“You see?” said Mr. Hardy, smiling. “Your powers of observation have not been trained. A good detective has to school himself to remember all sorts of little facts like that, until it gets to be a habit with him. Both of you have been looking at Mr. Norton for about three years and you don’t know the color of his hair. And if I asked you whether he was in the habit of wearing laced shoes or buttoned shoes you would be stumped altogether. As a matter of fact, Mr. Norton is bald and he wears a chestnut wig. You never noticed that? He always wears buttoned shoes, he belongs to the Elks, and his favorite author is Dickens.”

The boys looked at their father in amazement.

“But, Dad, you’ve never met him.”