"Legally, but not morally.We can't prevent them, I'm afraid.The only thing to do is to get there ahead of them.It will be a race for the sunken treasure, and we must get there first.""What do you propose doing, captain?" asked Mr.Damon."Bless my shirt-studs, but can't we pull their ship up on the island and leave it there?" "I'm afraid such high-handed proceedings would hardly answer," replied Mr.Swift."No, as Captain Weston says, we must get there aheadof them.What do you think will be the best scheme, captain?""Well, there's no need for us to forego our plan to get fresh water.Suppose we go to the island, that is, some of us, leaving a guard on board here.We'll fill our tanks with fresh water, and at night we'll quietly sink below the surface and speed away."They all voted that an excellent idea, and little time was lost putting itinto operation.
All the remainder of that day not a sign of life was visible about the Wonder.She lay inert on the surface of the lagoon, not far away from the Advance; but, though no one showed himself on the deck, Tom and his friends had no doubt but that their enemies were closely watching them.
As dusk settled down over The tropical sea, and as the shadows of the trees on the little island lengthened, those on board the Advance closed the Conning tower.No lights were turned on, as they did not want their movements to be seen, but Tom, his father and Mr.Sharp took their positions near the various machines and apparatus, ready to open the tanks and let the submarine sink to the bottom, as soon as it was possible to do this unobserved.
"Luckily there's no moon," remarked Captain Weston, as he took his place beside Tom."Once below the surface and we can defy them to find us.It is odd how they traced us, but I suppose that steamer gave them the clue."It rapidly grew dark, as it always does in the tropics, and when a cautious observation from the conning tower did not disclose the outlines of the other boat, those aboard the Advance rightly concluded that their rivals were unable to see them.
"Send her down, Tom," called his father, and with a hiss the water entered the tanks.The submarine quickly sank below the surface, aided by the deflecting rudder.
But alas for the hopes of the gold-seekers.No sooner was she completely submerged, with the engine started so as to send her out of the lagoon and to the open sea, than the waters all about were made brilliant by the phosphorescent phenomenon.In southern waters this frequently occurs.Millions of tiny creatures, which, it is said, swarm in the warm currents, give an appearance of fire to the ocean, and any object moving through it can plainly be seen.It was so with the Advance.The motion she made in shooting forward, and the undulations caused by her submersion, seemed to start into activity the dormant phosphorus, and the submarine was afloat in a sea of fire.
"Quick!" cried Tom."Speed her up! Maybe we can get out of thispatch of water before they see us."
But it was too late.Above them they could hear the electric siren of the Wonder as it was blown to let them know that their escape had been noticed.A moment later the water, which acted as a sort of sounding-board, or telephone, brought to the ears of Tom Swift and his friends the noise of the engines of the other craft in operation.She was coming after them.The race for the possession of three hundred thousand dollars in gold was already under way.Fate seemed against those on board the Advance.
