“Yes, I have read a good deal about the underwater ships,” March said. “I always did think those first experimenters had a lot of guts. Imagine that Dutchman, Van Drebel, submerging a boat more than three hundred years ago.”

“Sure, and he stayed down two hours,” Stan agreed. “Made about two miles—with oars for power!”

“He must have been a clever guy to have those oars sticking out through leather openings sealed so tight that not a drop of water could come in,” March said. “But it was the Americans who really made submarines go.”

“Yes—isn’t there a ship named after Bushnell,” Stan asked, “the man who made that submarine during the American Revolution?”

“Sure, a submarine tender, naturally,” March replied. “Too bad his idea didn’t work better. It was a clever one.”

“I had never realized until today,” Stan said, “that Robert Fulton had anything to do with submarines. I thought inventing the steamboat was enough for any one man. But now I find out he invented pretty good submarines long before he did the steamboat. But he just couldn’t get anybody to listen to him.”

“Well, the sub really couldn’t develop into a reliable ship,” March said, “until electric motors and storage batteries came along. There were some pretty good attempts, of course, and John Holland and Simon Lake, the two Americans who really made subs that worked, turned out some fair ones driven by gasoline engines, steam engines, and compressed air.”

“And don’t forget the Diesels!” Stan laughed. “My sweethearts, the Diesels! They were the last things needed, after storage batteries and electric motors, to make subs really dependable and good.”

“I won’t forget your Diesels, Stan,” March said. “I’m going to have to learn plenty about them in the next few weeks, and I know almost nothing now. And you’ve got to learn plenty about other things, too.”

“Sure, it’ll be tough going,” Stan said. “But it’s a wonderful idea to have every officer, no matter what his specialty, able to take over almost any department on a sub if he has to.”