He was seriously annoyed; not at the immediate danger, but at the failure of his device to ward off obstructions; for in ascending the submarine had risen immediately underneath the anchor-chamber of a mine that had broken adrift, but still retained the metal box containing the depth-regulating mechanism. The anchor-chamber had engaged on the inside of the starboard girder, and what was more, a length of loose rope had trailed aft and was almost within the sweep of one of the twin propellers. In another few seconds the rope would be wound round and round the boss as tightly as a steel hawser.

Promptly the electric motors were switched off. For the time being one danger was averted. It remained to shake the submarine clear of the powerful charge of explosive that was. .h.i.tched up within seven feet of the conning-tower. One slight tap on one of the many sensitive "feelers" of the mine would result in the total destruction of the submarine and her daring crew.

"Flood auxiliary ballast-tanks," ordered the Lieutenant-Commander.

Slowly, as the water hissed into the strong steel compartments, the submarine sank in a vertical direction. For the nonce her diving-rudders were useless. She was stationary as far as movement in a horizontal direction was concerned.

The officers anxiously watched the hand of the steel indicating the depth. At twelve fathoms the downward movement ceased. The Lieutenant-Commander had hoped that the buoyancy of the mine would release the anchor-chamber from the steel girder that in this instance had proved to be a source of danger rather than a protection; but no--the submerged vessel had drawn both anchor-chamber and mine beneath the surface.

"Prepare to anchor--let go!"

With a sullen roar, intensified by the confined s.p.a.ce, the stockless anchor was released from its "housing" at the for'ard end of the keel.

Suddenly the studded-linked cable "snubbed" as the flukes obtained a hold; then, anch.o.r.ed at fifteen fathoms beneath the surface, the submarine fretted easily at her cable in the five-knot current.

Again the Lieutenant-Commander peered through the scuttle. At that depth the light that filtered through the water was just and only just sufficient to enable him to discern the deadly object still clinging tenaciously to the submerged craft. Under the action of the current it tilted ominously, though fortunately not sufficiently for any of the projecting "feelers" to come in contact with the metal plating of the anch.o.r.ed submarine.

"We'll stand easy," remarked the skipper to his augmented group of officers. "We're safe enough for the present, only it's a wicked waste of valuable time. As soon as it gets dark we'll ascend and cut the blessed thing adrift."

Half an hour later the officers were sitting down to a hot meal cooked on an electric grill. The repast over, Lieutenant-Commander Huxtable turned to his companion and coolly suggested a hand at bridge.

d.i.c.k took a hand with the three executive officers of the submarine, but his luck was out. He could not concentrate his mind upon the game.

His eyes were constantly wandering. Almost every minute he glanced at the clock, the hands of which appeared to move with exasperating slowness.

"Come, come!" exclaimed the Lieutenant-Commander. "You'll be cleared out if we go on playing for another hour. Pull yourself together, man."

But the encouragement was thrown away, for although the three submarine officers played with the greatest enthusiasm, d.i.c.k made a sorry show.

"Hanged if I can play, sir!" he declared. "I wonder how you can, with that mine alongside."

"You'd soon get used to it," replied the Lieutenant-Commander. "I don't mind admitting that we all feel a bit jumpy at first, but it pa.s.ses off. But it's after sunset. We'll see what we can do directly we've finished this round--your deal, partner."

The game over, the Lieutenant-Commander returned to his post in the conning-tower. He was hoping against hope that during the interval the buoyancy of the mine might have been sufficient to break the already rotten rope, but on flashing a powerful electric torch through the gla.s.s of the scuttle the formidable cylinder could still be discerned.

The order was given to weigh, and under the action of an electric winch the cable came home fathom by fathom until the anchor was once more housed in the recess provided. No longer held, the submarine was drifting backwards in the steady current.

"Blow auxiliary tanks."

Quickly the water ballast was dispelled from the supplementary tanks, and relieved of this weight the vessel slowly rose until her conning-tower and deck were awash.

Opening the hatch, the Lieutenant-Commander, accompanied by a petty officer and a leading seaman, gained the open air, and at once proceeded to remove the deadly mine.

There was a certain amount of reflected glow from the search-light that, once their eyes grew accustomed to the comparative darkness, enabled them to see fairly distinctly.

Clambering cautiously along the horizontal strut that strengthened the curved girder, the men made a careful survey of the metal cylinder before attempting to handle it. Apparently it had been in the water for some weeks, for barnacles and slimy weeds were adhering to its surface. The "horns" or "feelers" were, fortunately, pointing away from the hull of the submarine; nevertheless the task of disengaging the mine without allowing it to sc.r.a.pe or jam against any form of solid resistance was fraught with danger. A slight tap upon one of those numerous spike-like projections would result in death to every man on board.

Examination proved that not only was the mine with its attendant anchor-chamber entangled by means of a hempen rope, but a length of wire had stubbornly intertwined itself round a portion of the girder, so that the mine, swinging towards the metal hull, was practically midway between it and the curved side of the vessel.

"A hack-saw there," ordered the Lieutenant-Commander. "Oil it well, or the rasping will give the show away."

The required tool was quickly forthcoming, and the two men tackled their dangerous task. For twenty minutes they worked desperately, momentarily expecting to be "picked up" by the search-lights that were playing ominously close to the dark-grey hull of the submarine.

"Through, sir," announced one of the men breathlessly. "Shall we topple it over?"

"No, no," replied the skipper hurriedly. "Are you quite sure that everything's clear?"

"Aye, aye, sir."

The mine was now held in position only by the triangle formed by the girder, its horizontal brace, and a two-inch teak plank placed diagonally across the metal work. Fortunately the sea was now calm and the submarine's motion barely perceptible.

"Diving-stations," ordered Huxtable. "It's neck or nothing."

The water-tight hatches were closed and secured, and water admitted into the ballast tanks, both main and auxiliary, for it was her commander's intention to submerge the submarine in a vertical position without having recourse to the use of the propeller and diving-planes.

In sinking, the submarine, he hoped, would be automatically freed of its dangerous enc.u.mbrance, since the buoyancy of the mine would float it clear when the craft was completely submerged.

Instinctively d.i.c.k shut his jaw tightly as he heard the hiss of the water pouring into the tanks. He fully realized the delicate operation, for a list of any magnitude would result in the mine toppling over from its insecure perch as it did so. It was not pleasant to realize that he was in a hermetically sealed steel box with a dangerous neighbour in the shape of seventy-six pounds of gun-cotton.

He glanced at the Lieutenant-Commander, who was peering anxiously through the slit in the conning-tower, and although he moved not a muscle the perspiration was standing out in beads on his temples.

Presently he turned his head.

"At that!" he ordered, addressing the men standing by the valve of the ballast chamber. "Turn horizontal rudders to ten degrees down. Half speed ahead."

A gasp of relief echoed through the confined s.p.a.ce. The men gave a cheer. They understood: one danger had been successfully combated.

The steady thud of the throttled-down motors alone imparted the sense of motion as the submarine, fifty feet beneath the surface, resumed her blind grope up The Narrows.

Twice only during the negotiation of that intricate pa.s.sage did the Lieutenant-Commander show the top of the periscope above water. The first observation revealed the feet that Nagara was well on the starboard hand, and that an alteration of helm was necessary to avoid piling the submerged craft upon shoals that, owing to the irregularity of coast-line, were directly ahead.

The second convinced Huxtable that the course was now practically a straight one for the Sea of Marmora as far as direction went; but he knew that in that stretch of water which lay between him and the inland sea were at least six rows of anch.o.r.ed electro-contact mines.

"A vessel on our port bow, sir," declared d.i.c.k, who before the submarine could submerge her periscope had glanced into the object-bowl. It was a picture of darkness which met his eye, but across that expanse of dull leaden colour, that indicated a blend of sea and sky on a rainy night, he had detected a still darker object travelling slowly across the "field" of the periscope, the "iris" of which was opened to its fullest extent in order to admit the maximum amount of light, which was very small.

"A torpedo-boat," decided the Lieutenant-Commander after a brief survey. "She would make an easy target, but we'll let her go. It would mean betraying our presence, and that would never do. One thing she's taught us, that is that the pa.s.sage through the next mine-field is hard against the Asiatic side. We'll let her pa.s.s, and then pick up her wake."

The Turkish torpedo-boat was evidently bound from the neighbourhood of Nagara for the Bosphorus. She was steaming at fifteen knots and, judging by the clouds of black smoke tinged with dark-red and orange flames, was under forced draught.

Unsuspectingly the boat held on her course, little thinking that within two cables' length of her a British submarine was following the phosph.o.r.escent swirl that marked her track. Either the men of her watch on deck were lax in their duties or else they devoted their attention to keeping a look-out ahead and abeam, for the cascade of foam that marked the swiftly-moving periscope pa.s.sed unnoticed.

Ready at the first alarm to tilt the horizontal diving-rudders, Huxtable conned the submarine. He was in high spirits, for the thought that an enemy torpedo-boat was acting as a pilot amused and elated him.

Although prepared to take the risk of diving under the mine-field, he fully admitted his preference to be conducted in safety through the danger-zone.

Once the torpedo-boat sharply ported her helm. For the moment it seemed as if the submarine had been spotted, but since no sh.e.l.l was fired from the Turkish craft the Lieutenant-Commander surmised that the change of course had been rendered necessary by the intricacies of the secret pa.s.sage through the mine-field.

Allowing sufficient distance the submarine followed suit, until the torpedo-boat swung round on her former course. She had cleared the danger-zone, and her imitator had done likewise.

Slowly but surely the Turkish craft was out-distancing the invisible submarine, whose utmost limit when submerged was not equal to that of the torpedo-boat. Half an hour later all traces of her had disappeared. Even the churned wake had blended utterly with the surrounding waves.

The submarine was now about to enter the Sea of Marmora. The search-lights of Gallipoli were broad on the port beam. On the port bow a row of flickering lights marked the camp-fires in the Bulair lines. A triple row of anch.o.r.ed mines had to be avoided before the British craft was clear of the upper reaches of the Dardanelles.