Such was the letter addressed to the government of the United States. As to the person who had placed it in the mail-box of the police, no one had seen him.

The sidewalk in front of our offices had probably not been once vacant during the entire night. From sunset to sunrise, there had always been people, busy, anxious, or curious, passing before our door. It is true, however, that even then, the bearer of the letter might easily have slipped by unseen and dropped the letter in the box. The night had been so dark, you could scarcely see from one side of the street to the other.

I have said that this letter appeared in facsimile in all the newspapers to which the government communicated it. Perhaps one would naturally imagine that the first comment of the public would be, "This is the work of some practical joker." It was in that way that I had accepted my letter from the Great Eyrie, five weeks before.

But this was not the general attitude toward the present letter, neither in Washington, nor in the rest of America. To the few who would have maintained that the document should not be taken seriously, an immense majority would have responded. "This letter has not the style nor the spirit of a jester. Only one man could have written it; and that is the inventor of this unapproachable machine."

To most people this conclusion seemed indisputable owing to a curious state of mind easily explainable. For all the strange facts of which the key had hitherto been lacking, this letter furnished an explanation. The theory now almost universally accepted was as follows. The inventor had hidden himself for a time, only in order to reappear more startlingly in some new light. Instead of having perished in an accident, he had concealed himself in some retreat where the police were unable to discover him. Then to assert positively his attitude toward all governments he had written this letter. But instead of dropping it in the post in any one locality, which might have resulted in its being traced to him, he had come to Washington and deposited it himself in the very spot suggested by the government's official notice, the bureau of police.

Well! If this remarkable personage had reckoned that this new proof of his existence would make some noise in two worlds, he certainly figured rightly. That day, the millions of good folk who read and re-read their daily paper could to employ a well-known phrase, scarcely believe their eyes.

As for myself, I studied carefully every phrase of the defiant document. The hand-writing was black and heavy. An expert at chirography would doubtless have distinguished in the lines traces of a violent temperament, of a character stern and unsocial. Suddenly, a cry escaped me a cry that fortunately my housekeeper did not hear. Why had I not noticed sooner the resemblance of the handwriting to that of the letter I had received from Morganton?

Moreover, a yet more significant coincidence, the initials with which my letter had been signed, did they not stand for the words "Master of the World?"

And whence came the second letter? "On Board the 'Terror.'" Doubtless this name was that of the triple machine commanded by the mysterious captain. The initials in my letter were his own signature; and it was he who had threatened me, if I dared to renew my attempt on the Great Eyrie.

I rose and took from my desk the letter of June thirteenth. I compared it with the facsimile in the newspapers. There was no doubt about it. They were both in the same peculiar hand-writing.

My mind worked eagerly. I sought to trace the probable deductions from this striking fact, known only to myself. The man who had threatened me was the commander of this "Terror" -- startling name, only too well justified! I asked myself if our search could not now be prosecuted under less vague conditions. Could we not now start our men upon a trail which would lead definitely to success? In short, what relation existed between the "Terror" and the Great Eyrie? What connection was there between the phenomena of the Blueridge Mountains, arid the no less phenomenal performances of the fantastic machine?

I knew what my first step should be; and with the letter in my pocket, I hastened to police headquarters. Inquiring if Mr. Ward was within and receiving an affirmative reply, I hastened toward his door, and rapped upon it with unusual and perhaps unnecessary vigor. Upon his call to enter, I stepped eagerly into the room.

The chief had spread before him the letter published in the papers, not a facsimile, but the original itself which had been deposited in the letter-box of the department.

"You come as if you had important news, Strock?"

"Judge for yourself, Mr. Ward;" and I drew from my pocket the letter with the initials.

Mr. Ward took it, glanced at its face, and asked, "What is this?"

"A letter signed only with initials, as you can see."

"And where was it posted?"

"In Morganton, in North Carolina."

"When did you receive it?"

"A month ago, the thirteenth of June."

"What did you think of it then?"

"That it had been written as a joke."

"And now Strock?"

"I think, what you will think, Mr. Ward, after you have studied it."

My chief turned to the letter again and read it carefully. "It is signed with three initials," said he.

"Yes, Mr. Ward, and those initials belong to the words, 'Master of the World,' in this facsimile."

"Of which this is the original," responded Mr. Ward, taking it up.

"It is quite evident," I urged, "that the two letters are by the same hand."

"It seems so."

"You see what threats are made against me, to protect the Great Eyrie."

"Yes, the threat of death! But Strock, you have had this letter for a month. Why have you not shown it to me before?"

"Because I attached no importance to it. Today, after the letter from the 'Terror,' it must be taken seriously."

"I agree with you. It appears to me most important. I even hope it may prove the means of tracking this strange personage."

"That is what I also hope, Mr. Ward."

"Only what connection can possibly exist between the 'Terror' and the Great Eyrie?"

"That I do not know. I cannot even imagine."

"There can be but one explanation," continued Mr. Ward, "though it is almost inadmissible, even impossible."

"And that is?"

"That the Great Eyrie was the spot selected by the inventor, where he gathered his material."

"That is impossible!" cried I. "In what way would he get his material in there? And how get his machine out? After what I have seen, Mr. Ward, your suggestion is impossible."

"Unless, Strock--"

"Unless what?" I demanded.

"Unless the machine of this Master of the World has also wings, which permit it to take refuge in the Great Eyrie."

At the suggestion that the "Terror," which had searched the deeps of the sea, might be capable also of rivaling the vultures and the eagles, I could not restrain an expressive shrug of incredulity. Neither did Mr. Ward himself dwell upon the extravagant hypothesis.

He took the two letters and compared them afresh. He examined them under a microscope, especially the signatures, and established their perfect identity. Not only the same hand, but the same pen had written them.

After some moments of further reflection, Mr. Ward said, "I will keep your letter, Strock. Decidedly, I think, that you are fated to play an important part in this strange affair or rather in these two affairs. What thread attaches them, I cannot yet see; but I am sure the thread exists. You have been connected with the first, and it will not be surprising if you have a large part in the second."

"I hope so, Mr. Ward. You know how inquisitive I am."

"I do, Strock. That is understood. Now, I can only repeat my former order; hold yourself in readiness to leave Washington at a moment's warning."

All that day, the public excitement caused by the defiant letter mounted steadily higher. It was felt both at the White House and at the Capitol that public opinion absolutely demanded some action. Of course, it was difficult to do anything. Where could one find this Master of the World? And even if he were discovered, how could he be captured? He had at his disposal not only the powers he had displayed, but apparently still greater resources as yet unknown. How had he been able to reach Lake Kirdall over the rocks; and how had he escaped from it? Then, if he had indeed appeared on Lake Superior, how had he covered all the intervening territory unseen?

What a bewildering affair it was altogether! This, of course, made it all the more important to get to the bottom of it. Since the millions of dollars had been refused, force must be employed. The inventor and his invention were not to be bought. And in what haughty and menacing terms he had couched his refusal! So be it! He must be treated as an enemy of society, against whom all means became justified, that he might be deprived of his power to injure others. The idea that he had perished was now entirely discarded. He was alive, very much alive; and his existence constituted a perpetual public danger!

Influenced by these ideas, the government issued the following proclamation:

"Since the commander of the 'Terror' has refused to make public his invention, at any price whatever, since the use which he makes of his machine constitutes a public menace, against which it is impossible to guard, the said commander of the 'Terror' is hereby placed beyond the protection of the law. Any measures taken in the effort to capture or destroy either him or his machine will be approved and rewarded."

It was a declaration of war, war to the death against this "Master of the World" who thought to threaten and defy an entire nation, the American nation!

Before the day was over, various rewards of large amounts were promised to anyone who revealed the hiding place of this dangerous inventor, to anyone who could identify him, and to anyone who should rid the country of him.

Such was the situation during the last fortnight of July. All was left to the hazard of fortune. The moment the outlaw re-appeared he would be seen and signaled, and when the chance came he would be arrested. This could not be accomplished when he was in his automobile on land or in his boat on the water. No; he must be seized suddenly, before he had any opportunity to escape by means of that speed which no other machine could equal.

I was therefore all alert, awaiting an order from Mr. Ward to start out with my men. But the order did not arrive for the very good reason that the man whom it concerned remained undiscovered. The end of July approached. The newspapers continued the excitement. They published repeated rumors. New clues were constantly being announced. But all this was mere idle talk. Telegrams reached the police bureau from every part of America, each contradicting and nullifying the others. The enormous rewards offered could not help but lead to accusations, errors, and blunders, made, many of them, in good faith. One time it would be a cloud of dust, which must have contained the automobile. At another time, almost any wave on any of America's thousand lakes represented the submarine. In truth, in the excited state of the public imagination, apparitions assailed us from every side.

At last, on the twenty-ninth of July, I received a telephone message to come to Mr. Ward on the instant. Twenty minutes later I was in his cabinet.

"You leave in an hour, Strock," said he.

"Where for?"

"For Toledo."

"It has been seen?"

"Yes. At Toledo you will get your final orders."

"In an hour, my men and I will be on the way."

"Good! And, Strock, I now give you a formal order."

"What is it, Mr. Ward?"

"To succeed! This time to succeed!"