She trembled and vibrated as the powerful electric motors turned her propellers, and Tom, having seen that all was running smoothly in the main engine room, called Mr. Damon, Ned, and Mr. Hardley to him.
"We'll go into the forward pilot house and give Mr. Hardley a view under water," he announced. "Of course, you'll see nothing like what you'll view when we're in the ocean," added the young inventor, "but it may interest you."
The four were soon in the forward compartment of the craft. She could be directed and steered from here when occasion arose, but now Tom was letting his navigator direct the craft from the controls in the main engine room. A conning tower, rising just above the deck of the craft, gave the pilot the necessary view.
"Here you are!" exclaimed Tom, as he switched out the lights in the cabin. For a moment they were in darkness, and then, with a click, steel plates, guarding heavy plate glass bull's-eyes, moved back, and Mr. Hardley for the first time looked out on an underwater scene. He saw the murky waters of river down which they were proceeding to the bay moving past the glass windows. Now and then a fish swam up, looking in, and, with a swirl of its tail, shot away again, apparently frightened well-nigh to death.
"Bless my shoe laces, Tom!" exclaimed Mr. Damon, "this isn't a marker compared to some of the sights we've seen, is it?"
"I can imagine not," said Mr. Hardley. "But it is interesting. I shall be anticipating more wonderful sights."
"And you'll get them!" exclaimed Ned. "Do you remember, Tom, the time the big octopus tried to hold us back?"
"Yes, indeed," answered the young inventor. "That gave us a scare for the time being."
Steadily the M. N. 1 kept on her way under water. Her path was illuminated to a considerable degree by a broad, diffused beam of light from a powerful searchlight that was fixed just back of the conning tower, giving the helmsman a certain degree of vision. This light also served to illuminate the water, so that those in the forward cabin could see what was going on around them.
"There isn't much of interest in the river," said Tom. "No big fish, or anything else of moment. Even in the bay we won't see much to attract our attention. But I want to make sure everything is working smoothly before we start for the West Indies."