"What's it for?" asked Foster.
"To sink the boat in case of fire. It's an inheritance from steamboats—pure precedent—and useless, for a submarine cannot catch fire. Why, a few turns of that wheel when in the awash trim would admit enough water in two minutes to sink the boat. I've applied for permission to abolish it."
"Two minutes, you say. Does it turn easy? Would it be possible to accidentally turn it?"
"Very easy, and very possible. I caution my men every day."
"And in case you do sink, and do not immediately suffocate, how do you rise?"
"By pumping out the water. There's a strong pump connected with that motor aft there, that will force out water against the pressure of the sea at fifty fathoms down. That is ten atmospheres—pretty hard pressure. But, if the motor gets wet, it is useless to work the pump; so, we can be satisfied that, if we sink by means of the sea cock, we stay sunk. There is a hand pump, to use on the surface with dead batteries, but it is useless at any great depth."
"What do you mean by the awash trim, lieutenant?" asked Foster, who was now looking out through the deadlight.
"The diving trim—that is, submerged all but the conning-tower. I'll show you, so that you can say that you have really been under water."
Ross turned a number of valves similar to the sea cock, and the girl's face took on a look of doubt and sudden apprehension.
"You are not going to sink the boat, are you, Mr. Ross?" she asked.