The Evolution of Useful ThingsBy: Henry Petroski How did the table fork acquire a fourth tine? What advantage does the Phillips head screw have over its single grooved predecessor? Why does the paper clip look the way it does? What makes Scotch tape Scotch? In this delightful book Henry, Petroski takes a microscopic look at artifacts that most of us count on but rarely contemplate, including such icons of the everyday as pins, Post its, and fast food "clamshell" containers. At the