"In a moment you won't see it," declared the doctor, as he adjusted the tweezers, getting a careful grip on the end of the hair. "Here it comes." Then he quickly drew it out and Nemo started a bit, but was quieted by Grody. "Young man," said the doctor, "look at this. This hair appeared to be about an inch in length, but now it is three inches long. It is not broken off, and yet it has no root. I will guarantee there is not another hair on this horse like it! I will guarantee it did not grow on this horse! I will guarantee it was what made this horse lame! And I do not want my fee if this horse shows any lameness two hours from now!" The boys were astonished, as their faces indicated. "But, doctor, I do not understand!" cried Frank. "You must explain. How could a hair----" "I will explain. It's an old trick, but one seldom tried. This hair came from the tail of a white horse. It was threaded into a long, keen needle. The fellow who got at your horse yesterday was an expert. With one jab of that needle he passed the hair through the flesh just back of this cord. It went in at one side, and came out on the other. After that, while he was pretending to look at the horse's feet, he clipped off the ends, and the hair was left in there. It could remain a day or so without doing any particular injury, but it was bound to make the horse lame as soon as he used that leg much. If it had been left there permanently it might have ruined the horse. That is all, young man." "Why was a white hair chosen, doctor?" "The fellow felt sure it would not be noticed, and yet he could quickly locate it by its color when the time came for him to cure your horse of its lameness." Once more the boys looked at each other, and this time it was plain they realized there were some things they did not know. "Doctor," said Frank, promptly, "I wish to beg your pardon. I believe I said something rather hastily, but now I wish to say that you know your business thoroughly." The doctor smiled, and closed his case. "I have been in the business all my life," he said, "but I expect to continue to learn something new about it as long as I live. I will say that I doubt if I should have seen what was the matter with your horse if you had not told me of the fellow you believed had lamed him and how the horse kicked up a racket when the man was in the stall. That set me to looking for tricks, and I found the hair." Frank offered to pay the doctor, but he refused to take it then, saying: "Here's my card, young man. If your horse is all right this afternoon you may send me five dollars. You may need me again some time." Then he strode out of the stable, flung the case under the seat, scrambled into his carriage, caught up the reins, and away he went in a hurry. "Well, may I be farred and tethered--I mean tarred and feathered!" cried Harry Rattleton. "I never saw anything like that before."