"But how about the color of his hair? There must have been two men," said Joe. "Think so? I have my own theories. But then--the average witness is very unreliable. For instance, I'll give you a test. You have each seen Superintendent Norton of Bayport high school--well, how often?" "About two or three thousand times, I guess," answered Frank. "Over a period of three years. Well, what color is his hair?" Frank looked blankly at Joe. "Why, it's--it's--" Joe scratched his head. "Brown, isn't it?" "I think it's black." "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." "I've never been introduced to him, but I've passed him on the street a number of times. When your powers of observation have been trained as mine have been it's no trick at all to take away a mental photograph of a man after seeing him once. If you are specially observant it isn't hard to notice such details as that regarding the wig. A wig never has the same appearance as natural hair." "But how do you know he belongs to the Elks?" asked Joe. "He wears the lodge emblem as a watch charm." "And how do you know his favorite author is Dickens?" "On three separate occasions that I met Mr. Norton I noticed that he was carrying a book. Once it was 'Oliver Twist.' Another time it was 'A Tale of Two Cities.' The third time it was 'David Copperfield.' So I judge that his favorite author must be Dickens. Am I right?" "He always talks Dickens to us at school," said Frank. "It's simple enough, once you get the habit," remarked Mr. Hardy. "You must train yourselves to be observant, so that in time you will automatically remember little details about people you meet and places you've visited. Now, if Harrity and Mr. Brown had been at all observant, in spite of the fact that they were surprised and frightened, they would have been able to give the police a very thorough description of the man who tried to hold up the steamboat office. And if the man happened to be a professional thief the description would have helped the officers ascertain who he was, because once a man has served a prison term his description is kept on file. As it is, all we know about him is that he is probably red-headed. That isn't very much to go on." "I'm afraid Chet hasn't much chance of recovering his roadster," said Joe.