IT is within my memory that Melville Clarendon, a lad of sixteen years, was riding through Southern Minnesota, in company with his sister Dorothy, a sweet little miss not quite half his own age. They were mounted on Saladin, a high-spirited, fleet, and good-tempered pony of coal-black color. Melville, who claimed the steed as his own special property, had given him his Arabian name because he fancied there were many points of resemblance between him and the winged coursers of the East, made famous as long ago as the time of the Crusades.