“I’m sure I hope so,” put in Jack.  “It would be no fun to have to take a shower bath in this place.”

After a meal, the boys and the professor took some more observations, but with all their efforts nothing could be seen below the ship but a vast black void, into which they were steadily descending.

“I wonder when we’re going to stop,” asked Mark.  “It’s like playing the game ‘Going to Jerusalem,’ you keep wondering when the music will cease and you will have a chance to grab a chair.  I only hope we have a chair or something else to sit on, in case we go to smash.”

“We’re not liable to have any accidents with the professor in charge,” Jack answered.  “Didn’t he bring us safe out of some pretty tight holes when we went to the north pole in the airship, and again when we found the south pole in the submarine?”

“Yes, but this is different,” objected Mark.

“Well, I’m not worrying,” Jack went on.  “It doesn’t do any good, and only makes you lie awake nights.  By the way, I wonder what time it is getting to be.”

He looked at his watch and found it was close on to eight o’clock in the evening.  So late had dinner been served, and so varied were the happenings of the last few hours, that time had passed quickly.

“Why it’s almost bed-time,” said Jack.  “I wonder if we are to go on dropping into the depths of nowhere all night.”

At that moment the professor entered the room where the boys were.  He seemed quite pleased over something, and was smiling.

“Everything is going along famously,” he said.  “I have just tested the air and find it is rich in oxygen.  We shall suffer nothing on that score.  The heat too, seems to have decreased.  On the whole, everything favors us.”

“Are we going on down?” asked Mark.

“As far as we can,” Mr. Henderson answered.  “Let me see how far we are below now.”

He went to the gage that indicated the vertical position of the ship.  Because of the changed conditions, the craft now sinking below the surface of the earth instead of rising above it, as was its wont, some calculations were necessary.  These the scientist made as quickly as he could.

“We are now ten miles underground!” he exclaimed.  “That is doing very well.  My theories are working out.  I think we shall land somewhere before long.”

“I hopes so!” exclaimed Washington coming in at this point.  “I’m mighty skeered shootin’ down int’ this dark hole, and no time-table t’ show when we’s due t’ arrive.”

“We ought to land in a couple of days more,” the professor answered.  “Never mind about worrying Washington, I’ll take care of you.”

“I hopes so, Perfesser,” the colored man said.  “I got a little girl waitin’ for me back in Georgia, an’ I’d like t’ see her ’fore I git burned up.”

Accompanied by the professor, the boys made a tour of the ship to see that all the machinery and apparatus were in working order.  Owing to the changed conditions the negative gravity engine had to be worked at faster speed than usual, since the downward pull of the earth was greater the farther they descended into the interior and they did not want to fall too swiftly.  But this was easily provided for, since the professor had made the apparatus capable of standing a great strain.