“Thank you, Benson,” acknowledged the major, also doffing his own cap.  Then, closing the door, Major Woodruff stepped back to the table on which lay chart and book.

“This chart, Benson, shows what the rascal Millard, has been doing out on the neck.  This book proves that he has been at work at some other points.  The book doesn’t tell much of the story, though.  Of that I am certain.  Millard, if he has been at work long, has compiled other notes in other written volumes.  If so, then he has also made other charts of our coast defenses.  For what other government has he thus marked a series of charts with our secrets?  And has Millard succeeded in getting other charts, and other books of notes, off to the foreign government he is serving—­or has he them hidden somewhere in this country, awaiting his chance to take the results of his spying out of the United States?”

“I wish I knew!” muttered Jack.

“I’m coming to the point,” continued Major Woodruff, briskly.  “Now, of course, when we discover evidence that spies of other governments are at work along our lines of national defenses, the first thing we try to do is to catch these foreign agents and all the material they have succeeded in getting together.”

Major Woodruff, who was becoming considerably excited, paused to light a cigar, ere he continued, more slowly: 

“Now, you and your two friends, Benson, know this fellow Millard.  You will spot him instantly, wherever you go.  I shall communicate with Washington, at once, by means of a telegram in cipher.  The War Department will order me to use all speed in catching Millard, and in finding out where he keeps his other stolen records.  Men and money will be used in running down this fellow.  Yet you and your two chums should be in the front ranks of pursuit, for you will know him the instant you lay eyes on him.”

“You want me to take my friends ashore, then, Major, and lay the ‘Spitfire’ up?”

“By no means,” answered Major Woodruff, decisively.  “In reality operations will be suspended at this point until we have run Millard down.  Yet we must have the appearance of being as busy as ever.  The submarine will hover about, and this tug will be busy, apparently, in laying the bay with mines.  You have a fourth man on your boat?”

“Yes, sir; Williamson, the machinist.”

“Can he run the engines all right?”

“As well as any of us, Major.”

“Then I will put aboard a man who can steer.  Thus the ‘Spitfire’ will be seen moving about the bay, and apparently at work.  I’ll also put aboard a guard of a sergeant and three or four soldiers of the engineer corps, and they’ll guard that boat from harm with their lives.  That will leave all three of you young officers of the ‘Spitfire’ free for shore duty.”

“It will, Major.  And now, sir, what is that shore duty to be?”

“Simply to locate Millard.  He may be at one of the hotels in Radford.”