This made the captain a happy man.

“I’ll go and tell my wife at once,” he cried. “When do we sail?”

“In one week from to-day.”

“Good! I’ll report for duty then. Good luck till I see you again.”

And the bluff captain was gone.

Frank had two valuable men in his employ who traveled with him the world over.

One was a negro, black as coal and jolly as could be. He rejoiced in the name of Pomp.

The other was an Irishman, as full of native wit as a nut is of meat. His name was Barney O’Shea.

Barney and Pomp were almost as famous as their young master and his inventions.

They were the warmest of friends, and yet to hear them talk one would have felt assured they were enemies, for they were fond of railing at each other in a mock serious way.

If Barney could play a practical joke upon his colored colleague he was happy, and Pomp seldom failed to retaliate in kind.

Really they were the life of any exploring expedition, and for faithful service and devotion Frank could hardly have replaced them.

They were anticipating the submarine voyage with a great deal of relish.

“Golly,” cried Pomp; “I’se jes’ gwine to be tickled to deff to git to trabeling once mo’. I’se been home jes’ long enough, dis chile hab.”

“Begorra, I’m wid yez, naygur!” cried Barney, bluntly. “It ain’t often we two uns agree, but be me sowl it’s united we sthand on that, sor.”

“It am yo’ fault, I’ish, dat we don’ agree on everyfing!” declared Pomp, solemnly.

“How do yez make that out?”

“Yo’ don’ take mah wo’d fo’ a cent.”

“Begorra, I’d hate to take yoursilf for that!” cried Barney, jocularly. “Shure I’d kape the cint.”

Pomp scratched his woolly head.

“Yo’ fink dat am bery funny.”

“It’s not so funny as yez are.”

“Yah, yah! am dat so?”

“Didn’t I tell yez?”

“Don’ yo’ git too gay wif me, chile. Dar am jes’ sand enough in mah wool fo’ to take de conceit out ob yo’.”

“Bejabers, I’d go soak me head if I had sand in me hair,” said Barney, contemptuously; “take a shampoo, naygur!”

“Yo’ am gettin’ sassy!”

“On me worrud, I’m the only gintleman on yer list av acquaintances, an’ bekase I tell ye yer faults it proves me your frind.”

Pomp scratched his head again.

Then he looked at Barney and Barney looked at him. Barney began to edge away and Pomp lowered his head.

“Look out fo’ yo’sef!”

“Kape away from me, yez black ape!”

But Pomp made a dive for the Celt. Barney let out with both his fists. They struck the darky’s head like battering rams.

But they might as well have been directed toward a stone post.

They glanced off that hard surface with the greatest of ease. Then Pomp’s head took Barney in the ribs.

The next moment the Celt was counting stars in a bewildering firmament. He recovered just in time to grapple with his assailant.

Then followed a genuine old-fashioned wrestling match.

The two jokers rolled over and over upon the ground, pounding and thumping each other until one or the other had enough.

Frank Reade, Jr., at once began to put the Dart in readiness for her great trip.

Stores enough to last for a period of many months were placed aboard.

Every part of her mechanism was carefully examined and tested to make sure that it was all right.

Three days before the appointed time for sailing Captain Bell and Prof. Von Bulow appeared in town.

They had arranged their affairs and were all in readiness for the expedition.

They were certainly the envied ones of a large coterie.

To take a trip across the Atlantic Valley in a submarine boat was certainly no light privilege.

The captain particularly was in excellent spirits.

“We are sure to reclaim that million and a half of treasure,” he declared, confidently. “It will be a big haul.”

Von Bulow was promising a hundred different scientific societies specimens from the bed of the sea.

“It will be a big benefit to the world of science,” he declared. “Ah, my soul! I will make great fame!”

Barney and Pomp were anticipating exciting adventures in the deep sea, and Frank was reflecting upon the success of his new invention.

Thus all had some cherished plan or motive in view.

While the people of the country waited expectantly for the day of departure, it came at last.

The Dart rested in a large tank in the yard of the machine works.

From this tank a wide and deep canal was locked twice into the river. The party went aboard exactly at noon. Frank had the moorings cast off, and the Dart entered the canal.

She glided through the locks gracefully and appeared in the river.

And now for the first time she was exposed to the view of the people.

The banks were thronged, and a great cheer went up as the new invention appeared.

Bands played and cannon fired salutes. The party of explorers remained on deck long enough to return the salutes.

Then a cry went up from the crowd.

“Sink her! Sink her!”

Frank knew that the people wanted a demonstration of the Dart’s capabilities.

And he was willing to gratify them. He went into the pilot-house and the others went into the cabin.

Then Frank pulled the steel lever which opened the reservoir. Water displaced the compressed air.

Gracefully the Dart settled beneath the surface. Frank pressed a key and the electric lights blazed forth.

The bed of the river was as plainly revealed as in daylight.

For some while the Dart remained under the surface. Then it reappeared once more.

The people were satisfied. The air was rent with cheers, and it was a triumphal parting which the submarine travelers received.

Then the Dart glided away upon her course.

Down the river with great speed she went. In due course of time she reached the open sea.

The great trip through the Atlantic Valley was begun.

For some days the Dart stood straight out to sea. Frank had made his course by the best of the submarine charts.

He had now reached what he believed to be the entrance to the great valley under the sea.

This was at the beginning of the southeast branch of the Gulf Stream. The submarine course would extend to within a few hundred miles of the Azores and then southerly, finally terminating at Bermuda.

All this vast space was a mighty depression, known as the Great Valley.

It has ever been a mystery to sailors and geographers from early times.

Ancient chroniclers speak of an old-time continent and nation of people due west from the coast of Spain.

As this continent does not exist to-day, it has been believed that it has sunk by some mighty process of nature many centuries ago.

There are plenty of mythical tales of the sunken world and its wonders now lying under the sea.

That the keels of our modern ocean greyhounds may daily pass over a sunken world is by no means improbable.

Perhaps some day our own American continent may be relegated to a like fate.

Let us hope that it will not come in our day.

But it can be seen that Prof. Von Bulow looked forward with immense interest to the possible revelations in store.

He had already pictured out cities and palaces, valleys and towns, forests and mountains under the sea.

Not until he was assured that he was at the entrance to the great Atlantic Valley did Frank make preparations to descend.

Then he made deep soundings, and becoming satisfied that he had reached the right point, the descent was made.

The travelers took a final walk on deck, and then the doors were hermetically closed.

Frank stepped into the pilot-house and pulled the reservoir valve.

Instantly the Dart began to settle.

Down she went with a graceful plunge. There was a peculiar jolting, jarring motion as she displaced the water.

Then the electric lights flashed forth. Those on board beheld a wonderful sight.

About them were the wonders of the sea.

The bed of the ocean lay below, replete with aquatic life and growth. The electric glare extended many hundred feet in all directions.

The Dart rested upon a small coral reef.

The whitest of sand lay spread between the clumps of sea plants.

There were grottoes and cavernous depths, miniature forests and castles of coral.

In all were specimens of curious submarine life.

Shell and other fish were everywhere.

Huge species of ray, sunfish, shark and octopus roved about.

The lights of the submarine boat seemed to draw them from all quarters.

They came with fish curiosity up to the very windows of the boat, and seemed anxious to effect an entrance.

This gave Prof. Von Bulow a much desired opportunity.

He studied them to his heart’s content while the Dart remained on the reef.

Captain Bell was also interested, and he and the professor became quite warm friends.

Frank was busy regulating the machinery of the boat preparatory to diving into the great valley.

In the submarine outfit was a number of diving suits of a pattern invented by Frank Reade, Jr.

They consisted of a helmet, with a reservoir of ample dimensions fastened upon the back, and which was supplied with air by a chemical generator, while the bad air escaped by a valve in the top of the helmet.

Upon the helmet was also placed a small electric lamp, but of great power of penetration.

With heavy weights upon their feet, the wearers of this ingenious diving suit, having not to depend upon cord or life line, could remain at great depths and for a long period under the sea.

It was proposed with Frank’s permission to use the diving suits that Captain Bell and the professor should don these suits and take a walk upon the sandy bed of the sea.

“Certainly you can take the suits,” said Frank. “Only be careful of sharks.”

“We will do that,” replied the captain. “I hardly think we need fear them with a good ax and knife.”

Barney brought up the suits from the lower cabin and he and Pomp helped the two explorers to don them.

Soon they were equipped and ready for the departure from the interior of the submarine boat. Both were eager and excited.