Mackinder dropped back upon the deck, limp and helpless, as the singing of the parted line told of his release.
With tender solicitude the boys mounted the ladder to assist their injured friend to the room below. Scarcely had the boys gained the deck when they were startled by a terrific explosion. As Ned afterward declared, it seemed as if they had been caught in a volcano of water.
"What has happened?" queried Jack, releasing his hold upon Mackinder.
A flood of sea water descending upon the little deck prevented an answer to his question. In a moment the lads were able to look about.
"Gone!" stated Ned, his voice trembling. "I'll bet that German torpedoed it! I'm glad we are on this 'U-13'!"
Echoing this sentiment, the lads hastily proceeded to lower Mackinder through the hatchway. This done, the injured man was deposited on a couch, the hatch was closed, and Ned began first-aid ministrations.
"What course shall I hold?" asked Jimmie.
"Better head on a southwest course," stated Ned, briefly glancing up from his work over Mackinder's leg.
"I can do that all right," responded Jimmie. "The gunboat and the submarine can fight it out alone."
"We've got a clear field, Jimmie, so shove the little wagon along for all she's worth," put in Jack.
Mackinder had been exercising wonderful command of himself, but in spite of his best efforts a groan now and again escaped. The injured leg was proving a painful matter.
"We'll do all we can for you, Mackinder," Ned offered, "but we need better skill than is available here. Would it not be best to make at once for some port where we can secure the services of a surgeon?"
Mackinder's only reply was a nod. His teeth were closed tightly to suppress the cry of anguish from his hurt.
"Keep on the surface, boys," urged Ned as he went about making the man comfortable with such simple means as were at hand. "I believe we are not far from the coast."
Surrendering the wheel to Frank, and with Jack at the engines, Jimmie insisted upon mounting to the deck again to look about them.
Cool and sweet the air gushed down the little open hatchway upon the injured man. Under its influence and aided by the ministrations of Ned, the proprietor of the third "U-13" rapidly gained control of himself.