"Boat ahoy!" came the hail from the lookout.

Captain Restronguet replied as before, but this time the look-out was not satisfied.

"What boat is that?" he shouted.

"Customs!" roared the captain with a lucky inspiration.

Muttering a malediction on all custom-house officials, especially on those in this particular boat, the seaman resumed his walk up and down the fo'c'sle deck. He remembered a certain half a pound of tobacco that had got him into trouble with His Majesty's Customs, and the incident still rankled in his manly bosom.

Without further interruption the boat ran alongside the deck of the "Aphrodite." Her crew jumped aboard the parent vessel, hauled the collapsible on deck and folded it.

"Look sharp, sir!" exclaimed Gwennap. "There's a steam-boat bearing right down upon us."

There was no time to be lost. Hastily the folded boat was dropped through the hatchway, her crew quickly followed and the hatch was reclosed. One touch and the emergency chambers were flooded, and the submarine began to sink to the bed of the river. It was a close thing for the picquet boat. Had she been a quarter of a minute earlier they would have stove her bows in against the ma.s.sive plating of the elusive vessel. As it was she pa.s.sed over the after-conning-tower with less than half a fathom of water to spare, utterly ignorant of the narrow escape she had had.

"Welcome home once more, Kenwyn!" said Mr. Devoran cordially, extending his hand, which the new arrival gripped like a vice and shook like a pump-handle.

Had the chief officer of Southsea Coast Guard Station, or P.C. 445 of the A Division of the Borough of Portsmouth Police been present at this reunion, they would have had no difficulty in recognizing Mr. Kenwyn as the quiet and very retiring unknown who had landed under most unusual circ.u.mstances on Southsea Beach.

"I had to abandon my diving-suit, sir," explained Kenwyn, who served on board the submarine in the capacity of second officer.

"That I have already learnt from Press reports," replied Captain Restronguet. "And I was glad to know that you took particular pains to get rid of the air reservoir. That did the authorities nicely; they are welcome to the dress, and if they can a.n.a.lyse the metal it is composed of they are also at liberty to make use of the secret. It has not been patented. But how came you to get out of your bearings, Kenwyn? I notice you had to concoct a c.o.c.k and bull yarn about walking from the beach at Gosport."

"I never tell a lie, sir, under any conditions. As a matter of fact, after I left the 'Aphrodite' I did go ash.o.r.e at Gosport, somewhere behind a yacht yard. No one saw me. I then tried to cross to the Portsmouth side of the harbour to try and recover the submarine welding tool that Carnon, you may remember, dropped when we examined the entrance to No. 5 Shipbuilding Slip. Before I realized it the ebb tide caught me, and I was whisked off down the harbour at a rate of at least seven knots. As soon as I felt the current slacken I took compa.s.s bearings and came ash.o.r.e, and the rest you know."

"You have, of course, heard that we have a naval officer on board?"

"Heard? Rather. The papers are full of it, sir, and every one is talking about it. At Exeter Station and again at Millbay, on my journey down, it was the sole topic of conversation on the platform."

"And how does the Great British Public like it?"

"In a general sense they are thankful it is no worse, so to speak. It is recognized that you are a power that cannot lightly be ignored, and your magnanimity (that is the way they put it) has created quite a favourable impression. Even in the House it was suggested that it would be a master-stroke in world supremacy if you could be induced to hand over the 'Aphrodite'----"

"Never!" declared Captain Restronguet vehemently, and bringing his fist down heavily upon the table. "Never! They had their chance, but foolishly threw it away. Now, gentlemen, it is nearly one o'clock. I, for one, will be glad to have a few hours' rest," and with an inclination of his head Captain Restronguet retired to his sleeping quarters.

CHAPTER XI.

CONCERNING CAPTAIN RESTRONGUET'S RIVAL.

It was broad daylight when Arnold Hythe awoke. He was surprised to find the "Aphrodite" lifting to the heave of the open sea, and the sunlight pouring in through a small circular scuttle above his bunk. Hastily springing out of bed he looked out. As far as his limited vision extended he could see nothing but blue water--a sure sign that the submarine was far from land. Judging by the apparent motion of the waves the "Aphrodite" was running at a bare ten knots--possibly less.

And a few hours previously she had been lying motionless on the bed of the River Tamar.

Slung to the beams overhead was a metal bath, of a similar pattern to those supplied for officers' use in the Royal Navy, while in the bulkhead were two taps marked "hot" and "cold." On a chair by his bunk were his clothes, brushed and folded, while quite a large stock of new under-garments were lying on a folding table.

Hythe always prided himself upon being a sound sleeper, yet able to arouse at the slightest sound, but for once at least his faith in his capabilities received a rude shock. Some one had certainly entered whilst he slept, and also the "Aphrodite" had made a lengthy trip without his being aware of it.

The astonished young officer quickly tubbed and dressed. Then it occurred to him that he had not shaved. Lying on the dressing-table was a safety razor, also brand-new. Evidently his host had left nothing undone to contribute to the comfort of his guest.

His toilet completed Hythe stepped out into the alley-way. At the fore-end, and hitherto unnoticed by him, was a hatchway. It was now open and a ladder had been shipped under it.

An appetizing odour came from the captain's cabin. It made the sub feel hungry; but curiosity conquered, and he made his way on deck, or on Platform Number One as Captain Restronguet preferred to call it.

Hythe found himself on a flat deck nearly two hundred feet in length, and unbroken save for the low coamings of three hatchways and the fore and aft conning-towers. Metal stanchions and rails had been placed in position round the sides to prevent anyone from slipping overboard. As the sub looked down on the deck he noticed that, like the sides, it reflected his own image and those of other persons and objects on deck, but there was no dazzling glare from the sun that was now high in the heavens.

Cl.u.s.tered for'ard between the bows and the foremost conning-tower were nearly every member of the crew: twenty-five stalwart men all dressed in plain but serviceable rig. Pacing up and down between the two conning-towers were Mr. Devoran and some one whom Hythe had not previously seen--the Second Officer Kenwyn.

As they turned at the end of their promenade the two men caught sight of the sub.

"Good morning, Mr. Hythe," said the chief mate genially. "Quite a fine day after our sample of the English climate, eh? By the by, I don't think you know Kenwyn, our second officer? He only rejoined last night."

The three engaged in conversation of general interest for a few minutes, then Mr. Devoran asked Hythe if he had seen the captain that morning.

"Not yet," replied the sub. "I came straight on deck. It was a surprise to find myself at sea. Where are we?"

"Nearly twenty miles S.W. of Ushant," replied the chief mate. "We shall be cruising about here for a few days, as we expect to fall in with a certain vessel. We have left English waters for a time, at all events, but you need not worry about that, for the captain informed me that he received a reply to his note at four this morning. You are officially 'lent' to the 'Aphrodite' until further orders. But breakfast is ready, and Captain Restronguet will explain matters more fully."

The captain greeted Hythe with great affability, and both thoroughly hungry did justice to a good breakfast. Very little was said, and when the meal was over Captain Restronguet left the sub to his own devices while he made the customary rounds of the vessel under his command.

Accordingly Hythe went on deck once more. The "Aphrodite" was slowly forging ahead at a bare five knots, her course being N.N.W W. That meant although not actually retracing her course she was heading at an acute angle to it. It was a sort of "wash-and-mend clothes day," a function resembling the time-honoured custom of keeping Thursday afternoon on board the ships of His Majesty's Navy.

The French coast was still invisible, but less than five miles off the sky line was broken by curiously cut tanned sails of the Concarneau fishing fleet. Away to the north-west a huge liner, looking without masts and funnels more like an exaggerated Noah's Ark than anything else, was pelting through the water at a modest thirty-three knots.

Perhaps had her officer of the watch chanced to direct his telescope in the direction of the "Aphrodite" he would at once conclude that he had sighted the sea serpent, for, owing to the invisible hue of her hull only the seated figures of the men on deck would come within the field of vision.

The submarine was floating fairly high out of the water. More than half of her ballast tanks had been "started," and consequently there was sufficient freeboard to allow the side scuttles to be opened. With considerable buoyancy she rolled a good deal, but with a true-born sailor's delight Hythe revelled in the motion.

At noon Captain Restronguet appeared on deck. Kenwyn had just "shot the sun" and was working out the vessel's position.

"It's about time she was here, Devoran," remarked the captain. "That is, if the report is authentic. Has the submarine detector given no warning?"

"No, sir, I've stationed Polglaze by it, and he won't be caught napping.

She couldn't have pa.s.sed before we arrived, sir?"

"I made due allowances, giving her ten knots above her estimated speed.

But we must exercise patience. Ah! Mr. Hythe, no doubt you are wondering why we are dodging about here instead of playing harmless little tricks upon His Britannic Majesty's ships and naval establishments? Well, I think I ought to give you some explanation, so if you will kindly step below we can talk without interruption."

"By the by," continued Captain Restronguet, as the two men made their way to the cabin, "you asked me how the 'Aphrodite' is manoeuvred to bring her to the surface and vice versa. We have three distinct methods. The first is by means of horizontal rudders, there being a pair at both bow and stern; the second is by means of expelling water ballast, which is all very well so long as the ejecting pumps work properly. Hitherto we have had no trouble in this direction, but it is well to be prepared. Consequently we employ a third method--one for use in emergencies only. I make no secret of the fact that I borrowed the idea from the French. I prefer to be original, but at the same time in the interests of my crew I do not hesitate to adopt well-established devices. To each of the three sections of this vessel is fixed a detachable iron keel. The bolts are secured on the keelson by a single yet effective looking device. One thrust of a lever and a section of this keel is dropped. Should a compartment be half full of water there is sufficient buoyancy gained by the release of this dead-weight to lift the vessel to the surface."

"Isn't there a chance of the 'Aphrodite' buckling her plates in a heavy sea with that dead-weight split into three separate sections?" asked Hythe.

"As far as the 'Aphrodite' is concerned there are no heavy seas,"

replied his host. "At the first suspicion of bad weather we dive to eight fathoms, or more if necessary. Since, even in mid-Atlantic the waves rarely exceed forty feet in height, and the depth maintained by the submarine is regulated by the vertical height of water over her, there is nothing to be feared as far as the 'hogging' and 'sagging'

stresses are concerned."

At Captain Restronguet's invitation the sub threw himself into an easy chair. He was eager to hear everything about this mysterious man and his marvellous vessel, and the fact that the Admiralty had given a formal consent for him to remain on board as an official observer relieved him of all anxiety.