His aim was accurate.
Had the knuckles struck the mirror a smash would have followed that must have exposed the manner in which the trick was performed.
But Frank, like a flash, thrust out his left hand and caught the flying missile, preventing the catastrophe.
"The act of a ruffian!" he said, his eyes flashing. "It is exactly what I should expect from you, Harris!"
"Arrest him!" roared the red-faced man. "Where is a policeman? He'll stay in the lock-up to-night!"
The ushers started toward Harris.
"Keep away," warned the young ruffian. "If you chaps try to touch me, you'll get hurt!"
He reached toward his hip pocket, and the ushers stopped instantly.
"Call an officer!" directed Mayor Durgin, from his box. "Don't let him get away!"