"Well, that's a nice prospect," said Billy. "I don't know but what I should prefer their room to their company."

"Same here," chorused the others.

Hour by hour now the seaweed began to get thicker. At first spread in isolated clumps and drifting prettily on the waves, it now became so dense as to be a menace.

"We'll have to turn back," announced Frank, "we can't afford to risk snarling up the propeller."

Accordingly the Bolo's head was put about and she was headed westward again. When the seaweed became so thin as to not offer any serious impediment to navigation, the Bolo's heavy anchor was dropped. Luckily she carried six hundred feet of one inch manila, but even this was hardly enough for the depth of water and had to be eked out with every bit of chain and cable that could be spared. Fortunately under the circ.u.mstances the Bolo carried a capstan which could be thrown into a gear with the engine, otherwise it would have been impossible for her to anchor in that depth of water, as her crew could never have got up the mud-hook by hand.

The weather promised to be clear, and a consultation of the barometer showed the instrument to be absolutely steady. After breakfast the next day, therefore, the work of erecting the Golden Eagle at sea was begun. First the pontoons were lowered over the side and the boys, working from the Bolo's dory, connected them by the rigid vanadium steel framework provided for that purpose, and which fitted into brackets bolted to the sides of the tubes themselves. When connected up they formed a sort of catamaran with a s.p.a.ce of about twenty-five feet intervening between them. The cha.s.sis of the Golden Eagle, which was in sections, was then erected on a framework previously built and which was attached to the floating pontoons. This work occupied the greater part of two days, and impatient as Frank was to be off, he would not allow it to be slighted.

[Ill.u.s.tration: Erecting the Golden Eagle on the pontoons.]

The wing-supporting framework rising from the cha.s.sis next engaged the young workmen's attention, each part being screwed to the other and fixed in place with nuts locked by a spring devised for the purpose by Frank. This was necessary, as the incessant jarring of an aeroplane's powerful engines will work loose the most tightly screwed on nut if it is not locked, and, of course, the working loose of even a minor part on an air craft is a serious proposition indeed. The vanadium steel quadrangle being in place, the next task was to adjust the wide stretching wing-frames of the big plane. This was a tough job, but the boys managed to overcome the tendency of the floating craft to capsize under the uneven burden by placing a raft made of boards from the cabin floor of the Bolo under each wing tip as it was screwed in place.

Of course, as soon as the frames were bolted on on either side and the weight was equalized, the aeroplane balanced on her pontoons and there was no need for artificial support. Getting the engine in place came next, and for a time seemed to promise serious difficulties; but this problem was finally solved by towing the pontoon-supported air-ship alongside the Bolo, and then using her main boom as a derrick. Billy Lathrop and Ben Stubbs hauled on a tackle attached to the engine, and thence to the end of the boom, and the heavy bit of machinery swung outboard without a hitch. It was then an easy matter to lower the motor on to its bed, which had been previously set in place. It didn't take long to bolt the engine down, lay the propeller bearings and set the main shaft and its twin connections in place and "true" them up.

The last work, before adjusting the tanks for gasolene and oil, was to affix the propellers themselves. This was accomplished by erecting a rough stand on a platform of the cabin floor boards.

At last everything was p.r.o.nounced ready for a start and the finishing touches were completed. Harry even lovingly touched up some scratched places about the frame with the contents of a paint-pot he had found in a locker.

It was at this point that Billy Barnes made a great discovery.

"But say, Frank," he exclaimed, "when you start the propellers she is going to fly even though you may want her to skim the water."

"Is she, mister know-it-all?" laughed Frank, "that shows all you know.

See this pump?" He indicated a small centrifugal affair geared to the main shaft.

Billy nodded.

"Well," explained Frank, "when we want to keep the Golden Eagle down on earth, or rather sea, we fill the pontoon tanks to the necessary weight with this pump. When I want to rise, I pump the water out again."

"Gee, that's simple--like all your ideas, Frank," said the admiring Billy.

"When are we going to try a trial trip?" demanded Lathrop.

"No reason why we shouldn't start right away on one," declared Frank, "if you fellows will bear a hand and fill up the gasolene, radiator and lubricator tanks."

The receptacles were quickly replenished with fuel, water and oil, and then the young aviators waited in a thrilling state of suspense while Frank tested the engine. After a few adjustments of the bed, the machine fell to work as evenly as it had at Mineola, and Frank announced that he was ready to cast off the lines that restrained the aeroplane to the side of the Bolo.

With Frank in the driving seat, Harry at the engines and the others grouped in the cha.s.sis the start was made.

At Harry's cry of "All right," the young leader started up the power and threw in the propeller clutch. A shout broke from the throats of the adventurers as the Golden Eagle began to move gracefully ahead in her new element.

Soon she began to gather speed and skim rapidly over the water as Frank increased the power; but he soon came to a stop.

"We'll have to put more water in the tanks," he announced, "she's trying to rise."

More water was quickly pumped in by running the machine pump on the engine with the propellers cut out. As the ship settled lower and lower, Frank watched her carefully.

"That's enough," he cried at length to Harry, who was filling the tanks. The pump was stopped and the automatic caps screwed on the valve opening of the pontoons.

Once more Frank threw in the propeller clutch and started up the engine. This time he ran the motor to high speed without the aeroplane rising more than enough to just gracefully skim the top of the water, like a drinking swallow.

"It's better than flying," enthusiastically cried Billy, hugging Lathrop in his excitement, "and you don't have to keep still either,"

he added.

"Wall, I've followed the water for a good many years, but I never went to sea on a water air-ship before," was Bluewater Bill's contribution.

"You like it, don't you?" demanded Billy, almost fiercely.

"You bet cher life, I do," was Bill's truthful, if vulgarly expressed, rejoinder.

On and on skimmed the Golden Eagle, seemingly as much at home on the surface of the gently heaving South Atlantic as in the upper air currents. So exhilarating was the sensation, that Frank kept the winged craft straight on, holding her to her course with the air rudder, which worked as well on the water as in the clouds.

Then swinging in a long circle, so that the strain on the long pontoons and their bracings would not be too great, he brought the ship about and headed her back for the Bolo, that lay, a tiny speck, on the far horizon, so far and fast had they traveled.

They came back at the same swift gait as they had taken the outward spin, and all voted this new form of water riding as enjoyable as anything they had ever experienced.

That night was spent in making final arrangements for the dash in search of the golden galleon. As the adventurers did not want to carry more weight than could be avoided, it was agreed that Bluewater Bill, Lathrop and Billy Barnes should remain on board the Bolo, while the Boy Aviators and Ben Stubbs started on the aerial search for the treasure ship.

From the lat.i.tude and longitude in which they were then anch.o.r.ed, Bluewater Bill judged that the galleon could not lie much more than two hundred miles to the southeast, out across the wilderness of Sarga.s.so. Of course she might have shifted, but from an aeroplane it is possible to survey a tremendous area, and the young adventurers were confident of being able to pick up the prize.

Two more bitterly disappointed youths than Billy and Lathrop could hardly be imagined than they were when they learned that it would be impossible to take them on the scouting expedition. Frank, however, pointed out the utter foolishness of overloading the Golden Eagle--more especially as they might have to bring back a heavy load.

Being sensible boys, both Billy and Lathrop, therefore, soon got over their gloom.

Early the next morning, the final provisions were loaded into the aeroplane's cha.s.sis and her barometer, auto-clock and other instruments were adjusted by the Bolo's own and set in place. A careful note was then made of the Bolo's position and noted in Frank's pocket log-book. This done there only remained farewells to be said and these were necessarily brief.

It was ten-thirty o'clock on a cloudless, breathless morning that the Golden Eagle, with her pontoons empty, except for a supply of drinking water carried in the small reserve tanks at either end, shot into the air from the gla.s.sy sea.

Had any strangers been there to witness the start they could not have forborne to cheer at the sight the n.o.ble ship presented, soaring onward higher and higher, like a mighty sea-bird winging its way toward the unknown wastes of the mysterious Sarga.s.so.

CHAPTER XIX.

THE RAT SHIP.

Strong of wing and sound of engine, the Golden Eagle sped on through the clear, warm air, the rushing sensation of her flight sending the wind in a cooling stream against the faces of the occupants of her cha.s.sis. From time to time, Ben scanned the vast flats of ocean below them with the gla.s.ses, but for some time nothing appeared in the field of the binoculars to warrant them in changing their course. Seen from above, the mucilaginous character imparted to the Sarga.s.so Sea by the vast acreage of flowing seaweed, inextricably entangled, was clearly perceptible, even though from the deck of a ship the shallow layer of water that overlies the seaweed imparts the blue hue of open water to it and makes its treacherous character.

"It is like traveling over a water desert," declared Harry.

Far on the horizon were piled castellated cloud ma.s.ses, seemingly immoveable and changing in tint as the day lengthened. On all the vast stretch beneath them was not a sign of life. It was an ocean solitude indeed.

Suddenly Ben who had the gla.s.ses in hand gave a shout.

"I make out something!" he exclaimed.