In a twinkling, now, however, he threw open the sea-valves of other tanks, amidships and aft, until the gauge showed that they were running on an even keel and forty feet below the surface.  Their speed was now about five miles an hour, but could be increased.

Gradually, the ghastly lines on David Pollard’s cheeks began to soften.  His eyes gleamed.

“There’s nothing wrong!  We can run anywhere!” he shouted.

Yet there was something of hysteria in his voice.  Nor was it long before the others began to feel themselves similarly affected.

It was an eerie feeling that all hands had, running along like this, blind and guessing, in the depths.  Pollard was the only one aboard who had ever been below before in a submarine boat.  Though the rest had faced the chances coolly enough, they now began to feel the strain.

Even when it is broad daylight on the surface, with the sun shining brightly, the submarine boat, when a few fathoms below, is simply a blinded, groping monster.  There is no way of illuming the depths of the ocean.  Naval officers have suggested the placing of a powerful electric light at the bow of the submarine craft, but, when tried, it has been found quite useless.  The light will not project far enough ahead, through the dense water, to do any more than make the surrounding darkness all the more trying to brave men’s nerves.

“Take the wheel, Dave; it will steady you to have something to do,” spoke the builder to the inventor.  “As soon as you get the wheel, turn the course to due south.  Follow it to the line.”

Jack Benson slid out of the helmsman’s seat, giving way to the inventor, and stepped down the stairway.

At the foot he came upon Eph and Hal, standing there, their faces presenting a strange look.

“How do you find it?” asked Benson.

“Startling,” replied Hal Hastings.

“Yet nothing is happening to us,” contended Eph Somers, somewhat shaky in his tones.  “It’s just thinking what might happen—­if we were to strike a water-logged old hull of some vessel, say.”

“Or collide with a blue-fish,” suggested Hal, with a short, nervous laugh.

“I suppose we’ll be used to this, after a few more trips,” laughed Jack, with an effort.

“Are you scared, too?” asked Eph, keenly.

“Well, I can’t say I feel wholly comfortable,” admitted Jack Benson, candidly.

“Then you’re sitting down on your fears pretty well,” declared young Hastings, with an admiring look at his chum.

“We’ve got to,” returned Jack, stoutly.  “If we’re to go into the submarine boat line we’ve got to learn to look as though we liked anything under water.”

“Let’s take a look-in and see how Andrews likes it,” proposed Eph.

Peeping through the door of the engine room they beheld the man there sitting bolt-upright on one of the leather-cushioned seats, staring hard at the wall opposite.  He turned his head, however, as soon as he became aware of the presence of the submarine boys.