[Illustration: cover art]

The Sea-girt Fortress

[Illustration: "HAND OVER HAND HE CLIMBED TILL HE REACHED A METALLIC BEAM" Frontispiece]

The
Sea-girt Fortress

A Story of Heligoland

BY

PERCY F. WESTERMAN

Contents

THE

SEA-GIRT FORTRESS

CHAPTER I

Man Overboard

"Where are we now?" asked Oswald Detroit, emerging from the cabin of the Diomeda.

"Ask me another," replied his chum, Jack Hamerton, with a merry laugh. "We may be here, we may be there, for all I know. One thing I am certain of: I have just hove the lead, and found that we are in twenty-two fathoms, with a gravelly bottom. That's good enough for me. Also, by dead reckoning, we are three hundred and seventy-eight miles from Lowestoft, and I can't take an observation because of this fog."

"You don't seem at all anxious," remarked Detroit, who regarded the wall of thick white mist with evident mistrust.

"Why should I? The yacht's as sound as anyone could desire, and we've plenty of sea room. Now, if we were anywhere in the neighbourhood of the sandbanks at the mouth of the Elbe, I might feel jumpy. Take the helm, old man; north, eighty east, is the course. I'll get breakfast."

Jack Hamerton was a tall, broad-shouldered fellow of twenty years of age. He might well be described as thick-set, for his head was set upon his square shoulders by a short, thick neck, his arms were brawny, while his legs would have caused many a professional footballer to turn green with envy. His features were inclined towards heaviness, the bushy eyebrows and square jaw denoting force of character amounting to stubbornness.

He was a sub-lieutenant in the Royal Navy, and had lately been "paid off" from H.M.S. Blazer after an arduous commission in the Persian Gulf. Owing to the particular circumstances My Lords had granted Hamerton three months' leave, and the Sub, with an innate love for the salt seas, had chartered an eight-ton yacht, and with Detroit for company had started on a cruise to Kiel.

Oswald Detroit was physically different from Hamerton. He was tall, but slenderly built, yet there was a suppleness in his muscular limbs that had stood him in good stead in the athletic world. His features were clean-cut and regular, his hair of a light-brown hue and inclined to curliness, while his fair skin, in spite of exposure to the wind and sun, contrasted forcibly with Hamerton's almost swarthy complexion.

Detroit was an American by birth—a native of Richmond, Va.—and American in character to his finger tips. He had great faith in his country, and a heap of self-reliance that had carried him through many difficult places. His powers of argument were marvellous, although he invariably hid his most telling points in debate under a thin covering of dry humour.

It was at Lowestoft that the Sub met his future sailing mate for the first time, only a few days before the momentous voyage commenced. Oswald's sister had married a naval lieutenant, a distant cousin of Hamerton's, and thus the two men came in contact with each other.

In a very few hours a bond of friendship was found, for despite their physical difference Hamerton and Detroit had a lot in common. Both were keen sportsmen, and each took a deep interest in yachting, the American being an active member of the exclusive Marblehead Yacht Club. When Hamerton spoke of a cruise to the Baltic, with the crowning attraction of participating in the international racing at Kiel, Detroit's interest was so marked that it wanted little persuasion on the Sub's part to induce the American to accompany him.

Accordingly the eight-ton ketch Diomeda was chartered. Although somewhat small for an extensive voyage across the North Sea, she was far more seaworthy than many a craft of twice or even thrice her tonnage. Hamerton fell in love with her at first sight. It was not on account of her lines, for an almost total lack of sheer, bluff bows, and rounded run aft were not exactly pleasing to the eye. But there was a substantial appearance about the craft that was far more important than artistic curves, while closer acquaintance revealed the fact that she did not belie her appearance.

Barely twenty-eight feet in length, with a generous beam of a third of her over-all dimension, and a draught of nearly six feet, the Diomeda was snugly rigged and canvased. Her cabin-top was low, offering little resistance to the wind, while her cockpit, lead-lined and self-emptying, was essential for passages across the short steep seas betwixt the east coast of England and the opposite shores of the North Sea.

Descending the short flight of steps leading to the cabin, Hamerton discarded his dripping oilskin, and methodically hung it on two hooks in a cupboard devoted to that purpose.

He was in no hurry: he rarely was, save when occasion necessitated, and only then did his activity become apparent. Otherwise he did things in a cool, calculating way that seemed in keeping with his ponderous form.

The cabin was plainly yet comfortably furnished. On either side were sofa bunks, terminating with spacious lockers screened with curtains. Two scuttles in the rise of the cabin-top and a skylight overhead were sufficient to impart plenty of light, but owing to the flying spindrift these were securely fastened. In the centre of the linoleum-covered floor stood a swing table, on which was spread a chart of the North Sea. On the chart lay a pair of parallel rulers and a dividing compass.

The Sub rolled the chart—placing it in a rack so as to be easily got at should it be required—dived into the pantry, and produced a couple of enamel mugs, plates and rather tarnished knives and forks. Then from another division he hauled out a teapot, some bread, butter, and a bundle of rashers.

Taking the latter, he made his way along the steeply inclined floor towards the fo'c'sle.

On the for'ard bulkhead was a clock and a barometer, surrounded by four signal flags representing the yacht's name in code. The hands of the clock pointed to a quarter to five, the barometer, 30.01, steady; both pieces of information Hamerton entered in a rough logbook.

The fo'c'sle was small, and, being battened down, ill-ventilated. The heat from the Primus stove and the odour from the frizzling bacon, combined with the erratic pitching and listing of the yacht, would have upset many an experienced sailor, but unperturbed the amateur cook proceeded with his self-imposed task.

"On deck, there!" shouted Detroit, raising his voice to make himself heard above the roar of the atmospheric stove.

There was something urgent in the tone of the American's voice. Hamerton backed out of the narrow fo'c'sle door, and, without waiting to put on his oilskin, ran up the ladder and gained the cockpit.

The fog was not so dense as it had been ten minutes previously. The rising sun had partially dispelled the white wall of vapour, so that it was possible to see about fifty yards ahead.

"Listen!" exclaimed Oswald.

"Yes, I hear," replied the Sub. "A steamer of some sort, tearing along at a furious pace. A quarter of a mile off, I should say, but close enough in this mirk."

With that Hamerton snatched up a fog trumpet that lay on the lee seat of the well, and made the welkin echo to three loud blasts—the recognized signal of a sailing vessel with the wind abaft the beam.

No reply came from the unknown vessel. Momentarily the noise of her engines and the swish of water as her bows cleft the waves grew louder and louder.

"Down helm, sharp!" ordered Hamerton. "What in the name of Davy Jones is that idiot carrying on like that for?"

Round swung the Diomeda slowly yet surely, but before the sails began to flap, the disturber of her crew's peace of mind loomed out of the fog.

It was a large destroyer, painted a dull grey. She was travelling at close on thirty knots. Dull red flames were spurting from her four squat funnels. Her decks were being swept from end to end with water, while the spray, dashing against her funnels, trailed off into wisps of steam, leaving the fore side of the smoke-stacks bleached with salt. In spite of the wave-washed decks, men, clad in greenish-grey oilskins, were standing by the two torpedo tubes on deck, while right aft stood a seaman holding a red-and-white flag in his extended hands.

This much the crew of the Diomeda had barely time to take in, for close astern of the leading destroyer came another, and another, and yet another, less than thirty feet separating the black cross ensign of the leading boat from the knife-like bows of the one next astern. Any miscalculations on the part of the coxswains of the several boats would inevitably result in disaster.

Just as the fourth destroyer darted past the violently pitching yacht—for she was in the thick of the combined "wash"—one of her crew, who was in the act of securing a stanchion rail, slipped on the heaving, wave-swept deck. Unnoticed by his comrades, he rolled under the rail and fell into the sea.

The Diomeda was "in irons". Her sails were slatting violently in the wind. She carried no way, nor would she answer to her helm, and some minutes elapsed ere the ketch fell off sufficiently for her canvas to draw.

Running forward and gripping the shrouds, Hamerton seized a boathook. The unfortunate man still floated, face upwards, but made no attempt to save himself.

"Guess he's broken his back," shouted Detroit to his companion, in reply to which the Sub nodded. Falling off a boat travelling at thirty knots, a man would strike the water with terrific force.

"Now luff!" bawled Hamerton. "Easy with your helm—port a little."

Leaning outwards to the full extent of his left arm, the Sub made a futile attempt with the boathook to reach the sailor.

"Up helm, and gybe her," he shouted. "We'll pick him up on the next tack."

Then to his surprise Hamerton saw the American leap out of the cockpit, steady himself on the waterways for a brief instant, then plunge into the sea.

"Silly ass!" grunted the Sub, although recognizing Detroit's pluck. "I'll have two men to haul aboard now instead of one."

With that he made his way back to the cockpit to steady the yacht on her helm. Then it was that he found that Oswald had acted with discretion as well as bravery, for before leaping he had taken a turn of the end of the mainsheet round his waist. Rescuer and rescued were trailing astern at the end of forty feet of rope.

Hauling the Diomeda's headsails to windward, Hamerton soon had the yacht hove-to, though forging slowly through the water. It was then a comparatively easy task to get the mainsheet in until Detroit and the seaman were alongside. Then waiting till a wave brought the man within arm's length, the Sub clutched hold of him, and with a powerful heave lifted him on deck and into the well.

Without assistance Detroit scrambled up, and assisted his comrade to attend to the rescued seaman.

[Illustration "WAITING TILL A WAVE BROUGHT THE MAN WITHIN ARM'S LENGTH, THE SUB CLUTCHED HOLD OF HIM">[

"He's alive all right," announced Hamerton. "A lump of a fellow, by Jove!" he added, critically regarding the stalwart, fair-haired Teuton. "We'll get those wet clothes off him and carry him below. You will do well to change. Never mind about the boat, she'll take care of herself for a while."

The destroyers were now out of earshot, swallowed up in the still dense watery mist. More than likely the absence of the unfortunate seaman would not be noticed for some considerable time, and then it was doubtful whether the vessels of the flotilla would retrace their course far enough to come in touch with the Diomeda.

"I'm glad I didn't miss that sight, by Jove!" said Hamerton, with unstinted praise. "Those Germans know how to handle their torpedo craft. Fancy taking them at that bat through a fog!"

"It's fools' work," said Detroit, who was struggling into a change of clothing.

"All the same, it's part of the game, and only by constant practice can they keep in a state of efficiency. Our fellows are pretty smart at manoeuvring, but these Germans appear to run all sorts of needless risk, and still manage without serious accidents. Finished changing? Good! You might get on deck and see how things are progressing."

Barely had Detroit resumed his post at the helm when out of the fog came a succession of dull flashes, punctuated by the deafening detonation of a number of quick-firing guns. Then, like a veil rent in twain, the fog partly lifted, revealing a large battleship, cleared for action, and blazing away with her light armament in the direction of the small British yacht.

CHAPTER II

Through the Fog

"A German man-of-war!" exclaimed Detroit.

"Yes, one of the 'Deutschland' class," added Hamerton, who at the first report had followed his companion on deck. He recognized the battleship by her three telescopic funnels as belonging to a type immediately preceding the first of the Kaiser's Dreadnoughts. Although her principal armament consisted of only four eleven-inch and fourteen six-inch guns, she was not an antagonist to be despised.

A bugle blared and the firing suddenly ceased.

"She's engaged in manoeuvres," continued the Sub. "Those destroyers we saw are evidently about to attack her, and in the fog she mistook us for one of them."

"Is that likely?" asked Oswald.

"Rather. I know what it is to be on the qui vive. Officers and men are bound to get jumpy, and a dinghy might easily be mistaken for a torpedo boat. Remember the case of the Russian Baltic Fleet and our trawlers in the North Sea some years ago. But now's our chance to get rid of the poor fellow we picked up. Hand me the Code Flag and letter H."

Deftly Hamerton toggled the flags, signifying "Important; I wish to communicate", to the halyards, and hoisted them to the peak.

The German battleship was now less than four hundred yards to leeward and moving slowly through the water. At any moment she might be swallowed up in the fog, which showed signs of increasing in density.

"There's the reply," exclaimed Detroit, as two flags fluttered from the after-mast of the battleship.

"'I F,'" announced the Sub, placing his binoculars on the seat and seizing the codebook. "The rotters! They decline to hold any communication. There, she's off! Steady on the helm, old man! It's time I saw to those rashers."

Once more Hamerton entered the cabin. The rescued man was still lying on the floor, staring vacantly at the skylight.

"Are you better?" asked the Sub in as good German as he could muster. His command of foreign languages, like that of the majority of British officers, was poor. His German in particular was execrable.

"Ja," answered the man, without removing his gaze from the skylight. The reply was purely mechanical, for Hamerton could see that the fellow was not in full possession of his faculties.

"He'll recover all in good time," soliloquized Hamerton as he made his way to the fo'c'sle. "A glass of brandy and water will do wonders. Hallo! What's this?"

For the young officer had made the disconcerting discovery that in the "wash" of the destroyers the frying-pan had jumped off the stove, and four rashers lay stuck to the fo'c'sle floor in their own fat, whilst rivulets of dried grease had traced fancy patterns on the sides of the lockers and over a bundle of spare sails. To complete the disorder, a can of paraffin and a tin full of soda had come into violent contact, with the result that the contents of both gave additional flavour to the stranded rashers. But for this, Hamerton might have replaced the bacon in the frying-pan, reflecting that much of the pleasure of yachting consists in tolerating discomforts. He drew the line at rashers à la soda and paraffin.

"You'll have to whistle for hot grub, Detroit," he called out. "There's a most unholy mess for'ard. Hot coca and biscuits are the best I can do."

Detroit's reply was to give a tremendous salute upon the foghorn, an action that brought the Sub on deck.

"Destroyers are coming back," announced the American, "and the fog is as thick as ever it has been. We've tumbled into a regular hornet's nest of torpedo craft."

Five minutes later the sharp rattle of quick-firers announced that the battleship had been attacked by the destroyers, a form of practice that is regularly gone through by the Kaiser's ships. Then all was quiet.

Two more hours sped. The Diomeda still maintained her course, slipping through the fog-enshrouded water at a bare four knots.

The German sailor, having been given a "stiff peg", was able to sit up. Beyond feeling stiff and bruised by reason of his fall, he was little the worse for his immersion, and, upon being questioned, gave his replies in an intelligent and straightforward manner.

His name, he said, was Hans Pfeil. His rank corresponded to that of Chief Yeoman of Signals in the British navy. His ship was S167, one of, the most powerful of the Elbing-built destroyers, and belonging to the Second Division of the Borkum flotilla. The boats had left Borkum at midnight to deliver an attack upon the battleship Hannover.

"What was the approximate position of the division when you fell overboard?" asked Hamerton.

"Twenty miles due west of the Borkum Flat lightship."

The Sub whistled.

"We're out in our dead reckoning, Detroit," said he. "I thought we'd left the lightship well on our starboard quarter. If this man's story is correct—and I have no reason to believe otherwise—we ought to be within hearing distance of the lightship. This fog is the most persistent I have ever experienced."

"We will soon be in the way of steamship traffic in and out of the Elbe and Weser."

"Or else piled up on one of those treacherous sandbanks. I'll see what the North Sea Pilot says. Ah! Here we are: 'Borkum Riff, or Flat; syren in fog, one blast of five seconds every minute'. That's what we have to listen for, old man."

Returning to the cabin, Hamerton resumed his conversation with Hans. The seaman was profuse in his expressions of gratitude, for he realized that but for Detroit's plucky act he would be lying in the bed of the North Sea, twenty fathoms deep, instead of finding himself in the cabin of the Diomeda. He knew Kiel well, for not only had he been stationed there, but before he was called up for sea-service in the imperial navy he had been a fisherman at Flensburg, a town in the province of Schleswig. Thus he was able to give his benefactor much valuable information concerning the yacht anchorage in the neighbourhood of Kiel Bay.

The man was evidently troubled. His sense of duty, fostered by the cast-iron discipline of the German navy, prompted him to report himself as soon as practicable, and Hamerton, nowise loath to recognize a praiseworthy trait in Hans Pfeil's character, promised to tranship him to the first steamship bound either for Hamburg or Bremen.

"There's the Borkum Riff," announced Detroit.

"You're right," assented the Sub, after listening till the lightship again gave its warning note; "but goodness only knows the direction whence the sound comes. Seems as if it's on our port bow."

"Starboard, I think," remarked his companion.

"The fog's not only trying to the sight, but to the sense of hearing as well. We'll carry on, and trust to luck. It's my trick at the helm now, my boy."

For another hour the Diomeda hung on her course. The syren of the lightship sounded louder and louder, while the hooters of several vessels, adding to the din, betokened the fact that the yacht was crossing one of the great steamship routes.

Then, with the same sort of suddenness that characterized the previous temporary dispersal, the fog cleared, revealing a large red vessel with three masts. On her fore- and mizen-masts were black globes, with a pyramid-shaped cage on the main, while any doubts as to her identity were set at rest by the words "Borkum Riff" on the side showing towards the yacht.

Several of the lightship's crew gazed stolidly at the unfamiliar rig of the Diomeda, and, in response to a wave of Hamerton's arm, gravely raised their caps.

Ten minutes later the long-sought-for sea mark was lost to sight.

Hamerton missed an opportunity. He could have signalled or hailed the lightship with the news that he had rescued a sailor from a German destroyer, The intelligence would then have been sent by wireless to the mainland. But he did not, and subsequent events brought home to him the error he had made in omitting to do so.

"All plain sailing now," he remarked. "Keep as we are; we'll soon pick up the Norderney Gat lightship, and then the Elbe. I'm jolly glad we made Borkum Flat light-vessel, for, as I said before, I've no wish to find myself amidst the sandbanks to leeward."

"The Germans are fortifying Borkum very heavily, I believe," said Detroit. "In fact, they are turning the whole of the Frisian Islands that belong to them into fortresses. Guess they'll take the rest of the islands as well before long. John Bull is asleep, I guess, or he would demand an explanation."

"John Bull sleeps with one eye open, old man. Take my word for it. Besides, the Germans are at perfect liberty to defend their coasts."

"Admitted; but it is not a question of defence. These naval bases are also for offence, and, what is more, they exist solely for a torpedo raid on British ports when 'The Day', as they call it, comes. There can only be one predominant race in the world, and that ought to be the Anglo-Saxon."

"Because you are a member of our branch of the family."

"Guess you've hit it, Hamerton. Imagine an offensive and defensive alliance between Great Britain and the United States! Nothing could stand against it. Other European and Asiatic countries, realizing the impossibility of continuing in the race for world supremacy, would climb down. Reduction of armaments would follow automatically, and we should be entering into a state that the most ardent delegate to the Conference at The Hague never dreamt of."

"Until Great Britain and the United States quarrelled," said Hamerton.

"And if they did they would soon patch matters up, like two children. Our old axiom, 'Blood is thicker than water', still holds good, and will do so till the end of time. That's why it licks me to understand why Great Britain contracted that alliance with Japan."

"My dear Detroit," exclaimed the Sub deprecatingly, "you must allow that the powers that be are better able to decide these matters than you or I. For my part, as an officer of the Royal Navy, I must take things as they are, unquestioning and loyally."

"Yet you must have your own views on the subject?"

Hamerton shrugged his shoulders.

"See what a rotten mess of things has resulted," continued Detroit. "You may not admit it, but I reckon in your innermost mind you do. Here's the U.S.A. on the verge of a quarrel with Japan over the yellow immigration question. Great Britain is forced to increase her naval expenditure out of all proportion to the rest of the proceeds of taxation, in order to maintain a superiority over Germany's rapidly growing navy. Your Two-Power Standard was knocked on the head years ago. Yet, because of a sort of sentimental yearning on the part of your diplomatists towards Japan, there is a peril of a disagreement between the two great Anglo-Saxon races, whereas they should be shoulder to shoulder."

"Then where does France come in?" asked the Sub, unconsciously warming to the discussion. "We have an understanding with her."

"With all due respect to your Gallic neighbours, friend, France will have all her work cut out to attend to Austria and Italy, who will assuredly side with Germany."

"And Russia?"

"Ah! There you have a totally different case. Russia, after the ordeal of her disastrous struggle with Japan, is gradually but surely regaining her position as a naval and military power. In the near future she hopes to see a solid, compact Slav Empire extending from the Arctic Ocean to Cape Matapan. Then, profiting by her experiences, she will again meet Japan but not until the Anglo-Japanese alliance is dissolved. Once these aims are realized, Russia will stand aloof in all European disputes until the Triple Alliance is weakened either by victory or defeat. Since the barren Steppes of Siberia cannot support her surplus population, she must find another outlet, and that will be west-wards, as soon as she is strong enough to measure weapons successfully with Germany, for the Slavs and the Teutons never will hit it off together."

"You foresee drastic changes on the face of the map of Europe?"

"Of the whole world, I guess."

"Plenty of opportunity to consider the situation when the time comes," said Hamerton, with true British indifference. "Meanwhile, here we are in the North Sea, with a thick fog hanging about, and a lee shore not many miles away. This situation is more important to me than the whole of the international complications put together."

"I hope you'll always have cause to think so," added Detroit.

CHAPTER III

A Loss and a Find

Late in the afternoon, the wind falling light, Norderney lightship was passed. Curiously enough, with the breeze dropping the fog dispersed, and Hamerton was able to set a course for the Elbe light-vessel.

"Here's a tramp bearing down upon us," he announced, after intently watching the oncoming craft through his binoculars. "We'll signal her." Again the flags that the German warship had all but ignored were hoisted, and before long the crew of the Diomeda saw the steamship alter helm and head so as to pass within a cable's length of the yacht.

She flew no ensign, neither did she reply by signal to Hamerton's request to communicate.

"I'll semaphore her," announced the Sub, producing two red-and-yellow hand flags from a locker. For nearly two minutes he vainly attempted to enter into conversation.

"The bounders don't understand," he growled. "She's not a British vessel, I'll bet my bottom dollar on it. We'll hoist the ensign, and hail them through the speaking trumpet."

Out fluttered the red ensign. Still there was no reply that gave a clue to the tramp's nationality. But she was now within hailing distance.

"Vat you vant?" shouted a voice from the tramp's bridge.

"We've rescued a German seaman from a destroyer. Can you give him a passage?"

"Vat you say? Me no onderstan'," came the exasperating reply.

"She's either a Dutchman or a German," said Detroit. "The name on her bows conveys nothing. Why not hail them in German?"

"Couldn't trust myself to make a public confession of my inability," replied Hamerton, with a laugh. "But, by Jove, although we're doing all this for Pfeil, I quite forgot him. He can do the chin-wagging part of the business."

In answer to a shout from the Sub, Hans Pfeil, who had been asleep in the fo'c'sle cot, came on deck. His clothes were still wet, since the air was too moist for drying purposes, and a comical figure he cut, wrapped up in a blanket, with his oilskin coat flung round his shoulders.

The sailor hailed, and an animated conversation took place between him and the skipper of the tramp.

"Heave her to," ordered Hamerton, seeing that the German tramp's propeller was going astern, and that the vessel was losing way. "They're going to lower a boat."

The two craft were now less than a cable's length apart and hardly moving through the water, but Hamerton would not risk running the Diomeda alongside the wallowing hull of the tramp. He waited for a boat to be sent.

Meantime Pfeil went below to assemble his saturated garments. Then, clad only in his oilskin, and with the bundle of clothing under his arm, he took leave of his rescuers, again thanking them for saving his life.

This done, he entered the waiting boat, and was taken to the tramp. Without further delay the steamship gathered way, hoisting and dipping her ensign, to which the Diomeda replied, while from the taffrail could be discerned the oilskin-clad figure of the German sailor, still waving adieux to the men who had saved him from a watery grave.

"Haul down that ensign, old man," said the Sub when the tramp was almost out of sight. "It's too pretty to be flapping itself against the mizen halyards, now that a breeze is springing up."

Detroit, with his usual energy, sprang out of the cockpit and lowered the bunting, rolled it in a professional manner and jammed it between his knees, while he secured the halyard to a cleat. While thus engaged one end of the halyard slipped from between his fingers, and streamed to leeward. Hurriedly grasping the mizen shroud with one hand, he leant outboard to recover the errant cord. As he did so the sudden movement dislodged the ensign, and in an instant it was overboard.

"I'm right-down sorry, Hamerton," he exclaimed ruefully.

"Can't be helped," was the reply. "Accidents will happen, you know. We can get another for a matter of five or six marks at the first chandler's shop we come to ashore. But I rather fancied myself dropping anchor off the custom house at Cuxhaven with the red ensign at the masthead to signify that we had sailed a little eight-tonner from England."

"I'm an awkward mule," ejaculated Detroit. "Hope you are not superstitious; losing an ensign looks like a bad omen."

"Thanks, I'm not in the least superstitious," was the reply. "After all, it's of little consequence. But it's high time I went below and filled and trimmed the lamps."

The Diomeda's lamp-room was a small cupboard in the fo'c'sle. To get to it Hamerton had to remove the topsail that had reposed on the fo'c'sle floor since the previous night. As he did so he noticed a book lying under one of the folds of the canvas.

It was a small, blue-covered volume, saturated with salt water. A glance at the title told him the nature of the work. It was a treatise on the Schwartz-Kopff twenty-five-inch torpedo, a highly confidential work of which the British Admiralty had failed to obtain a copy in spite of the most strenuous efforts on the part of the Naval Intelligence Department.

"By Jove, this is a find!" ejaculated the Sub gleefully. "It must have fallen out of Pfeil's jumper when we slipped off his wet clothing. But I must stow it away very carefully, for there'll be considerable trouble if the German custom-house authorities chance to lay their hands on it when they start rummaging in search of contraband. Let me think, now; where's the best place?"

It was certainly curious that, though the Sub had often mislaid articles on board, and only after a laborious search had he been able to find them (for below decks the yacht was a labyrinth of lockers and odd corners), now, because he wanted to conceal a small book, he was at a loss to find a suitable hiding place.

"Capital idea!" he exclaimed, slapping his thigh, and at the same time giving his head a tremendous blow against an obtrusive deck beam. "I'll stow it in the false bottom of the stove. It will stand a good chance to dry, and at the same time ought to be quite safe from detection."

As soon as the "manual" was hidden, Hamerton proceeded with his task of getting the lamps ready for their night's work.

"It's piping up," announced Detroit, as a vicious puff struck the yacht's sails, causing her to heel till her lee planks were awash.

"Yes, the glass is falling rapidly," said the Sub. "We're in for a dirty night."

"Going to cut and run for it?" asked the American.

"No, not with a dangerous lee shore. If I knew the coast it would be a different matter. We'll heave to on the port tack as soon as it gets dark. Meanwhile we'll stow the mizen and change the jibs. Easy canvas is best for a job of this sort."

With the rising wind came the rain, hissing upon cabin top and obliterating everything beyond a few yards. Snugly clad in oilskins, the two men remained on deck, for although the helm was lashed and the yacht hardly making half a mile an hour to windward, neither cared to go below and turn in.

Hour after hour passed without any attempt at conversation. Occasionally Detroit would make some remark about the state of the weather, to which Hamerton would reply with a grunt that could be taken as expressing assent or otherwise.

Fortunately the rain served a good purpose. It kept down the sea, so that, instead of vicious, crested waves breaking inboard, there was little more than a long, sullen roll.

"Lights ahead!" announced Detroit, as a faint luminosity became visible in the rain-charged darkness.

"Yes, searchlights. They always look like that in rainy weather. We're apparently in the thick of the German naval manoeuvres. It may be Heligoland. They say the place bristles with powerful searchlights."

"Heligoland, eh? I'd just like to have a look at that place," exclaimed the American. "Many years ago my father spent a holiday there. That was when it was a British possession, used principally as a bathing resort for German visitors. He lived in Germany for some time when he was about my age."

"I'm afraid you won't be able to gratify your wish, old man," said the Sub. "It's forbidden ground now. In 1913 it was strongly fortified, and shortly after that the island was given over solely to military and naval purposes. The civil population had to clear out. It's a sort of second Kronstadt. Our Intelligence Department would dearly like to know a great deal more about it than they do at present."

"Don't you think the British Government was a bit of a fool to give the place away?"

"No, certainly not. We did jolly well out of the deal. Had a vast tract of territory in Africa in exchange for a little lump of sandstone that looked very much like falling into the sea."

"That's the average Britisher's notion—that is, if he thinks about it at all. The German view is very different. As colonists the Teutons do not shine, except, curiously enough, when under any Government but their own. Very well. They give you a slice of virgin territory. You develop it, and it increases in value a thousandfold in a couple of decades. When 'The Day' comes, should Great Britain be overwhelmed by the Triple Alliance, Germany takes back her former territory—and a lot besides—all ready for her much-wanted place in the sun."

"You're a jolly old croaker, Detroit," exclaimed the Sub. "I'll bet my last halfpenny that the British navy will be top dog for a good many years to come. I don't fancy that you and I will see the Teutons walking through London with fixed bayonets, and the Kaiser dictating terms of peace in Buckingham Palace. Hallo! The searchlights are out. Evolutions finished for the night. What's the time, I wonder?"

Thrusting back the sliding hatch, Hamerton looked at the clock on the fore bulkhead of the cabin. It was just 2 a.m.

As he reclosed the hatch his foot slipped on the wet grating, and his rubber-soled boot came in contact with a hard substance close to where the yacht binnacle stood.

"Good job I didn't sit on the compass, by Jove!" ejaculated the Sub. "But what's this? What idiot placed it there?"

For the object he had kicked was a large belaying pin that unaccountably had been propped up against the binnacle.

"I'll swear I didn't," declared Detroit.

"The mischief is done, at all events," continued Hamerton. "The attraction of that lump of iron has affected the compass. We may be points out of our course. Just watch."

Bringing the belaying pin back to its former position, Hamerton carefully observed its effect upon the sensitive needle of the liquid compass.

"Twelve degrees out, at least," exclaimed Detroit.

"And goodness only knows how long it has been like that. Perhaps before the yacht was hove-to perhaps even when we passed Norderney Gat."

"Well, we've a good offing, so there's little harm done. The wind is falling some, and if only this tarnation rain would quit——"

"What's that?" interrupted Hamerton, holding up his hand.

"Nothing, I guess," replied Detroit, after a few moments. "What's the matter with your nerves?"

"There's nothing the matter with my nerves," asserted the Sub with asperity. "Feel my pulse. But I could swear I heard a fellow calling out, 'Who goes there?' in German."

Detroit chuckled.

"Guess I'll have to take your word for it," he said. "I'll git. It's time I made some coffee."

The Sub watched his companion descend into the cosy cabin and strip off his glistening oilskins. Then, to avoid the glare, he closed the sliding hatch, and peered steadfastly into the mirky night.

The rain was coming down with torrential violence. The wind had died utterly away, and the saturated sails were slatting violently from side to side with the motion of the craft.

Beyond the patter of the heavy raindrops, no sound came from the black vault that encompassed the Diomeda on every side.

"If only I could pick up a light!" he muttered; then, mainly with the idea of doing something, he picked up the coiled lead-line.

"Five fathoms, by Jupiter!" he exclaimed; then, seized by an inspiration, he dived into the cabin and bent over the chart. According to the course the minimum depth ought to be thirteen.

"We've muddled the whole show, Oswald," he announced. "We're inside the five-fathom line, and that means we are only a few miles from shore. I'll put her due west, and see what comes of that. There's enough wind now to give her steerage way."

"Couldn't do better," replied Detroit laconically, "unless it's to have some coffee and a few rusks. I'll be slick about it."

Hamerton returned to his rain-exposed post, put the little craft's head in the desired position, and waited. Five minutes later he made another sounding. This time it was four and a half fathoms.

"I'll carry on," he resolved. "It may be a slight irregularity in the ground, although the general tendency is for it to deepen."

Four fathoms—three and a half.

"Say, ready for your coffee?" asked Detroit, holding a cup in his extended hand through the partially open hatchway.

"Far from it," replied the Sub. "Come on deck and give a hand to put her about. The water's shoaling rapidly."

"How's her head?"

"Nor'-nor'-west. I'll keep her at due south for a bit until we find deeper water."

Slowly the Diomeda came into the wind and paid off on the other tack. As she did so Hamerton noticed that, in spite of the heavy rain, the seas were steeper, and showed a decided tendency to break.

"Guess that's surf," said the American, as the dull rumble of a heavy ground swell was heard above the hiss of the rain. "Dead ahead, too."

Hamerton heard it also. The Diomeda was making straight towards a sandbank. Unhesitatingly he put the helm hard up. He would not risk going about; he chose the lesser danger of gybing all standing.

With a thud the boom swung over, and the stanch little craft drew away from the hidden danger. Her course was now nor'-west.

"Still shallow," announced the Sub. "It's less than four fathoms, but the water seems calmer."

"Light ahead!" shouted Detroit. "Showing red and white. We're right on the dividing line between the two sectors."

"I see it now," replied Hamerton, as he altered his helm to bring the Diomeda more into the arc of the white light. "Hanged if I know what or where it is, but, by Jove, there's a crowd of lights beyond!"

Through the rain a multitude of yellowish lamps blinked after the manner of a street, except that, instead of two rows, there were four or five. The water, too, was almost calm, ruffled by a faint breeze that contrasted vividly with the strong wind but a few hundred yards astern.

The Sub's ready wit grasped the situation. Unknowingly the yacht had entered an anchorage, for the lights represented the anchor lamps of a number of vessels.

"This is good enough for us," he exclaimed. "We'll bring up here till daylight. I shouldn't wonder if we're off the mouth of the Jade or the Weser. Stand by and let go, old man. I'll bring her up into the wind."

Two minutes later the rattling of the chain cable announced the fact that Detroit had let go the anchor. The saturated sails were quickly lowered and stowed, the navigation lights removed, and an anchor lamp hung from the fore stay.

A final look round satisfied Hamerton that he had done all that was humanly possible. The Diomeda was riding snugly in a safe but unknown anchorage.

"Watch below, all hands!" he exclaimed cheerily. "We'll sleep like logs. To-morrow, my dear Detroit, we'll wake up and find ourselves close to a picturesque little German village, and you can go ashore and buy fresh milk and new rolls. Think of that, and dream on it, old man."

Detroit merely nodded. He was already half-asleep. Before the Sub was ready to turn in, his companion was breathing heavily. Five minutes later the crew of the Diomeda were fast asleep, heedless of the peril that overshadowed them.

CHAPTER IV

Arrested

The bump of some heavy object against the yacht's side caused both sleepers to wake simultaneously. It was day; a dull light filtered through the skylight, though not strong enough to be caused by the sun. The Diomeda was rocking sluggishly in the slight swell as she rode to her cable.

"Eight o'clock, by Jove!" exclaimed Hamerton drowsily; "and drizzling with rain, I fancy. What was that noise?"

"We won't find out by lying here," said Detroit, setting the example by springing out of his cot. As he did so came the unmistakable sound of a boathook engaging the little craft's rigging screws, and a peremptory voice hailed in German.

"Custom-house people. They're early," announced the Sub. "It won't do to keep those gentlemen waiting, so I will interview them in my pyjamas."

Pulling back the sliding hatch, and pushing open the half-doors, Hamerton went on deck. Lying alongside was a grey cutter manned by seamen whose cap ribbons and blue-and-white jerseys, showing between the V-shaped opening of their jumpers, betokened them to be man-o'-warsmen of the Kaiser's navy. In the stern sheets sat two fair-haired officers—their chief characteristics fiercely upturned moustaches.

"What ship is that?" asked the elder of the two officers, whose gold-lace distinction marks showed that he was a lieutenant-commander.

"Yacht Diomeda," replied Hamerton promptly.

"You are foreigners?"

"Yes, British."

"Said I not so, Heinrich?" said the senior officer to his companion in a tone of triumph. "Ach! Why have you not your ensign hoisted on the mainmast-head? Why, indeed, are you flying no ensign at all? Do you know this is a forbidden anchorage?"

To reply to this battery of questions, rapped out with a harsh guttural voice, was a matter of difficulty to Hamerton, whose acquaintance with the German language was somewhat limited. Accordingly he solved the difficulty by answering the last.

"I did not know this is a forbidden anchorage, Herr Lieutenant. That being so, I will change into more suitable attire, and shift my berth as soon as possible."

"What does he want, Jack?" asked the American, who had just appeared from the cabin.

"We've got to clear out. By Jove, we've tumbled into the anchorage off Heligoland!"

For a glance towards the lofty red sandstone rock, fringed with a belt of dazzling white sand and capped by the brilliant hue of the grass, recalled to the Sub the old Frisian rhyme—

"Gron is dat Land,
Rohd de Kant,
End witt de Sand—
Dat is dat Wapen von Helgoland"
("Green is the land,
Red the cliff,
And white the sand—
These form the arms of Heligoland")

—as shown by the colours of the old Victorian postage stamps of the island.

"Stop!" exclaimed the German officer peremptorily. "You must not go below."

"Why not?" asked Hamerton coolly. "It is none too warm or pleasant standing out here in——"

And not knowing the German for "pyjamas", he pointed meaningly at the thin pink-and-white garment he wore.

"By order. You must not go below," replied the officer. "You will enter this boat, to be taken to be interviewed by the commandant of the fortress."

"But——" began Detroit indignantly.

"We can explain everything," said Hamerton. "We'll come out with you directly we get our clothes."

With that the Sub turned his back on the representatives of the Imperial German Navy, and made a step towards the companion hatchway, with a view to making himself more presentable and better attired for the depressing atmospheric conditions.

This laudable intention was nipped in the bud by a couple of bluejackets jumping out of their boat and agilely scrambling upon the Diomeda's cabin top.

For an instant Jack Hamerton's eyes glinted ominously. He was within an ace of knocking the intruders overboard but, recalling that such an act might be disastrous to his comrade and himself, he controlled his feelings with a strong effort.

"It's no use resisting, old man," said he to Detroit, who was beginning to follow the drift of things. "They have put us under arrest for contravening some silly regulation. We've got to go ashore in their boat. Hang it! How can a fellow stand on his dignity when he's rigged out in pink-and-white pyjamas?"

"Enter the boat instantly," ordered the German officer. "Your clothes will be handed to you."

The two members of the Diomeda's crew stepped into the boat. One of the officers boarded the yacht, and, accompanied by a seaman, entered the cabin. Presently the latter reappeared bearing an assortment of clothing.

Detroit grabbed his trousers and felt in his pockets.

"They have taken possession of my purse!" he exclaimed.

"And mine too!" added the Sub, after a hasty examination. "And my pocketbook and cigarette case! Here, this won't do!"

"Give way!" ordered the German officer.

"Stop!" said Hamerton. "Before we go we want our purses and other personal property that have been taken from our pockets."

"It is unnecessary," was the reply. "There will be no need for you to have money ashore."

The oars dipped and the boat glided towards a stone pier, leaving the junior officer and two men in possession of the Diomeda.

Hamerton made good use of his eyes during the passage. By a pure fluke the Diomeda had entered the newly completed artificial harbour, and was anchored within fifty yards of the nearest of a triple line of grey torpedo-boat destroyers. Beyond them, and closer inshore, were more than twenty of the latest type of German submarines, vessels of slightly over twelve hundred tons, and capable of action within a radius of seven hundred miles. One peculiarity he especially noticed: in addition to the twin periscopes there were four slender cylinders of almost the same height, although inclined at various angles with the deck.

So keen was his interest that the German officer leant forward and tapped him on the shoulder.

"You are forbidden to look about you," he said.

"All right, my attentive fire-eater," mused the Sub. "You've caught me napping. I ought not to have let you see that I was curious. All the same, I think I know what those tubes are for. If they are not pneumatic guns for discharging aerial torpedoes from a submerged submarine, I'll eat my hat."

Nevertheless Hamerton ignored the lieutenant's order, although he concealed to some extent the fact that he was making extraordinarily good use of his powers of observation.

The face of the cliff was bristling with heavy ordnance, some of the guns being at least equal to the heaviest weapons mounted on the Royal Sovereign and her sisters—the latest completed battleships of the British Navy. As the boat drew nearer, the Sub could distinguish numbers of quick-firers mounted on the edge of the precipitous sides of the island, with searchlights on covered stands a short distance in the rear of the guns; while to prevent the possibility of unauthorized persons landing and scaling the cliffs, a formidable barbed-wire fence, projecting at an acute angle, rendered any attempt in that direction a total failure.

All the while Hamerton and his American friend were scrambling into their clothes, and by the time the boat ran alongside a sheltered stone jetty they found themselves "rigged out" in a medley of garments. Detroit was accommodated with one of his comrade's flannel shirts, since the German officer had not exercised any discrimination in the hurried selection of the garments. Hamerton, unable to button a waistcoat over his broad chest—for the two waistcoats provided both belonged to Detroit—gave up the attempt, and devoted his attention to his footgear. This was made up of two old tennis shoes that the Sub used for rough work on board, and one sock that had the day before been utilized as a "swab" for mopping up a capsized paraffin lamp.

"Say, this is hardly the rig for Coney Island!" exclaimed Detroit. "Guess we look like a pair of hoboes."

"I'll kick up a fuss about this, by Jove!" ejaculated the Sub furiously. "Directly I——"

"Silence!" interrupted the German lieutenant, mistaking Hamerton's attitude for a display of "bluff" on the part of a spy caught redhanded. "It is forbidden!"

"Everything seems to be forbidden as far as you are concerned, my friend," replied Hamerton. "You are certainly labouring under a delusion. I was——"

"Silence!" repeated the officer. "Ascend this moment."

He pointed to a flight of granite steps alongside of which the boat was being held by the bowman and the coxwain.

At the head of the steps stood a marine, dressed in a blue tunic, white trousers, and a brightly-polished brass helmet. The man brought his rifle smartly to the salute as the German officer passed, then, shouldering his piece, paced the quay in the stolid manner so typical of the Kaiser's soldiery.

Thirty or forty yards away stood another sentry; farther on there were more. The whole place seemed crowded with marines on duty, while every person that Hamerton could see wore either a military or a naval uniform. The civilian element was totally lacking.

The Sub had very little time to make the observation, for from the shelter of a stone building that served as a guardroom a file of marines appeared. With fixed bayonets they fell in on either side of the two members of the Diomeda's crew.

"Great snakes, we're arrested!" exclaimed Detroit.

"I imagined so long ago," replied Hamerton. "No matter, they can't bring a case against us. They've no proof. We'll be out of this mess within the next few hours."

Even as he spoke he remembered the confidential book hidden in the stove on board the yacht. If the officials should chance to discover that incriminating article! The thought struck the Sub in a very unpleasant manner, but the next instant his confidence returned. After all, he could explain, and the seaman Pfeil would, he felt sure, corroborate his statement.

"Now, what's going to happen?" asked Detroit, as the pair found themselves alone in a small, whitewashed room, with a heavily barred window several feet above their heads, and a securely locked door between them and the open air.

"Only another exhibition of German high-handedness," replied the Sub. "We'll spring a mine on them. They'll be rather surprised when they learn that you are the son of a United States official in high quarters, and that I am a British naval officer. We'll hold our tongues till we are face to face with the commandant: then, by Jove, we'll enjoy ourselves."

"Guess I wish I had decent things on," remarked Detroit, ruefully surveying his disreputable attire. "Say what you like, Jack, gold lace does not make a man, but a fellow can't stand on his dignity like this."

"I'll have a jolly good shot at it, anyhow," retorted the Sub. "Now, stand by, there's someone coming."

Outside, along the stone corridor, came the sound of spurs jingling on the pavement. Then the door was thrown open, and the lieutenant who had effected the arrest entered, accompanied by a major of infantry.

"You are British?" began the latter in tolerably fluent English. "What is your name, your station, your address of residence?"

"Before we go into these details, Herr Major," said Hamerton, "we should like to know why we are brought here?"

"That is to be told some time after," replied the military officer. "Tell me your names."

"Not at present," said the Sub sturdily. "We'll explain everything to the commandant. We request that we be taken to him with the least possible delay."

"Gott in Himmel!" ejaculated the major. "Do you know who I am?" and twisting his heavy, upturned moustache, their captor tried to impress the two prisoners with the fear of Teutonic officialdom.

"Cannot say I've met you before, Major," replied Hamerton carelessly. "Perhaps my memory is slightly at fault?"

"Sir, I am Major Karl von Schloss."

It was on the tip of the Sub's tongue to express his ignorance of the major's identity, but reflecting that perhaps, after all, it would be well to exercise discretion, he replied:

"I think I can remember that name, Herr Major."

"You will have good cause to do so," retorted the German grimly. "Now, your name?"

"Not until I see the commandant."

"And yours?" demanded the Major, addressing the American.

"Guess that can be held up a bit," replied Detroit.

"Held up? What you mean?"

"I'll explain to the commandant," said Detroit resolutely.

"Very good, if you can," remarked the Major, as he prepared to take his departure. "I will, nevertheless, tell you. You will be charged with espionage. You will be lucky if you get less than three years in a fortress, for we Germans have been plagued enough with foreign spies—especially English."

CHAPTER V

A Discovery

Sub-Lieutenant Jack Hamerton was fairly well-informed as far as British naval officers go, and his information regarding the island fortress of Heligoland was fairly extensive, but he still had a lot to learn.

He knew the history of the island from its capture by the British from the Danes in the first decade of the nineteenth century. For nearly ninety years Heligoland existed as a British possession, its safety entrusted to a handful of coastguards, its ordering to a British governor, and its spiritual welfare to a Lutheran pastor. Up till 1850 the then pastor used regularly to offer up a prayer in the presence of his flock that a storm might arise to cast a valuable wreck upon the cliff-bound coast, for the Frisian inhabitants of Heligoland were to a great extent dependent upon the unlawful harvest of the sea.

As for the governor, his office was little more than a sinecure, once the regulations forbidding gaming were enforced. It was said that one of these officials was responsible for the introduction of rabbits upon Sandy Island, in order that his guests might while away the otherwise tedious hours by indulging in a little shooting. To-day, where the twelve-bores of the sportsmen used to bowl over harmless rabbits, enormous Krupp guns, on disappearing mountings, are cunningly concealed in strongly protected pits, for Sandy Island—now known as Sandinsel—has been artificially increased until it is nearly twice as large in extent as Heligoland itself.

Even Heligoland has undergone a complete metamorphosis. The little red sandstone rock, barely three-quarters of a mile in length and a quarter of a mile in breadth, had long been threatened with destruction by the action of the sea. Neglected under British rule, the island seemed fated to be wiped off the map, for after every heavy storm huge masses of sandstone would slide into the raging waters.

But directly Heligoland became a German possession prompt steps were taken to prevent further inroads of the ocean. The worthless rock was destined to be one of the most powerful fortresses in the North Sea, and a perpetual thorn in Britannia's side. Accordingly a massive sea wall of granite was built to encircle the island and baulk the billows of the German Ocean. This done, the work of fortifying the island with modern weapons was begun, and had been rapidly yet secretly carried out.

The British Government was cognizant of the fact that Krupp guns had been mounted, presumably equivalent to the nine-inch weapons. But it did not know that the ordnance consisted chiefly of fifteen-inch guns, conveyed under the most elaborate conditions of secrecy to the island.

His Majesty's Intelligence Department knew of an ammunition tunnel piercing the island from north to west; it knew nothing of the presence of vast artificial caves filled with oil fuel, with discharging pipes capable of supplying a fleet of the largest battleships with crude petroleum in the minimum of time.

The British Admiralty official charts and sailing directions gave the depth of the anchorage in North Haven at less than four and a quarter fathoms anywhere south of a line drawn due east of Nathurn, the northernmost extremity of Heligoland. By the same authority the maximum depth in South Haven, and within a mile of the Unterland, was given as three and three-quarter fathoms. In reality, thanks to strenuous dredging operations between the two islands, a fleet of the deepest-draughted battleships could lie at anchor, protected from all winds by the enormous harbour works that had sprung into existence during the last fifteen or twenty years.

The natural features of Sandinsel Island were favourable for this work, for stretching in a north-westerly direction for almost three miles were a number of rocky ledges, many of their points drying at low tide. Already the Olde Hoven Brunnen and the Krid Brunnen were converted into firm ground faced with granite or ferro-concrete walls, while the work of reclaiming the Witt Klif Brunnen was actively progressing. Although Sandinsel had already outgrown its companion isle in point of size, reclamation works were in a state of activity at Heligoland itself. Wharves extending nearly a mile from Sathurn—the southernmost limit of the original rock—formed an efficient breakwater to South Haven; and the area thus enclosed had been adapted for the purpose of berthing twenty submarines and eighty first-class torpedo boats and destroyers attached to the Heligoland command.

The submarines were the latest creations of the renowned Krupp Germania yard—large, speedy, and capable of operating within a thousand miles of their base without having to be dependent upon fresh supplies of gasoline. Submerged, they could travel a distance that would bring them within striking range of any port on the east coast of Great Britain. They were armed, in addition to the four torpedo tubes, with two fourteen-pounders on disappearing mountings, and, as Hamerton had discovered, with high-angle pneumatic guns, so as to be able, even when submerged, to attack aircraft with a great possibility of success.

Undoubtedly the new Heligoland was a strong fortress for defence. It was more: it was a base for offence, for why were ocean-going destroyers and submarines stationed there if their sole duty was to defend the comparatively short stretch of coast line that forms the German Empire's bulwark on the North Sea?

Heligoland, like the newly created fortresses of Borkum and Westerland Sylt, was a menace, directed principally against Great Britain and the British Empire.

And by a strange freak of navigation the Diomeda had dropped anchor in South Haven. Possibly had the lighthouse been showing its powerful light Hamerton might have picked up his position even in the thick, drizzling rain; but, in accordance with notices supplied to mariners by the German Admiralty, the light was extinguished whenever night operations were in progress in the vicinity of Heligoland. The leading lights on Sandinsel and the lamps at the extremities of the Moles had likewise been temporarily discontinued; yet in spite of these disadvantages, the German authorities had the mortification of knowing that a small craft, unpiloted and unseen, had crept up to the anchorage in the dead of night.

On the face of it there could be no other explanation than that the crew of the yacht were spies. The failure on their part to show a light under the bowsprit by night, or hoist their national ensign to the masthead by day, was in itself suspicious; and, left to their own resources in their temporary prison, Hamerton and Detroit agreed that the action of the German authorities was to a certain extent justifiable.

"Directly we explain matters to the commandant we'll be released," said Hamerton; "but I don't see the fun of having to give explanations to that arrogant sweep of a major."

"Nor I," added Detroit. "And I guess I'd just like to have half a dozen rounds with that yellow-haired lieutenant. I'll bet the other fellow is having a high old time rummaging our belongings."

The Sub did not reply. Again the thought of what might happen if the compromising Schwartz-Kopff torpedo book were discovered flashed across his mind. He almost wished that he had tossed the thing overboard, for he had not had an opportunity of reading it and committing the salient facts to memory, and its recovery by the German authorities would mean not only that the information was lost to the British Admiralty, but that the crew of the Diomeda would be placed in a very awkward predicament.

"It's real rotten being hung up here," continued the American. "See, the sun is shining again." He pointed towards the single-barred window four feet above their heads, through which the sunshine was streaming brilliantly. Even as he spoke the shaft of light was suddenly obscured, and a dull whirring sound came from without.

"Here, give me a leg up!" exclaimed the Sub. "Bend down, and I'll get upon your back."

Detroit immediately complied, and with considerable agility Hamerton clambered on to his friend's shoulders.

With hardly an effort the muscular American stood upright, in spite of the Sub's bulky proportions, and Hamerton was able to grasp the bars of the window and look out.

He was not disappointed in what he saw. An enormous military Zeppelin had just descended, and was being guided by several hundred soldiers along the sandy stretch between the Unterland and the sea. The afterpart, with the twin propellers and rearmost nacelle, was alone visible from the Sub's outlook. The car contained a Krupp seven-point-five-centimetres automatic gun, firing twelve-pounder shrapnel shells specially intended for use against hostile aeroplanes. At a range of four thousand yards the flying portions of the shell covered a radius of twenty yards, while the disturbance of the air caused by the explosion of the projectile was calculated to imperil the equilibrium of any heavier-than-air craft within a hundred yards of the point of detonation.

On the upper side of the rounded aluminium envelope was a small platform on which stood another automatic gun on a vertical mounting, so as to be able to fire at any aeroplane that might venture to assail the Zeppelin from above.

To each of these platforms were attached two small cigar-shaped ballonettes, fitted with life-lines. These were obviously intended to act as aerial life-buoys should disaster overtake this mammoth of the air; but what struck Hamerton most forcibly was the sight of a couple of officers standing in the rearmost nacelle and actually smoking cigarettes.

"These fellows have a supreme faith in the nonporosity of their gasbag," he thought. "With that immense volume of hydrogen, and the fate of previous Zeppelins in their minds, I am surprised that they dare risk such a thing. I wonder if they've discovered another gas of the same or greater lifting-power than hydrogen? Or perhaps some of the German savants have found a means of rendering hydrogen non-inflammable. I'd like to find out, by Jove!"

The Zeppelin came to a standstill with her nose almost touching the Waalhorn monument, and her tail within a few feet of the disused lifeboat slip. With the utmost celerity several lengths of hose were coupled up, and the work of replenishing the petrol tanks was begun. The two officers who were smoking descended from the nacelle and walked away in the direction of the Oberland, a mechanic gave the signal, the hoses began to swell, and the liquid, under the force of gravity, poured into the storage tanks.

The sound of approaching footsteps caused Hamerton somewhat reluctantly to descend. Detroit, red in the face, had already begun to realize that, muscular though he was, the Sub's weight could not be borne with equanimity.

The door was unlocked and thrown open. A file of marines with side-arms entered, headed by a sergeant. Without a word the men surrounded the two prisoners; the non-commissioned officer pointed meaningly towards the open door.

Through the cleanly kept streets of the Unterland the two comrades were hurried, then up the zigzag path communicating with the plateau known as the Oberland, where the larger portion of the residential buildings was situated. Hamerton recognized the old and the new lighthouses and the Bull Beacon from sketches on the Admiralty chart; but he was somewhat surprised to find that even in the short journey between the Unterland and the Government House there were no less than ten large guns in armoured casemates, searchlights galore, and a network of ammunition lines, on which ran trucks actuated by electric power.

In front of the Government House stood a lofty flagpole, from which fluttered the German national ensign. One thing he remarked was that every passer-by saluted the emblem of the Mailed Fist.

"Guess I'll bet you a dollar we're free in less than twenty minutes," said Detroit to his comrade, as they were marched up the stone path towards the commandant's dwelling.

Before Hamerton could make any remark, one of the hitherto silent and stolid marines turned his brass-helmeted head and added: "I don't tink!"

CHAPTER VI

Von Wittelsbach's Plan

General Heinrich von Wittelsbach, the commandant of the garrison of Heligoland, was a man of fifty-five years of age, of medium height, corpulent and choleric. His iron-grey hair, growing low on his forehead, literally bristled; the ends of his bushy eyebrows well-nigh touched the tips of his upturned moustache, which as the result of years of training outvied those of his Imperial master.

Von Wittelsbach was a pronounced Anglophobe, and on that account was a great favourite with the German Crown Prince. On the other hand, his hot-headed outbursts against everything British were discountenanced by the Kaiser, who took a more level view of things. The time was not yet ripe for Germany to measure steel with the nation that in the Teutonic mind formed the sole barrier to colonial expansion, and for the present it was considered advisable to remove Von Wittelsbach to a more remote sphere, where his activities could be prosecuted in secret and with an energy that suited the old veteran's ideas to a nicety. So the general was placed in command of the important military and naval station of Heligoland.

Like most German officers Von Wittelsbach was badly attacked by the espionage mania. In his eyes every man not in German uniform was a spy. In one or two instances he had burned his fingers rather badly, for, having caused supposed spies to be arrested and sent to the Supreme Court at Leipzig for trial, he failed to make good his case. A section of the German Press, loath to miss a chance of revenge upon the autocratic Von Wittelsbach, held him up to ridicule. The general vowed that the next time there would be no mistake, and took the precaution of obtaining authority to try supposed spies summarily, instead of sending them to the Saxon town.

Still attended by their armed guards, Hamerton and Detroit found themselves in the room where the preliminary examination was to be held. It was to be a trial behind closed doors, for in addition to the prisoners and the file of stolid marines the only persons present were General Heinrich von Wittelsbach, Major Karl von Schloss, Naval-Lieutenant Schwalbe—the officer who had effected the arrest—and a military secretary.

The room was a large one, simply furnished as an office, the only attempt at ornamentation being the presence of a large bust of the Kaiser set in a niche above the mantelpiece. At one end of the room stood a table about twenty feet in length and fifteen in width, the top being carefully covered with a green baize cloth. Had that covering been removed, Hamerton would have been able to see a chart of the North Sea, the land being shown in relief. On this, from information supplied by trustworthy agents, the position of every unit of the British fleet was recorded as quickly as reports came to hand. Every battery, aircraft station, regimental depot, and railway communication was carefully shown, so that a reliable and up-to-date plan lay ready to hand when "The Day" came.

The President made no attempt to address the prisoners in German. Schwalbe had already acquainted him with the fact that one of the accused spoke that language fairly well, but Von Wittelsbach told him that he would not listen to a vile smattering of the language of the Fatherland by one of these rascally Englishmen. So all communication between the President and the prisoners was to be made through the medium of the former's secretary.

"You are accused of unlawfully committing acts of espionage against the imperial defences of Heligoland," announced the secretary. "Accused, what have you to say?"

"Not guilty," replied Hamerton and Detroit firmly.

There was a few moments' silence, broken only by the scratching of a pen as the secretary recorded the replies.

"What is your name?"

"John Ambrose Hamerton."

"Your profession, other than that of a spy."

"I am not a spy," declared the Sub forcibly.

"Your occupation, then?"

"Sub-Lieutenant of His Britannic Majesty's Navy."

"Ach!" ejaculated Von Wittelsbach, rubbing his hands. "Good! Look up his record, Herr Schwalbe."

The lieutenant took down a leather-bound volume, and Hamerton was somewhat surprised to hear the record of his various appointments read out.

A shade of disappointment flitted over the commandant's face when he heard that the whole of the prisoner's sea time had been spent on tropical stations. He had hoped that this English officer belonged to one of the ships of the Home Fleet.

"And your name?" demanded Von Wittelsbach through his secretary, addressing the American.

"Oswald P. Detroit, aged nineteen, American citizen, native of Richmond, Virginia, U.S.A. Say, my man, any further information you may require will be trotted out with the utmost celerity."

The secretary stared, unable to grasp the full meaning of the verbosity of the accused. Lieutenant Schwalbe turned and whispered into the President's ear.

"An American?" repeated Von Wittelsbach, hardly able to master his surprise. "Are you certain?"

Receiving an affirmative reply, the President leant back in his armchair and reflectively stroked his moustache. Here was a new phase, one that he had not bargained for.

It did not take him long to make up his mind.

"Remove the accused," he ordered. "The evidence for the prosecution is not yet complete. Inform them that they must be kept in confinement till Friday next."

"I presume we will be given an opportunity of communicating with our friends?" asked Hamerton.

For the first time Von Wittelsbach replied to the prisoner direct.

"No," he replied; "spies are not entitled to any consideration of that description. What news we think fit to give to your friends in England—and America—will be imparted in due course. Marines, remove the accused."

General Heinrich von Wittelsbach waited till the sound of the retiring file of marines had ceased. He was still pondering over the scheme that had suddenly suggested itself. His subordinates, knowing his fiery disposition, stood motionless, waiting for their commandant to speak.

"Schwalbe," he exclaimed at length, "has the yacht been carefully examined?"

"Lieutenant Dort is still on board, sir."

"Have a signal made for him to come ashore immediately."

"Very good, sir," replied the lieutenant, showing remarkable energy as he made for the door.

"Now, Von Schloss," continued the commandant, as soon as Schwalbe had taken his departure. "We will discuss this matter. I may as well mention that I had no idea that one of the prisoners was an American subject. You think his statement is correct?"

"It may not be, sir."

[Illustration: "'SPIES ARE NOT ENTITLED TO ANY CONSIDERATION OF THAT DESCRIPTION'">[

"The best thing we can do is to proceed with the case against both prisoners. To release one would be prejudicial to the interest of the Fatherland, even though he be an American—which I doubt."

"What, then, sir, do you propose to do to satisfy any enquiries on the part of the United States Ambassador at Berlin? There is bound to be an outcry; these Americans are so upset over little trifles."

"There I agree, Herr Major. You say that the prisoners have not given their names to anyone belonging to the garrison before appearing here? No? Ach! I have it. Of course they are spies?"

"Undoubtedly, sir. The mere fact that they came in under cover of night, evaded our patrol boats, and brought up close to our latest submarines is suspicious. Add to that the fact that they hoisted no ensign and made no attempt to communicate with the harbour officials, and the case is as clear as daylight."

"Rutter," said the general, addressing his secretary, "what names did the accused give?"

"John Ambrose Hamerton and Oswald P. Detroit, sir."

"That is a mistake. Cross the names from your notebook. Now tell me a common English name."

"Smith, sir."

"Then enter the names of the prisoners as John and Wilhelm Smith, brothers, of London."

"John and William Smith, sir," corrected the secretary, and without evincing the faintest surprise he made the alterations according to the commandant's directions.

"But the yacht, sir?" expostulated Major Von Schloss, who was beginning to see the drift of his superior's plan.

"That I have not overlooked, Herr Major. Wait until Lieutenant Schwalbe returns. Meanwhile, Rutter, let me have those papers for signature."

The secretary handed his chief a bundle of documents, and stood ready with a blotter. Von Wittelsbach did not shirk his work. Unlike many highly-paid British Government officials, who perfunctorily place their signatures to documents while hardly condescending to acquaint themselves with the nature of their contents, the commandant carefully read every paper before putting his signature to it.

At the same time he was no blind devotee of red-tapism. Amongst that pile of papers there was not one that could be regarded as purely formal; every one had some direct bearing upon the vast establishment under his command.

Before this particular task was completed Lieutenant Schwalbe returned, accompanied by Lieutenant Dort, the officer who had been left in charge of the Diomeda. Seeing their superior engaged, they drew themselves up and stood stiffly at attention till the last signature had been written and the documents handed back to the secretary.

"Well, Herr Dort, any evidence?"

"I have had the yacht ransacked, sir, and nothing incriminating has been found."

"Nothing, sir?" said the commandant meaningly.

"Unless I except the charts—they're useless as far as the defences of the island are concerned—a telescope, and a camera."

"Camera? Any plates or films exposed?"

"There were four films out of the twelve exposed, sir."

"Have you had them developed?"

"Yes, sir, they will be dry in less than half an hour; but the views are only of some English and Dutch fishing boats."

"And, Herr Dort, another matter. Have all traces of your search on board the yacht removed, and make all snug. Directly it becomes night detail a torpedo boat to tow this craft towards Norderney Gat. When within a league or so of the lightship cut the yacht adrift."

"And scuttle her, sir?"

"No," replied the commandant after a moment's reflection. "No; only cast her adrift with all sail set. Report to me in the morning. Now, Major, you see what I am aiming at, and what I mean to carry out?"

"Yes, sir," replied Von Schloss.

"Then draw up a report to the effect that two Englishmen, John and William Smith, were detected in the act of spying upon the fortifications of Heligoland. Give a description as different as possible of the prisoners, and any other details that may tend to remove suspicion as to their actual identity. Have the report telegraphed to Berlin, and say I propose to deal with the accused by virtue of the power vested in me by the recent Imperial decree. Send a similar dispatch to Reuter's agent, and the news will be all over the world in less than half an hour from its receipt. I think this plan will suit admirably; do not you, Herr Major?"

"But the prisoners, sir?" asked Von Schloss, who, although the task was repugnant to him, had no option but to obey orders. "How long do you propose to keep them in detention?"

"A matter of two years. Ere then will come 'The Day'. After that it matters little whether this John Hamerton be John Smith or otherwise. Now, gentlemen, you know your orders; above all, impress upon every man in this affair the utmost importance of secrecy and reticence. Tell them to spread the report that the two Englishmen are to be released to-night and taken clear of the island in their yacht by one of our torpedo boats. Decide upon the details between yourselves, but in any case report to me early to-morrow morning."

CHAPTER VII

Official Hindrances

On the day following the preliminary examination of the two alleged spies the London evening papers published with double-leaded headlines:

"TWO ENGLISHMEN ARRESTED AS SPIES"

(Reuters Special.)

"Hamburg, Tuesday, 5 p.m. Telegraphic advice from Heligoland reports that two Englishmen, giving the names of John and William Smith, and aged about forty, were arrested on a charge of espionage early this morning. It is alleged that the prisoners, taking advantage of a dark and rainy night, eluded the cordon of patrol boats and succeeded in landing upon Sandinsel. When arrested they were in the act of photographing a highly important part of the defences. The open motor boat in which they visited the island has been seized, and drawings and photographs of various government establishments and ships were found concealed behind the petrol tanks. The accused, who admitted that they were in the employ of the British Intelligence Department, will be tried summarily by the Governor of Heligoland, General Heinrich von Wittelsbach, on Friday next. It is understood that the British Consul at Bremen has applied to have access to the prisoners."

This announcement naturally caused a great deal of comment amongst the British public. The general opinion was that the alleged spies knew the risk they were running and must take the consequences. Various attempts were made on the part of the press to discover the identity of John and William Smith. Enquiries at the Naval Intelligence Department gave no tangible result. The authorities there expressed their ignorance of the whole business.

The morning editions on the following day came out with highly coloured reports emanating from imaginative German journalists; but the only particle of truth was the information that the request of the British Consul at Bremen had been refused. In order to give the accused every possible advantage a military officer of high rank had been dispatched from Berlin to act as "prisoners' friend". Owing to the possibilities of important military and naval secrets being disclosed at the impending trial, the proceedings were to be conducted behind closed doors.

Even with this announcement the Great British Public maintained its customary apathy. Had some Polish revolutionary been tried under similar circumstances in far-off Russia a certain section of the British Press would have howled itself black in the face at the injustice and inhumanity of the proceedings. In this instance it was merely an attempt on the part of two venturesome Englishmen to gain notoriety at the expense of risking our amiable relations with a friendly State. John and William Smith must take the consequences.

In a paper of the same date appeared a short column headed:

"FEARED FATALITY TO TWO ENGLISH YACHTSMEN

"A ketch yacht, named Diomeda, has been brought into the port of Delfzyl by the Dutch steam trawler Hoorn. The master of the trawler reports having found the yacht derelict, with all sails set, nine miles N.N.W. of Norderney. There are three yachts named Diomeda in Lloyd's Register, but from the Dutch skipper's description the abandoned yacht is the property of Mr. Octavius Valerian Smith of Lowestoft."

At ten o'clock a telegram was handed in at the London offices of The Yachtsman's Journal. It was from that paper's Lowestoft correspondent:

"Smith, owner Diomeda, reports yacht chartered Sub-Lieutenant Hamerton, R. N. Owner starting Delfzyl immediately. Shall I accompany?—Stirling."

The editor thought over the message for some minutes. Here was a chance of obtaining copy direct from the scene of the disaster. He would dearly like to steal a march on his contemporaries. The mystery might prove far more exciting than it looked according to the morning dailies. But there was the expense; The Yachtman's Journal had not a large amount of capital behind it. Of course, Stirling would not want a large sum for the trip, but there were the travelling expenses.

A thought struck him: why not consult his friend Thompson, the news editor of the influential Westminster Daily Record?

"Is that you, Thompson?" he asked on the telephone after several vain attempts to get through.

"Yes, old man," replied the editor of The Westminster Daily Record, who recognized his friend's voice.

"Anything fresh about the yacht found adrift in the North Sea?"

"Nothing—why?"

"Just heard she was chartered by a naval officer. I fancy there's something behind this. Stirling, my Lowestoft correspondent—a smart, reliable fellow; I know him personally—has just wired to ask if he should go to Holland."

"Well?"

"He can speak German and Dutch remarkably well."

"Hanged if I can see what you are driving at, old man. Send the young chap by all means if you want to. By the by, what's the naval officer's name?"

The editor of The Yachtsman's Journal diplomatically ignored the latter question.

"I'd send him like a shot," he replied, "only it's a question of, £, s., d. What do you say? Will you guarantee half the expenses? It's a chance of a good scoop, the information to be solely for our joint use."

Thompson grunted.

"No," he said brusquely; "can't be done. It's not of sufficient interest to the general public."

"Not when a naval officer is involved?"

"H'm—well, I'll tell you. Send your man. If the stuff's of use to us we'll pay all expenses. Anything out of the ordinary he can wire us. If there's nothing meriting notice we'll only pay a quarter of the expenses. Game?"

Something seemed to whisper in the mind of the Yachtman's Journal editor: "Accept his terms. You'll be sorry if you don't."

"Agreed," he replied.

"Right! Ring off," was Thompson's laconic acceptance, and he resumed his chair in order to tackle the final proofs of the evening's issue.

Shortly after eleven Gordon Stirling, amateur yachtsman and yachting correspondent of The Yachtman's Journal, received a wire from town:

"Proceed to Delfzyl. Wire report if urgent. All expenses guaranteed.

"EDITOR."

Stirling gave a whoop of delight when he read his sailing orders, and considerably astonished his landlady by executing a dance round the room. Perhaps such an exhibition was pardonable in a high-spirited youth of nineteen, but Mrs. Grimmer surveyed her paying guest with evident concern and unrestrained curiosity.

"It's all right, Mrs. Grimmer," he explained. "I'm off to Holland for a few days."

"Not in that little boat of yours, sir?"

"No, by steamer. I'll have to leave here before twelve. Now I must pack my bag. You might ask Dick to take a note round to Mr. Smith for me."

The note was simply to the effect that the writer had made arrangements to accompany the owner of the Diomeda to Delfzyl, and would meet him at the station at 12.15.

This written and dispatched, Gordon Stirling proceeded to cram a variety of clothing into a serviceable leather bag, regardless of how they were stowed so long as the bag could be closed.

Stirling was very fortunately situated. He held an appointment at Lowestoft under the Inland Revenue; he had just started his annual leave and was meditating a trip on the Broads. To that end he had drawn a small sum from the savings bank, to which was added the greater part of his last month's salary, and thus he found himself with a little over twenty pounds in his pocket and fourteen days in which to spend it. Here was a chance of having a holiday on the Continent, with the prospects of getting hold of some exciting news and recouping all his expenses. Truly he was in luck's way.

"Glad you managed it," was Octavius Smith's greeting as the two met at the railway station. "Look alive and get your ticket. Single to Harwich only, mind."

Octavius Valerian Smith was a striking contrast to his companion, for Stirling was a short, thick-set fellow with a perpetual beam on his rounded features, whereas the owner of the Diomeda was over six feet in height and as slender as the proverbial barber's pole. It would be difficult to describe his complexion. Exposure to the salt-laden breezes of the North Sea had tanned his features to a brick-red colour. In spite of his approximation to Euclid's definition of a line he was muscular and sinewy, and as hard as nails. Possessed of small private means, he augmented his income by writing, and made a fairly good thing out of it. Few of the hundreds of love-sick maidens who read the romantic stories appearing in various women's journals under the name of "Reginald Beaucaire" would recognize their favourite author in the person of the taciturn-featured O. V. Smith.

Yet even in the flood tide of literary success there are irritating counter-eddies—periods of pecuniary embarrassment. The owner of the Diomeda, always careless with his money while he possessed any, had a few days before found himself in low water.

This inevitable condition compelled him, much against his will, to charter the yacht to Sub-Lieutenant Hamerton, and now he was on his way to recover his most precious possession from the hands of the Dutch salvors.

"You've got the yacht's papers, I hope?" asked Stirling as the train glided out of the station.

"No, I haven't. How could I? They went with the boat."

"Then how do you propose to establish your identity? The Dutchmen won't feel inclined to hand the Diomeda over until you prove you are the lawful owner."

"I've sufficient documentary evidence," replied Smith. "You leave that to me."

"If you're satisfied I am," remarked Stirling. "By the by, what were those fellows like who chartered her?"

The Diomeda's owner proceeded to give a detailed description of the unfortunate Hamerton and his chum Detroit. This done, he took up a newspaper and began to read, while Stirling wrote an account of the two supposed victims for the benefit of the patrons of The Yachtman's Journal.

"By the by," said Stirling, "is there any more news about that spy case? I suppose the two men are no relations of yours?"

"We all belong to the great and noble family of Smiths," replied the literary man oracularly. "It's a bit confusing at times, especially when one receives a blue envelope intended for a very distant relation. I've had some."

Octavius once more buried himself in his paper. Stirling resumed his scribbling, and thus the time passed until the train reached Harwich.

It was half-past eleven on the Thursday morning when Smith and his companion arrived at Delfzyl. Both were dead tired, for the tedious railway journey, especially between Zwolle and their destination, was the last straw.

The good folk of Delfzyl were evidently thought-readers, for directly the Englishmen left the station they were surrounded by a gesticulating mob, every man, woman, and child in the crowd pointing out the way to the quay where the Diomeda lay.

It was low tide, the Dollart and the estuary of the Ems River were one expanse of sand and mud. The yacht lay against a staging of massive piles. On the quay was a line of stolid Dutchmen, all peculiarly garbed in quaint cutaway coats, baggy trousers, klompen or wooden shoes, and dull-black high-crowned hats. There they stood, hands in pockets, long pipes in their mouths. Hardly a word was being spoken. They seemed perfectly content to stand on the quay-side and gaze meditatively at the mysterious craft that the steam-drifter Hoorn had brought in.

The arrival of the Englishmen with their attendant throng roused the lethargic Dutchmen. They too added their voices to those of their fellow townsfolk.

"Thank goodness the yacht seems all right," ejaculated Smith fervently. "Let's get on board. It's the only way to escape the babel."

The Diomeda looked exactly as if she had been lying on her own moorings in Lowestoft harbour. Her sails were neatly furled, her flemished ropes were exactly where they ought to be, her decks had been washed down, her brasswork glittered in the sunlight.

"How are we going to get on board?" asked Stirling, regarding the twelve-foot drop from the stage on to the deck with apprehension. "Besides, the cabin is locked, and you haven't the keys."

"I'll manage it," replied the owner confidently. "Stand by and throw me down the luggage when I reach the deck."

At this juncture a man interposed his bulky frame and held up his hands.

"Mynheer Englishman must see the harbourmaster," he announced.

"Where is the harbourmaster?" asked Smith.

A score of voices joined in giving him directions. Forty hands or more pointed in the direction of the red-tiled house, with green doors and window frames, where dwelt Cornelius van Wyk, the guardian of the maritime interests of Delfzyl.

"You do the tongue-wagging, old chap," said Smith to his companion as they were ushered into a spotlessly clean parlour. The mob of curious townsfolk, debarred from entering by the sturdy demonstrations of the harbourmaster's hus-vrow, lapsed into comparative silence. Pipes were filled, precious matches handed round, and the expectant throng waited for the Englishmen's reappearance.

The two travellers had to wait nearly an hour for the official's appearance. Van Wyk had gone down the estuary on duty. Meanwhile his wife brought refreshments, for which both men were truly thankful, as they had eaten nothing since leaving The Hook.

"You, Mynheer, are the owner of this yacht?" asked the harbourmaster on his return. He spoke excellent English, with an East Anglian accent, acquired by reason of his frequent intercourse with vessels hailing from the ports of Norfolk and Suffolk. "You, of course, have the papers?"

"No," replied Smith. "They are on board."

"I think not, Mynheer. I had to make examination, and there are no papers."

"They were in a cupboard on the port side of the for'ard bulkhead," asserted the owner.

Van Wyk shook his head.

"I remember that cupboard. It is empty."

"Is it likely that two men should disappear and take the yacht's papers with them?" asked Smith.

The harbourmaster shook his head.

"Curious things happen at sea," he said. "Dirk Apeldoorn, the mate of the Hoorn, told me the yacht had all her sails set. The tiller was not lashed; her dingy was towing astern. She was pointing towards the land, first on one tack and then on the other. It was this strange thing that attracted his attention. But, Mynheer, why should the papers disappear? Without them who can tell who is the owner?"

"I have these," replied Smith, pulling out several documents relating to the transaction between Hamerton and himself.

"Heaven forbid that I should doubt you," exclaimed Van Wyk, "but duty is duty. I have the keys; I am authorized to receive the money due for salvage; but before I can allow you on board I must have a declaration on oath that you are in truth the owner, and a copy of the yacht's papers."

"But," expostulated Smith, "I am the owner, you know."

"It is easy to say so, Mynheer. I might say I am the Prince Consort, but without proof——?"

"This looks like a week's business," said Smith savagely, as the twain regained the cobbled street. "I suppose the old chap is within his rights. We'll have to write off to the Board of Trade for duplicates of the Certificate of Registry and the Declaration of Ownership."

"And make a sworn declaration before a lawyer that you are indeed Octavius V. Smith," added Stirling.

Two days later the owner of the Diomeda skipped out of the post office at Delfzyl, holding in triumph a blue envelope with the inscription "On His Majesty's Service". Ten seconds later his exultation was changed into deep disgust, for the Board of Trade authorities had asked for additional information. They had already heard that the yacht had been picked up practically intact. Her papers were known to be on board when she left Lowestoft; what explanation, they asked, had Mr. Smith to offer for their disappearance? Pending satisfactory evidence the Board declined to issue duplicate certificates.

Time was pressing. In desperation Octavius Smith penned a lengthy epistle explaining that he was in utter ignorance of the fate of the documents, and that the harbourmaster of Delfzyl had flatly refused to give up possession of the Diomeda until such documentary evidence were forthcoming.

Two more days passed. Then, with a promptitude surprising for a British Government Department, the duplicates arrived.

"Ah! That is all in order," exclaimed Mynheer van Wyk. "All that is now required is to pay the salvage. Then you take possession."

"I see," agreed Octavius Smith, though not with any degree of enthusiasm. He had no doubt that the executors of the supposed deceased Jack Hamerton would ultimately pay all expenses in connection with the redemption of the Diomeda, but for the present he would have to be out of pocket. "What is the value of your yacht?" asked the harbourmaster, who also held the office corresponding to that of British Receiver of Wrecks.

"Two hundred pounds," replied the owner.

Van Wyk slowly turned over the documents before him.

"That may be so," he remarked; "but I see no copy of the bill of sale. How am I to know that this is the value of the yacht?"

"My word for it," replied Smith heatedly.

"Is not good enough," added the harbourmaster.

"Then why in the name of thunder didn't you ask me to get it with the other papers?"

Van Wyk shrugged his shoulders.

"I shall require it," he said simply.

"What's wrong now?" asked Stirling, as his chum rejoined him in the street.

"Every mortal thing. Wants a copy of the bill of sale to prove how much I gave for the yacht. Luckily I have that at home. I'll wire for it. This petty officialdom is enough to make a fellow wild."

"I thought petty officialdom existed only in England. Such used to be your opinion," said Stirling slyly. "Buck up, old man, we'll soon be afloat. By the by, here is a newspaper. They've given these sixty-ninth cousins of yours pretty stiff sentences, by Jove!"

Octavius Smith glanced at the printed matter, "'Pon my word, they have," he replied. "After all, they were asking for it."

CHAPTER VIII

Sentenced

The eventful day fixed for the trial of the two alleged spies came at last. Hamerton and Detroit found themselves, not, as they expected, in a crowded court, bristling with lawyers, witnesses, and keenly interested spectators, but in the same room in which the preliminary examination had taken place.

The court was modelled on the lines of the tribunal in the Zabern incident. It was virtually within closed doors, the military and naval element constituting judges, prosecutors, and witnesses.

Only Von Wittelsbach's warped sense of Imperial devotion, coupled with his cast-iron belief that the accused were really spies, urged him to proceed with his plan. To him it was inconceivable that two foreigners should be able to navigate a yacht in thick weather and in the dead of night right up to the strictly prohibited anchorage reserved for the exclusive use of the "Mosquito" flotilla of the Imperial German Navy.

He was, of course, unable to form any definite idea of the amount of important information that the alleged spies had acquired. They might have gained priceless secrets during the short period the yacht was at anchor under the lee of Heligoland or they might have had their plans nipped in the bud by their prompt arrest.

In any case he concluded that the release of the accused would result in a menace to the safeguards of the empire, and that must be avoided at all costs.

It cannot be said that his immediate subordinates would have been completely in accord with his ideas had the true facts been known to them. Even Von Wittelsbach had his doubts as to whether he could overcome their sense of justice and fair play. On the other hand, the officers—imbued from the day they first donned the uniform of the German Empire with the outstanding idea that a soldier must unquestionably obey orders—were not likely to cause obstacles to the commandant's plan could he but impress upon them that the prisoners were spies, and as such a serious danger to the welfare of the State.

Von Wittelsbach was quite convinced in his own mind that once the alleged spies were convicted they would be kept out of mischief till the necessity for strict secrecy regarding the naval and military preparations of the Fatherland ceased to be of paramount importance.

Great was Hamerton's and his companion's consternation when they found themselves indicted under the names of John and William Smith, on a charge of unlawfully obtaining information of the Sathurn, Waalhorn, and Kordberg batteries situate upon the Island of Heligoland; the Braaknocke, Kalbertan, and Olde Hoven batteries on Sandinsel Island; and the submarine and torpedo-boat harbours in South Haven, adjacent to the said Island of Heligoland, such acts being unlawful and prejudicial to His Imperial Majesty the Emperor and the German people.

For three hours the tedious case dragged on. There was a call for witnesses for the defence, and, none being forthcoming, the president asked if either of the accused wished to give evidence on his own behalf.

Through the interpreter Hamerton strenuously denied that either he or his companion was guilty of spying; that by a sheer fluke they found themselves in a prohibited anchorage; and that, had they been asked, they would at once have tendered their apologies and set sail.

"As regards the book dealing with the Schwartz-Kopff torpedoes," continued the Sub, "I can easily account for its being in my possession. It fell from the clothing of a German seaman, Pfeil by name, whom we rescued after falling from your torpedo-boat destroyer S167. No doubt the man, if produced, will corroborate my statement."

Von Wittelsbach looked astounded. This admission took him completely by surprise. Then with an effort he concealed his astonishment and ordered the court to be adjourned for luncheon. In the interval he sent for Lieutenant Dort.

"What is this about the Schwartz-Kopff manual?" he asked. "Where is the one you found on the yacht?"

"I found nothing of that description, Herr Commandant," replied the lieutenant.

"The prisoner says he had one. You must have overlooked it. And now that accursed yacht is drifting in the German Ocean with a priceless secret stowed away on board. I would give twenty thousand marks to get her back again. Hasten and order the fourth flotilla to cruise in search of her."

"It is already too late, sir. The yacht was picked up by a Dutch trawler and towed into the Dollart. I thought——"

"You thought, dolt!" interrupted the commandant angrily. "Yet it may not be too late. Find out at what port this yacht is lying. Get our agent there to keep us well-informed of all that occurs. The craft will doubtless be sailed back to England. After to-day you will cruise off the Dollart. It will not be necessary to keep out of sight of land provided you raise no suspicion. Two torpedo boats will be sufficient, or even one. Directly the yacht sets sail our agent will wire to me. I will communicate with you by wireless if you do not observe her leaving port. Then do something that will enable you to take possession of the vessel without exciting undue attention."

"We could disable her by collision, sir."

"Excellent. Mind you do it; but take care that she is not sunk. Then tow her back here. We will then be able to discover the all-important book that this fool of an Englishman has babbled about."

Von Wittelsbach was extremely reticent during the luncheon interval. In his innermost mind he devoutly wished that he had exercised more discretion before issuing orders that Hamerton and the American were to be arrested as spies. But the die had been cast. He had taken the first step. His iron will must see the business through. And then the complication in connection with the torpedo manual? He realized that if the book still remained on board the yacht it would sooner or later be discovered. To allow a confidential book like that to fall into the hands of a foreign Government—the British, above all!—was bad enough. Add to that the consternation that the discovery of the book would occasion; and it became fairly evident that there would be embarrassing questions raised by parties interested in the supposed deceased crew of the yacht. Hence his anxiety to regain possession of the Diomeda.

When the court reassembled it was merely to conclude proceedings. The prisoners were found guilty and sentenced to five years' close confinement in the fortress of Heligoland.

A confidential report drawn up in Von Wittelsbach's own handwriting was dispatched to the Admiralty at Berlin, and an official account of the trial sent to the Press. The latter had been carefully censored by the commandant. He felt tolerably safe, except for the fact that the Diomeda was not back in South Haven at Heligoland. His secret was shared by five men only: the others present in the court were, owing to their inability to understand English, ignorant of the material facts of the case. Each of those five he thought he could rely upon, since their career depended solely upon the commandant's periodical reports to the German War Office.

And strangely enough his motives were actuated by a hatred of the British Empire; his deep reluctance to swerve from a resolution once formed, and an overwhelming desire to serve the Fatherland, completely overruled all sense of fair play.

CHAPTER IX

On the Scent

"Thank goodness we are on board at last!" exclaimed Octavius Smith, as the two chums entered the companion-way of the Diomeda. "Those Dutchmen seem the essence of honesty. As far as I can see not a thing is missing."

"Except the papers," added Stirling.

"Of course; but I mean since the yacht was picked up. We'll have an overhaul to make sure."

"Strikes me I am not setting the Thames on fire over this business," remarked Stirling ruefully. "I've sent off three separate reports, but, between you and me, they are not startling enough to merit the expense of sending me out here. I suppose I lack journalistic ability to put the finishing touches to a rather bald account of the accident."

"Conjecture ought to be the journalist's sheet-anchor."

"Unless his theories are contradicted in the next issue, my dear chap. Then there's a breeze. But when do you propose sailing?"

"As soon as we get a fair slant of wind. I've no mind to go plugging against a south-wester for a week on end."

"I hope to goodness we get a fair breeze before that, or my leave will be up. But let's to work! We'll examine everything carefully and make an inventory of all that belongs to the late charterers. We'll turn out the contents of that rack first."

"Hold on; here's the logbook," exclaimed Smith. "I wonder if Hamerton—poor chap—entered anything in it. By George, he has!"

The entries extended up to 1 a.m. on the fateful Tuesday morning. The sighting of the Norderney light, the error in the compass course, and the fact that the yacht had been steered in a north-westerly direction to claw off the sandbanks and the mouth of the Elbe were set down in the Sub's handwriting.

"Five fathoms. Something wrong. Still heavy rain," read the last entry.

"Seems funny," remarked Stirling thoughtfully. "They speak of a strong breeze, and sailing under reefed mainsail, close-reefed mizen, and storm jib. That is early on Tuesday morning. That same evening the yacht is picked up forty miles in almost the opposite direction to the course shown in the log. Her reefs were all shaken out, and she had her large jib."

"Perhaps the wind dropped during the day."

"Then why wasn't that part recorded in the log? Hamerton seems to have been most conscientious in writing it up. Every hour there is a fresh entry, yet at 1 a.m., when it is blowing hard, there is a sudden break."

"H'm! I don't know. There's your chance to use your gift of conjecture."

The work of clearing the rack on the port side of the cabin proceeded apace. It was not a congenial task separating the effects of the two missing men from such articles as belonged to the owner.

Suddenly Stirling gave a low whistle.

"What do you make of that, old man?" he asked, holding up a carefully folded newspaper.

"Nothing," replied Smith laconically. "I can't make head or tail of German: never could, and don't want to—why?"

"It's a copy of the Tageblatt."

"And what of it?"

"Look at the date: Tuesday the 10th inst. Now how would Hamerton get hold of a German newspaper without going ashore? Mind you, this is the date on which the accident is suppose to have occurred."

"Rather extraordinary. But perhaps the skipper of the Hoorn left it there."

"Hardly likely. He had been out in the North Sea for a week before he picked up the yacht. Directly he brought her in here she was handed over to the harbourmaster. I think I'll see Van Wyk. He may be able to throw some light upon the matter."

"Wait till after lunch. He's bound to be out somewhere. Look here! I'll finish this sorting business; suppose you carry on and fry that steak."

"Righto!" replied Stirling, and reaching for a paper parcel containing a pound of very juicy steak he disappeared into the fo'c'sle.

Very soon the "Primus" stove began to roar, and an appetizing odour filled the interior of the little craft.

Smith cleared away the pile of articles from the rack and proceeded to prepare the table for the meal. In the midst of his activities the sliding door of the fo'c'sle was thrust back, and Stirling's head and shoulder's appeared, backed by a cloud of vapour with which the little compartment was filled.

"Blessed if I can understand what's wrong with the oven," he exclaimed, wiping the tears from his eyes, for the smoke had caused them to water freely. "It went all right for about five minutes, then there was a regular burst of beastly smelling smoke."

"Let me have a look at it," said Smith, with grim determination in his voice. "I'll soon see what's wrong. Open that forehatch, old chap, and let's get rid of the infernal smoke."

The raising of the hatch and the accompanying cloud of vapour was the signal for a chorus of exclamations from the line of phlegmatic Dutchmen on the quay, who, for want of something better to do, were passing the time in meditative contemplation of the Diomeda. The roaring of the stove deadened all external sound, but a minute later the occupants of the fo'c'sle were saluted by a deluge of water. Imagining that a fire had broken out on board, two of the good folk of Delfzyl had adroitly poured a couple of buckets of water down the forehatch.

Hurried explanations and a profound apology from the well-meaning Dutchmen followed. The crew of the Diomeda once more dived below to change their saturated garments.

"Now let's have another shot at it," said Smith, as he removed the steak, soaked with salt water, to a safe distance from the stove. "There's something fizzling away in the double bottom. Hand me that screwdriver, my young friend."

It was an easy task to remove the front of the stove, revealing a deep cavity in which was a steaming mass of paper.

"That's the cause of it all," announced Octavius Smith, as he hooked out the offending object. "It's a book. How on earth did it get there?"

Stirling took the still moistened volume and examined the title page.

"It's a German book," he said. "Something to do with torpedoes."

"Is it?" grunted Smith. "I'll swear it wasn't there a fortnight ago. Anyway, I don't want to get into trouble about it in case we have to put into a German port. Heave the blessed thing overboard."

"Not much!" replied Stirling, quietly but firmly.

Smith looked at his companion with surprise depicted on his features. Stirling was generally of a complaisant disposition.

"Why not, you silly cuckoo? That will be enough to get us five years in a fortress, like my sixty-ninth cousins, John and Bill Smith. I'm not taking any, thank you."

"All the same, I don't think I'll throw it overboard. I've got to go ashore for more steak; we can't possibly eat that stuff—it's smothered with salt water. I'll pack up the book and send it to my address by registered post."

"Please yourself," retorted Smith ungraciously. "So long as it isn't on board I don't mind, but I'm hanged if I can see what possible use it can be to you."

"Never know your luck," replied Stirling as he backed into the cabin. "I wonder if there's any brown paper on board."

"Why not dry the blessed thing first?" asked Smith, always more thoughtful for others' pockets than he was for his own. "It won't cost so much for postage."

"Not a bad idea," was the reply. "I'll hang it up under the skylight. That's it. Now for the shore."

Presently Stirling returned with a fresh supply of steak. Once more the stove was lighted, and without further mishap the meat was served.

"Can't help thinking about those fellows who were collared at Heligoland," remarked Stirling.

"Don't see why you need worry about them," said Smith. "I wonder you don't suggest that they are our friends Hamerton & Co. in disguise. Anyhow, they took the risk and failed. Spying is a rotten game, when all's said and done."

"There I don't agree with you. It's an honourable profession. A few men risk their liberty in trying to gain information that in the event of war will save hundreds of their fellow countrymen's lives. It's necessary; both Great Britain and Germany have regular men for the purpose of espionage."

"Hanged if I looked upon it from that point of view; but it seems a downright low trick for a fellow to sell naval and military secrets."

"Rather! There I agree with you. There's a vast difference between a spy and an informer. The first is, I might also say, a humanitarian; the second is a traitor. There's no doubt about it, the Germans have the advantage of us in the espionage line. There isn't a Government building, dock, or battery on the east coast but is known to the German Government. They have spies everywhere."

"We have caught a few."

"Yes, we began at first by letting them off with a caution—gave kindly advice, so to speak. Then they collared some of our secret-service men and gave it to them fairly stiff. We retaliated, and the business became a ding-dong affair, each country increasing the severity of the punishments inflicted upon the spies they detected. But, as you said, five years is a bit stiff."

"Hallo! There's the harbourmaster!" exclaimed Stirling, catching sight of the official through one of the scuttles of the cabin. "I'll ask him about the newspaper."

Both men ran on deck. The crowd of Dutchmen was still in evidence, only the attention of the idlers was directed seaward, A telescope was being handed round, the usually stolid Delfzylers showing considerable eagerness to obtain a loan of the instrument.

"What is the matter, Mynheer van Wyk?" asked Smith.

"Only a German torpedo boat," replied the harbourmaster. "She is lying off the Dollart, though why I cannot make out."

"Nothing out of the way, is it?" asked Stirling. "It's German territory across the Dollart, isn't it?"

"Aye," replied Van Wyk. "But it is out of the common for a vessel of war to remain there. We are sending out a tug to see if she requires assistance. Look! We have signalled her, but she has made no reply."

"Are you busy for a moment, Mynheer?" asked Stirling. "We've found a German newspaper on board, and we want to know how it got there."

"I do not love the Germans, Mynheer, nor do I ever look at a German paper. I did not put it there. Perhaps your unfortunate fellow countryman placed it there?"

"We think not. We have a reason for asking. Do you think the master of the Hoorn left it on board?"

"There stands Dick Apeldoorn, the mate of the Hoorn," said the harbourmaster, pointing to a little wizened man leaning against a bollard and looking at the torpedo craft through a pair of binoculars. "He was the only man who went below, besides myself. Why not ask him?"

Dick Apeldoorn was positive he had not handled a newspaper for days, let alone a German one. He was a true Hollander, who looked upon the Germans as land grabbers, intent upon overrunning Holland directly they had an opportunity—if they could. He would scorn to be beholden to the Tageblatt for any information.

"That settles one point," remarked Stirling to his companion. "The Dutchman didn't put the paper in the rack of the cabin; it's morally certain Hamerton couldn't; so who did?"

"Speculate upon it, my dear fellow. It's worth a page in The Yachtsman's Journal. Conjecture something startling, only leave me in peace this afternoon. I must knock up a pot-boiler for The Gentlewoman of Fashion, or there will be no shot in the locker when I get home. As it is, this blessed salvage business has seriously depleted the treasury."

Octavius Smith produced a "block" and a fountain pen, and was soon lost to his surroundings in dashing off about a thousand words an hour. When he did work he worked at a tremendous pace, and his companion knew the risk he incurred should he disturb him. So Stirling took up the log of the Diomeda and began to follow it from the time the yacht left Lowestoft on her momentous cruise.

As he read he compared the log with the chart, following Hamerton's notations with the deepest interest.

Suddenly he gave an exclamation of surprise. Smith, deep in his work, went on unheedingly. Stirling had come to the incident of the Diomeda's meeting with the German torpedo boats and the rescue of Hans Pfeil.

"H'm! I wonder if I could get into touch with this fellow Pfeil," he meditated. "Perhaps he might be able to throw some light on the matter. At any rate I'll try. Here's the making of a sensational yarn in the log. But, hang it all! would 'Hans Pfeil, H.I.M. Navy, Germany,' be a sufficient address?"

Something prompted him to reach for the torpedo manual that hung from a hook under the skylight. Its pages were now almost dry, but it required a certain amount of caution to separate the leaves.

"Hurrah!" exclaimed Stirling.

"Shut up, can't you!" ejaculated Smith.

"Not much!" retorted Stirling, for on the flyleaf appeared the words: "Hans Pfeil. S.167;" and the counter-signature of the lieutenant commanding the torpedo-boat destroyer. "Not much! Chuck it, for the time being, old man, and listen. I've found out how the torpedo book came on board. At least I think I have. Hamerton mentions that he rescued a seaman washed overboard from a German destroyer. He gives the man's name. It is the same as the one appearing in the book."

"Well?"

"This Hans Pfeil might be able to give us some definite information. Of course I won't say a word about this book."

"I don't see what the fellow can do or say in the matter," objected Smith. "Hamerton in the log says he was transferred to a tramp steamer. That ends the business. Whatever happened to Hamerton and Detroit occurred some time after the incident."

"All the same I'll have a shot at it. I'll write, and pack up the torpedo book at the same time."

"All right!" drawled Smith. "Please yourself."

And with that he refilled his pipe and resumed work.

CHAPTER X

In the Prison Cell

Immediately after the ending of the trial the two prisoners were separated. Hamerton was escorted through the streets of the Oberland, past the old Frisian church, and lodged in a massive stone building almost adjacent to the north-east angle of the barracks.

During and long previous to the British occupation of Heligoland this building had been used is a fish store. It stood on solidly constructed arched pillars, the entrance being by means of a flight of stone steps protected by a wrought-iron railing. Latterly the space under the vaulted arches had been enclosed by galvanized-iron fencing and utilized as a store for engineering tools and plant. The building above was subdivided into eight narrow rooms, each lighted by a rectangular window about three feet in height and eighteen inches in width. Each of these windows was heavily barred.

Surrounding this massive structure was a wall twelve feet in height, surmounted by revolving rods studded with steel spikes, and pierced by a narrow gateway sufficiently wide to admit the passage of a handcart. This wall abutted on the barracks, and the space between the house and the wall, paved with stone flags, served as an exercising ground for the prisoners who were confined within. These were mostly men serving long sentences for insubordination and other serious offences against military and naval discipline.

Just inside the outer gateway was a small guardhouse in which were quartered the soldiers detained to act as warders. Here Hamerton was handed over to the jailers, and compelled to have a bath and don a suit of blue-and-yellow cloth that made him look like a football player. All his personal belongings—and they were few in number owing to his hurried departure from the yacht—were taken from him, with the exception of his watch. This done, he was escorted up the exterior staircase of the main prison and placed under lock and key in the room at the north-eastern angle of the building.

"Well," he soliloquized, "if this is to be my quarters for the next five years—though I don't think it will be, as long as there is a strong man at the head of the Foreign Office—I may as well make myself comfortable. It's rotten being without Detroit though. They might have left us together. Now, let us see how the land lies."

His first step was to attempt to drag the iron bed frame across the floor and place it under the window.

"Confound it!" he muttered. "They've bolted the thing to the floor. No matter, I'll see what I can do with the stool."

Altering the position of that article of furniture to the desired spot, the Sub found that he could just grasp the bars of the window. Then, at the expense of a pair of skinned knees, he succeeded in drawing himself up sufficiently to be able to look out.

The aspect was not satisfactory. The outlook was to the paved courtyard, a high blank wall of a large building on the other side of the street, the upper part of the church tower, and an expanse of cloudy sky.

"Well, if I am condemned as a spy I jolly well will be one," he continued. "There's not much to be seen from the window, so the sooner I see about getting out the better."

With that he descended from his uncomfortable position and began to pace the narrow limits of his cell. Round and round he went, almost aimlessly. It reminded him of an incident of his youth. He had caught a hedgehog, and, wishing to keep it as a pet, had enclosed a small extent of grass-covered ground with a circular fence of wire netting. As soon as the hedgehog had uncoiled itself it began to run round and round the fence, its nose continually poking at the meshes in the hope of finding an exit. The animal eventually made its escape by burrowing. Good heavens! The thought suddenly occurred to him: why could he not burrow his way out of his prison?

He sounded the walls. They seemed solid enough. The floor, too, looked of far too massive construction to be disturbed without the aid of proper tools. It was paved with stones averaging two feet square, set in hard cement. Every flag he tapped with his heel. The result was not encouraging. No hollow sound rewarded his efforts.

"I'll tackle it somehow," he muttered.

His usually deliberate manner seemed to have deserted him on the first day of his imprisonment. He felt consumed by an almost overwhelming desire to exercise all his energy at once, only prudence asserted itself.

"I'll lie low for a day or so," he resolved. "It will give me time to find out what routine is carried out. If they don't inspect the cells during the night I'll be able to work unmolested. If they do, by Jove! it will be a risky business."

Just then came the sound of men's footsteps along the stone passage. Planting his ear against the door Hamerton listened intently. Again he was unrewarded, for not a word was spoken by the men without. A door was unlocked, slammed, and locked again, and the sound of footsteps grew fainter and fainter.

A little later a couple of soldiers entered the Sub's cell. One of them remained just inside the threshold, the other placed an earthenware plate containing a piece of black bread and a morsel of cheese upon the bed and a jug of water on the floor.

"Look here," said Hamerton, looking disdainfully at the frugal repast and addressing the men in their own language; "is this the best I am to have?"

"Ja," was the stolid reply.

"I've money. There's a fairly large sum belonging to me on the yacht. Can't I have food sent in to me from outside?"

"Ja."

"Will you let me have paper and pencil so that I can ask the commandant?"

"Ja."

"Very good; I'll give you a sovereign—that's equal at least to twenty marks."

"Ja."

The men backed out, relocked the door, and left Hamerton to his meditations and his supper. He ate all the food that had been provided for him, and drank about half the contents of the pitcher. The rest he saved to quench his thirst during the long hours of the night, for he had a foreboding that he would obtain very little sleep during the hours of darkness.

He half counted upon the return of the jailer with writing materials, but no one came. He must exercise his patience and wait. "If I get hold of my spare cash within a week I shall be lucky," thought he.

The increasing gloom of the cell warned him of the approach of night. While the light remained he arranged the coarse blankets of his bed. The supper plate he placed against the door, so that upon anyone attempting to enter, the clatter would warn him. Directly it became night the searchlights along the edge of the cliff flashed incessantly.

Partially divesting himself of his clothing, Hamerton lay down upon the uncomfortable bed. There he remained without any desire to sleep. His mind was revolving the events of the day. His unjust trial, the separation from his companion, rankled within his breast. He wondered how Von Wittelsbach, with all his cunning, would continue to conceal the identity of his victims. What were the secrets of the forbidden land that were so jealously guarded?

Tap, tap, tap, tap, tap!

Hamerton raised himself upon his elbow and listened intently.

"What on earth's that?" he asked aloud.

The tapping sound was resumed. The noise seemed to come from the adjoining room.

"Great Scott! Is it someone trying to call me up in Morse?" he asked. "It may be Detroit."

Springing out of bed he groped for the plate that he had placed against the door. "Tap, tap—tap—tap, tap—tap," he signalled, the double sounds corresponding with the "dashes" of the Morse code.

To his inexpressible delight the question came.

"Is that Ham? I'm Det."

"How did you know I was here?"

"Guessed it."

"Think we'll be heard?"

"No; only be careful."

For the best part of an hour the friends conversed at the rate of about six words a minute. It was slow work, but the fact of being able to communicate at all was a source of mutual satisfaction. Caution prevented them from discussing any probability of escape, for should their jailers hear and understand the messages that passed between the prisoners it would be almost a certainty that one of them would be moved to a more remote part of the building.

At intervals during the night communication was re-established. Dawn found Hamerton weary-eyed and pale. He had not slept a wink.

At seven the warders appeared, bringing the Sub's breakfast. This consisted of a kind of coarse porridge and a slice of rye bread.

"Good morning!" said Hamerton, as a preliminary to further conversation.

"Ja," came the response.

"Are you bringing the writing materials?"

"Ja."

Without waiting to be questioned further the men took the plate that they had left overnight and went out.

"That fellow won't break his jaw through too much talking," commented the Sub. "One blessing, they didn't trouble us during the night. I'll start tunnelling this very evening."

An hour later the door was opened again. This time there were two different soldiers. One of them carried a broom, which he gave to Hamerton and signed that he should clean out his cell.

"I speak German," announced the Sub.

"Ja," came the reply in a tone meant to imply that the information was not of the slightest interest to the taciturn fellow.

They waited till Hamerton had completed his task. The broom and the breakfast utensils were placed outside the cell, and the Sub was ordered to follow his jailers.

"They overheard us signalling," he thought. "We are to be kept apart."

However, such was not the case. Hamerton was conducted into the exercise yard and allowed to walk up and down for the space of nearly an hour. This over, he was taken back to his cell and locked in.

At tea-time he deliberately dropped the earthenware plate upon the stone floor, and selecting a pointed fragment hid it under his bed. When the jailers returned, one of them carefully gathered up the remaining fragments, received the Sub's explanations with the perpetual "Ja", and went out.

The Sub reckoned that he would be uninterrupted until seven o'clock; he had nearly three hours to conduct operations. Selecting a slab of stone in a dark corner of his cell adjoining that tenanted by Detroit, he began to attack the cement. It was almost as hard as iron. The fragment of earthenware was a most unsatisfactory tool, for at the end of three hours he had made only a deep scratch in the cement, and had chafed his hands till they were covered with blisters. Yet so intent had he been on his stupendous task that, until he "knocked off", he was unaware of the damage he had wrought to his hands. That night he spent in alternately communicating with Detroit and attacking the stubborn cement, snatching a few hours' sleep towards morning.

Exercise time came round. On the previous day he had kept his eyes well about him, studying the relative position of the windows and the ground, and mentally measuring the height of the enclosing walls. This time he paced up and down, never walking over the same track twice. He kept his eyes on the ground, hoping to find some piece of metal which he could press into his service. With his eyelids half-closed his demeanour excited no suspicion amongst the soldiers detailed to keep him under observation.

Presently he caught sight of what appeared to be a rusty nail, almost buried in the narrow strip of cultivated ground bordering one side of the paved courtyard.

Thrice he passed it before he purposely tripped over a conveniently uneven stone, and fell full length upon the ground, his hands sprawling in a seemingly vain endeavour to save himself. Even his wooden-faced guards smiled at the sight of the Englishman kissing the ground. But when Hamerton regained his feet a piece of steel, nearly seven inches in length, was reposing within his sleeve.

As soon as he was relocked in his cell he eagerly examined his prize. It was a portion of a steel prong, doubtless snapped off by a sudden contact with the stone wall. It was rusty, but the rust had not eaten deeply into the metal. It rang truly when dropped upon the floor. Hamerton would not have parted with it under present conditions for a hundred pounds.

The next thing to be done was to find something suitable for a handle. Experience had already taught him the need for a protection for the hands.

Upturning the stool, he examined the joints of one of the legs. It was not screwed, but merely jammed into the thick wooden seat. Before wrenching it off he bored a hole into one end with the pointed part of the steel, enlarging the hole sufficiently to be able to insert the blunted end. This took him nearly two hours' continuous work, but at the finish he found himself in possession of quite a sharp and efficient tool.

Well before the time of his jailers' visit he withdrew the steel and hid it in the under side of the bed, replaced the leg of the stool, and resigned himself to a period of inaction.

As soon as it became dark the searchlights were switched on. Hamerton could see the giant beams travel slowly across the sky, although most of the searchlights were trained to sweep the surface of the sea. At frequent intervals the bark of quick-firers shook the solid building. A night attack, one of the frequent attempts upon Heligoland by the Borkum flotilla of destroyers, was in progress. Similar manoeuvres were of almost nightly occurrence.

The detonations of the ordnance were of immense service to Hamerton. He could begin operations with less chance of being detected, for the rasping of the steel point against the cement was inaudible during the firing.

Nevertheless, it was slow work chipping out minute particles of the stoutly resisting substance. Frequently he paused to gather up a handful of the debris and hurl it out of the window. In two hours he had cut out the cement to a depth of two inches round the fairly large slab which he had fruitlessly attacked with the fragment of the broken earthenware plate.

Shortly after eleven o'clock the firing suddenly ceased, although the searchlights were still flashing across the sky. There was now more need for caution. The Sub stuck grimly to his task, pouring water into the little rectangular trench in order to deaden the sound of the steel. Several times he had to "knock off" in order to reply to a signalled message from Detroit.

"You are not communicative to-night," tapped the latter.

"No, not in the sense you mean," replied the Sub. He would dearly have liked to inform the American of the work he was undertaking, but, fearing that the conversation was possibly being listened to by a third person, he refrained. "I'm dead tired," he added.

"Of doing nothing?" asked Detroit.

Hamerton looked at his bruised and blistered hands and smiled grimly. The irony of the American's question tickled him.

Far into the night he toiled. The stone showed no sign of loosening in its bed. Again and again he ground the edge of the piece of steel and attacked the stubborn cement, which seemed to possess the toughness of iron.

"I'll carry on for another quarter of an hour," he said to himself, as he wiped the perspiration from his forehead. "I wonder what's——"

The rasping of a key being inserted into the lock of the door caused him to start to his feet. There was no time to replace the leg of the stool, which was lying on its side. Thrusting the precious implement under the mattress, Hamerton leapt into the bed, drew the blanket well over his face, and simulated a snore.

The door was thrown open. There was a pause. It seemed to the Sub like the slow passing of at least half an hour. In his heated imagination he fancied the intruder had discovered the signs of his handiwork. He could discern through his almost closed eyelids the glimmer of a lantern upon the whitewashed stone walls of the cell.

He attempted another snore. It was a dismal failure; it seemed to him more like a pig's grunt than anything else he could think of. Then the light vanished, the door was closed with less noise than it had been opened with, and once more he was alone.

For nearly ten minutes Hamerton lay still. He was half-afraid that the suspicions of his visitor had been aroused, and that the man had gone away to bring the guard and make a thorough examination of the place. At length, pulling himself together, the Sub got out of bed, removed the steel from its handle, and replaced the leg of the stool. The dust that he had not thrown away he mixed with grease from the remains of his supper, and worked it into the crevices surrounding the stone that he was determined to remove.

This done, he threw himself upon his bed, and, being thoroughly tired out, was soon in a sound, dreamless sleep.

CHAPTER XI

A Night of Toil

Four days passed. Hamerton's jailers, in spite of the monotonous "Ja's", had neither brought the promised writing materials nor taken any steps to help the prisoner to recover his money.

The work of loosening the refractory stone made steady progress. Once or twice the Sub fancied that it was shaking in its hard setting. He even went so far as to break off the tip of his steel instrument in a vain attempt to prise up the slab. The experiment was almost a disastrous one, for Hamerton had to regrind the steel ere he could start afresh. Luckily it was still long enough for the purpose, and also more rigid, while he had still the broken part as a supplementary tool.

"Hans," remarked Hamerton to one of the jailers in quite a casual tone, when the fellow brought a basin of soup to the prisoner, "could you let me have a little pepper?"

The man eyed Hamerton suspiciously; then, instead of the monotonous "Ja ", he demanded:

"What for? I suppose you would like to have some? It would come in useful to throw in my eyes, and you would try to break out of prison, eh?"

"No," replied the Sub coolly. "I can assure you that I would not use it for that purpose. I have a cold in my head."

"Better, then, apply to see the doctor."

"It's not worth that. I have always found pepper an excellent remedy when nothing better is to hand. Can't you get me a little?"

"I'll see," replied Hans.

A quarter of an hour later he re-entered the cell.

"Here you are, Englishman," he said, handing Hamerton a small paper parcel. "It's strong enough to blow your head off."

"Thank you, Hans!" said the Sub.

Directly the man went out Hamerton placed the packet of pepper in the only pocket of his coat, in which there was already a couple of handkerchiefs and his watch.

"I didn't think I should obtain the pepper so easily," he soliloquized. "It will come in very handy before many days are past."

Hamerton made a late start that evening. Detroit was in a very communicative mood, tapping out messages with tremendous zeal, till his friend had to caution him not to make so much noise, through fear of being overheard.

It was just twelve when Hamerton, using the steel as a lever, found to his great delight that the stone was actually loose. For the next half-hour he worked like one possessed, with the result that the slab was displaced. Half-dreading the outcome of his investigations, Hamerton groped cautiously with his hand into the deep cavity. Almost at arm's length his fingers touched a mass of rubble. The floor was hollow.

Now, for the first time since his incarceration, the Sub wedged the door of his cell by means of the stool. Thus he was fairly safe from interruption, and in the event of a nightly visitation he might be able to replace the stone and hide the traces of his handiwork before admitting his jailers.

This done, he attacked the slab adjoining the hole in the floor. By dint of much heaving he succeeded in displacing it without having recourse to the tedious process of chiselling out the cement.

"I wish I had a box of matches," he muttered. "Only a mole could find its way about in that hole. Well, here goes!"

So saying, he lowered himself into the pit, so black that by contrast his cell was fairly illuminated, for the searchlights were constantly flashing skywards.

Between the under side of the stone floor and the rubble on which he stood was a space of about eighteen inches in height. It was like sitting on the summit of a mound, for the surface descended on all sides. Hamerton was standing on the crown of one of the vaulted arches of the store under the prison cells. During his exercise hour in the courtyard he had made the discovery that the room on the ground floor was vaulted.

"Easy ahead!" he muttered between his closed teeth, for the dust rose in clouds in the confined space. Before he had crawled very far the height increased sufficiently for him to be able to kneel upright. Then his hands came in contact with a wall—the division between his cell and that occupied by the American.

"Rough luck!" he ejaculated. "More miniature pick-and-shovel work, I suppose. Ah, there's Detroit tapping again! Sorry I can't attend to you, old man."

Groping with his left hand Hamerton followed the course of the parting wall, hoping that he might find an opening into the space beneath Detroit's cell. His hopes were realized, for almost at the junction with the outer wall of the building was a gap in the stonework.

"It will be a tight squeeze, by Jove!" he ejaculated. "I'll risk it; but what a mess I'll be in!"

He had not before taken into consideration the fact that the state of his clothes would "give the show away" to his jailers. Retracing his steps he regained his cell, and promptly stripped off his hideous prison garb, shook out the dust, and laid the garment on the bed.

Once more he dropped into the hole, and with more confidence crawled to the corner of the space where he had located a means of communication with the corresponding cavity on the other side of the dividing wall.

It was a dangerous performance wriggling through the narrow aperture. More than once Hamerton had to stop through sheer exhaustion. The rough stonework grazed his ribs and lacerated his elbows and thighs. It seemed as if he stood a great chance of becoming jammed, for, having succeeded in forcing his shoulders through, his hips obstinately refused to scrape between the sides of the opening. To add to his discomfort, the air was far from pure, and he was seized by an attack of dizziness.

Temporarily panic-stricken, he struggled furiously and contrived to back out of his dangerous predicament.

"It will mean enlarging that hole," he thought. "I've done enough for the time being. To-morrow night I'll have another shot at it."

With this resolution he returned to his cell, washed off the dirt, and turned in, glad to rest the bruised angularities of his aching body.

Presently he began to ponder over the difficulties that had beset him. "Either I'll have to make that hole larger or I'll have to reduce my fat," he said to himself, with a laugh. "Talk about a square peg in a round hole, or a round peg in a square hole. By Jove! I'm an ass. The hole is square right enough, but my midship section isn't round—it's oval. If I had only kept my hips in two opposite corners instead of trying to squeeze through on my stomach I could have done it hands down. I wonder what the time is?"

He sat up and pulled out his watch. There was too much gloom to see the hands.

Even as he looked a brilliant beam of light flashed straight in through the window. It was a quarter to one. For a few seconds only the searchlight rays played upon the building; then all was darkness, rendered the more opaque by reason of the sudden change.

"A searchlight from an airship," exclaimed the Sub. He knew perfectly well that since from his window he could see nothing of the searchlight apparatus placed on the fortifications, it was conversely impossible for one of those searchlights to throw a direct beam through the window of his cell.

In a trice he was out of bed. Propping the partially dismembered stool against the wall, he climbed up to the window and looked out. He was just in time to see a large Zeppelin in the act of descending somewhere to the left of his prison. By the arrangement of the cars he knew that it was not the same craft that he had seen recharging her petrol tanks on the morning of his arrest.

"I wonder whether they are stationed here?" he asked himself. "An airship of that size must need an enormous shed, yet I'll swear I never saw one when I was being taken ashore. And they would never risk mooring a lubberly craft like that in the open."

As there was nothing more to be seen, the Sub clambered down from his insecure perch and prepared once more to turn in. Suddenly he felt inclined to put his theory to the test. It was not yet one o'clock, four precious hours yet remained ere dawn. He would make another attempt to squeeze through that baffling hole in the wall.

This time he succeeded with comparative ease, although his bruised hips gave him a bad time of it during the operation. In his sense of elation pain and discomfort were forgotten, for he was now underneath the cell occupied by his comrade, with only six inches of stone floor to separate them.

It puzzled Hamerton considerably to know how the stone flags were supported, since there was a cavity underneath the floor, but now he made a discovery that he had hitherto overlooked. The floor had been constructed at a fairly recent date, and was supported by slight iron girders, spaced about eighteen inches apart, which were in turn supported by small brick piers rising from the upper side of the vaulting. Fortunately the Sub had by chance decided to remove a stone that was only partly resting on a girder and held in position by a wedge-shaped stone—the second one that he had removed.

"It's about time I gave Detroit a hint," he thought. "I'll tap out a message as lightly as possible, in case the sound travels to another part of the building."

"Am crawling under the floor of your cell," he announced. "Will try and join you either to-night or to-morrow. Have you anything you can use to help shift one of the stones?"

"Nothing," came the reply. "But hustle some; I'm right keen on seeing you."

Considering Hamerton had been "hustling" like a nigger for hours this request struck him as being a cool one; but, guessing rightly that it was owing solely to Detroit's enthusiasm at the prospect of being joined by his chum, the Sub began to tackle the new phase of his arduous task.

Feeling for a stone that projected farther than the rest, Hamerton began to tug at it with his hands. It was seemingly immovable. He realized that the only way to shift it was to dig out the cement, as he had done in the case of the one in his cell. But there was a difference. He had to be on his back; the dust fell upon him, getting into his eyes, nose, and mouth, and causing him acute discomfort. Only by his sense of touch could he determine whether he was attacking the cement or merely the hard stone.

At length his physical strength began to fail; his arms refused to obey the dictates of his active mind. Reluctantly he abandoned his task for that night and painfully crawled back to his bed. It was then a quarter-past three. For close on two hours and a half he had toiled under adverse conditions, yet the result of his labours was satisfactory. He had almost established a direct communication with his friend without having recourse only to conversation in Morse.

With this solace to act as balm to his wearied body the Sub was soon fast asleep, nor did he awake till his jailers appeared with his breakfast.

CHAPTER XII

Investigations

On the following night, as soon as the bugles sounded "Lights out", Hamerton returned to his labours. Barricading the door and wrenching up the loosened slabs of stone, he descended beneath the floor, wriggled through the hole in the parting wall with comparative ease, and with renewed energy began to prise away at the stubborn cement. At about every quarter of an hour he would seize the projecting stone and shake it violently. Perhaps he had become hardened to the work, for he imagined that the cement was not so hard or tenacious as it had been when he began operations. "The cement is cracking," signalled Detroit, who for the last two hours had been lying at full length on the floor feeling for the first decisive tremor of the paving stone.

Then Hamerton had an inspiration. He knew that the stone was wedge-shaped; perhaps by pressing upwards against it he might force it out of position.

Crouching immediately under the projecting piece of masonry, he applied his shoulder to the base of the wedge and exerted all his strength.

For a few seconds there appeared to be no result, then, almost without warning, the stone gave quite a couple of inches, till it was flush with the adjoining slabs.

Detroit felt it rise. Desperately he wrenched at it with his bare hands. Hamerton, rolling over on his back, pushed as hard as he could with his foot. The next instant he felt the American's sinewy fingers grasping him by his toes.

"Chuck it, old man!" whispered the Sub. "That's my toes you've got hold of."

"Guess I don't care, so long as I've got hold of some part of you," was the glad response. "Let's have your hand, then."

It did not take very long for the hole to be enlarged sufficiently to allow Hamerton to enter the American's cell. By a sheer piece of luck the aperture bore the same relative position to the floor as did the one in the adjoining room. It was almost in the corner, where, in the daytime, by contrast with the light filtering through the window, it was almost dark.

For some considerable time the reunited comrades whispered in tense, excited tones, their conversation being the outcome of joy rather than the discussion of a definite plan of action. But by degrees they grew calmer, and Detroit asked what the next move was to be.

"Get out of this show as soon as possible," announced Hamerton with determination.

"And then? We are not paladins; we cannot hope to overpower the whole garrison. There are sentries at every few yards; every boat is guarded. We will have to remain hidden on this little rock till hunger compels us to give ourselves up."

"We'll risk that. In almost every enterprise there is an element of chance that oft leads to success. Once we break out of this place we'll have a good look round. They've condemned me as a spy, and, by Jove, I'll do a little espionage!"

"And I'll have a shot at it," added Detroit. "Who knows but that some day the United States Navy may be glad of certain information concerning this island."

"'Of course we may stumble upon a boat," continued Hamerton. "In that case we'll appropriate her without the slightest compunction, get under way, and trust to luck to be picked up by a passing steamer. A few miles either to the north or south, and we'll be right in the regular steamer tracks across the North Sea."

"But the searchlights?" objected Detroit. He was game enough for any enterprise, but with natural caution he preferred to weigh up the risks.

"If we start just before dawn we need not worry about searchlights. I noticed they ceased operations at 4 a.m. the other day. We ought to be able to put five miles between us and the rock before it is light enough for them to spot us."

"All right, then!" assented the American. "But we're not out of the wood yet. What's the next performance?"

"I'm off back to my cell. Take care to replace the stone carefully and fill up the joints with dust. I'll leave you this little tool—I can't let you have the handle, for, as you see, it's the leg of a stool. If you feel particularly energetic, old man, you might start at the sockets of the window bars. You'll have to be very cautious. Do they march you out for exercise?"

"Every day. Why?"

"I have an hour of it also. Thus I was able to take stock of the building. Your window is directly above a flight of steps; mine is some distance clear of it. Consequently your window is the more convenient one for us to tackle."

"I'll have a slog at it."

"Good! Well, I'm off. Au revoir till to-morrow night!"

The next day passed in a most tedious fashion. Hamerton was on thorns more than once, for in his heated imagination he fancied that his jailers purposely prolonged their visits to his cell.

"To-morrow," announced Hans, "you will roll up your blankets. Clean ones will be served out. You will also have to scrub your floor, because the governor of the prison and the medical officers are going to make an inspection."

This was disconcerting news. It was a case of to-night or not at all, for it was quite evident that should the two comrades not succeed in making their escape before the morrow, the visiting authorities would be almost certain to discover the displaced stones in the floor.

Accordingly the Sub continued his preparations. In spite of his hearty appetite he set aside one-half of his day's rations, since it was doubtful whether he would be able to obtain food outside.

Evening came with a furious easterly gale. The wind howled, heavy drops of rain fell in torrents and beat in at the open window, for during the summer months the glass was regularly removed from all the prison cells.

Hamerton welcomed the storm. It was an asset in their favour, although for the time being it was useless to expect to be able to get away from the island in a boat.

"How are you getting on?" he asked, as he crawled into Detroit's cell.

"Guess I've just about shifted those bars," was the American's reply. "The cement was rotten."

"It's too early to make the attempt yet," said the Sub.

"Rather," agreed Detroit; "besides, we haven't made the ropes yet. Bear a hand with this blanket; we'll soon manage that, I think."

"Pretty tough stuff," commented Hamerton, as the property of the German Government was remorselessly torn into strips. "All the same I'd rather have a good piece of manila or three-strand hawserlaid tarred rope. Even a sheet would make a better rope."

In spite of his objections Hamerton tackled the task with energy, and as a result of their joint labours the comrades had the satisfaction of being in possession of thirty feet of apparently serviceable rope.

"Time!" whispered the Sub laconically.

Five minutes sufficed to complete the removal of the bars. Hamerton, having made one end of the rope fast to the bed frame, clambered up the ledge, and listened intently. Not a sound was audible above the howling of the wind and the hissing of the rain. The Heligoland searchlights were not running, but from Sandinsel four powerful beams were swaying across the cloudy sky like gigantic inverted pendulums.

"All clear!" he whispered.

Detroit handed up the coiled rope. The Sub was about to drop it into the black vault beneath him, when he saw the glimmer of a lantern on the rainswept pavement below. Crouching on his narrow perch the Sub waited. The rays of the lantern reflected in the puddles of the courtyard; it glinted upon naked steel and upon the brass helmets of a file of soldiers.

"What's up?" whispered Detroit, unaware of the reason of the delay.

"Hist!" exclaimed Hamerton, not trusting himself to say more.

Straight towards the staircase came the men. The Sub felt his head throbbing violently. They were more than likely sent to escort the alleged spies to another place of detention.

With a dull crash the butts of a dozen rifles struck the stone pavement as the men halted and grounded arms. With bent shoulders, in a vain attempt to shelter themselves from the rain, the soldiers waited while the sergeant, lantern in hand, ascended the steps, followed by an enormous bloodhound.

Hamerton durst not crane his neck to see what went on almost underneath the window. He could distinguish Hans's voice replying to the sergeant's questions, but the din of the storm prevented the listener from understanding the nature of the conversation.

Then, after what seemed to be an age of terrible suspense, the Sub saw the sergeant return to his men. The soldiers recovered their arms, faced about, and marched towards the outer gateway. The light vanished, and the tramp of their feet was soon lost in the moaning of the wind.

Hamerton waited no longer; at any moment the jailers might intrude. Noiselessly he allowed the coil of blanket-rope to drop into space, then, grasping one of the bars which still remained, he assisted Detroit to clamber up beside him.

"You go first," he whispered. "You're lighter than I am. If the rope should break when I descend, don't wait, but clear out."

"I won't," replied Detroit. "We'll stand by each other at all costs. Well, here goes!"

The next moment he was lost to sight. Hamerton could feel the rope stretching and jerking under the strain of the descending man's weight. Presently the tension ceased. The American had reached the steps beneath the window.

Without hesitation Hamerton followed. He realized that should the soft fabric give way a fall of about ten feet, followed by a headlong tumble down the stone steps, would be the inevitable result, and to a man weighing close on fifteen stone that was far from pleasant to contemplate.

But the rope stood the strain, and with a muffled exclamation of thankfulness Hamerton felt his feet touched one of the stone steps.

"Heave away!" he whispered, placing the rope in Detroit's hands. Both men pulled their hardest. The blanket rope parted, leaving about ten feet of it in their possession. Then the American saw his companion do a strange act. Hamerton drew a packet from his pocket, and, holding his nose tightly with his left hand, scattered something on the ground. It was as much as Detroit could do to restrain his curiosity.

The outer wall with its array of spikes presented little difficulty. Detroit clambered on to Hamerton's shoulder, grasped one of the revolving rods, and passed the bight of the rope around it. By this means he was able to draw himself up and crouch astride of the obstacle until Hamerton swarmed up beside him. The drop on the other side was a more nerve-racking ordeal, for neither of the fugitives knew what was beneath them. Fortunately it was a vegetable garden belonging to one of the jailers, and the soft earth effectually neutralized the otherwise nasty jar of a twelve-foot drop.

Once again Hamerton stopped to scatter something from the packet. Detroit recognized it now. It was pepper. It nearly made him sneeze. Then he realized what his companion was about. Hamerton meant to baffle the bloodhounds that were kept on the island for the purpose of assisting the sentries in arresting all suspicious characters and maintaining the jealously guarded secrets of the island fortress.

"Now, which way?" whispered Detroit. "To the Unterland?"

"Rather not," replied the Sub. "It's too well guarded. We'll strike inland and make good use of our liberty until the alarm is raised."

Guided by the chain of searchlights, which were now in full swing, Hamerton and his companion set off in a north-westerly direction. Once clear of the buildings they felt the force of the wind, which had now backed to the north-west. It was a struggle for them to keep their feet. Every now and again a vicious blast would bring them up "all standing", as Hamerton would have described it in naval parlance. As for the rain, it was too torrential to aid their flight, for at any moment they might blunder upon the sentries, since they could see barely twenty yards ahead, and that only very indistinctly.

Away on the right a wind motor, perched on a cast-iron tower, added to the din. It was one of several used for generating electric current for the searchlights, and could, if necessary, be lowered into a concrete-lined pit, so as to be out of reach of a hostile fire.

Hamerton pushed forward, counting the number of the steps he took. At the sixty-first he stopped abruptly and threw himself flat upon the grass, an example that Detroit promptly imitated.

Just in front of them was a high barbed-wire fence. On the furthermost side a sentry was standing, his hands resting on the muzzle of his rifle and his head bowed till the brim of his flat-topped cap touched his fixed bayonet.

For nearly five minutes the man remained in this position, though fortunately his face was turned slightly away from the two recumbent figures on the ground. Then, sloping his rifle, the sentry faced about and stolidly marched away, following the direction of the fence.

"There must be some object in posting a sentry so far from the road and away from the cliff," thought Hamerton. "I'll investigate."

With that he rose to his feet, grasped the lowermost of the barbed wires, and held it up as high as the tension would allow. The quick-witted American understood, and, throwing himself flat on the ground, crawled under the formidable fence. In turn he performed a like service for the Sub, and the two adventurers found themselves within an entanglement out of which they could not easily escape should their presence be detected by any of the sentries.

While negotiating the fence Hamerton noticed one remarkable thing: the standards supporting the spiked wires were set in hinged sockets. Also, about five feet from the fence lay several half-rounded pieces of metal, each about ten feet in length.

"They are in the habit of lowering the fence for something," said the Sub to himself. "These sections are to place over the wire when it is lying on the ground. Seems as if they take rather fragile objects into the enclosure; which, I wonder?"

"Steady on!" cautioned Detroit. "Here's something."

The something proved to be the stone facing of a steep incline cut into the earth. The investigators had the choice of two routes, either to bear away to the left and follow the natural terrain, or take the right-hand direction and descend the incline. They chose the latter.

The shelving ground was slippery with rain. Close to the concrete wall was a small channel through which the surface water poured in a miniature torrent. Extreme caution was necessary, since at any moment the two comrades might find themselves precipitated over the edge of a pitfall.

"Come this way," said Hamerton in a low voice. "I want to find out the width of this incline." And setting off at right angles to his previous direction he began to measure the distance. At the eightieth pace—equal to one hundred and twenty feet—the adventurers found themselves confronted by a wall similar to the one on the other side of the incline. They had stumbled upon a broad way, leading they knew not whither or for what purpose.

"Keep to this side," continued Hamerton. "It's more sheltered."

"Better not," objected Detroit. "If there are any people about they will naturally choose the lee side of this wall. We can't get much wetter, and we stand a better chance over there."

"Right!" assented the Sub. He was not above paying good heed to the American's sagacity.

Accordingly they retraced their steps to the left wall of the incline and then resumed the downward direction. Higher and higher grew the wall, till it was lost to sight in the darkness. It seemed as if they were descending into the bowels of the earth. Presently both men involuntarily paused. Through the rain-laden atmosphere came a red glare. It only lasted a few seconds and then disappeared.

"A furnace," whispered Hamerton. "Luckily it was not on our side. Ha! what's that?" His feet came into contact with the metal rail of a narrow-gauge tram line, emerging from a cave-like chamber in the wall and running athwart the incline. Further investigations revealed the presence of a siding on which were several trucks laden with coal. The trucks had been filled by means of a number of shoots. Close by, under a lean-to shed, were nearly a hundred barrels, some empty and lying in disorder, and others filled and stacked in tiers.

Even as Hamerton and his companion were making this discovery an arc lamp above their heads was switched on, flooding the ground with its powerful light. Simultaneously the door of the subterranean store was thrown open and a row of trollies, propelled by an electric motor, emerged from a tunnel that had hitherto escaped their notice.

To stay where they were meant detection. Flight was equally dangerous, since they would have to cross the brilliantly lighted ground. By a common impulse the Sub and his comrade vaulted into two upturned barrels.

They were just in time. The trucks came to a standstill almost opposite their place of concealment, and a squad of men, dressed in engineers' uniform, began to fill the tilt-wagons. This they did by the aid of small electric cranes. Rapidly the heads of the requisite number of barrels were stove in, and the casks, raised by means of cliphooks attached to the wire ropes of the cranes, were emptied into the waiting trucks.

Hamerton could overhear the sergeant in charge of the party grumbling about the weather.

"Be careful, men," he cautioned; "if the moisture gets to the alum there will be a row. Now, sharp with the trucks, or Herr Captain will be in a rage. 'Z 21' must be filled before daylight. Hurry up, I say."

Away rumbled the trucks, the men either clambering upon them or returning to the subterranean room from which they had emerged. The arc lamp was switched off and all was dark once more.

Then the blaze of red light reappeared. Hamerton understood. This was the hydrogen factory where the gas for filling the Zeppelins was manufactured. He remembered that woollen or linen fabrics saturated in a solution of alum become practically non-inflammable. There were the men shovelling lumps of alum into one of the retorts.

"I have it," he muttered triumphantly. "They have discovered a process of making hydrogen practically non-explosive. By Jove! I wish I could wrench the secret from them. However, it's a step in the right direction."

Noiselessly the pair emerged from their place of concealment. Detroit was curious to know the nature of the conversation, but for the present it was extremely hazardous to speak. He had, however, made the discovery of the former contents of the barrel in which he was hidden, for happening to put his finger to his lips the unpleasant taste of alum asserted itself.

Stepping cautiously over the tram lines, since one of them might be a "live rail", Hamerton and Detroit resumed their down-grade journey till they had traversed nearly a quarter of a mile of the incline.

"I believe we've tumbled upon the approach to a submarine tunnel to Sandinsel," whispered Detroit.

"Much too wide for that," replied the Sub, "unless, of course, there is a subsidiary tunnel. But, look, we are getting to the end. There's rock ahead of us."

The incline terminated in a large circular basin roughly two hundred yards in diameter. Opening out of it were three lofty artificial caves, hewn out of the sandstone. This much Hamerton was able to observe in a momentary burst of starlight through a rift in the swiftly-moving clouds.

"Come on," he said. "We're in luck's way. There's no one about. Follow the cliff; I'm curious to see what is in these caves."

The first cavern was apparently empty. The floor was paved with slabs of cement, the walls were of glared brick. Close to the mouth was a little hut, the door of which was locked; but judging by the number of insulated wires running from it the Sub concluded it was the operating station for lighting the vast recess.

The second cave, its entrance being almost at an angle of ninety degrees with the first, was tenanted. Both men recognized in the snub-nosed object projecting far above their heads the bow of a military Zeppelin.

Hamerton could have danced with sheer delight. He had discovered what was supposed to be the shell-proof lair of three powerful airships. Deep in the bowels of the earth they were immune from hostile shell. A high-angled fire might result in a projectile dropping into the vast circular pit, but the possibility of the aircraft being damaged by fragments of shells was guarded against by the provision of massive steel doors sliding on rollers.

Evidently the Zeppelins were being made ready for a flight, for the doors were wide open. In the third cavern lights burned at the farthermost end, and a party of officers and men were busily engaged in overhauling the after-car.

"Seen enough?" asked Detroit. "Let's quit."

"Suppose we must," replied Hamerton reluctantly. "It must be close on dawn, and we'll have to find a place to stow ourselves away."

"I say," began the American.

"Well?"

"That airship facing the incline can come out of its dogbox all right, but I don't see how the others can be turned. There can't be more than a few feet between their extremities and the cliff when they are hauled out."

"They can be guided round by ropes."

"Hardly. The faintest bump would do no end of damage."

"I wish the whole crowd of them would meet with no end of damage," said the Sub vengefully. "But come on, we mustn't hang about here till morning. I heard those fellows say that one of the airships was to be made ready by daybreak."

"One minute; I guess I'd like to look around over there," said Detroit, pointing to the centre of the circular bed of the pit. So saying, he made his way cautiously from the shelter of the cliff, and Hamerton, guessing that his comrade was on the verge of a new discovery, followed.

For the first ten yards the floor was literally covered with a network of tram lines. There were treble parallel tracks, points, and sidings galore. It reminded the Sub of a miniature Clapham junction.

Presently Detroit stopped abruptly.

"I thought so," he announced. "We've hit the edge of a gigantic turntable. This is how they slew round their blessed Zeppelins."

The floor of the turntable was almost as smooth and level as a billiard table. There was not a single projection that would form the slightest hindrance to its intended burden. Almost in the centre were a couple of flat trapdoors for the purpose of gaining access to the machinery underneath, but the actual moving of the turntable was controlled by means of electric switches from a cabin close to the wall of the basin.

"Say, why not hide down there?" suggested Detroit, pointing to one of the trapdoors.

"Good idea!" assented Hamerton. "I don't suppose anyone goes down except to oil the machinery. The place looks large enough to hide a dozen people quite comfortably. Besides, we might be able to see something by daylight. Give me a hand with this lid."

Luckily the traphatch was not locked. The authorities regarded themselves as being immune from the inquisitiveness of intruders and the mischievousness of small boys.

Detroit descended first by means of a vertical iron ladder. Hamerton followed, and was in the act of reclosing the lid of the aperture when the whole of the Zeppelin sheds and approaches were illuminated by arc lamps fixed from brackets to the side of the cliff.

And right in the centre of that blaze of light, his head and shoulders showing conspicuously above the level of the turntable, Hamerton remained as if rooted to the spot. The sudden glare temporarily blinded him. He felt incapable of moving hand or foot.

CHAPTER XIII

An Experiment with a Zeppelin

"Look slick!" hissed Detroit. "Don't stand there looking in the air."

The American's words roused Hamerton to action. Quickly he descended below the level of the floor of the turntable, the flap fell with a dull thud, and the two fugitives found themselves in darkness, save for a faint circle of light where the exterior glare filtered through the narrow space between the round platform and the edge of the pit in which it stood.

Then came the tramp of many feet. Not knowing whether they had been "spotted" by a keen-eyed sentry, Hamerton and his comrade remained on the thorns of expectancy. Alternate hopes and fears flashed across their minds in quick succession. Detroit was mentally bemoaning the rashness that prompted Hamerton to suggest the exploration of the aircrafts' subterranean shelter instead of making for the base of the cliffs; while the latter regretted that he had not been able to continue his nocturnal tour of investigation.

Yet, although men were running hither and thither, none came across the floor of the turntable. Trucks were rumbling along the tram lines, men were shouting in guttural tones, electric motors were whizzing and buzzing. The place, hitherto practically deserted, resembled a gigantic beehive.

"They are not looking for us," whispered the Sub. "They are evidently getting one of the Zeppelins ready for a flight. I hope we won't be disturbed. We may as well have a tour round our limited quarters, to make ourselves acquainted with our hiding place."

"Go steady," cautioned Detroit.

"Trust me for that," rejoined Hamerton, "We don't want to electrocute ourselves, or start the turntable spinning round at the rate of knots."

"Like a new form of joy-wheel," added the American. "It would be a bit of a joke to see the soldiers attempting to reach the traphatch with the platform spinning round at twenty miles an hour."

Their eyes were now getting accustomed to the gloom, for there was a fair amount of reflected light that at first was almost unnoticeable after the powerful glare without.

The place of refuge was certainly expansive, but much of the space was taken up with complicated machinery. The turntable itself worked on steel rollers set in a "race", the upper bearing surface consisting of steel skeleton trestles, which in turn supported the revolving platform. Between the latter and the edge of the circular concrete wall was a width of less than eight inches, insufficient to allow a man to crawl through. The only means of gaining the machinery chamber was by the two trapdoors.

"Shall we barricade the hatchways?" asked Detroit.

"No use," replied Hamerton. "It would only arouse suspicion. Then we should either be starved out or run the risk of being potted, for the floor is not proof against rifle fire. No, the best thing we can do is to keep quiet. Should anyone come we must endeavour to dodge behind some of this gear."

"Guess I'm getting precious hungry," remarked the American.

"Now you mention it I begin to have a sinking sensation: a kind of famine and hunger strike rolled into one. But we can't go too strong in the provision line."

Six half-slices of rye bread, two small pieces of cold meat, and about a pound of fish formed the sum total of the commissariat, barely sufficient, even with stringent economy, to last over twenty-four hours.

The food, after reposing in their pockets, was not pleasing to the eye, but adverse circumstances settled all qualms. Both men ate with avidity, though sparingly.

At length daylight gained the mastery over artificial lighting, and the arc lamps were extinguished. With the morning the rain ceased and the wind dropped.

Peering through the gap between the turntable and the encircling wall, Hamerton could see the sun shining upon the upper portion of the red sandstone cliffs that enclosed the vast artificial basin. His field of vision was limited, but he was able to come to the conclusion that the floor of the airship sheds was nearly two hundred feet below the surface of the tableland that comprised the major part of the island.

Between each pair of caverns constructed for the accommodation of the Zeppelins was an iron ladder running perpendicularly up the sheer wall of sandstone. These were connected by an open lattice platform just above the crown of the arch formed by the caves, and were evidently for the purpose of facilitating the movements of the airships when entering or leaving their bases. Curiously enough, both Hamerton and Detroit had previously failed to notice these ladders when making a circuit of the basin.

"They are naval airships," announced the Sub, for men were swarming up and down the ladders with a seeming recklessness that only seaman dare show, and they were wearing the uniforms of the German Imperial Navy.

"Here she comes," said Detroit, as the huge bulk of a Zeppelin emerged slowly yet steadily from its resting place.

"What a superb target!" commented the Sub. "A dose of shrapnel would knock the whole concern to smithereens, while one of our seaplanes with a one-pounder automatic gun would make rings round her."

"I don't know so much about that," said Detroit. "Just look at the aluminium body just abaft the 'midship car. It's been holed at one time, and they've put a patch on it."

"An accident, perhaps," rejoined Hamerton. "The airship looks rather old."

Over the heads of the two watchers passed the unwieldy craft. Now they could hear the jar of the framework as it settled on the turntable. Then, with hardly a sound and barely a tremor, the platform began to move until the bows of the Zeppelin pointed in the direction of the great incline. The six propellers began to revolve, and the airship, gathering way, rose rapidly and steadily, keeping almost parallel with the slope. Then, gaining an altitude of nearly five hundred feet, she circled slowly and disappeared beyond the limits of the vision of the two spectators in the pit.

Within a quarter of an hour of its leaving the cave the Zeppelin returned to earth. Anchored fore and aft it strained and staggered in the still strong wind. The officers and crew descended by means of a rope ladder, then the holding ropes were cast off and the aircraft bounded upwards. Hamerton could see that it was still connected with the ground by a flexible steel rope. The propellers were revolving and the rudders set hard over, consequently the Zeppelin was describing circles in the air at a height of a little over five hundred feet.

"What's the game?" asked the Sub.

The words were hardly out of his mouth when the sharp, rapid detonations of a pom-pom were heard. Almost simultaneously with the screech of the projectiles sinister dark marks appeared on the aluminium cover of the Zeppelin; yet to the Sub's surprise the one-pounder shells without exception did not burst, neither did the airship appear to lose its reserve of buoyancy.

For nearly fifteen seconds the firing continued. Nearly four times that number of projectiles had been fired, many of the shot-holes overlapping each other.

Upon the conclusion of this severe test the Zeppelin was brought down, and, controlled by about fifty men holding guide ropes, was taken down the incline.

As it neared the turntable Hamerton was able to come to some conclusion as to the nature of the self-closing material surrounding the ballonettes. In one place the havoc wrought by the concentration of several projectiles had completely torn off a strip of aluminium measuring roughly two feet six inches by two feet. Within the cavity could be seen the inner lining of aluminium, which had been badly perforated, thus releasing all the hydrogen from that particular ballonette. At the edges of the perforations a substance resembling dirty cotton waste had been forced out. Only the width of the fissure prevented the closing up of the textile fabric.

As the Zeppelin was being guided on to the turntable a fragment of the plugging material fluttered to the ground. A breeze caught it and swept it towards the edge of the turntable pit. There it stopped, provokingly out of reach even if the Sub had dared to stretch out his hand to grasp it.

Just then one of the sailors manning the trail ropes kicked the piece of packing. It fell literally into Hamerton's hands.

Hamerton and his comrade exchanged glances of satisfaction. They dared not speak. They realized that they had made a great discovery.

Directly the experimental airship was safely housed the men in attendance were marched off, presumably to breakfast, and the occupants of the machinery pit were able to discuss their find.

"It's cotton waste, right enough," said Hamerton.

"And asbestos fibre," said Detroit, plucking out a piece of core. "I suppose that renders the waste non-inflammable?"

"Hardly," replied the Sub. "Besides, how do you account for the stuff being gas-proof? It's as porous as a sponge."

Detroit put a small quantity of the stuff between his teeth.

"Ugh!" he exclaimed. "There's alum in it, and gum arabic in a viscous state, only this piece has got slightly dry. I guess I see the trick. They pack the space between the outer and inner skins with the stuff under pressure. There is not sufficient resistance to cause the shell to explode, therefore the projectile passes completely through, making only a small aperture that instantly closes behind. They made a severe test, for the Zeppelin was practically a captive balloon. Had she been travelling at from thirty to fifty knots at an uncertain range it would have been a difficult matter to get a shot home."

"Do you know what they were firing with?" asked Hamerton.

"A pom-pom, I should imagine."

"Yes, firing a one-pound shell, almost the identical weapon we mount on our seaplanes. Every blessed experiment these Germans make seems directed solely against the recognized means of offence adopted by the British Government."

"Shrapnel's the thing."

"Aye, coarse-charged with irregular pieces of metal in the place of the bullets used in shells when directed against troops. These Zeppelins, with their non-explosive hydrogen and their fireproof, shot-closing envelopes will be a tough nut to crack in the next war, I fancy. Look here, Detroit, old man, this stuff's worth keeping. We'll divide it into four parts, and wear it in our shoes like cork socks; then, if we are collared, we may stand a chance of keeping it in our possession."

While the two friends were thus engaged the dull boom of a gun fired thrice in quick succession struck their ears. This was followed by a bugle-call that Hamerton recognized as the "Assembly" of the German Army. This was taken up in other parts of the island till the whole garrison was aroused.

Hamerton glanced at his watch. It was just after seven o'clock, at which hour their jailers were wont to bring in the prisoners' breakfasts.

"They've discovered we've broken ship," he said. "Hans and company have found that our cells are empty. Now comes the fun."

It seemed as if the caves in the sandstone cliffs surrounding the Zeppelin station disgorged human beings, for within a few seconds of the alarm being given two hundred men were drawn up in divisions, while their officers were discussing amongst themselves the probable reason for the unexpected summons.

Up ran a portly sergeant-major. He was almost out of breath, yet he spoke in such a loud voice that the Sub was able to interpret every word.

"A message has just come through on the telephone, Herr Major," he announced; "those rascally English spies have escaped. The general orders are that all commanding officers shall post double sentries over all confidential posts; the rest of the men are to be employed in the search. No leave is to be granted until the spies are recaptured."

The major shrugged his shoulders. He was not at all pleased with the telephone message, since he had arranged to spend the following Sunday at Flensburg.

"Why have we not turned out the bloodhounds, sir?" asked a captain. "The scent must be hot."

"Ach, I know not!" was the reply.

"All the dogs were taken across to Sandinsel yesterday, Herr Major," announced another officer, a tall, fair-haired subaltern. "Colonel Dietrich wished to try the hounds on a trail laid on the sand."

"And, as a result, we have two English spies roaming over the island," added the major. Then, giving the order to march, he led the four companies under his command up the steep incline. "Now the fun commences," observed Detroit, when all seemed quiet once more. "Thank goodness they have no suspicions that we made our way here!"

"And it's lucky for us that the bloodhounds are away," rejoined Hamerton. "One never knows; they might be able to follow a trail in spite of a couple of ounces of pepper."

Before Detroit could express his opinion a deep baying sound came from the heights above.

Both men looked at each other as if to say: "We counted our chickens before they were hatched;" then, without a word, they made their way to a different part of their place of concealment whence they could command a view of the summit of the artificial cliffs.

Standing out clearly against the white drifting clouds were four large hounds. With their noses almost touching the ground they moved deliberately and unhesitatingly, while behind them walked a number of officers and men, the latter armed with rifles and bayonets.

The bloodhounds, keeping close to the brink of the abyss, gradually approached the spot where the inclined plane met the level ground of the tableland. Here they paused but for a brief instant; then they began to trot straight towards the fugitives' hiding place.

"They've tracked us right enough," muttered the Sub dejectedly.

CHAPTER XIV

The Second Night of Liberty

"Going to make a fight for it?" asked Detroit calmly.

Hamerton shrugged his shoulders.

"Hardly," he replied. "I don't believe in kicking up a fuss when we're cornered with no chance of escape. Mind you, if there were any possibility I'd fight tooth and nail. But there is not. We've had our fling, and I suppose we must pay the piper. Luckily those brutes can't get to us."

"I cotton to it," agreed the American. "I look upon it as a sort of Thanksgiving Day—a few hours of real enjoyment and then days of hard graft to follow."

Both men relapsed into silence, and gloomily watched the progress of events.

On came the hounds, the mob of excited Germans at their heels. Then the animals lost the scent—that is, if they ever picked it up—for turning abruptly they made their way across to the other side of the incline. Hamerton and his companion had never been near that part of the ground.

Round and round went the bloodhounds, sniffing and baying. Shouts of encouragement from their masters failed to meet with the response that they desired. Presently one of the large beasts raised its head and opened wide its mouth. The fugitives could see the sharp white teeth and the red, frothing tongue of the brute as it gave vent to a prodigious howl.

Then, followed by the rest of the hounds, the animal retraced its steps until it gained the summit of the slope. Here the baffled trackers stood still for a brief interval. All inducements to get the dogs to take up the scent failed, and dejectedly their masters led them back to the kennels.

"Excellent, by Jove!" exclaimed Hamerton in high spirits. "The pepper did the trick, after all. Obliging Hans! He deserves a special vote of thanks."

"Guess we aren't out of the wood yet," Detroit reminded him. "What's the programme now?"

"Stay here till night," replied the Sub. "Then more investigations and grub. Man, I feel as if I could eat a joint of beef straight away. Look here, we'll strip off these wet clothes and hang them up to dry in this draught. To continue wearing them in this state is to court disaster. There's a bin of cotton waste; we'll burrow in it and snatch a few hours' sleep. It's very necessary, I think."

These suggestions were acted upon. A few days previously the two men would have regarded their proposed bed with the utmost repugnance, but, as Detroit observed, circumstances alter cases.

In less than two minutes the fugitives were sound asleep, utterly indifferent as to what befell them. Rest and slumber were the only antidotes to hunger and bodily and mental fatigue.

"Time to be up," whispered Detroit, shaking his companion by the shoulder. Hamerton roused himself. It was still daylight without, although the sun had set. Ten hours had passed like as many minutes.

Quickly they donned their clothes, which still felt clammy to the touch. Another sparse and hasty meal was partaken of, during which Hamerton took stock of the surroundings.

Work for the day had apparently ceased. Each of the airship sheds had been closed by means of the sliding steel doors, and the vast artificial basin was deserted. With the setting of the sun the wind had risen, though the velocity was not so great as on the preceding night. The sky, too, was obscured with heavy clouds. Everything seemed in favour of the fugitives.

"Now, boss, what's the programme?" demanded Detroit, with forced jocularity.

"Wait till it's dark, then make our way up the incline, double back along the top of the cliff, and head towards the north-western part of the island. I shouldn't be surprised if we stumble across some more wonderful creations of our dearly beloved German cousins."

"But suppose there are sentries posted up there?" asked the American, pointing to the farthermost part of the slope.

"Not much! This place is all enclosed with that barbed-wire fence. That's where the sentries are to be found, and that is what is going to give us a lot of trouble."

"And when do we make an attempt to seize a boat?"

"Not while this wind is blowing, thank you. Better to prowl about half-starved in a German fortress than to be lying on the bottom of the North Sea."

"You cautious critter!" ejaculated Detroit.

"Exactly, my dear fellow. Caution is the modern naval officer's sheet anchor. Caution is instilled into him from the moment he's placed in charge of a ship's boat under sail. No doubt it's the means of often neglecting to make full use of an opportunity; but there you are. Modern warfare has no use for fire-eating daredevils; it's the level-headed admiral who will win the next great naval war. It's prosaic, but it's hard facts. Now, easy ahead; it's time to get under way."

Making his way up the vertical iron ladder, Hamerton raised the trapdoor a few inches and listened intently. All was quiet. He emerged from his hiding place, waited until Detroit rejoined him, then carefully replaced the cover on the aperture.

Bearing in mind the experience of the previous night, how without warning the place was flooded with light, the Sub and his companion made their way as stealthily and rapidly as possible to the base of the artificial cliff where the incline merged into the circular basin. Then, keeping close to the wall, they headed towards the upper level.

Suddenly Hamerton came to an abrupt halt and stood with his back hard up against the cliff. Detroit did likewise.

Faintly discernible against the loom of the skyline was a great-coated sentry pacing up and down across the brink of the inclined plane. Barely had he turned to commence another round when a second sentry appeared on the opposite side. Both met approximately in mid-distance, faced about, and retraced their steps.

It was evident that escape in that direction was almost beyond the bounds of possibility.

Awaiting a favourable moment when the nearmost sentry's back was turned, the fugitives crept cautiously down the slope, never halting till they came to the piles of empty casks that had served them so well less than twenty hours previously.

"Now what's to be done?" asked Hamerton.

"Have a shot at those steel ladders—the ones between the Zeppelin sheds."

"By Jove, smart idea of yours, old man! The sooner the better."

Without mishap the two comrades gained the base of one of the ladders that reared itself vertically to a height of nearly two hundred feet. It was to be a climb that would tax their powers of endurance to the uttermost.

"Gently does it," cautioned Hamerton. "One limb at a time, mind, and don't look down. Up you go."

With this parting injunction in his mind Detroit commenced to mount, making sure of each rung before he moved a step higher. He realized that a slip might result in the loss of his comrade's life as well as of his own.

The American was in excellent training, although somewhat handicapped for want of proper food. His muscles were flexible, his grip as firm as iron; nevertheless, by the time he gained the cross-platform connecting the ladders at a level slightly above the arch of the airship shed he was glad to sit down and rest.

"All right?" asked Hamerton anxiously.

"Guess I am," was the reply. "Now for the last lap."

Detroit spoke cheerfully, but the "last lap" was roughly three times the height of the portion already climbed.

Doggedly the two men stuck to their task. Once Detroit whispered that one of the rungs felt insecure. Beyond that not a word was spoken.

Hamerton could hear the American's laboured breaths. His own heart was throbbing violently against his ribs, his arms felt as heavy as lead, while the muscles of his calves had a decided tendency to "bunch"—the forerunner of the dreaded cramp.

Many a time during his terms at Dartmouth he had climbed over the fore-topmast crosstrees of the old hulk Britannia. In those days he had thought nothing of it, but now, unaccustomed to strenuous exercises of that sort, he felt the severity of the task.

Detroit was slackening his pace now. A few inches above his head Hamerton could see the American's heels mount step by step on a seemingly endless task. It reminded him of a pet mouse in a wheel.

Up, up, up! It was by this time little better than a tedious crawl. Once or twice the American stopped to regain his breath, and then plodded resolutely on his upward way. Then, to the Sub's delight, he saw Detroit lurch forward and throw up his heels. His comrade had reached the summit, and was sprawling, wellnigh exhausted, upon the turf.

Summoning up his remaining energies Hamerton also gained the much-desired resting place. Side by side they lay drinking in the cool breeze that came straight from the foam-flecked sea, on which innumerable lights, like stars on a dark night, twinkled incessantly.

"Time!" ejaculated Hamerton, rolling over and kneeling up. "Now, easy ahead; we'll come across another wire entanglement unless I'm very much mistaken."

They were now going with the wind—the worst possible direction, since the sound of any danger in front of them was carried away, while their own approach could be heard by any sentry who happened to be to leeward.

Thirty yards from the edge they threw themselves upon the grass. Within a stone's throw was a great-coated figure standing stockstill. It was one of the chain of sentries guarding the barbed-wire fence that completely encircled the secret Zeppelin station.

Motioning with his hand, Detroit indicated that they should make a detour. Hamerton shook his head. He could just distinguish the outlines of another sentry a hundred yards to the right. "Wait!" whispered the Sub.

Presently the nearest sentry sloped his rifle and began to pace in the direction of the one Hamerton had discerned to his right. When the two met they evidently indulged in a breach of discipline, for although the fugitives heard not a word the sentries were apparently talking.

"I want to make sure of the length of his beat," whispered Hamerton. "Then the next time he clears out we'll make a dash for the fence."

Back walked the sentry. Stopping for a moment to draw up the collar of his greatcoat, for it was just beginning to rain, he made his way past the two lurking men and disappeared in the murky darkness.

Presumably the soldier was not on speaking terms with the sentry at the other end of his beat, for in a very short space of time he returned. Almost abreast of the fugitives he stopped short, faced outwards, and levelled his rifle and bayonet, as if something suspicious had attracted his attention. Then, having satisfied himself that there was no cause for alarm, he made off towards the post on his left.

"Now!" whispered Hamerton.

"Just you wait!" replied the American. "Let's shift back a bit."

He pointed towards a speck of light that flickered in the now howling breeze.

"It's the rounds, by Jove!" muttered the Sub. "That's right; we'll hide in this hollow and trust to luck."

"Halt! Who goes there?" demanded the sentry in German.

"Rounds," was the reply.

"Advance, rounds; all's well!" exclaimed the soldier, recovering his rifle.

An officer and a file of men, one of whom held a lantern, came tramping through the long, damp grass. The Sub seemed to feel the glare of the light. Instinctively he buried his face in his arms and hid his bare hands under his coat. For the gleam to fall upon any light-coloured object was to arouse suspicion.

"Anything to report?" demanded the officer.

"No, sir. Once I fancied I saw one of the bloodhounds."

"Then don't fancy. I may as well tell you that the dogs are safely chained up. It would go ill with some of you men if they were at large on a night like this. Besides, the hounds are too valuable to risk being shot by an imaginative sentry. Now, remember, challenge once only and then fire, should any suspicious person approach your post. It means promotion to the man who succeeds in shooting or capturing those troublesome spies."

[Illustration: "'IT'S THE ROUNDS, BY JOVE!' WHISPERED THE SUB">[

The rounds passed on. The sentry resumed his walk without attempting to give the salute. This Hamerton noticed particularly. As in the British Army, it was forbidden to give or acknowledge compliments after sunset. This knowledge he hoped to profit by, since it was within the bounds of possibility to impersonate a German officer and thus get safely away in one of the boats at the beach of the Unterland.

"Now!" whispered the Sub once more.

Silently the two comrades made their way to the fence. This time the lowermost wire was set up taut, and Hamerton had the greatest difficulty in holding it up sufficiently for Detroit to crawl clear of the sharp barbs. Before the sentry had set out on his return beat the fugitives had put a safe distance between them and that particular danger.

They were now within a hundred yards or so of Sathurn, the northernmost part of Heligoland, that terminates in a sheer cliff one hundred and sixty-six feet in height. Close to the point rises a detached pinnacle of rock, known as Hengst, its summit being only three feet lower than that of Sathurn.

"You stop here," whispered Hamerton. "The sentries seem as thick as flies. I'm going to crawl a few yards. One may escape detection where two will not."

With this injunction the Sub left his companion, and on all-fours made his way towards the extremity of the cliff. On his left was a building that a few years previously had been used as a fog-signal house. A light was burning within, and the sharp click of a shutter told the Sub that someone was using a Morse signalling apparatus.

Profiting by the glare, Hamerton crawled closer. The door of the hut was ajar. Within were several engineers standing by in readiness to work a powerful searchlight. To the left of the hut, and protected from leeward by a mound of earth, was a long metal cylinder about eighteen inches in diameter. A stray beam of light showed Hamerton that one end of this object was carefully covered by a tarpaulin.

"What's this arrangement, I wonder?" he thought. "Looks like a sort of torpedo tube. I'll——"

His hands clutched at empty air, he lurched forward, up went his heels, and the next instant he felt himself falling.

Like a flash the thought went through his brain: "I'm done for this time—I've toppled over the cliff." Yet not a sound escaped his lips, even when completely taken aback by the sudden plunge.