“That’s good, sir.”

“So it is. You may proceed at twenty-five knots.”

The D-16 gathered headway and soon was traveling along under the water at a great rate.

“Won’t we have to be careful of mines along here, sir?” asked Jack.

“I do not believe they have mined much as yet. They figure that there is little danger of the Allies forcing an entrance for some time to come. However, we may as well be careful. Take the lookout, Mr. Chadwick.”

Frank saluted and returned to his post.

“The only place we shall have to be really careful,” said Lord Hastings, “is when we near Constantinople. No matter how safe the Turks may have felt, it is hardly possible they have not taken all emergency precautions.”

“If not,” said Jack, “the German officers who have been put in charge of their forces will have done it for them.”

“I guess there is no doubt about that,” was the reply. “The Germans are thorough in everything they do.”

“Shall we land in Constantinople, sir?”