"What I advise you to do, gentlemen, is to go ahead and prosecute the fellow Gaston on the charge of felonious a.s.sault. I would, however, try to avoid having any testimony brought out in court to-day. I will send one of my officers to see the public prosecutor, and ask that official to have the case continued for one week. I will also wire the Navy Department at Washington, and await the reply of the Secretary before taking any other steps or offering you any other advice. But do not needlessly alarm Lemaire or the young woman away from here."

So well did the lieutenant commander accomplish his purpose that, when Jack and Hal went to the local court that forenoon, the public prosecutor promptly asked to have the case against the chauffeur continued for one week, and the court as promptly a.s.sented.

Gaston was taken back to jail. Though the fellow was well supplied with money, he did not have anywhere near enough to put up the five thousand dollars cash bail demanded by Florida justice.

At the jail a watch was kept to see whether Gaston would have visitors, but none came. M. Lemaire and Mlle. Nadiboff were known to be still at the hotel, but they did not go near their man in trouble. Neither did Lemaire or the Russian appear about the grounds of the hotel.

At noon a letter from Lieutenant Commander Kimball came aboard the submarine, inquiring whether Captain Benson could make it convenient to take him and several officers out to sea afternoon and give an exhibition of the boat's diving powers.

"After we've taken the boat out ourselves, and tested her," was the answer Captain Jack sent back. "With so many spies about we want to be sure that the boat is in safe running order before we risk the lives of half a dozen naval officers."

A luncheon was eaten, after which, the young submarine captain hastily climbed the stairs to the conning tower.

"Throw on the gasoline, Hal," he called back over his shoulder. "And, as soon as we get way, test all the electric connections, before we attempt to do any diving. Be sure of everything old fellow."

Forward in the engine room the gas motors were soon moving merrily. By the time that Eph had cast loose from moorings Jack signaled for slow speed ahead, and the grim-looking little Benson moved on out of the harbor.

Once out of the harbor Captain Jack rang, successively, for two higher speeds. The "Benson" answered both like a charm.

"The gasoline part of the craft is working all right," declared the youthful skipper to Eph, who had come up into the tower.

Fifteen minutes later Hal shouted up:

"All electric connections appear safe, Captain. And all the air compressors are working."

"Are you ready to shut off the gasoline motors?"

"Yes, sir."

"Go ahead, then, and we'll take a dive." Down they shot below the surface, the boat going on a diving keel. Then, for some minutes, Captain Jack ran his submarine pride along at a depth of fifty feet below surface.

"Might as well rise, Captain," called up Mr. Farnum, coming from his stateroom.

So Eph, at the young commander's orders, stood by to let the compressed air gradually into the water tanks. As gracefully as ever the "Benson"

rose to the surface. Gasoline power was turned on again.

"Everything is all safe, Captain," nodded Mr. Farnum. "Run back and get your naval party."

As they were to run, now, on the surface, Jack stepped out to stand by the deck wheel Eph and Hal came out with him, David Pollard standing further aft.

As the submarine rounded in under the gunboat's stern the voice of Kimball called:

"As well done as ever, Mr. Benson! When shall we come on board?"

"As soon as we're moored, sir," Jack shouted

As the "Benson" ran to her moorings the youthful captain espied a sh.o.r.e boat that bore, as sole pa.s.senger, one of the uniformed, colored bell boys from the hotel.

When Eph made the mooring cable fast, this sh.o.r.e boat ranged alongside.

"Box for Captain Benson, sah," called the negro.

"Right here," acknowledged Jack, going over to the rail. The box proved to be of pasteboard.

"Are you going to open it?" whispered Farnum.

"Why, yes, sir; of course," Jack answered.

"Better do it on deck, then," came the dry answer. "It might contain something explosive, you know."

Though he laughed, young Benson carefully untied the string that held the lid on, also carefully removing the latter. Inside he discovered a handsome bouquet of roses, with a card attached.

"Well, of all the a.s.surance in the world?" gasped Jack Benson.

"What's the matter!" queried Farnum.

"Read what's written on this card, sir."

The inscription ran:

"Mlle. Sara Nadiboff is delighted at learning that Captain Jack Benson has returned in safety from his long walk."

"Any answer, sah?" demanded the darkey in the boat.

"None, thank you," replied Captain Jack, in an even tone.

The boat continued on its way to the sh.o.r.e.

"Say, what do you think of that?" demanded Eph, after he, too, had taken a look at the card tied to the flowers.

"It is plain enough that our charming young Russian doesn't mean to drop Captain Benson's acquaintance just yet, if she can help it," laughed the shipbuilder.

"What are you going to do with the flowers, old man?" asked Hal.

"Flowers should be put in water, to make them keep, shouldn't they"

queried the young submarine skipper, innocently.

"Yep," nodded Eph Somers.

"I hope these will keep fresh a long time, then," murmured Benson.

Raising the bouquet he dropped it overboard the harbor--on the side of the boat away from the hotel.

CHAPTER XV

CAPTAIN JACK BECOMES SUSPICIOUS