Brian Robertson, age 17, of Mt. Prospect, Ill., for his question:
HOW DOES A PIPE ORGAN WORK?
More than 2,000 years ago the world's first pipe organ was built. In the mid 1900s an electronic organ was developed which many performers quickly accepted. Today, the electronic organ ranks right behind the piano and guitar as the mos widely played instrument in the United States. Both electronic and pipe organs have one or more keyboards that resemble piano keyboards.
A pipe organ actually creates its sound by forcing air through wooden or metal tubes that are called pipes. It is the largest and most powerful musical instrument of all. The music from a pipe organ can have as much grandeur and as many effects as a symphony orchestra, or it can play a simple, delicate melody in hushed tones.
A few hundred pipes are used in small organs while as many as 5,000 go into the large models. Some pipes are so big that they must be built as part of the structure where the organ is used. Most pipes are made of lead or lead mixed with tin, while others are made of other types of metal or wood.
Most organs have two types of pipes: flue pipes and reed pipes. Flue pipes work like simple whistles, where air enters from a hole in the bottom and causes the column of air inside the pipe to vibrate. The vibration creates the sound. A reed pipe has within it a small, thin brass reed that vibrates as air passes around it.
About 80 percent of all the organ's pipes are shaped like cylinders and no two of them sound exactly alike. The size and shape of the pipes determine the sounds they make. Lowest notes come from a pipe that may be more than 30 feet high and one foot in diameter.
Smallest pipe on an organ, from which the highest notes originate, is about seven inches long and a quarter of an inch in diameter. Most pipes measure less than four feet long.
A pipe organ can have as many as six keyboards which are called manuals. Most also have a pedalboard, a keyboard which the organist plays with his feet. Each keyboard operates a number of rows of pipes, with all being arranged on a box called a wind chest. Each wind chest receives a steady flow of air which comes from a reservoir.
A thin strip of wood or plastic called a slider lies under each rank of pipes on a wind chest, and it regulates the passage of air into the pipes.
A pipe organ's sliders are controlled by knobs near the manuals called stops. By pulling on a stop, the organist can move the slider into position under the pipes so that just the right amount of air can enter.
A valve called a pallet in the wind chest allows air to flow into a compartment called the key channel. Wind actually enters the pipes from the key channel.