An instant of silence, during which the two men eyed each other; then, Sweetwater, with an ironical smile directed towards the pistol lightly remarked:

“Mr. Challoner and other men at the hotel are acquainted with my purpose and await my return. I have come—” here he cast a glowing look at the huge curtain cutting off the greater portion of the illy-lit interior—“to offer you my services, Mr. Brotherson. I have no other motive for this intrusion than to be of use. I am deeply interested in your invention, to the development of which I have already lent some aid, and can bring to the test you propose a sympathetic help which you could hardly find in any other person living.”

The silence which settled down at the completion of these words had a weight which made that of the previous moment seem light and all athrob with sound. The man within had not yet caught his breath; the man without held his, in an anxiety which had little to do with the direction of the weapon, into which he looked. Then an owl hooted far away in the forest, and Orlando, slowly lowering his arm, asked in an oddly constrained tone:

“How long have you been in town?”

The answer cut clean through any lingering hope he may have had.

“Ever since the day your brother was told the story of his great misfortune.”

“Ah! still at your old tricks! I thought you had quit that business as unprofitable.”

“I don’t know. I never expect quick returns. He who holds on for a rise sometimes reaps unlooked-for profits.”

The arm and fist of Orlando Brotherson ached to hurl this fellow back into the heart of the midnight woods.

But they remained quiescent and he spoke instead. “I have buried the business. You will never resuscitate it through me.”

Sweetwater smiled. There was no mirth in his smile though there was lightness in his tone as said:

“Then let us go back to the matter in hand. You need a helper; where are you going to find one if you don’t take me?”

A growl from Brotherson’s set lips. Never had he looked more dangerous than in the one burning instant following this daring repetition of the detective’s outrageous request. But as he noted how slight was the figure opposing him from the other side of the threshold, he was swayed by his natural admiration of pluck in the physically weak, and lost his threatening attitude, only to assume one which Sweetwater secretly found it even harder to meet.

“You are a fool,” was the stinging remark he heard flung at him. “Do you want to play the police-officer here and arrest me in mid air?”

“Mr. Brotherson, you understand me as little as I am supposed to understand you. Humble as my place is in society and, I may add, in the Department whose interests I serve, there are in me two men. One you know passably well—the detective whose methods, only indifferently clever show that he has very much to learn. Of the other—the workman acquainted with hammer and saw, but with some knowledge too of higher mathematics and the principles upon which great mechanical inventions depend, you know little, and must imagine much. I was playing the gawky when I helped you in the old house in Brooklyn. I was interested in your air-ship—Oh, I recognised it for what it was, notwithstanding its oddity and lack of ostensible means for flying—but I was not caught in the whirl of its idea; the idea by which you doubtless expect, and with very good reason too, to revolutionise the science of aviation. But since then I’ve been thinking it over, and am so filled with your own hopes that either I must have a hand in the finishing and sailing of the one you have yourself constructed, or go to work myself on the hints you have unconsciously given me, and make a car of my own.”

Audacity often succeeds where subtler means fail. Orlando, with a curious twist of his strong lip, took hold of the detective’s arm and drew him in, shutting and locking the door carefully behind him.

“Now,” said he, “you shall tell me what you think you have discovered, to make any ideas of your own available in the manufacture of a superior self-propelling air-ship.”

Sweetwater who had been so violently wheeled about in entering that he stood with his back to the curtain concealing the car, answered without hesitation.

“You have a device, entirely new so far as I can judge, by which this car can leap at once into space, hold its own in any direction, and alight again upon any given spot without shock to the machine or danger to the people controlling it.”

“Explain the device.”

“I will draw it.”

“You can?”

“As I see it.”

“As you see it!”

“Yes. It’s a brilliant idea; I could never have conceived it.”

“You believe—”

“I know.”

“Sit here. Let’s see what you know.”

Sweetwater sat down at the table the other pointed out, and drawing forward a piece of paper, took up a pencil with an easy air. Brotherson approached and stood at his shoulder. He had taken up his pistol again, why he hardly knew, and as Sweetwater began his marks, his fingers tightened on its butt till they turned white in the murky lamplight.

“You see,” came in easy tones from the stooping draughtsman, “I have an imagination which only needs a slight fillip from a mind like yours to send it in the desired direction. I shall not draw an exact reproduction of your idea, but I think you will see that I understand it very well. How’s that for a start?”

Brotherson looked and hastily drew back. He did not want the other to note his surprise.

“But that is a portion you never saw,” he loudly declared.

“No, but I saw this,” returned Sweetwater, working busily on some curves; “and these gave me the fillip I mentioned. The rest came easily.”

Brotherson, in dread of his own anger, threw his pistol to the other end of the shed:

“You knave! You thief!” he furiously cried.

“How so?” asked Sweetwater smilingly, rising and looking him calmly in the face. “A thief is one who appropriates another man’s goods, or, let us say, another man’s ideas. I have appropriated nothing yet. I’ve only shown you how easily I could do so. Mr. Brotherson, take me in as your assistant. I will be faithful to you, I swear it. I want to see that machine go up.”

“For how many people have you drawn those lines?” thundered the inexorable voice.

“For nobody; not for myself even. This is the first time they have left their hiding-place in my brain.”

“Can you swear to that?”

“I can and will, if you require it. But you ought to believe my word, sir. I am square as a die in all matters not connected—well, not connected with my profession,” he smiled in a burst of that whimsical humour, which not even the seriousness of the moment could quite suppress.

“And what surety have I that you do not consider this very matter of mine as coming within the bounds you speak of?”

“None. But you must trust me that far.”

Brotherson surveyed him with an irony which conveyed a very different message to the detective than any he had intended. Then quickly:

“To how many have you spoken, dilating upon this device, and publishing abroad my secret?”

“I have spoken to no one, not even to Mr. Gryce. That shows my honesty as nothing else can.”

“You have kept my secret intact?”

“Entirely so, sir.”

“So that no one, here or elsewhere, shares our knowledge of the new points in this mechanism?”

“I say so, sir.”

“Then if I should kill you,” came in ferocious accents, “now—here—”

“You would be the only one to own that knowledge. But you won’t kill me.”

“Why?”

“Need I go into reasons?”

“Why? I say.”

“Because your conscience is already too heavily laden to bear the burden of another unprovoked crime.”

Brotherson, starting back, glared with open ferocity upon the man who dared to face him with such an accusation.

“God! why didn’t I shoot you on entrance!” he cried. “Your courage is certainly colossal.”

A fine smile, without even the hint of humour now, touched the daring detective’s lip. Brotherson’s anger seemed to grow under it, and he loudly repeated:

“It’s more than colossal; it’s abnormal and—” A moment’s pause, then with ironic pauses—“and quite unnecessary save as a matter of display, unless you think you need it to sustain you through the ordeal you are courting. You wish to help me finish and prepare for flight?”

“I sincerely do.”

“You consider yourself competent?”

“I do.”

Brotherson’s eyes fell and he walked once to the extremity of the oval flooring and back.

“Well, we will grant that. But that’s not all that is necessary. My requirements demand a companion in my first flight. Will you go up in the car with me on Saturday night?”

A quick affirmative was on Sweetwater’s lips but the glimpse which he got of the speaker’s face glowering upon him from the shadows into which Brotherson had withdrawn, stopped its utterance, and the silence grew heavy. Though it may not have lasted long by the clock, the instant of breathless contemplation of each other’s features across the intervening space was of incalculable moment to Sweetwater, and, possibly, to Brotherson. As drowning men are said to live over their whole history between their first plunge and their final rise to light and air, so through the mind of the detective rushed the memories of his past and the fast fading glories of his future; and rebelling at the subtle peril he saw in that sardonic eye, he vociferated an impulsive:

“No! I’ll not—” and paused, caught by a new and irresistible sensation.

A breath of wind—the first he had felt that night—had swept in through some crevice in the curving wall, flapping the canvas enveloping the great car. It acted like a peal to battle. After all, a man must take some risks in his life, and his heart was in this trial of a redoubtable mechanism in which he had full faith. He could not say no to the prospect of being the first to share a triumph which would send his name to the ends of the earth; and, changing the trend of his sentence, he repeated with a calmness which had the force of a great decision.

“I will not fail you in anything. If she rises—” here his trembling hand fell on the curtain shutting off his view of the ship, “she shall take me with her, so that when she descends I may be the first to congratulate the proud inventor of such a marvel.”

“So be it!” shot from the other’s lips, his eyes losing their threatening look, and his whole countenance suddenly aglow with the enthusiasm of awakened genius.

Coming from the shadows, he laid his hand on the cord regulating the rise and fall of the concealing curtain.

“Here she is!” he cried and drew the cord.

The canvas shook, gathered itself into great folds and disappeared in the shadows from which he had just stepped.

The air-car stood revealed—a startling, because wholly unique, vision.

Long did Sweetwater survey it, then turning with beaming face upon the watchful inventor, he uttered a loud Hurrah.

Next moment, with everything forgotten between them save the glories of this invention, both dropped simultaneously to the floor and began that minute examination of the mechanism necessary to their mutual work.