"But leaves a mystery as to his identity," put in Bud with a "mystery smile".
"No, I don't think there's any question as to his identity."
"Have you worked it out by mathematics, dad?" Cub inquired.
"Yes, by sines and cosines."
"What are sines and cosines?" asked Hal.
"You'll find out when you go to college and study trigonometry," Mr.
Perry replied.
"Oh, I've seen those words," Cub answered, with some of his alleged characteristic "highbrow eagerness". "You spell sine, s-i-n-e, and cosine, c-o-s-i-n-e."
"Exactly," smiled Mr. Perry. "Those are terms used in higher mathematics. But, in order that you youthful minds may not work too hard over my trick, I'll admit that in my mind I spelled sine s-i-g-n, and cosine, c-o-s-i-g-n."
"No use to try to get ahead of my father," Cub declared, shaking his head. "He could prove that water runs uphill by mathematics. He means the signs and cosigns indicate that—. What do they indicate, dad? We got off the question just because you wanted to carry your point with a pun."
"I meant to say that this fellow whom you cornered and chased out of the air is one of the fellows who hazed Hal's cousin by marooning him on this island," Mr. Perry answered.