Captain Jack rapidly indicated the points at which the wrench was to be operated, adding: 

“I want you to note these points as I explain them, for after I start with the wrench I shall have to work rapidly along from bow to stern tanks.  Otherwise we would shoot up perpendicularly, instead of going up on a nearly even keel.  Mr. Hastings, are you all ready at your post?”

“Aye, aye, sir,” came back the engineer officer’s reply.

“On post, Mr. Somers?”

“Aye, aye, sir.”

Lieutenant Jack applied the wrench, calling snappily: 

“Watch me.  I’ve no time to explain anything now.”

With that he applied one of the wrenches and gave it a turn.  Instantly one of the electric motors in the engine-room began to vibrate.

Almost imperceptibly the bow of the “Dodger” began to rise.  Lieutenant Jack, intent on preserving an even keel as nearly as possible, passed on to the middle station with his wrench.

Just as he applied the tool the electric motor ceased running.

“What’s the matter, Mr. Hastings?” Jack inquired quietly.  “Something blow out of the motor?”

The submarine remained slightly tilted up at the bow.

“I don’t know, sir, as yet, what has happened,” Hal Hastings answered back.  “I’m going over the motor now.”

In a moment more he stepped into the cabin, a much more serious look than usual on his fine face.

“This, looks like the man Morton’s work,” Hal announced holding a small piece of copper up before the eyes of the midshipmen.  “Gentlemen, do you notice that the under side of this plate has been filed considerably?”

“Yes, sir,” nodded Dan Dalzell, a queer look crossing his face.  “Won’t the motor operate without that plate being sound?”

“It will not.”

The other midshipmen began to look and to feel strange.

“Then are we moored for good at the bottom of the bay?” asked Jetson.

“No; for we carry plenty of duplicate parts for this plate,” replied Ensign Hal.  “Come into the engine room and I will show you how I fit the duplicate part on.”

Hal led the midshipmen, halting before a small work bench.  He threw open a drawer under the bench.

“Every duplicate plate has been removed from this drawer,” announced Hastings quietly.  “Then, indeed, we are stuck in the mud, with no chance of rising.  Gentlemen, I trust that the Navy will send divers here to rescue us before our fresh air gives out!”

CHAPTER X

“We belong to the navy, too!”

“You mean, sir,” asked Midshipman Jetson, his voice hoarse in spite of his efforts to remain calm, “that we are doomed to remain here at the bottom of the bay unless divers reach us in time?”

“Yes,” nodded Hal Hastings, his voice as quiet and even as ever.  “Unless we can find a duplicate plate—–­and that appears impossible—–­the ‘Dodger’ is wholly unable to help herself.”