"I will ask Professor Grimm to smell of that," Jack continued, thrusting the rag under the teacher's nose.
"Arnica!" exclaimed the instructor. "The same that you used, and which enabled me to discover it was you who played the trick."
"It is arnica," Jack admitted, "but it happens I was not the only one who used it that night. I have also to show this article, which was picked up in your room, Professor Grimm," and Jack extended the spark plug Budge had given him.
"Ha! What is that?" asked Mr. Grimm.
"It is some part of an automobile," Dr. Mead said. "Who, of our students, has one. Ah! I begin to see," he added.
"Adrian Bagot, I will return your duster to you," Jack went on, walking forward and passing the rust-stained automobile garment to young Bagot. "I had to borrow it from your room, but I am through with it now. You may also have your spark plug, and this rag I had to take from your wrist rather unceremoniously last night."
"You're a thief!" burst out Adrian, but Jack stopped him with a gesture.
"I'll not take that from you or any one else," exclaimed Jack. "Dr.
Mead," he went on, "I ask that you inquire of my friends, Sam
Chalmers, Dick Balmore and Fred Kaler when they last saw Adrian in
his auto."
"When did you?" Dr. Mead asked the boys.
"The night the bell was stolen," answered Sam, and the others agreed with his testimony. Jack told the story of the collision and how his ankle was injured.