The adventures detailed by the captain and the professor were thrilling, indeed, and the others listened to them with interest.
“It will be hardly safe to repeat that sort of thing!” said Frank; “the next time you gentlemen go out on an exploring expedition, I think that one of us who is more experienced in that sort of thing had better go with you.”
“We shall not demur,” said Captain Bell, with a laugh. “I am afraid we are hardly qualified to face such risks.”
After Frank had concluded his inspection of the machinery it was decided to at once continue the journey into the Atlantic Valley.
So the machinery was put in motion, and the boat dove into the dark depths to be lost from the world for many months.
The searchlight showed all about for a great distance as plain as day.
But the boat passed over immense depths where all was darkness far below, and into which the boat could not descend on account of the enormous pressure.
There was an automatic gauge on the pilot-house which registered this pressure and determined the depth to which it was safe to go.
Below this the boat would be crushed like an egg shell.
But as a general thing the Dart was enabled to keep in view of the bed of the ocean.