Two minutes later the “Pollard” emerged from the water, several hundred yards away.  Those on the deck of the “Farnum” had a splendid view of the other boat’s emerging performance.

Now, other sections of cadets were transferred from the gunboat to the two submarines, and the trips below surface proceeded.

The last section of all to go aboard the “Farnum” had just finished their first experience under water, when the gunboat signaled: 

“‘Farnum,’ take a half-hour’s run below the surface, then come back above surface.”

“That will be a longer experience than I have yet had for one time,” remarked Mr. Trahern, with a smile, as he interpreted the signal to Captain Jack.

“We have run for hours below, with safety, sir,” Benson answered.

Two minutes later the section of middies that had just come up from a brief trip under water were below again.

“I think you’ll find, gentlemen, that it will seem like the longest half hour you can remember,” announced young Captain Benson.  “My friends and I have spent many long hours under the surface, though we have never yet gotten over the terrible monotony of such a trip.  Twenty-four hours under, I think, would make a lunatic of the bravest or the most stolid man.”

As they ran along, in the silence and the darkness, the young midshipmen began to look curiously at one another.

“Did you misunderstand the time, Mr. Benson?” asked one of the midshipmen, at last.  “It’s surely more than a half hour since we made the last dive.”

“Almost twelve minutes,” Jack corrected, quietly.

“Whew-ew-ew!” whistled several of the naval cadets.  Not one of them was a coward, yet, in their experience, the thought that they had put in barely more than a third of the ordered time under water made some of them fidget.

“Say, this gives us some idea how long a whole hour would be,” remarked one of the midshipmen.

“Stop that man from talking,” jibed another severely.

Jack had most of the time clear for instruction, after that, as few of the young men cared to talk.  But at last another ventured to inquire: 

“How much of the time is gone?”

“Nineteen minutes,” Benson answered, after a look at his watch.

“O-o-o-oh!” The response came in a chorus that sounded like a protest.

Then passed what seemed like an eternity of seconds.  All the time the electric motors ran, almost noiselessly.  The slight tremor imparted to the craft by the propeller shafts seemed like an ominous rumbling.  Jack’s voice had ceased.  No one felt like talking.  From time to time Skipper Jack glanced at his watch; his face, expressionless, gave no clue to the eagerly watching naval cadets.  But at last young Benson’s hand reached toward the compressed air apparatus.

“A-a-a-ah!” It was meant for a cheer, but it sounded more like a groan.