James LaFarge, age 13, of Marion, Ohio, for his question:
HOW MANY PIPES ARE IN A PIPE ORGAN?
A pipe organ is a musical instrument that creates sounds by forcing air through metal or wooden tubes called pipes. Pipe organs vary in size. A small pipe organ has only a few hundred pipes but a large one can have more than 5,000 pipes.
Largest and most powerful of all musical instruments is the pipe organ. Many are so large that they must be built as part of the building where they are to be used. A large pipe organ can produce effects of grandeur that some symphony orchestras cannot duplicate. It can also play delicate and refined music.
The pipe organ can be traced back more than 2,000 years. Most today are found in churches, concert halls and theaters.
Most pipes used in organs are made of lead or of lead mixed with tin. Some, however, are made of other metals or wood.
An organist creates music by combining the sounds of different ranks or rows of individual pipes. Each pipe in a rank is tuned to a single pitch and produces only one musical tone. Some ranks are pitched one or two octaves higher or lower than others.
Most organs have two types of pipes: flue pipes and reed pipes. Flue pipes work like simple whistles. Air enters from holes in the bottoms of the pipes and causes columns of air inside the pipes to vibrate. The vibrations create the sounds. Reed pipes contain thin brass reeds that vibrate as air passes around them.
About 80 percent of the pipes in an organ are shaped like cylinders. But no two pipes of an organ look or sound exactly alike. The shape and size of the pipe determines the sound it makes.
The longest pipes, which produce the lowest notes, may be mroe than 30 feet long and 1 foot in diameter. But most pipes measure less than 4 feet long. The smallest pipes, which produce the highest notes, are only 7 inches long and less than a quarter of an inch in diameter.
Most pipe organs have one, two or three keyboards. A few of the very large ones have as many as six. The additional keyboards enable the organist to create a wider variety of musical effects than would be possible with a single keyboard.
The keyboards played with the hands are called manuals. Most organs also have a pedalboard, a keyboard that the organist plays with his feet. Each manual and pedal board operates a number of ranks. Every key, in turn, controls several pipes.
All ranks operated by a keyboard are arranged on a box called a wind chest. Each wind chest receives an even flow of wind or air from a reservoir. An electrically powered fan fills the reservoir with wind.
A thin plastic or wood strip called a slider regulates the passage of wind into the pipes. Sliders are controlled by stop knobs, commonly called stops, near the manuals.
To let wind into certain pipes, the organist presses the key that controls these pipes. This action opens a valve called a pallet in the wind.chest and allows wind to flow into a compartment called the key channel. Wind enters the pipes from the key channel.