The body or hull of the Dolphin was composed of thin plates of steel closely riveted together. They were tough and capable of resisting a great pressure.
The hull was especially constructed for descending to great depths, where the pressure was liable to be very great.
The stern of the Dolphin was shaped like the broad tail of a fish. Beneath it was the rudder and screw propeller.
Lateral fins served to keep the boat’s equilibrium.
Forward were two huge bull’s-eye windows in which were set powerful searchlights.
In general this was a description of the exterior of the Dolphin. They now passed into the interior.
Passing through the door, which could be hermetically sealed in an instant, if necessary, they stood in a sort of vestibule.
A door led into the cabin. Here Frank paused and said:
“This is the vestibule. By its means one can leave the boat while it is under water.”
“Leave the boat while under water!” exclaimed Stanhope in surprise. “How on earth can you do that?”