This was enough to make Nick certain that no serious harm had come to him, but he was instantly made aware of it in another way.
Cautiously Chick lifted an eyelid. A less acute observer than Nick would not have seen the movement.
The eye opened wide, and then it winked. Chick was all right.
"Shall I cut this rope?" asked Nick.
Chick spoke straight through the gag with very little trouble.
"It isn't necessary," he said. "I can get loose at any moment. Dr. Jarvis is not an expert at tying knots, though there are some other things that he understands pretty well."
"How did this happen?"
"It was a clever trick," said Chick. "He threw some kind of a drug into my face. If I hadn't known—thanks to your teaching long ago—just what to do in a case of that kind, I should have gone to sleep in a second.
"As it was, the drug made my head swim. But I kept it out of my lungs, and pulled through.
"Of course, I pretended to be unconscious, for I wanted to see what he would do. He tied me up rather clumsily; gagged me exceedingly well; and laid me on this slab, after removing a headless body.