Hal Hastings now appeared on deck, gravely saluting.
"Captain Benson," he stated, "I have inspected all the submerging machinery, the tanks, the compressed air apparatus, and all, and find everything in good order. We can go below the surface at any moment."
Two or three of the naval cadets smiled broadly at hearing the title bestowed on a boy younger than many of themselves.
"No levity, gentlemen," broke in Ensign Trahern, rather sternly. "Mr.
Benson is captain to his own chief engineer."
Jack waited until he saw the signal flags break out at the foretop of the "Hudson." It was an inquiry as to whether he was prepared for diving.
"Yes," signaled back the "Farnum's" flags.
"Dive at will, but keep to a due east or west course. Be careful to avoid collision with the sister craft," came the next order from the parent boat.
"All below!" ordered Benson, crisply.
Ensign Trahern waited until the last of the cadets had filed below, then followed them. Last of all came Jack Benson, after having lowered the short signal mast and made other preparations. Now he stepped inside the conning tower, swiftly making all fast. Then he called Midshipman Surles up the stairway to the tower wheel.
"Do you think you can head due east, and keep to that course under water,
Mr. Surles?" asked the young submarine instructor.