THE three caught sight of the helicopter in the same instant. The strange machine was rushing through the air like a colossal eagle. Professor Morgan had seen the group while some distance away and headed for it, sailing at a height of less than two hundred feet and rapidly descending. Instead of approaching in a direct line, he made a sweeping circle and came down in the ordinary way by volplaning instead of making use of his uplifter.

While these manoeuvres were going on Dick Hamilton stepped across to his brother and reached out his hand.

“Let me have the rifle, Harv; it looks as if we’re going to have lively times.”

“Gee!” gasped the terrified Bunk; “yo’ ain’t gwine to shoot him!”

“That depends; if you try any tantrums I may have to plug you first. Understand, Bunk, that you are to stand back and not open your mouth or do a thing till I give you permission.”

“Yas, sir.”Harvey would have made protest, for he was filled with shuddering dread, but he realized that for the present he stood in the same situation as Bunk. The big brother had stepped to the front and taken charge of affairs. Moreover, he never forgot the truth that in dealing with an insane person you must first impress him with the fact that you do not hold him in the slightest fear. While as a rule it is not wise to dispute or argue or try to turn him aside from his purpose by force, occasions may arise like the present when no other course is possible.

Professor Morgan must have read the meaning of the sight that brought him to the spot. He recognized Harvey before he stepped out of his machine and his rage flamed up against him. Ignoring the other two, he strode toward the young aviator with clenched fists and with murder in his blazing eyes. In a thunderous bass he demanded:

“What business have you here? I’ll teach you—”

He had said this much and his long legs were still in motion, when Dick leaped between them and holding his rifle at his hip with muzzle leveled at the infuriated man, he commanded:

“Stop! if you touch him I’ll let daylight through you!”The Professor halted and turned upon the other, his frame trembling with surcharged fury.

“I’ll kill you!”

It is impossible to picture the frightful scene at this moment. Bunk Johnson was silent and awed. Harvey was a little to one side and in front of him, while in the other direction stood Dick, one foot advanced as if ready to bound forward, his right hand inclosing the lock of his gun, so that the forefinger could be seen crooked around the trigger. The weapon was so pointed that only a slight pressure was needed to send a bullet through the long gaunt body hardly a dozen feet away.

“All right,” calmly replied Dick; “you can begin as soon as you please, my distinguished friend, but before you reach me you will have to stop ten spheres of lead and by that time I calculate I shall be able to handle you without the need of my Winchester.”

Professor Morgan may have been “off his base,” but he could not fail to read the meaning of those words, backed up by the pose of him who uttered them. He stopped like a tiger baffled of his prey.

“Why don’t you shoot?” he hissed.

“You haven’t given me the excuse I’m waiting for; in the case of every one of the seven men I have shot my explanation secured my acquittal in the courts. I’m taking the same course with you.”

The sight of Harvey seemed to concentrate once more the lunatic’s resentment against him. But for the presence of that Winchester and the man behind the gun, he would have rended the youth, provided the latter did not stand him off with his Colt.

“What business, I demand, have you to come here?”

“Please address your remarks to me,” said Dick; “I’m boss of this job and that brother of mine over there hasn’t a word to say. He came up here, I may tell you, to take Bohunkus Johnson home with him, and he’s going to do it as sure as two and two make four. If you have any views to express on the situation do so now or forever after hold your peace.”

Checked thus the Professor turned toward the paralyzed Bunk.

“Do you wish to go with me to Africa?”

“Yas, sir.”

“Have these people any right to stop you?”

“Yas, sir.”

“Oh!” exclaimed the Professor, with the first oath that his two listeners had ever heard him utter, “have done with that damnable ‘Yas, sir!’ I’m tired of hearing it.”“Yas, sir,” replied Bunk, who must not be blamed, for really he hardly knew whether he was standing on his head or feet.

“I have brought food to last our trip and everything is ready. Go to your seat in the machine and we will start at once.”

“Yas, sir,” responded the negro lad, taking a step in the direction of the monoplane, only to find that Dick Hamilton was as alert as before.

“Back with you! If you want to save what little brains you have don’t take another step in that direction.”

Poor Bunk halted and stared in wretched perplexity at the young man. Could Professor Morgan at that moment have caught his eye, he would have controlled him absolutely through that mysterious hypnotic power with which nature had endowed him. But it was Dick who now held him enchained.

“Bunk, start for the lake and start a-running. When you get there, wait for us. GO!”

The lad broke into a headlong dash, shouting at the top of his voice:

“Murder! fire! robbers! thieves! sabe me!”

And he kept it up until he crashed out of sight of the three who remained behind. By a tremendous effort, Dick Hamilton maintained his sternness of expression. As for Harvey, he did not try to restrain his silent laughter. It was the most comical incident he had seen in many a day. Professor Morgan glared and was mute. He seemed utterly at a loss and unable to grasp the situation.

“My dear Professor,” said Dick addressing him, “don’t you think it is about time you ended this call? We are growing a little weary of you.”

“Are you my master?” asked the lunatic in his sepulchral voice.

“It looks that way just now; if you have any doubt let’s test it.”

Harvey wished to ask one or two questions, but thought it would be unwise. It was clear that the Professor hated him unspeakably for the overthrow of his plans. No doubt, as has been said, he would have leaped upon the youth but for that other young man who held a deadly Winchester in his grasp. It should not be thought that Harvey felt any personal fear. He had his revolver at command and would have used it if necessary to save his own life, but he dreaded any such an issue unspeakably.

“Professor,” said Dick in the even tone he had used from the first, “why don’t you start for Africa? You won’t have Bunk for a companion and you are gaining nothing by this delay. How long do you think you will be on the road?”

Harvey could not prevent himself from saying:

“I hope the Professor won’t try it.”

“It’s easy to prevent him, if you wish it.”

“How?”

“Which is the most vulnerable part of his helicopter?”

“I am not sure; why?”

“It strikes me that the tank will answer best for a target; I can put a bullet through that and let out all that wonderful fluid which is to furnish his motive power. I rather think the Professor will have to make a little longer delay, and in the meantime we can see that he is placed in an asylum, where he belongs.”

“What’s the use of this dilly-dallying?” suddenly broke out Dick Hamilton, whose patience was ended. “Professor, if you don’t board that machine and go back to your workshop at Purvis, I’ll bore a hole through it and then perforate you similarly. Step lively! Get a move on you!”

“I’m not through with you!” warned the aviator, still quivering with rage; “I go, but I return and will make you rue this hour!”

“By-by; I shall be ready for you whether you call by day or at night.”With two bounds the lunatic reached his machine, sprang into his seat, jerked the lever which controlled the uplifter, and began rising from the earth. As soon as he was clear of his surroundings, he sailed away at terrific speed, and it was noticeable that he headed south, which was in the direction of his Purvis workshop.