marine orderly.

Admiral Timworth was seated at his desk. Beside him was Captain Allen, commanding officer of the battleship "Hudson," flagship of the Mediterranean Squadron.

Lieutenant Totten and Cushing were also present.

"Good evening, gentlemen," was Admiral Timworth's greeting, after salutes had been exchanged. "Accidentally, you became spectators this evening, at a little drama connected with both the diplomatic and the secret service of your country."

The admiral paused, but both young officers remained respectfully at attention, making no response, as none was needed.

"You are aware," continued the admiral, "that Mr. Cushing was knocked down and robbed of an important government paper. Now, it happens that this paper was the key to a code employed by the State and Navy Departments in communicating with naval commanders abroad."

This time Dave actually started. The loss of such a code would be vitally important. The State and Navy Departments almost invariably communicate with naval commanders by means of a secret code, which can be read only by commanders possessing the key. Thus, when cablegrams are sent from stations in foreign countries, their import can be understood only by the officers to whom the communications are addressed.

"That strikes you as a most serious loss, does it not?" asked Admiral Timworth, smiling.

"Why, yes, sir; so it would seem," Dave answered, bowing.

"The code that was stolen to-night," laughed the admiral, "will be of but little value to the government into whose hands it may fall. The code in question was one that was used in the year 1880, and has not been employed since. Nor is it likely ever to be employed again."

Captain Allen joined in the admiral's laugh.

"We had every reason," continued the admiral, "to believe that an attempt would be made to steal that code ere Mr. Cushing delivered it to me. In fact, our government allowed it to be rather widely known that Mr. Cushing had left Washington to turn over to me a code. So, of course, Mr. Cushing has been followed. As a matter of fact, the code that we have been using for the last six months has not been changed. I was delighted when I learned that Cushing had been assaulted and robbed. Mr. Cushing himself took the loss seriously, for he did not know, until he came aboard a few moments ago, that the United States government had hoped he would be robbed. Lieutenant Totten was sent ashore, ostensibly to look after the launch, but in reality, to learn, if possible, whether Cushing's assailant put off in the launch of another power, and if so, which power. Ensigns Darrin and Dalzell, you noted, did you not, the nationality of the launch in which Mr. Cushing's assailant escaped?"

"I did not, sir," Dave replied. "It was not a naval launch, and therefore did not belong to any ships belonging to the Entente Allies' naval vessels in port here."

"Then, gentlemen," continued Admiral Timworth, his voice in tones of formal command, "you will not at any time mention this matter to any one unless so directed by me. I have had just one object in sending for you and giving you this order. For some time our Government has known that secret efforts are being made to discredit us with the allied powers of Europe. I feel rather certain that this fleet, while in the Mediterranean, will be closely watched by plotters serving one of the Central European powers, or else acting on their own account in the hope of being able to succeed and then claim reward from that government. Keep your eyes open. You may meet other spies and have reason to suspect them to be such. Do not be fooled by the apparent nationality of any man's name. A spy uses many names in his course around the world. Few international spies ever use their own names. The man in the green hat, who assaulted Mr. Cushing to-night, is one of the cleverest of his kind, and perhaps the most able with whom we shall have to contend. The fellow's name is supposed to be Emil Gortchky. At one time or another he has served as spy for nearly every government in Europe. He is a daring, dangerous, and wholly unscrupulous fellow. Ensigns Darrin and Dalzell, I sent for you in order to tell you these things, and to add that if, during this cruise, you run across the fellow at any point, you are to report the fact to me promptly. Of course you will understand that the seal of official secrecy attaches to all that I have said. That is all, gentlemen. Good evening."

Saluting, Ensigns Darrin and Dalzell promptly withdrew. They were still a good deal puzzled.

"I'll come to your quarters in a minute, if I may," murmured Danny Grin, as he reached the door of his own cabin.

"I want you to come," Dave answered dryly.

So, in another minute, Dan Dalzell, minus sword and gloves, bobbed into Dave's room.

"Now, what do you make out of all we have heard and seen?" breathed Dalzell tensely.

"Just what the admiral told us," answered Darrin.

"Nothing more?" pressed Dan.

Dave was thoughtful for a few moments before he replied:

"Danny, boy, we have our orders from the commander of the fleet. If we encounter Mr. Green Hat anywhere in the future, we are to report the fact. That is the extent of our instructions, and I think we shall do very well not to think too much about the matter, but to be ready, at all times, to follow our orders."

"I was in hope that you could evolve something more romantic than that," returned Dalzell disappointedly.

"It is very likely," went on Dave judicially, "that we have already had as large a hand in the affair as we are going to have. I doubt if we shall hear anything more of Mr. Green Hat; even if we hear of his further deeds, we are not likely to have any personal part in them."

"I'm disappointed," Dan admitted, rising. "I'm going to bed now, for I have to be up at half-past three, to turn out on watch at eight bells. You, lucky dog, have no watch to stand until after breakfast. Good night, Dave!"

"Good night; and don't dream of Mr. Green Hat," smiled Darrin. "You'll never see him again."

In that prediction Ensign Darrin was destined to find himself fearfully wide of the mark. Mr. Green Hat was not to be so easily dropped from the future calculations of the youngest naval officers on the "Hudson."

None of our readers require any introduction to Dave Darrin and Dan Dalzell, ofttimes known as "Danny Grin." These two fast friends in the naval service were members of "Dick & Co.," a famous sextette of schoolboys in Gridley. Dick Prescott, Greg Holmes, Dave Darrin, Dan Dalzell, Tom Reade and Harry Hazelton first appeared in the pages of "The Grammar School Boys Series," in which volumes were described the early lives of these young American schoolboys.

We found the six boys again in the pages of the "High School Boys Series," in the volumes of which the athletic triumphs of Dick & Co. were vividly set forth. In the "High School Boys' Vacation Series" were recounted their further adventures.

At the conclusion of their high school careers the six chums separated to seek different fields of endeavor. Dick Prescott and Greg Holmes secured appointments as cadets at the United States Military Academy at West Point, as narrated in the "West Point Series." Dave Darrin and Dan Dalzell were nominated as midshipmen to the United States Naval Academy at Annapolis, and all that befell them there is set forth in the "Annapolis Series." The great things that happened to Tom Reade and Harry Hazelton are told in the volumes of the "