The Probert Encyclopaedia of Recreation

POLO

Polo is a four-a-side game with players mounted on horses who use wooden mallets to strike a wooden ball in an attempt to score goals. The ball is struck with the side of the mallet, and horses of any size may be used. The full sized ground is 300 yards long and 200 yards wide if unboarded and 160 yards wide if boarded. The boards on the side are nine inches high and designed to keep the ball in play.
Research Polo