prison camp.

"Good-bye, smith," shouted Dick in German. "Don't be in too great a hurry to inform the authorities that you have been aiding the English by repairing one of their battleplanes. Kaiser Wilhelm might be very angry with you."

The next instant the machine rose with a bound, and fleeting before the still strong westerly gale, resumed her flight towards the Russian frontier, leaving the astonished and dumfounded smith to realise the magnitude of his unwitting offence against the German Empire.

For the next few hours the aerial voyage was comparatively uneventful. The rescued prisoner, who gave his name as Private Tom Smith, of the "Chalkshires," and who had been taken prisoner early in the campaign, was now fast asleep, after a good hot meal and a change of clothing.

The battleplane, flying at an immense height, was now far above the rain-clouds and bathed in brilliant sunshine. Looking downwards nothing was visible of the earth, a seemingly unlimitable expanse of dazzling white clouds forming an effectual screen between the airmen and the dreary soil of East Prussia.

"Time we descended to verify our position," announced Blake. "Although in this case it is preferable to overshoot the mark we don't want a long flight against this gale if we can help it."

Cleaving her way through the clouds and leaving an eddying wake of fleecy vapour behind her, the battleplane again came within sight of the earth.

It was no longer raining. A clear view could be obtained for miles—but instead of the flat plains of Russia a vast sea met the airmen's gaze.

"We're a bit out," declared Blake. "We're right over the Baltic."

Before either of the lads could comment upon the somewhat disconcerting nature of the discovery Blake suddenly thrust a lever hard over, automatically locking the wings.

"Take charge, Athol," he exclaimed hurriedly. "Keep her as steady as you can, and check any tendency for her to heel. I'm going outside for a few moments."

To the young airmen's astonishment the inventor began to discard his heavy coat and boots.

"What's wrong?" enquired Athol.

"Only that rod," replied Blake. "The securing nut is working loose. We can't afford to let both drop or it will mean complete disaster for us all."

"Then I'm the man for that job," decided the lad promptly. "I'm light and agile and—and——"

He stopped abruptly. It was on the tip of his tongue to add the words "you are not," but checked himself in time.

Every moment was precious. There was no time for argument. Blake instantly realised the force of his young assistant's remarks and acquiesced.

Knotting a rope round his waist, and holding a spanner in his mouth, Athol dropped lightly upon the rigidly locked wing, gripping the foremost edge in order to save himself from being swept away by the terrific rush of air.

Foot by foot he made his way along the trembling fabric until his head and shoulders projected beyond the tip of the aluminium wing. Although by this time well acquainted with dizzy heights the lad dare not look down upon the distant expanse of water. He kept his eyes fixed upon the loose nut, a foot or so on the underside of the wing. Only three or four threads were holding. In a few minutes, had not the defect been noticed, the actuating rod would have become detached, with the result that the wing, no longer held in position, would have folded itself. Like a crippled bird the battleplane would have crashed through thousands of feet with incredible speed, sealing the fate of all on board.

"Got you, you brute!" ejaculated Athol triumphantly as he gave a final wrench to the now secure nut.

The task accomplished it was no easy matter for the lad to regain the chassis. Temporarily exhausted with his exertions and buffeted by the cutting wind he lacked the strength to haul himself from the wing to the upper side of the fuselage; but Dick came to Athol's aid, and at length the lad was dragged into safety.

"Good man!" exclaimed Blake approvingly as he again actuated the wings.

There was little margin to spare. Already the battleplane had volplaned to within a thousand feet of the sea.

It was not until the mechanical bird had regained her former altitude that her crew were able to discuss the factor that had carried them so far out of their course. An explanation was necessary in order to explain satisfactorily why, instead of being over the province of Courland, the airmen found themselves miles from land and over the expansive Baltic.

CHAPTER XIX

A DUEL WITH A ZEPPELIN

"The gale must have backed to the south'ard," explained Desmond Blake. "It has carried us well northward of our proper course. There's a large vessel almost immediately beneath us, Athol. Get your binoculars and see if you can make out her nationality, and, what is equally important, the direction of the wind."

"By Jove!" exclaimed Athol, after a brief investigation. "It is not a vessel—it's a Zepp. She's not so very far above the surface; I can tell that by the position of her shadow on the waves."

"Here, take the helm," said Blake, handing over the steering wheel to the lad. "Let her volplane in spirals. I must see what this game is."

It did not take Blake long to form a pretty accurate idea of the situation. The sea was fairly calm, showing that here, at least, the gale had blown itself out. The water, too, was clear and comparatively shallow, the bed consisting chiefly of white sand. Visible against the bottom of the sea was a long grey object, sufficiently distinct to enable Blake to decide that it was a submarine.

Less than three hundred feet above it hovered the Zeppelin, flying slowly dead into the eye of the light breeze and thus endeavouring to keep almost stationary over the submerged craft.

On her part the submarine was creeping over the sandy bottom, sometimes backing astern and striving to hide herself in the disturbed water from the watchers on the Zeppelin.

The airship, intent upon the destruction of the submarine, had now descended to within two hundred feet and was dropping specially shaped bombs resembling aerial torpedoes. On striking the surface of the water these diabolical contrivances would plunge to the bottom under their own weight and momentum, then exploding with sufficient force to destroy any craft within fifty feet. Up to the present, however, the Zepp had not scored, although the crew were getting nearer their objective with each missile they dropped.

A sharp order and Athol and the sergeant manned the two automatic guns. Although the weapon did not fire shells, the peculiar nature of the bullets would enable them to rip up the airship's envelope like a jagged knife once the gun could be brought to bear.

All intent upon the destruction of the submarine the crew of the gas-bag had no inkling of the presence of the battleplane until a regular sheaf of bullets struck the Zeppelin well for'ard. In a couple of seconds the pilot's gondola was completely wrecked; but the ballonets came off comparatively lightly. There was a rush on the part of the Zeppelin's crew to man their guns, while with a bound the airship shot vertically upwards, intent upon gaining a greater altitude than that of her attacker.

But for once the commander of the airship had underrated the climbing capacity of a "heavier-than-air" machine; for, anticipating the manoeuvre, Blake set the battleplane to climb at her maximum speed.

With her fuselage pointing almost vertically the battleplane rose under the powerful beats of her wings. Thanks to the balanced gear of the seats, all four of her crew felt no inconvenience. Athol and Sergeant O'Rafferty were pumping in hundreds of nickel bullets, until it seemed as if the Zeppelin must be riddled through and through.

Still the gas-bag rose. Two of her guns were replying to those of the battleplane, firing a sort of combined high explosive and shrapnel three-pounder shell.

Long rents were now visible in the glistening sides of the envelope, as the shower of bullets completely penetrated the frail covering to the numerous gas-filled sub-divisions of the air-ship. Yet she showed no tendency to drop. Her upward motion seemed uninfluenced by the loss of hydrogen; but whether this was owing to the great reserve of buoyancy or to the immense quantities of ballast thrown overboard, none of the battleplane's crew could decide.

While the British automatic guns were making hit upon hit the German fire was becoming more and more erratic. The first few shells hurtled perilously close to the battleplane; fortunately the time fuses had been badly adjusted, for the missiles burst harmlessly a couple of hundred yards beyond their objective. But after a few rounds a kind of panic must have seized the Hun air-pirates. Perhaps they realised that they were "up against" something that was their superior in manoeuvring and offensive powers, for they blazed away recklessly without scoring a single hit.

Throughout the race skywards the battleplane easily held the ascendancy, and as the Zeppelin reached a great altitude the increasing rarefaction of the air, in addition to the loss of hydrogen through the perforation of the ballonets, began to tell.

"She's dropping," exclaimed Dick, enthusiastically, as the huge fabric began to drop stern foremost.

Right above the now doomed Zeppelin flew the battleplane. In this position she could no longer give or receive blows, for the Zepp mounted no guns on the upper side of the envelope while the battleplane's automatic weapons could not be sufficiently depressed to bear upon her antagonist. Had Blake any bombs in reserve he could have easily destroyed the airship with one properly-placed missile, but his last had already been used to good purpose in the raid upon the German capital.

In almost absolute silence the battleplane dropped in short spirals, following the downward plunge of her defeated foe.

Suddenly the British machine gave a terrific lurch. To the lads it seemed as if the whole bulk of the mechanical bird was being hurled sideways. They were dimly conscious of the fuselage turning rapidly and erratically around the gimballed seats, while the air was rent with vivid flames and pungent volumes of black smoke.

In vain Blake attempted to lock the wings, The controls, fixed to a dashboard on the coaming in front of his seat, were moving too rapidly past his outstretched hand as the body of the machine rolled over and over.

The horrible thought that the battleplane was rushing headlong to destruction gripped the minds of all on board, yet not a cry burst from their tightly set lips.

With a rending crash something penetrated the floor of the fuselage, and, missing Athol's feet by bare inches, vanished outwards through the deck, tearing a jagged gash through which the lurid smoke-laden clouds could be plainly discerned. Fragments of metal, none of them of any size, began to patter upon the aluminium framing.

All this took but a few seconds, for with a rush like that of an express train emerging from a dark tunnel, the battleplane, still tilted on her side, shot into the pure sunlit air. Then, gradually recovering her normal trim, she allowed herself to come once more under the control of her designer, builder and pilot.

Shaken and well-nigh breathless, for the atmosphere through which the machine had plunged was highly charged with poisonous fumes, it was some minutes before Athol and Dick fully realised that they were still alive. Almost their first thoughts were concerning the Zeppelin. In vain they looked over the side of the chassis in the hope of seeing a tangible proof of their victory. The airship was no longer in existence. An explosion, either the result of an accidental ignition of the escaping hydrogen or of a deliberate act on the part of the crew, had literally pulverised the huge and frail structure. The battleplane, almost immediately above the source of detonation, had narrowly escaped destruction, having been enveloped in the terrific up-blast of the fiery gases. The sliver of metal that had only just missed Athol's legs was a piece of aluminium sheeting from the dismembered Zeppelin, for it was afterwards found bent round one of the girders of the landing-wheel framework.

"I'd like to wait till the submarine reappears," remarked Blake, "but it's getting too late to-day. We are, I should imagine, less than a hundred miles from Riga, and it wants but an hour and a half to sunset. By the by, has any one seen anything of Private Smith?"

No one had. When last heard of the ex-prisoner had been sleeping soundly in one of the bunks.

"See where he is, sergeant."

O'Rafferty descended from his perch and entered the interior of the fuselage. The bunk was empty. A couple of blankets hitched up upon some hooks in the ceiling trailed forlornly to the floor.

"You there, Smith?" shouted the sergeant.

"Here, sergeant," replied a drowsy voice from the very after end of the tapering body. "Have they finished strafing us yet?"

Wedged in so as to be incapable of moving hand or foot was the imperturbable Private Thomas Smith. When the battleplane had commenced her almost vertical leap in her encounter with the Zepp, the Tommy had been shot from his bunk. Alighting on the floor he had slid aft to the position in which O'Rafferty had discovered him. There, throughout the erratic and violent motions of the battleplane following the explosion of the airship, he had lain, too sleepy to realise what was taking place, and when roused by the Sergeant's voice he was still under the impression that he was in a dug-out somewhere in France during a heavy bombardment by hostile guns.

The sun had dipped behind the waters of the Baltic as the battleplane flew serenely across the broad waters of the Gulf of Riga. A thousand feet beneath the airmen lay a powerful Russian squadron, including dreadnoughts, armoured cruisers and destroyers.

Keenly alert to the possibilities of hostile vessels from the air the Czar's sailormen were quick to discern the approach of a strange and altogether remarkable battleplane. Soon the distinctive tri-coloured circles could be discerned. All doubt as to the nationality of the mysterious aircraft was now at an end, and the British machine was given three ringing cheers, the volume of sound being easily heard by her crew.

Five minutes later the battleplane came to earth upon the Ruski Aviation Ground, a few miles eastward of the Slavonic stronghold of Riga.

Upon alighting Blake and his companions were warmly greeted by a group of Russian staff officers, some of whom spoke English fluently, while all could converse with the utmost ease French.

"You are slightly beyond the scheduled time, Monsieur le Capitaine Blake," remarked a courteous colonel of the Preveski Guards. "We trust that you met with no misfortune?"

"Slight mishaps that proved blessings in disguise," replied Blake, as he proceeded to give a brief outline of the battleplane's adventures.

"Extremely gratifying," declared the Russian. "And your compatriots have done well in the raid, although, alas, they have lost heavily. Of the number that left the soil of France for this lengthy flight only six have contrived to arrive here."

"And one cannot make omelettes without breaking eggs," added another of the Czar's officers. "Ma foi! From all accounts you British have made a fine hash of Berlin."

CHAPTER XX

LIBERATED

A prolonged spell of steady westerly winds delayed the British air squadron's return to the Western Front. A week or more had passed since the arrival of Blake and his companions on Russian soil, and although the hospitality of their hosts exceeded all expectations, the airmen eagerly looked for a favourable breeze to aid them on their lengthy flight.

Especially was there anxiety when they learnt the news—a widespread secret—that the great Anglo-French offensive was shortly to take place. On the Eastern Front, especially in Bukovina, the Muscovite troops were displaying great activity. Already the Austrians were being pushed back in headlong rout towards the Carpathians. In Italy, too, their frenzied offensive, which in the first instance had pushed Cadorna's troops from the Trentino Mountains, had been checked and hurled backwards by the magnificent valour of the Italian armies.

On the Western Front Verdun was still proving the grave of thousands of the Kaiser's troops, who, in hopes of being able to announce a splendid though costly victory, had been ineffectually hurled day after day upon the grim, determined lines of Frenchmen backed by their tremendously effective "Seventy-fives."

Meanwhile in the neighbourhood of Riga Hindenburg had to be watched. More, his projected offensive had to be met and broken. Here, too, there was a good prospect of success for the Allied arms, for not only had the Russians vast reserves of men and munitions, but since the bad smashing of the German Fleet off the Jutland shore, the danger of a naval attack upon Riga was at an end. And not only that; the almost intact Russian Baltic Fleet, aided by a number of British submarines, could co-operate with the land forces and seriously menace the left flank of the German armies in Courland.

Private Thomas Smith, who was now putting on weight rapidly and was fast recovering his normal health and spirits, had been made a supplementary member of the battleplane's crew. On learning the names of his new officers he made the announcement that for three months during his incarceration at Meseritz he had been acting as servant to Athol's father.

There were, he reported, four British officers at the prison camp, on whom the task of maintaining discipline devolved; for, owing to the horrible sanitary conditions and totally inadequate food, typhus had broken out in the camp. It was Wittenburg all over again. The Prussian guards, terrorised by the thought that they were exposed to the dread disease, had kept well aloof from their prisoners, supplying them food by means of iron trucks that were hauled in and out of the camp by endless ropes. To make matters worse the trucks were liberally sprinkled with chloride of lime, which had the effect of making the already unwholesome food absolutely unpalatable.

"Not a single man of us left the camp alive during those days," continued Smith. "Afterwards it got a lot better, so they hired us out like a lot of cattle. As things went it turned out all right for me. No, sir, I haven't seen anything of Colonel Hawke for nearly six months. He was all right then—as well as could be expected in that horrible den."

At daybreak on the following morning the rumble of guns, that for the past week had been intermittent, increased into a continuous and terrific roar. All along the Courland Front dense clouds of smoke drifted slowly across the Russian lines. The ground, twenty miles from the actual scene of the furious cannonade, trembled under the pulsations of the concentrated artillery.

"Would you like to have a nearer view of the action?" enquired the courteous Russian colonel who acted as the British officers' principal host. "To-day we hope to achieve something."

"Our battleplane is at your service, sir," replied Blake.

"No, no," protested the Russian. "That is not what I meant. Your work is best performed on your own front when the climatic conditions permit of your return. Here, while you are on Russian soil, it is our duty to take good care of you. Nevertheless, should you wish to see how your Russian brothers-in-arms can fight the Huns——?"

"Assuredly," replied Blake.

Within five minutes a swift motor-car was in readiness. Accompanied by two Russian officers, Blake, Athol and Dick were soon speeding over an excellent road that had only recently been completed—one of the vast network of communications made by the Russians during the winter of 1915-16, and which enabled them to move their troops with the same facilities as did their highly-organised foes.

"This is as far as I dare take you, gentlemen," announced one of the Russian officers, as the car came to a standstill in the rear of a slightly-rising ridge. "His Excellency Colonel Dvouski has impressed upon me the necessity of caution. It will be fairly safe to walk to the summit of this hill. From it we can see much of the operations."

The party alighted and accompanied their guide. The view at first sight was distinctly monotonous. Both the Russian and the German triple lines of trenches were completely invisible, the zigzag lines of clay being garbed in a verdant cloak of wavy grass interspersed with gay-coloured flowers. But, although the trenches were concealed from direct view the Russian gunners had the range of the hostile guns to a nicety, thanks to the efficient aid given by their observing aeroplanes.

As far as the eye could reach the German lines were being subjected to a terrific bombardment. Clouds of dust and smoke, mingled with flying timbers, sandbags, human bodies and limbs testified to the stupendous power of the high-explosive shells which Russia's erstwhile foe was now lavishly pouring into her new ally's magazines.

Two miles beyond the German third line trenches another deluge of shells was falling, forming a "barrage" or impassable zone of fire in order to prevent the enemy's reserves from being rushed up to assist the already demoralised front line defenders.

The Russian officer consulted his watch.

"In seven and a half minutes from now," he announced laconically and as calmly as if he were stating the time of departure of a train.

Breathlessly Athol and Dick watched the bursting shells, mentally comparing the hail of friendly projectiles with the state of affairs when they were "foot-slogging" in the Flanders trenches. Then they were in the unenviable position of being subjected to a heavy "strafing" with the disconcerting knowledge that the Huns were sending three shells to the British one. Now, thanks to energetic measures to provide munitions, it was the other way about. The sight that the lads witnessed near Riga was but a part of a similar and concerted plan of action stretching between the Baltic and the Carpathians on the Eastern Front; from the North Sea to the Swiss frontier on the Western, and in no less a degree against the Austrians on the Italian border.

Suddenly the guns pounding the German first line trenches "lifted," transferring their hail of projectiles to a line well beyond. Simultaneously swarms of grey-coated Russian infantry appeared from the invisible trenches, clambered over the parapets, and surged shoulder to shoulder across the intervening "no man's land."

Numbers fell, for the Huns had contrived, even amidst the inferno of high explosive shells, to keep some of their machine-guns intact.

But the Czar's troops were not to be denied. With the sunlight glinting upon their long bayonets, and with a succession of rousing cheers they swept forward unfalteringly and irresistibly.

Penetrating the barbed wire entanglements they closed. Here and there bayonet crossed bayonet, or clubbed rifle fell upon foeman's skull, but for the most part the Huns, their spirits crushed by the nerve-racking bombardment, threw down their rifles and raised their hands above their heads in token of surrender.

Over the parados of the captured trench swept the triumphant troops, hurling hand grenades by hundreds into the second line of Hun defences. The reserve trenches shared the same fate, and in less than forty minutes the surviving Germans, unable to flee owing to the steady barrage fire, surrendered to their hitherto despised foes.

Already swarms of prisoners, closely guarded, were being marched to the rear of the Russian positions, while a long line of wounded, some supported by their comrades, others borne in stretchers, and others walking slowly and painfully, testified to the stubbornness of the conflict.

"What are those fellows doing, I wonder?" asked Dick, indicating a large body of unarmed men who were approaching with every indication of delight. They were still some distance off, but by the aid of their binoculars Blake and his party could see the men with comparative distinctness.

They were clad mostly in a motley of rags Their faces were black with dirt and almost hidden by long, straggling beards. Yet in spite of their battered and scarecrow appearances they marched with a good idea of military order.

"Poles, perhaps," suggested one of the Russian officers. "The Huns have forced a lot of them into their ranks. That is what the Germans meant by granting them self-government."

"You are wrong there, Alexis Ivanovitch," said his brother officer, speaking in French, for, out of politeness to their guests, they had refrained from talking to each other in their native tongue. "Those men are not Poles; they are English and French."

"Surely?" inquired Blake incredulously.

"I am certain of it," continued the Russian. "They are some of the prisoners whom the Huns have sent from their concentration camps to work in their trenches on this front. These Germans have a saying, 'Scratch a Russian and you will find a Tartar.' The whole civilised world can now very well say, 'Show me a Hun and I will show you a brute.'"

Nearer and nearer marched the ragged regiment, proceeding along a road that led about a quarter of a mile from the hillock on which Blake and his companions were standing.

"Let us go and give the poor fellows a bit of a welcome," he suggested, to which the Russian officer agreed.

Suddenly, to his comrades' surprise, Athol broke into a run and made straight for the advancing men. His sharp eyes had discovered a tall, attenuated figure at the head of the column. In spite of the grey beard, the hollow cheek, and bent shoulders the lad recognised his father. Not so Colonel Hawke; he never expected to find his son, a tall strapping youth in the uniform of an officer of the Royal Flying Corps, on this remote corner of Russian soil.

When at length the colonel grasped the situation, he could only gasp in speechless wonderment, while Athol shook his hands as if they were a couple of pump-handles.

The rest of the released prisoners, numbering half a dozen British and French officers, and about four hundred men, halted, broke ranks, and crowded round the rest of Blake's party, filled with delight at the sight of the well-known uniforms once more.

At the same time a Russian regiment on its way to the captured positions halted. The troops with characteristic kindness were soon offering their water-bottles, rations and tobacco to their starving allies.

"It has been simply hell," declared Athol's father, after he had recovered from the surprise that had all but rendered him speechless with emotion. "Those swine of Germans compelled our poor fellows to slave in their first-line trenches. Our spirit was broken by hunger and exhaustion. We would have welcomed a Russian shell, but even that was denied us. They pushed us into dug-outs and mine galleries, and kept us there for three days without food. Thank heaven, though, the boys kept their end up pretty well. At least three large mines failed to explode as the Russians stormed the first line trenches, and I think I know why. We tampered with the wires."

"We have a motor-car which is at your disposal, Colonel Hawke," said the Russian officer responsible for the safety of the British airmen. "It will indeed be an honour to offer you hospitality."

Athol's parent shook his head.

"Many thanks, sir," he replied, "but I must decline. Until I see these men safely quartered and given a good meal my place is with them. Well, good-bye, Athol, for the present. I'll try to look you up this evening. I say," he added anxiously, "what's this we've heard about a great German naval victory in the North Sea?"

"If the fact that Wilhelmshaven and Kiel are chock-a-block with crippled German warships, that a score or more are at the bottom of the North Sea, and that Jellicoe's fleet still holds undisputed mastery of the sea—if that constitutes a German victory they may repeat their success as many times as they like," observed Desmond Blake. "I suppose that in Germany the people still believe the tissue of lies issued by the German Admiralty. Already neutrals know the truth. I feel sorry for the Kaiser when his subjects learn the actual facts."

"I feel sorry for no German," declared Colonel Hawke. "I never was of a vindictive nature, but—a Somali would give a Hun points as far as 'culture' is concerned, while an Afghan or a Turk is streets above the brutal, degraded louts who sport the Kaiser's uniform. My great wish at the present moment is to get back to England as soon as possible, pick myself up—and I want a lot of feeding up, I fancy—and then have another go at the Huns."

CHAPTER XXI

ONE GOOD TURN DESERVES ANOTHER

For another three days the battleplane rested on Russian soil, the climatic conditions remaining unfavourable for the much desired return journey.

During that period Athol saw a good deal of his father, for the rescued prisoners were quartered in a little village within three versts of the flying-ground.

There was every possibility of the colonel's wish being speedily gratified, for arrangements were already in progress for sending the released officers and men back to England by ship from Archangel.

Private Tom Smith elected to go with them, although not until he had spent many an anxious hour deliberating the matter in his mind. He was already a keen airman; he realised his debt of gratitude to Dick and the battleplane's crew for getting him out of a most unpleasant situation. On the other hand he was deeply attached to his old master, Colonel Hawke. With him he had shared the horrors of the Meseritz Prison Camp, and the private's sense of loyalty to his chief, coupled with his desire to share in the colonel's resolution to "get his own back" upon his former captors, decided him to throw in his lot with his master.

At five o'clock in the morning of the seventeenth day of their visit to Russia the battleplane's officers were aroused by Sergeant O'Rafferty announcing that the wind had veered and was blowing steadily from the north-east and seemed likely to remain so.

Wireless reports from Russian warships far out in the Baltic confirmed the statement. There was every indication of the favourable air-drift continuing for some days.

Already the battleplane was in readiness for flight. Her tanks had been replenished with petrol, her motors overhauled. There was still an ample reserve of machine-gun ammunition, while the Russian authorities had supplied a dozen bombs filled with a super-powerful Japanese high-explosive. The rents in her wings and in the body of the fuselage had been made good, numerous neat patches bearing a silent testimony to the ordeal through which she had successfully passed.

In accordance with the perfect array that existed between all the Allies Blake had given the Russian aeronautical engineer every facility to study the constructive details of his invention; and it was more than likely that before the war had come to a victorious conclusion, battleplanes after the model of the mechanical bird would be seen operating under the control of Russian airmen.

Having taken farewell of their hospitable hosts the crew of the battleplane prepared to set out on the return journey. This time they flew alone, for the remaining British biplanes that had taken part in the raid had already left. Acting under previous orders they had flown southward, and after a rest at Odessa, had passed over Constantinople, arriving safe and sound at the Allied Camp at Salonika.

Amidst salvoes of cheering from the swarm of grey-coated Russians the battleplane—"secret" no longer—rose steadily and faultlessly, and shaped a course towards the Baltic.

"I've decided upon an alteration of plans," announced Blake. "The deciding factor is the petrol question. If we fly direct and over German territory, we may run short of fuel and have to descend. You see, the spirit we are now using is different from the prepared petrol that brought us here. Whether we can cover the whole distance or not without replenishing remains to be seen. So I propose keeping over the Baltic and thence over the Cattegat and Skager Rack. By the time we are in the vicinity of the Skaw I shall be able to determine whether there will be enough petrol to carry us the rest of the way."

"And if not?" enquired Athol.

"Details already arranged," said the inventor, with a grim chuckle. "The Admiralty have instructed a tank-vessel, escorted by cruisers and destroyers, to lie off the Norwegian coast, well outside the three mile limit. That's a pretty tangible proof that we hold the sea."

At a rate approaching one hundred and eighty miles an hour the battleplane was soon out of sight of land. She had at first held a north-westerly course in order to avoid passing over Libau, then in the possession of the Germans. Blake, although he would not have declined another aerial fight, was anxious to traverse the Baltic before the Huns were aware that he had left the Russian frontier. There was work awaiting the battleplane in France—work of far more importance than engaging individual hostile seaplanes in the neighbourhood of the Cattegat.

Fifty minutes after leaving Riga the Swedish island of Gothland was sighted. At this point the course was altered to the south-west, until the island of Bornholm was discerned.

Although numerous Russian warships and patrol-boats had been sighted at the entrance to the Gulf of Riga the Baltic was almost deserted, except towards the Swedish shore, where several enemy merchantmen were hugging the coast in order to avoid the studied attentions of the British and Russian submarines. But of German warships there was no sign.

Presently Blake's trained ear caught a disconcerting sound that was repeated time after time with increasing frequency. Dick, sliding from his seat, made his way to the motor-room; then, after a brief examination, approached his chief.

"She's firing badly," said Blake gravely.

"Yes," assented Dick. "It's not the ignition this time. It's the petrol. It is my belief that either the stuff is very inferior or else that it has been watered. Whatever it is the rotten stuff is now passing through the carburettors. Hitherto we've been running on the petrol we brought with us."

"Was it strained?" asked Blake anxiously.

"I stood by and saw it done," reported Dick. "Of course some one might have tampered with the tanks during the night. There are spies with the Russian troops as well as there are in the French and ours, worse luck. There she goes again," he added, as the motors faltered badly for several strokes and then spasmodically fired again. "Ought we to turn back?"

"I don't believe in turning back," said the inventor. "No, the sea is calm, there are no vessels in sight. We'll volplane down, rest on the surface and re-strain every drop of petrol on board."

Preparations were quickly made for the venturesome enterprise. The hatchway in the floor of the fuselage, which was already shut, was now hermetically sealed by means of wing-nuts that jammed the metal flap hard down upon an indiarubber seating. A similar watertight covering closed the aperture through which the bombs were dropped in action. The exhaust, which generally led through a pipe on the underside of the rear part of the chassis, was diverted by means of a two-way union so that the former escaped from an outlet and projecting well above the deck. Thus, in less than five minutes the hull of the battleplane was made absolutely watertight and ready to float upon the waves.

Being unprovided with floats like those fitted to naval seaplanes the machine took the water clumsily. The sudden resistance of the girders carrying the landing-wheels as they encountered the water, caused the body to tilt nose downwards. With solid water well over her forepart, the battleplane shook herself free, bobbed violently several times and finally rocked easily upon the placid waters of the Baltic.

Leaving Athol to keep watch all remaining hands set to work. First the contents of the carburettors were strained. Globules too heavy to pass through the fine meshed gauze confirmed Dick's suspicions. The petrol had been heavily "doctored" with water.

It was a lengthy and disagreeable task draining each of the tanks and refiltering the liquid fuel. The atmosphere of the confined space reeked of petrol fumes; the unusual motion of the hull as it pitched and rocked to the action of the sullen waves added to the discomforts of the highly necessary work. Sergeant O'Rafferty, almost overcome with nausea, stuck gamely to his job, while both Dick and Desmond Blake felt their heads whirling under the powerful influence of the volatile gas.

Suddenly Athol perceived two pole-like objects forging slowly through the water at a distance of nearly a quarter of a mile. Only the feather of spray caused by the resistance of the vertical objects betrayed their presence. They were the twin periscopes of a submarine.

At his shout of alarm Blake and the rest of the crew left their task and hurried to their respective flying-stations. Anxiously they awaited developments. Was the submarine a friend or foe?

Flight, under present conditions, was impossible.

Until the whole of the petrol in the tank nearest the carburettors was completely strained, it would be impossible to get the motors to fire.

Quietly Athol and the sergeant fitted ammunition belts to the two automatic guns. Although the bullets did not possess sufficient penetrative powers to perforate the shell of a submarine the hail of projectiles would be sufficient to prevent any attempt on the part of the vessel's gunners from using their quick-firers—provided they kept within range. Nor could the submarine make use of a torpedo, for the lightness of the battleplane's draught—floating she drew but four or six inches—offered no target to an under-water missile unless the weapon struck the girder-work of the landing-wheels which projected several feet underneath the surface.

Nevertheless the situation was a perplexing one. Should the submarine prove to be German, she could either shell the battleplane from a distance or else summon, by means of wireless, Zeppelins and seaplanes to finish off the helpless aircraft by means of bombs.

Several long-drawn-out minutes passed. The eyes of the periscopes were steadily fixed upon the battleplane as the invisible submarine slowly approached. At length, apparently satisfied with her investigations, the submerged craft housed her periscopes and made off, leaving a tell-tale swirl upon the surface of the water.

"She's off, sir," exclaimed O'Rafferty.

"Yes, for the present," replied Blake. "She'll be at it again, I fancy. Come on, lads, let's carry on. Another half hour will see us straight."

Leaving Athol still on watch the rest of the crew resumed their labours, but before they had been at work for another five or ten minutes the submarine appeared upon the surface at a distance of nearly two miles.

"The brutes!" ejaculated Blake. "They've spotted our automatic guns. We'll be having some three pounder shells this way before long."

Bringing their glasses to bear upon the low-lying hull of the submarine the airmen found that their fears were realised. The vessel was a large unterseeboot flying the Black Cross ensign of Germany. She was lying broad-side on and forging ahead at a rate of about five knots. The two quick-firing guns were already raised from their respective "houses" or watertight troughs, and were being served by their gunners.

A flash followed by a dull crack announced that the submarine had opened the ball.

"You'll have to do better than that, old sport!" exclaimed O'Rafferty disdainfully, as the projectile struck the water at a hundred yards beyond the target, and ricochetting with a tremendous splash, finally disappeared a mile and a half away.

Again and again the Huns fired, each shell approaching with uncanny and methodical exactness nearer and nearer the crippled battleplane. They were blazing away with plugged shell, and that fact, combined with the evident reluctance of the submarine's crew to score a direct hit, told the airmen pretty plainly that the Germans wished particularly for their surrender and the capture of the battleplane intact.

From time to time Athol and the sergeant let loose a few rounds of ammunition, but in spite of the extreme elevation of the sights of the automatic weapons the bullets all fell short.

Suddenly Athol ducked his head as a projectile hurtled through the air less than ten feet above him. He could distinctly feel the windage of the missile, while the screech was appalling. The Huns, getting out of patience with the resistance of the British battleplane, were trying to shell it in grim earnest.

But before another shell could be fired from the U boat, a column of foamy water shot up a couple of hundred feet into the air. For a brief instant the bow and stern of the submarine showed, tilted up at different angles to the surface of the water. Then, as the muffled roar of an explosion was borne to the ears of Blake and his companions, their antagonist simply vanished, leaving a maelstrom of boiling water to mark her tomb.

"Hurrah!" shouted Dick, the first of the delighted and astonished men to find his voice. "She's gone. Wonder what's happened?"

"One of her torpedoes gone off by accident, I expect," hazarded his chum. "It seemed like an internal explosion."

"At any rate, she's gone," observed Blake thankfully. "Now, lads, let's get on with the business, before there are a swarm of patrol boats on the scene. I shouldn't wonder if the noise of that explosion were heard fifty miles away."

Leaving Athol again on watch the others continued their interrupted labours; but before another ten minutes had elapsed came the watcher's doleful shout:—

"Another submarine!"

The new-comer had appeared upon the surface apparently without any preliminary investigation. At least Athol had not noticed the periscopes until the vessel rose at a distance of a cables length away.

She bore no number or distinguishing marks, but hardly was she awash when the conning-tower hatchway was opened, and a seaman dressed in a thick "fearnought" suit, appeared. Making his way aft he tugged at the halliards of a short flag-staff, and instantly a flag was "broken-out," fluttering proudly in the breeze.

It was the glorious White Ensign.

Others of the crew now appeared, as the submarine, forging gently ahead like an enormous porpoise, closed with the battleplane that she had so timely rescued. Then, slowing down, she came to a standstill ten yards to windward of the crippled aircraft.

"Heave us a line if you have one on board," shouted a boyish-looking lieutenant-commander, who, as he smiled displayed a set of white teeth that contrasted vividly with his deeply bronzed complexion. "We'll have all on board in a jiffey."

"We haven't a line," replied Blake courteously, "and we don't want to come on board, thanks all the same. We're effecting repairs and then we're off, I hope."

"Thought that Hun was strafing you," remarked the young officer.

"He was about to, when—I suppose you bagged him."

"We did," agreed the lieutenant-commander with pardonable pride. "We're out of your debt now, I take it."

Blake was genuinely taken aback.

"You've a bad memory, I'm afraid," continued the skipper of the submarine. "T'other day a Zepp was strafing us, and you strafed the Zepp. We came to the surface in time to see you sheering off. Nasty quarter of an hour while it lasted, by Jove! So now we're quits. Well, what's wrong?"

The difficulty with the watered petrol was explained.

"Don't bother about the rest," said the lieutenant-commander. "We've plenty on board. Only replenished at Cronstadt yesterday, and we don't do much surface running. We'll soon fix you up."

In a brief space of time a delivery hose was passed from the submarine to the battleplane, and with a prodigal generosity gallons of petrol were pumped into the latter's tanks.

During the operation Athol was engaged in conversation with the sub-lieutenant of the submarine, each, with pardonable pride, maintaining that his branch of the respective services afforded the greater excitement. While the lieutenant-commander of the submarine paid a visit to the battleplane, Athol went on board the naval craft, and was shown most of the wonders of the latest type of under-water warship.

Just then the skipper of the submarine made a flying leap from the deck of the battleplane to the platform of his own craft.

"Back with you!" he exclaimed, addressing Athol, who was in the act of emerging through a hatchway. "Sharp as you can, unless you want a trip with us. There's another strafing match about to commence."

High up and several miles away to the south-westward at least a dozen black specks were visible against the cloudless sky. A fleet of hostile seaplanes was approaching with the evident intention of making it hot for the British submarine.

"Sure you can start?" shouted the lieutenant-commander as he slid down the conning-tower hatchway.

Blake gave an affirmative reply, which was confirmed by the engines being set in motion.

"S'long!" was the naval officer's farewell greeting as he slammed the rubber-lined hatchway cover. Then, forging quickly ahead the submarine dipped her nose and slid swiftly beneath the surface.

CHAPTER XXII

ALL GOES WELL WITH ENGLAND

With her replenished stock of fuel the battleplane had no difficulty in rising once she was clear of the surface; for, owing to the absence of properly contrived floats and the restricted limit of the beats of her wings, the tips of which could not be dipped into the water without considerable risk, she could not soar at her usual angle. It was only after "taxiing" for nearly two hundred yards that she was able to shake herself clear of the unnatural element.

"Much more of this sort of business and I shall have to modify the design," declared Blake. "Ah, here they are again," he added, indicating the approaching seaplanes.

"Stand by with the guns. I'm going right through them."

With this laudable intention Blake took the battleplane up quite a thousand feet above the altitude of the hostile aircraft, and at full speed tore to meet the hostile seaplanes.

By this time the Huns had learnt of the presence of the battleplane. Recognising her by the beat of the powerful wings they one and all declined combat, and scuttling like a flight of wild duck, made rapid tracks for home.

"That's decided me," declared the imperturbable pilot. "We'll make a short cut for home. O'Rafferty."

"Sir?"

"Send off a wireless to the petrol depot ship. We are within call, I fancy. Tell them not to wait. We have more than enough petrol to take us home."

"Now, Athol," continued Blake, "I'll give you fellows a sight of the Kiel Canal and of Heligoland. I don't suppose any British airman has seen Billy's ditch from the air before."

At an immense altitude the battleplane swung round, crossing the Schleswig-Holstein isthmus at a height of seventeen thousand feet. Unseen—or if she were seen no attempt on the part of the Huns was made to molest her—she glided serenely across to Heligoland Bight, the islands of Heligoland and Sandinsel looking like mere dots in the sea. Then following the chain of Frisian Islands she skirted the Dutch coast on her way south-westwards.

In about nine hours—including the stop for repairs—the battleplane had covered a distance of nearly a thousand miles, and was within half an hour's run of the opposing forces on the Western Front.

Already the airmen could feel a strange rumbling sensation in the rarefied air. It was not the thunder of the guns in Flanders—it was something far louder than that. The concentrated fire of hundreds of enormous allied guns was literally shaking the firmament.

"I know where we are now," declared Blake. "That town we can see ahead is Peronne. By Jove! we're in time to see the 'Big Push,' lads. Look, our line is different from what it was three weeks ago. It's beyond that village—Fricourt, I think is its name."

In vast circles the battleplane volplaned earthwards, the two lads and O'Rafferty surveying the scene of terrific carnage by means of their binoculars.

There was no doubt about it. Our khaki-clad troops, recking not the stubborn resistance of the grey-coated Huns, were pressing forward with bombs and bayonets. All along the line, as far as the limit of vision permitted it to be seen, the lads could mark the irresistible progress of their brave countrymen and the equally gallant French allies. Overhead, although at a considerably lesser altitude, flew swarms of aeroplanes, all bearing the distinctive marks of red, white and blue. Of the Black Cross machines not one was visible. It was an Allies' day with a vengeance.

Unable to take part in the operations for want of previous instructions, Blake manoeuvred the battleplane up and down the changing line of opposing forces. The spirits of the two lads rose to high water mark. They realised that this was the beginning of the end; the set purpose, which after weeks and months of tedious and seemingly wasteful inactivity, was to justify the waiting tactics of the silent Joffre.

Suddenly Athol noticed an ominous movement in our part of the far-flung line. A village, although the buildings were almost levelled by the accurate gunfire of the British, was still being held with the utmost stubbornness by the Huns.

Evidently the enemy had preserved a number of machine guns intact in spite of the terrific hail of shells. The British, pinned to the earth by the terrific machine-gun fire, were unable to advance; while evading the "barrage" of shells, strong reinforcements of Germans were being rushed forward to convert the British check into a defeat—glorious but none the less a set-back that might adversely influence the concentrated operations.

And, with the exception of Blake's battleplane there was no other British machine to warn the infantry of the approach of the German reserves.

"Now for it!" shouted Blake, the glint of battle in his eye. "Let 'em have bombs and flêches when I give the word. Get ready with the automatic guns."

Athol, the end of the ammunition belt already in the breech mechanism, depressed the muzzle of his weapon. O'Rafferty was ready on his part, while Dick stood by to operate the bomb dropping gear, keeping one hand on the lever that would release hundreds of steel darts upon the close columns of German troops.

Like a hawk the battleplane swooped down, descending to less than four hundred feet. Greeted by a terrific fusillade from the rifles of the astonished and demoralised Huns she returned the compliment with interest. Bombs, darts and bullets wrought havoc in the crowded ranks, until the survivors broke and fled, leaving a trail of dead and wounded as they sought a doubtful shelter from the terror of the skies.

Dismayed by the rout of their supports the defenders of the ruined village slackened their fire. Quick to seize the advantage the British troops, with a cheer that could be distinctly heard above the roar of battle, swayed forward on and over the rubble of masonry and carried the position.

This much Athol saw. Then his attention was attracted by a groan. With his head and shoulder resting over the coaming lay Sergeant O'Rafferty, the blood oozing from a bullet wound in his neck. Before Athol could make his way to the sergeant's assistance Blake called to him in an unsteady voice to take the steering-wheel.

"The blighters have got me," he exclaimed. "Plugged through both wrists."

"Dick," shouted his chum. "Bear a hand with the sergeant. He's hit. Sharp as you can, then stand by with the motors."

"We'll have to come down," replied Dick. "Petrol tanks perforated."

Only sufficient fuel for half an hour's run remained before the damage was done; with the precious spirit trickling in a steady stream it was doubtful whether the engines could be kept running more than a few minutes.

Dick, too, did not mention that he had stopped a bullet, which, passing through the fleshy part of his right arm, had rendered that limb useless and was causing him exquisite pain.

Just then the motors coughed and stopped abruptly. Athol was only just in time to grip the steering wheel when the long volplane to earth began.

He attempted to tilt the aerilons. The operating rods responded stiffly to the action of the levers. The movable tips to the wings were firmly locked. Absolute control of the battleplane was no longer possible.

"There'll be a most unholy smash!" muttered the lad between his clenched teeth.

The next instant the battleplane flattened out, not under the influence of the pilot's guidance, but through some freakish aircurrent. Then, before she could gather momentum for her tail-dive she crashed to earth.

Myriads of white lights flashed in front of Athol's eyes, and then everything became a blank.

When Athol recovered consciousness he found himself in a base hospital. By his bedside stood Desmond Blake and Dick, both swathed in bandages.

"How goes it?" asked Athol feebly.

"The battleplane's done for," replied Dick.

"She's done her bit, and for a wonder we're all here to tell the tale."

"But the Big Push?" persisted the lad.

Desmond Blake's features were wreathed in a smile that betokened confidence.

"Don't worry, Athol," he replied. "So far all goes well with the arms of England and France."