“Twenty feet, mate!” came the voice of Dick.

“That will do, Speake,” called Bob.

The tanks were closed.

“Drive her ahead, Dick!” cried Bob.

The motor was speeded up and the Grampus hustled onward below the surface. While Bob unlashed the wheel and brought the boat more directly into her course, a loud boom and a splash were heard.

“What’s that?” demanded Speake.

“The steamer is firing at us,” answered Bob.

“Let ’em shoot,” laughed Dick. “A heap of good it will do them to drop shot into the sea.”

“How’s Gaines, Dick?”

“Coming along full and by, forty knots. He’s sitting up and beginning to take notice.”