Madden glanced about. He stood in a room whose roof formed a half circle over his head. The place seemed as full of machinery as a watch case. Fore and aft were circular partitions of steel, like drumheads. These were penetrated with sliding shutters, which stood open. Through the after shutter, Madden saw a large Deisel oil engine, flanked by a compact heavy dynamo. Looking forward, he could see steel cylinders trimmed in shining brass, and a maze of levers, gauges, dials, valves.
The central compartment in which the two stood was dominated by a little spiral stairway leading up into a steel dome. On a shelf set in the bulkhead was a chart, a telephone receiver, speaking tubes, dials with red and black hands, an array of electrometers, pressure gauges.
Glancing up the stairway into the little dome, Madden saw a pilot wheel, more levers and speaking tubes and telephone receivers, and a square of ground glass, that was lined off with delicate cross-lines.
"Where are we?" asked Madden, amazed. "What do they do here? I never saw so much machinery before in so small a space."
Caradoc was stooping over a heavy metal box down at the floor level at the side of the desk. It was one of a series of such boxes. "We're inside of that submarine you saw enter a few hours ago," explained the Englishman shortly.
Leonard stared around with new eyes. "So this is a submarine! Do you know anything about them? What's that spirit level for?" He pointed at a horizontal gauge.
"Measures air pressure—it's not a level."
"What's in these steel tanks overhead?"
"Compressed air."
"What's that you are getting into?" Here Caradoc lifted the lid, and Madden got a view. "Say, that's a torpedo, isn't it?" he asked quickly as he saw a long needle-pointed steel cigar with propeller and rudder on the aft end.