The Odon Calliope is a Cozatt "Air Organ" built in Danville, IL in the late 1970's. A company brochure can be found on the web from their early days with information about their products. Here is a link to a brochure that I downloaded: Cozatt Calliope Info .
Odon has been visited by another calliope from Rose Hulman -- it is a Tangley model. It is now back in Terre Haute in storage at the Institute.
Both models have the same basic parts: A blower providing a low-pressure air source into a wind chest. From the wind chest, there are 43 valves -- each valve is activated when a corresponding key (or note) is pressed on the keyboard. The valve allows air to travel from the wind chest through a host to the base of a pipe.
Air passing across the opening resonates at a frequency determined by the length of the pipe. Each pipe length is 'tuned' to a corresponding note on the keyboard -- exactly like a string on a piano.
Lower bass notes correspond to longer pipes which are also larger in diameter. The larger diameter is needed because of the size of the sound wave that is produced. Smaller pipes are required for higher notes.
There is a complex relationship between air pressure, length of pipe, size of the opening and diameter of the pipe. The reader can use google to learn more about this from various articles posted on the internet.
Calliopes have been built out of various materials. PVC pipe is popular among hobbyists because it is cheap and easy to work with. One design that you might find interesting is one that I proposed here: PVC calliope .
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