Christine Velis, age 13, of Salt Lake City, Utah, for her question:

HOW ARE PING PONG BALLS MADE?

A special machine is used to make the feather light balls we use to play Ping Pong, or table tennis. Made of thin celluloid, the ball measures between four and a half inches to four and three quarters of an inch in circumference and weighs just one tenth of an ounce. The balls are first made in halves but are sealed into the round shape by a special machine.

A British firm registered the table tennis name of Ping Pong in America in 1901 and soon after sold the rights to Parker Brothers. An international organization of players in 1921 adopted the unpatented name Table Tennis as the official name of the game.

The game was first called miniature lawn tennis when it was originated in 1884. Cork balls were first used; celluloid balls were introduced in 1890.