CHAPTER I In Which Zip Is Introduced to the Reader   Zip belongs to Dr. Elsworth, who lives in the big, white house with the green blinds on the edge of the village of Maplewood. And at the present minute he is asleep on the front porch on a soft cushion in an old-fashioned rocking-chair that is swaying gently to and fro, dreaming of the days when he was a puppy chasing the white spot on the end of his tail, thinking it was something... more...