by Roy Rockwood
CHAPTER XIII
DOWN INTO THE EARTH
It was now noon, but the adventurers did not think of dinner in theexcitement of approaching the mysterious island. The speed of the shipwas increased that they might the more quickly come to it. As theyapproached they could see the masses of vapor more plainly, and itappeared that some great commotion must be going on inside the big hole,since clouds of steam arose.
"I only hope it doesn't prove too hot for us," observed the professor."However, I provided a water jacket for the ship, and we may need it, aswell as the vacuum chambers to keep the heat from us."
It was about three o'clock when the flying ship reached the edge of theisland. From there it was about a mile to the rim of the big hole, overone side of which the waters of the ocean poured with a roar that couldbe heard over half a mile off.
"I think we had better halt and see that everything is in good shapebefore proceeding," said Mr. Henderson. "Jack, you and Mark make athorough inspection of the engine room, and see that all the apparatusis in working order."
The two boys prepared to do as they were told. Mark, who was walking alittle ahead of Jack, entered the apartment from which the storeroomopened. As he did so he saw, or thought he saw, the door of the placewhere the extra supplies were kept, close. Without saying anything toJack he hurried forward, and tried the knob. It would not turn.
"That's funny," said Mark to himself. "I could almost swear I saw someone go into that room. Yet I know the professor did not enter, for Ijust left him. And none of the others would dare to. I wonder if I willever solve the mystery."
But he had too much to do to allow him to dwell on that matter. Severalof the dynamos needed adjusting and for two hours he and Jack had allthey could do.
In the meanwhile the professor had gone over the other parts of theship, and gotten everything in readiness for the descent. The _Mermaid_was lowered to within a few hundred feet of the sea, and, through a hosethat was let down, the compartments, provided for this emergency werefilled with water. These compartments were between the outer and innerhulls of the lower part of the craft, and were designed to prevent theinterior becoming heated in case the travelers found they had to passclose to fire. There were also vacuum chambers, and from these the airwas exhausted, as of course every schoolboy knows a vacuum is anon-conductor of either heat or cold.
"Now I think we are ready," the professor announced at length.
"Everything's all right in the engine room," announced Jack.
"Yes, an' everything's all right in th' kitchen," put in Washington."I've got a good meal ready as soon as any one wants to eat."
"It will have to wait a while," Mr. Henderson remarked. "We are going tostart to make the descent before we dine."
The hose was reeled up, and the ship was sent a few hundred feet higherinto the air, as Mr. Henderson wanted to take a last good observationbefore he went down into the hole.
But having risen some distance above the masses of rolling vapors hefound he was at no advantage, since the strongest telescope he couldbring to bear could not pierce the cloud masses.
"We'll just have to trust to luck," the scientist said. "I judge we'reabout over the centre of the opening. Lower away Mark!"
The boy, who, under the watchful eye of the professor, was manipulatingthe levers and wheels in the conning tower, shifted some handles. Thegas was expelled from the holder, the negative gravity apparatus ceasedto work, and the _Flying Mermaid_ sank lower and lower, toward themysterious hole that yawned beneath her.
The hearts of all beat strangely, if not with fear, at least withapprehension, for they did not know what they might encounter. Perhapsdeath in some terrible form awaited them. But the desire to discoversomething new and strange had gripped all of them, and not one wouldhave voted to turn back.
Even old Andy, who seldom got excited, was in unusual spirits. He tookdown his gun and remarked:
"Maybe I can kill some new kind of animal, and write a book about itshabits, for surely we will see strange beasts in the under-world."
Lower and lower sank the ship. Now it was amid the first thin masses ofvapors, those that floated highest and were more like a light fog, thananything else. By means of a window in the bottom of the craft, whichwindow was closed by a thick piece of plate glass, Professor Hendersoncould look down and see what was beneath them.
"The clouds seem to be getting thicker," he said, as he peered throughthe small casement. "If they would only clear away we could seesomething."
But instead of doing this the vapors accumulated more thickly about theship. It was so dark inside the _Mermaid_ now that the electric lightshad to be switched on. In the room with the floor-window the lights werenot used, as had they shone one could not have seen down below.
The professor maintained his position. The descent was a perilous one,and he wanted to be on the watch to check it at once if the _Mermaid_was liable to dash upon some pointed rock or fall into some fiery pit.His hand was on the signal levers.
Suddenly he looked up and glanced at a gage on the wall. The hand of itwas slowly revolving.
"We are at the earth's surface," the scientist said. "Now we are belowit. Now we are fairly within the big hole! Boys, we may be on the vergeof a great discovery!"
An instant later it seemed as if a hot wave had struck the _Mermaid_, oras if the craft had been plunged into boiling water.
"It's going to be hot!" cried the professor. "Lucky I provided the waterjackets!"
Then the lights in the interior of the ship went out, leaving the wholecraft in darkness.
"What has happened?" cried Mark.
