"You'll have plenty of help in an hour or so," announced Captain Jones.

"That is, if you want any. There's a regular flotilla of stern wheelers coming up stream. They're flying the British Ensign."

"I heard they were on their way up," said Captain Restronguet. "They are from Lake Nya.s.sa. Let 'em all come, as the catch-phrase used to be when I was at school."

"Look here," said the airship's owner. "If you like I'll stand by and lend a hand. Please understand I don't want to take away any credit that belongs to the 'Aphrodite' alone; neither are we after a share in the prize money, although I hear the 'Vorwartz' is chock full of gold.

That's what's keeping her hard and fast, I should think."

"You are awfully good," replied Captain Restronguet. "I shall be only too happy to avail myself of your services."

"And the sooner the better," added Captain Jones. "Five additional helpers, all used to plenty of hard slogging, will soon make a show."

Telling Polglaze to make his way back to the spot where they had landed from the "Aphrodite," in order to let Devoran know that all was well, Captain Restronguet, accompanied by Hythe and Captain Jones, began a systematic examination of the captured submarine. Except for the maniac, who was now babbling in a childish manner and was quite unconscious of his surroundings, not a man of von Harburg's company remained. Everything on board showed signs of a hurried departure. In the galley the men's dinner was still in the boilers. The electric power had apparently failed, for some time since a temporary stove for burning wood had been erected in the galley, the funnel leading through the open fore hatch. By examining the thickness of the deposit of soot Captain Restronguet was able to come to the conclusion that the failure of the electrical supply coincided with the time the "Aphrodite's"

detector ceased to record the position of her rival.

Stowed away in the emergency water ballast tanks were hundreds of bars of gold--plundered from many a richly-laden vessel. This horde had not been touched, but almost all the specie and bullion in the after cabins had been removed.

"What prompted the rogues to make such a hasty flight, do you think, sir?" asked Hythe.

"They undoubtedly got wind of the news that we were on their track. The failure of their electrical gear added to their panic. They decided to remove as much of their plunder as they could conveniently carry, and trust to luck that the rest of the booty remaining on board might yet be recoverable. I think they must have gone up stream in a boat, since there are traces of their footprints through the gra.s.s."

"You mean to pursue your search?" asked Captain Jones.

"Certainly," replied Captain Restronguet with conviction.

"Judging by the state of the river," continued the captain of the "Pride of Rhodesia," "which is still falling, even a boat expedition will be a difficult matter. Why not make a voyage in my craft? We can follow the course of the river at any height you wish, and if Karl von Harburg has attempted flight by means of a boat we shall be bound to overtake him and effect his capture. I can easily find room for a dozen of your men."

"I will gladly accept your offer," replied Captain Restronguet without hesitation. "When will it be convenient for you to start?"

"At once," replied Captain Jones promptly. "We ought to complete the business and be back here well before night. Meanwhile those of your men who are left behind--I will leave some of my crew as well--can proceed with the unloading of the 'Vorwartz.' The gold will be perfectly safe ash.o.r.e, for there do not seem to be any inhabitants in this district. Even if there are, and they are tempted to give trouble, twenty rifles firing from the deck of the submarine will make them keep a respectful distance."

"Come along, Mr. Hythe; this will be another experience for you," said Captain Restronguet. "Carnon and Carclew you will come with us. Eh?

What's that? Mr. Hythe, here's your Irishman anxious to have an aerial trip."

Ascending the swinging ladder the men gained the platform connecting the two deck-houses of the airship. Hythe found himself on a promenade nearly three hundred feet in length and forty in width converging fore and aft, and terminated by the aluminium cabins that afforded sleeping accommodation for the crew and also means of manoeuvring the airship in bad weather.

"Cast off there," shouted Captain Jones.

Those of the airship's crew who remained ash.o.r.e hastened to unfasten the stout hempen hawsers that held the "Pride of Rhodesia" to the ground.

Since the total number of men on board was less than that of the present crew no throwing out of ballast was necessary. The airship rose swiftly and smoothly to a height of eight hundred feet.

"Guess we'd best descend at once," said Captain Jones.

"Descend--why?" asked Captain Restronguet.

The skipper of the "Pride of Rhodesia" pointed towards the broad Zambesi. Abreast of the junction of the stream in which the "Vorwartz"

had taken a vain refuge were three river gunboats.

The huge aerial propellers began to revolve and the "Pride of Rhodesia"

gathered way. In view of her skipper's remark Hythe could not at once understand this manoeuvre; but Captain Jones was not a man to waste gas when he could bring his airship to earth by other means.

Circling in ever-descending spirals the huge craft approached within fifty feet of the place where a few minutes before she had been anch.o.r.ed. The bow and stern ropes were thrown down, and a.s.sisted by the "Aphrodite's" men those of the crew of the airship who had been left behind dragged the "Pride of Rhodesia" to earth.

Almost as soon as Captain Restronguet, Hythe, and the skipper of the airship had alighted, a motor launch in which were several white-uniformed officers came pelting up stream and brought up alongside the captured submarine.

"We are a trifle too late, I see," exclaimed the senior officer from the gunboats, as salutes were gravely exchanged.

"Third in the field," commented Captain Jones, pointing to his airship.

"This is the lucky individual--Captain Restronguet."

"Thought we'd been done in the eye when we saw his submarine out in the stream," said the commodore of the flotilla. "Well, Captain Restronguet, we congratulate you upon having rid the world of a pest."

"The business is not finished yet," said the "Aphrodite's" captain. "We were on the point of following up the rascals."

"Some have escaped, then?"

"All save one, and he's as mad as a hatter."

"Well, it strikes me we are not required here," continued the commodore.

"But before we return we would very much like to look over both submarines."

"With pleasure," a.s.sented Captain Restronguet. "Unfortunately I cannot stay to have the honour of showing you round, as we wish to overhaul Karl von Harburg and company and be back before night. I'll have a signal sent to my chief officer, Mr. Devoran, and he will act as my deputy."

"Has the news of the capture been sent home?"

Captain Restronguet consulted his watch.

"I believe I am right in a.s.suming that already the newsboys are selling special editions in the streets of London."

"Smart work!" e.j.a.c.u.l.a.t.ed the commodore admiringly.

"Fairly," admitted the captain of the "Aphrodite" modestly. "The moment our flag was hoisted on the 'Vorwartz' the news was signalled to the top of the hill. Two of my men are stationed there. They in turn signalled on to my chief officer, who by wireless communicated direct with my London agent. He, I feel certain, lost no time in giving the news to the proper authorities; but making due allowance for slight delays I think my a.s.sumption is correct."

"What do you propose doing with the 'Vorwartz,' may I ask?"

"Tow her off as soon as possible and take her down the river. I hope before night to get into wireless communication with the officer commanding H.M.S. 'Pique,' and hand the prize over to him. He can then tow her to Cape Town and there the necessary transactions can be effected. But I must be going. If you will excuse us we will bid you good-day. Perhaps we may meet again in the near future."

Upon re-embarking Captain Jones gave the order for half speed ahead, and the "Pride of Rhodesia," at a modest twenty-five miles an hour, flew over the course of the tributary at a height of less than five hundred feet.

Gla.s.ses were brought to bear upon the country beneath them, and every rock and shoal in the river was thus carefully examined. The "Vorwartz"

had almost reached the limit for navigation, for at less than a mile above the spot where she had stranded the river shallowed considerably and was interrupted by a series of cataracts. In one of these Hythe spotted a bra.s.s-bound box wedged in between two rocks, and by the identification letters on its side Captain Restronguet knew that it was one from a liner's strong-room.

"They've been in difficulties already," he observed. "They've had to jettison some of their booty. Judging by the state of the river, I don't think they can have gone very far."

"There's a dense forest ahead," announced Captain Jones. "That makes our task more difficult. If the rascals have taken it into their heads to make a way through the trees, the thick foliage will screen them from view. However, I'll keep up-stream for some distance yet. Perhaps they haven't the sense of caution to destroy their boat or haul it up out of sight. However, we will see."

"No chance of a boat getting over that," exclaimed the sub, as after a short interval the airship came in view of a waterfall quite forty feet in height and extending from bank to bank. As the "Pride of Rhodesia"

drew nearer the noise of the falling water almost outvoiced the purr of the airship's motors. One glance was sufficient to show that nothing afloat would be able to surmount that formidable barrier.

"There's their boat," bawled Captain Jones, into the ear of his successful rival.