POLO BALLS.—Polo or Roller Polo (on roller skates) is played with a very hard rubber-covered ball, painted bright red and about the size of a baseball—9 inches in circumference. Cost, from ten cents to $1 each.
Equestrian Polo is played with a wooden ball, usually of willow, having no other covering than white paint. The Polo Association of America specifies such a ball 3-1/8 inches in diameter and not to exceed 5 ounces in weight. The English rules (Hurlingham) call for a slightly larger and heavier ball, 3-1/4 inches in diameter and 5-1/2 ounces in weight—material not specified. Willow balls cost $2 per dozen; others, $1.25 per dozen.
Water Polo is played with a ball of white rubber, inflated through a key afterward used to screw shut the opening. The official American rules for Water Polo call for a white rubber ball of not less than 7 nor more than 8 inches in diameter. Cost, $2 each.
PUSHBALL.—The game of Pushball is played with the largest ball ever constructed for any game. The ball measures 6 feet in diameter, and consists of an inflated rubber bladder inserted in a leather cover. Cost, $200 each.
RUGBY BALL.—See Football.
SOCCER BALL.—See Football.
SQUASH BALL.—For the game of Squash, a hollow rubber ball is used similar to a tennis ball, and about the same size. It measures 8 inches in circumference, and is covered with felt, black, red, or white; some have an overspun cover knitted on the ball in green or white. Cost, $6 per dozen. Enameled rubber squash balls in black or gray may be had at twenty cents each.
TENNIS BALL.—Tennis balls are of rubber, hollow, and are covered with white felt. The official specifications call for a ball measuring not less than 2-1/2 nor more than 2-9/16 inches in diameter, of weight not less than 1-15/16 nor more than 2 ounces. Tennis balls cost about $4 per dozen.
VOLLEY BALL.—Volley balls are quite similar to basket balls, but slightly smaller and lighter. They are suitable for games in which the ball is batted with the open hand or fist and where it is to be kept continuously in the air, such as the game of Volley Ball. The ball consists of a rubber bladder inclosed in a laced leather cover of white. The official specifications call for a ball not less than 25 nor more than 27 inches in circumference, of weight not less than 9 ounces nor more than 12 ounces. Volley balls cost from $2.50 to $4 each.