racquets, game played by two or four persons on a court 60 by 30 ft (18.3 m by 9.1 m); it is surrounded by three walls 30 ft (9.1 m) high and a backwall 15 ft (4.6 m) high. The ball, 1 in. (2.54 cm) in diameter, is made of polyethylene with an adhesive tape cover. The gut-strung racket is 30 in. (76.2 cm) long, has a circular head about 8 in. (20 cm) in diameter, and weighs 8 to 10 oz (about .25 kg). A service line is painted horizontally across the front wall a little over 9.5 ft (2.9 m) from the ground, and a short-line is painted 36 ft (11 m) from, and parallel to, the front wall. A line also extends from the center point of the short-line into two service courts. The rules of the game are similar to those of squash racquets. The hardness and speed of the ball makes racquets one of the fastest and most dangerous games. It originated in 18th-century England, probably in debtors' prisons, but was soon adopted by the wealthier classes. Expensive racquets courts were built in England, and racquets was introduced into the United States in the 19th cent. by way of Canada. The United States Racquets Association annually conducts national championship matches. The sport's popularity is limited to the NE United States and certain areas of Great Britain.