The young skipper noted, swiftly, that Miss Peddensen had taken the seat furthest aft in the cabin, while the young Englishman was seated at the forward end of the party of guests.

"Oh, I say, Captain Benson," called the Englishman, "are you permitted to show me how you know just how far below the surface you are?"

"The gauge tells that," replied Jack. "But I will ask you to excuse me from describing it, as I wish to keep my mind on the running of the boat. Mr. Hastings will oblige you; or, I don't doubt, one of the naval officers will."

Even this momentary distraction, however, had given Miss Peddensen time to slip something out of one of her wide sleeves into her lap. And now the young Swedish woman sat so that the object taken from her sleeve was concealed behind the woman who sat next to her.

It wasn't many moments ere Jack noted some thing about the young Swedish woman that caused the young skipper to turn, every now and then, for a swift though hidden glance in her direction.

"What on earth is Miss Peddensen doing?" wondered the submarine boy.

"Hang it, I believe she's up to something that she ought not to be doing!"

Through he did not turn and walk in her direction, Jack, thereafter, kept the young Swedish woman much more under secret observation.

"By Jove, I know what she's doing, now," muttered the young skipper.

"That movement of her elbow betrays her, and her eyes are fixed, much of the time on her lap. If she isn't sketching something, on the sly, then my eyesight isn't as good as it used to be!"

Captain Jack Benson found himself quickly aquiver with suspicion and indignation.

"Yet I can't afford to make any mistakes," he told himself, uneasily.

"I've got to be absolutely sure before I can take the risk of starting a human cyclone about my ears!"

CHAPTER XVI

THE GOVERNMENT TAKES A HAND

Yet, for a brief interval more, Jack Benson hesitated.

"Is the young woman sketching, or is she merely writing?" he wondered, anxiously. He watched her a little while longer.

"No; she's sketching. Those are drawing strokes she's making."

Then, looking wholly blank, Jack Benson turned on his heel. He looked first at one mechanism, then at another. Yet, presently, stood close to Lieutenant Commander Kimball's ear.

Only a few words were said, but the naval officer understood instantly.

As Captain Jack turned and went back, Kimball also sauntered along, although he did not appear interested in the submarine boy's movements.

Yet it was not long when both appeared before the young Swedish woman.

"Miss Peddensen," murmured the lieutenant commander, "may I see what you are writing?"

The woman looked up, her face composed, her eyes dancing with mirth.

"Why, surely, Mr. Kimball," she replied, laughing. "And very silly stuff you'll find it, too. I have been jotting down my impressions upon finding myself riding under the surface of the sea. I do not handle your English language very well, as you will see."

Mr. Kimball glanced hastily through the three or four pages of rather closely written note paper. It was, as the young woman had stated, a very amateurish composition, in very stilted English.

The naval officer felt a sense of mortification and his face reddened slightly. He had been led to expect that he would find something crime on these sheets of paper. Instead, he scanned a stupid piece of composition.

"I would die of humiliation, to have that read before all these people,"

murmured the young woman.

Lieutenant Commander Kimball gave Jack Benson a covert elbow-dig in the ribs, a move said, as plainly as words:

"The joke is on you."

Jack, however, through half open eyes, had been watching on his own account. Suddenly he made a dive forward, shooting his hands down close to Miss Peddensen's well-booted feet.

"That same old ship-rat!" exclaimed the submarine boy. "I'll catch the beast before he goes under your skirts, Miss Peddensen."

At the mention of a rat so dangerously close young woman almost shot out of her seat in anxiety to get away.

As she bounded something dropped down out of the wide right sleeve of her coat. It was a small memorandum book.

This was just what Jack Benson caught, in place of the pretended rat.

Moreover, the young skipper was clever enough to catch the book so that it fell into his hands open.

"It wasn't a rat, after all, Miss Peddensen," smiled Jack, straightening up and holding the open memorandum book so that both he and Kimball could see what was traced on the two pages that lay exposed.

There were sketches of the compressors, sketches of the mechanism by which the compressed air was forced into the tanks to drive the water out--in fact, sketches of many vital features in the control of the boat. Nor was more than a glance needed to make it plain that this young woman artist possessed expert knowledge of machinery.

At the cry of "rat" three or four women jumped from their seats. The one nearest Miss Peddensen moved hastily to the forward end of the cabin.

"My dear young woman," murmured the lieutenant commander, dropping into the vacated seat beside the Swedish girl, "you won't mind, will you, if I keep these little matters to look over at my convenience!"

There was something so compelling in the look that flashed briefly in the naval officer's eyes that Miss Peddensen lost color, and stammered:

"No-o-o, certainly not; if such silly things interest you."

"They interest me very much indeed," murmured Kimball, thrusting "composition" and sketches inside his blouse.

As the naval officer plainly intended to remain where he was, Jack Benson turned, sauntering forward.

"Another spy nailed, beyond a single doubt," muttered the young submarine commander. "Will there never be an end to them."

As Captain Jack glanced at the young Englishman, Drummond by name, he saw an unmistakable flash of hostility in the Englishman's eyes.

"So you're a spy, too?" quivered Benson, inwardly, turning on his heel.

After that, howsoever, the submarine boy took good care to keep Drummond under covert watch.

In time the "Benson" returned to the surface, being now much nearer land then when the aft had made its dive. A few minutes later the boat ran into the harbor and made fast at its moorings.

"What are you going to do about the young woman?" Jack found a chance to whisper, as all hands gathered on the platform deck.