"Help!" shouted Oliver, encouraged by what he heard.
"What is the matter?" demanded a voice outside. "Father, what are you doing?"
The old man looked disgusted and mortified.
"It's a lie!" said Oliver, in a loud voice. "I am a boy who has been lured in here by this old man, who wants to murder me."
"Open the door at once, father," said the voice outside sternly.
The old man was apparently overawed and afraid to refuse. He advanced sullenly and turned the key. The door was at once opened from outside.
A man in middle life entered. He took in the situation at a glance.
"You are at your tricks again, sir," he said sternly to the old man. "Put down that knife."
"Don't be harsh, Samuel," he said, in an apologetic tone. "You know that I am working in the interests of science."
"Don't try to impose on me with such nonsense. What were you going to do with that boy?"
"You were going to murder him, and the law would have exacted the penalty had I not interfered."
"I would have submitted, if I could have only demonstrated the great principle which----"
"The great humbug! Promise me that you will never again attempt any such folly, or I shall be compelled to send you back to the hospital."
"Don't send me there, Samuel!" said the old man, shuddering.
"Then take care you do not make it necessary. Young man, come with me."
It may be imagined that Oliver gladly accepted the invitation.
He followed his guide downstairs, and into the parlor, which was very handsomely furnished.
"I am very much mortified at the imposition that has been practised upon you, and alarmed at the thought of what might have happened but for my accidental presence at home. Of course you can see for yourself that my father is insane."
"Yes, sir, I can see it now; but I did not suspect it when we first met."
"I suppose not. In fact, he is not generally insane. He is rather a monomaniac."
"It seems a dangerous kind of monomania."
"You are right; it is. Unless I can control him at home, I must send him back to the hospital. He has been an eminent physician, and until two years ago was in active practice. His delusion is connected with his profession, and is therefore less likely to be cured. I am surprised that you accepted a stranger's invitation to dine."