The clang of the engine-room telegraph bell followed quickly, to the accompaniment of short, crisp orders and the trample of boots upon a metal deck.
It was already too late. With a rending crash the vessel, whatever she might be, ran bows on to the jagged rocks.
"That's done it! Her number's up," exclaimed the petty officer. "Now, lads, four of you come with me. There's work to be done there, I reckon. The others stay with this gentleman and guard the prisoner till we return."
"Look here," said the captive in well-nigh breathless expostulation. "You've made a rotten mistake. Spoilt everything."
Peter felt his heart give a furious beat. Regardless of regulations he bent over the prostrate prisoner and struck a match.
The flickering flame revealed the indignant features of Philip Entwistle.
CHAPTER XXIII
ON THE ROCKS
"So I haven't been able to chuck you fellows yet," remarked Lieutenant-commander Tressidar. "And what is more I see no likelihood at present of so doing. We've just had a wireless to proceed east to a position somewhere off the mouth of the Humber."
"We are not at all fed up with your hospitality, Tress," replied Fuller, "only we ought to have been on board the old 'Hippo' long ago. I think, if there's a chance, we ought to get ashore, report to the Commander-in-Chief and await orders."
The "Antipas" was steaming at a good twenty knots. It was late in the afternoon; the sea calm, the sky slightly overcast. With a steadily-rising glass the weather showed indication of continuing fine, notwithstanding the presence of patches of sea-fog.
Towards sunset the fog increased until it was no longer safe for the destroyer to maintain her speed. Fishing boats, dauntlessly risking the submarine menace, were frequently in these waters. To tear blindfold through the dense mist would be courting disaster.
The slowing down of the engines brought the three airmen on deck.
"Fog!" exclaimed Kirkwood. "Rough luck. I thought that we were entering port when the skipper rang down for easy ahead."
"Pretty thick, too," added Barcroft. "It's as much as I can do to see the bridge. Beastly calm, too; what do you say to returning to our little rubber of dummy?"
"Now I'm here I'll stop," decided Fuller, drawing his coat across his chest. "Hullo! they're taking soundings. That looks as if we were nearing shore."
For nearly an hour the "Antipas" literally "smelt her way." Darkness had fallen, and with it the fog bank increased in density and dimensions. No longer was it possible to discern anything beyond a couple of yards. No discordant hoot blared from the syren, no navigation lights were shown. Beyond slowing down nothing more could be done, owing to war conditions, to safeguard the destroyer from risks of collision.
"Hullo, you fellows!" exclaimed the lieutenant of the destroyer as, clad in oilskins, sou'wester and sea boots, he groped his way for'ard. "Have we made it too comfortable for you down below?"
"Didn't know that it was your 'trick,'" remarked Barcroft.
"Neither is it. That's one of the penalties of serving on a destroyer. You never know when you're off duty. The skipper's just spoken through: we're on the track of a strafed U-boat. Picked her up by microphone."
"Here's to the bridge, then," decided Fuller. "Come on, you would-be card-players. Let's see the fun."
"One of the advantages of going dead slow, I suppose," commented Tressidar as his guests rejoined him. "We've cut across the trail of a submarine, that's certain. Come in, and see how things are progressing."
The lieutenant-commander opened the door of the chart-room. Against one bulkhead stood the receiver of the submarine-signalling apparatus. Standing in front of it was a bluejacket with both ear-pieces clipped to his ears. With his left hand he was alternately actuating the switch that connects both receivers.
"Right dead on, sir," he reported. "Less than a couple of cables' lengths ahead, I'll allow."
Behind him stood the helmsman at the steam-steering gear, his eyes fixed upon the cryptic movements of the operator's hands, as the latter transmitted the course to the quartermaster.
The principle of the microphone signalling apparatus is simple enough. In the vessel's hold and as far beneath the waterline as possible, are two metal tanks each filled with water and containing two sensitive instruments that readily pick up sounds transmitted through the medium afforded by the sea. One tank is placed on the starboard the other on the port side, and both are connected by wires with the receiver in the chart-room.
Supposing the operator hears the thud of a distant propeller, and the sound is more distinct from the port side he knows that the submerged vessel is somewhere in that direction. Conversely, the sound being greater in the right-hand receiver he is able to locate the object emitting the sound as being on the starboard side of the ship. When the volume of sound passing through both receivers is equal the operator knows that the vessel's bows are pointing practically "dead on" to the unseen but audible peril.
"That's all very fine," remarked Kirkwood. "But supposing that man has a cold in one ear. How is he to guard against being misled by the inequalities of hearing? I've heard of a fellow being deaf in one ear and not knowing it for months."
"The inventors have taken that into consideration," replied Tressidar. "That's why both ears are connected with the receiver on one side only of the vessel at a time. As he turns that switch from side to side both ears are listening to the sounds from the port and starboard tanks alternately. What's that?" he added, addressing the operator. "Three cables ahead? This won't do; she's gaining on us."
The skipper quitted the chart-room, followed by the three airmen. Coming from the lighted compartment; they were momentarily dazzled by the transition from artificial illumination to murky, pitch-black night.
"Increase speed to fifteen knots," ordered Tressidar. "Where there's water for that strafed U-boat there's enough for us.... Overhauling her? All right; twelve knots, then."
"Those fellows have plenty of nerve," remarked Barcroft, "or else they've no nerves at all. Suppose fog doesn't make the slightest difference to them when they are submerged, but to us it appears otherwise. What is that U-boat doing, I should like to know, plugging along at twelve knots and in the direction of the British coast?"
"Keeping a pressing appointment, perhaps," said the A.P. with a laugh.
"Many a true word spoken in jest, old bird," rejoined the flight-sub. "It is——"
"A little less talking there, if you please," interrupted Tressidar curtly.
The three airmen took the hint. It was only on very rare occasions that the genial lieutenant-commander "choked any one off." It was an indication of the mental strain upon the skipper of the "Antipas."
"By Jove! if she does come up," thought Barcroft. "It will be Third Single to Perdition for a set of skulking pirates. The fog is lifting, too. I can distinguish the wave-crests nearly a cable's length ahead. We'll be into another patch in another minute, though, worse luck."
Suddenly the watchers on the destroyer's bridge caught sight of a short series of flashes slightly on the port bow, and perhaps at a distance of a mile.
In a trice Tressidar brought his binoculars to bear upon the glimmer of light, thanking Heaven as he did so that a rift in the fog enabled him to spot the presence of the hunted Hun. The powerful night-glasses revealed the outlines of a conning-tower and twin periscopes just emerging from the waves. Then as quickly as it appeared the light vanished. It was enough. The lieutenant-commander could still discern the patch of phosphorescence that encircled the partly submerged U-boat.
"Starboard ten!" ordered Tressidar, at the same time telegraphing for full speed ahead both engines.