"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.

"G.o.d! 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 Sat.u.r.day night?"

A quick affirmative was on Sweet.w.a.ter'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lips but the glimpse which he got of the speaker's face glowering upon him from the shadows into which Brotherson had withdrawn, stopped its utterance, and the silence grew heavy.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 s.p.a.ce was of incalculable moment to Sweet.w.a.ter, 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 Sweet.w.a.ter 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.

x.x.xVII. HIS GREAT HOUR

Sat.u.r.day night at eight o'clock.

So the fiat had gone forth, with no concession to be made on account of weather.

As Oswald came from his supper and took a look at the heavens from the small front porch, he was deeply troubled that Orlando had remained so obstinate on this point. For there were ominous clouds rolling up from the east, and the storms in this region of high mountains and abrupt valleys were not light, nor without danger even to those with feet well planted upon mother earth.

If the tempest should come up before eight!

Mr. Challoner, who, from some mysterious impulse of bravado on the part of Brotherson, was to be allowed to make the third in this small band of spectators, was equally concerned at this sight, but not for Brotherson.

His fears were for Oswald, whose slowly gathering strength could illy bear the strain which this additional anxiety for his brother's life must impose upon him. As for Doris, she was in a state of excitement more connected with the past than with the future. That afternoon she had laid her hand in that of Orlando Brotherson, and wished him well.

She! in whose breast still lingered reminiscences of those old doubts which had beclouded his image for her at their first meeting. She had not been able to avoid it. His look was a compelling one, and it had demanded thus much from her; and--a terrible thought to her gentle spirit--he might be going to his death!

It had been settled by the prospective aviator that they were to watch for the ascent from the mouth of the gra.s.sy road leading in to the hangar. The three were to meet there at a quarter to eight and await the stroke and the air-cars rise. That time was near, and Mr. Challoner, catching a glimpse of Oswald's pallid and unnaturally drawn features, as he set down the lantern he carried, shuddered with foreboding and wished the hour pa.s.sed.

Doris' watchful glance never left the face whose lightest change was more to her than all Orlando's hopes. But the result upon her was not to weaken her resolution, but to strengthen it. Whatever the outcome of the next few minutes, she must stand ready to sustain her invalid through it. That the darkness of early evening had deepened to oppression, was unnoticed for the moment. The fears of an hour past had been forgotten.

Their attention was too absorbed in what was going on before them, for even a glance overhead.

Suddenly Mr. Challoner spoke.

"Who is the man whom Mr. Brotherson has asked to go up with him?"

It was Oswald who answered.

"He has never told me. He has kept his own counsel about that as about everything else connected with this matter. He simply advised me that I was not to bother about him any more; that he had found the a.s.sistant he wanted."

"Such reticence seems unpardonable. You have--displayed great patience, Oswald."

"Because I understand Orlando. He reads men's natures like a book. The man he trusts, we may trust. To-morrow, he will speak openly enough. All cause for reticence will be gone."

"You have confidence then in the success of this undertaking?"