 For most of the twentieth century, Jack Purcell's tennis sneaker was required wear on all grass and clay tennis courts in the United States and, at least for a time, on newer, all-weather asphalt courts as well.Unlike basketball sneakers (running shoes hadn't been invented yet), Jack Purcell sneakers had perfectly flat soles, unmarred by grooves that could tear up clay or grass and skew the elasticity of tennis ball bounces.Everyone from the youngest learner to professional and amateur tennis stars on the international tour wore Purcell sneakers; no other company made them.