From time to time, as this whale-like ship plowed the waters of the Sound, a big wave would flow entirely over her, and the captain would be looking right into the foaming crest.  The boat was built for under-water going, so little daylight penetrated the interior through the few small deadlights, or round, heavy glass windows, but electric incandescent bulbs fed by current from the storage batteries lit the interior brilliantly.

The boat had not proceeded far when the captain ordered the crew to prepare to dive, and immediately the engine was shut down and the clutch connecting its shaft with the electric apparatus thrown off and another connecting the electric motor with the propeller thrown in; a switch was then turned and the current from the storage batteries set the motor and propeller spinning.  While this was being done another man was letting water into her ballast tanks to reduce her buoyancy.  When all but the conning tower was submerged the captain looked at the compass to see how she was heading, noted that no vessels were near enough to make a submarine collision likely, and gave the word to the man at his feet to dive twenty feet.  Then a strange thing happened.  The diving-helmsman gave a twist to the wheel that connected with the horizontal rudders aft of the propeller, and immediately the boat slanted downward at an angle of ten degrees; the water rose about the conning tower until the little windows were level with the surface, and then they were covered, and the captain looked into solid water that was still turned yellowish-green by the light of the sun; then swiftly descending, he saw but the faintest gleam of green light coming through twenty feet of water.  The Fulton, with six men in her, was speeding along at five knots an hour twenty feet below the shining waters of the Sound.

The diving-helmsman kept his eye on a gauge in front of him that measured the pressure of water at the varying depths, but the dial was so marked that it told him just how many feet the Fulton was below the surface.  Another device showed whether the boat was on an even keel or, if not exactly, how many degrees she slanted up or down.

With twenty feet of salt water above her and as much below, this mechanical whale cruised along with her human freight as comfortable as they would have been in the same space ashore.  The vessel contained sufficient air to last them several hours, and when it became vitiated there were always the tanks of compressed air ready to be drawn upon.

Except for the hum of the motor and the slight clank of the steering-gear, all was silent; none of the noises of the outer world penetrated the watery depths; neither the slap of the waves, the whir of the breeze, the hiss of steam, nor rattle of rigging accompanied the progress of this submarine craft.  As silently as a fish, as far as the outer world was concerned, the Fulton crept through the submarine darkness.  If an enemy’s ship was near it would be an easy thing to discharge one of the five Whitehead torpedoes she carried and get out of harm’s way before it struck the bottom of the ship and exploded.