“By Jove, sir! the way you explain it I can see the advantages,” said Jack eagerly.

“And so can I,” agreed Frank.

Lord Hastings smiled.

“You are easily convinced,” he replied.  “Had some of the admiralty officials been convinced half so easily, this submarine menace might have been effectually stopped long before this.”

As the motorboat continued down the Thames, each occupant remained busy with his thoughts.  It was Frank who broke the silence.

“What has happened to the torpedoboat destroyers, sir?” he asked.  “I understood they were the real submarine foe, with their heavy nets.”

“They are still in use,” replied Lord Hastings.  “You know how they work their nets, I suppose?”

“Why, I think so, sir.  The net is carried by two ships, and when a submarine crashes into the net she either tangles her nose or her stern in the net and can be disposed of with ease.”

“Yes, but what I want to know,” said Jack, “is why she doesn’t fire a torpedo through the net and sink the torpedoboat?”

“Because,” said Lord Hastings, with a smile, “being beneath the water, she is blind.  She doesn’t know in which direction to fire it.  You forget that the German submarines are not equipped as was the D-16.”

“The good old D-16,” said Jack.  “How I wish we had her again, sir.”

“And I,” agreed Lord Hastings.  “And yet she came near being the death of all of us.”

“So she did,” said Frank, “but at the same time I wouldn’t mind being aboard another such craft.”

“Well, just between the three of us,” said Lord Hastings, “I may tell you that another such craft now is nearing completion and probably will be at our disposal within a month.”

“You don’t mean it, sir!” exclaimed Frank happily.

“If he didn’t mean it he wouldn’t say so,” Jack reproved his chum.

“Oh, I know that,” replied Frank.  “But it seems too good to be true.”

“But just where are we bound now, sir?” asked Jack.

“Well,” said Lord Hastings, “at first we shall do a little cruising off the Irish coast.  In fact, most of the motorboat fleet is in Irish waters.  Since the sinking of the Lusitania, most of the work has been done there; and apparently the German government is still bent upon the destruction of big passenger ships, neutral or not.”

“Well, the sooner we can get busy the better it will suit me,” declared Frank.

“I agree with you there,” said Jack.

It was a long voyage for the little motorboat, and though Lord Hastings wished to join the others of the fleet at the earliest possible moment, he did not push the little craft, which bore the name of The Hawk.

Therefore, it was late the next day when they came to where the motorboat fleet had its base—­Bantry Bay, on the extreme southern coast of Ireland.

As the little motorboat nosed its way into the harbor, several others dashed forward, with guns bared and alert figures standing ready for action.  It was not until Lord Hastings had been satisfactorily identified that the warlike atmosphere disappeared.