“I did it because I must have a word with you in private, and this car must be thoroughly searched before other passengers are admitted.”

“Why?” demanded the conductor. The physician’s grave manner impressed them all and they gathered nearer in silence.

“Tilghman was murdered.”

“What?” chorused the men.

“Good God! Who did it?” demanded Barclay, recovering somewhat from his astonishment, while Professor Norcross asked:

“How was the crime committed?”

“One at a time.” Shively held up a protesting hand. “It is for us to discover who is the murderer.”

“Was he stabbed, sir?” asked the conductor.

“No; nor shot.” The physician seated himself and checked his remarks off on his fingers. “On superficial examination here, I concluded that Tilghman had died from cardiac syncope; he had apparently every symptom. But it happened that last night he came to me and asked for some cocaine to deaden the pain in his tooth. Before treating him with the cocaine, I tested his heart and found he had no valvular weakness. Therefore I was astounded as well as horrified by his sudden death, and determined to make an examination.”

“An autopsy?” gasped the conductor.