Kathy Hood, age 13, of McAllen, .Texas, for her question:

HOW IS A CARILLON PLAYED?

A carillon is group of 23 or more cast bells that is tuned to a chromatic musical scale of more than two octaves. The carillon is hung in a fixed position in a tower and is played manually by a keyboard called a clavier or automatically by a clockwork mechanism.

The lowest tones of a carillon are produced by the largest bells, some of which weigh several tons. The highest tones are made by wells weighing as little as 10 to 20 pounds.

When the carillon is played manually, the clapper of each bell is wired to the clavier keys. The bellmaster, or carillonneur, depresses the clavier keys with a closed hand and the clapper strikes the inside of the bell.

The essential difference between a chime and a carillon, both of which are constructed in the same way, are the number of bells and the method of tuning. The chime is tuned to the diatonic scale and has fewer than 23 bells.

The art of casting bells and making large carillons was perfected in Europe between the 15th and 18th centuries, particularly in Belgium, the Netherlands and France.

The world's largest carillon is in the Rockefeller Memorial Carillon in Riverside Church, New York City. It contains 74 bells including one weighing 20.5 tons.