A pipe which produces its sound by the action of air against the edge of the pipe mouth in combination with the resonance of a column of air within an open or closed pipe. One of three basic families of pipes: 1. Flue, as just described. 2. Reed pipes, which produce sound by the vibrations of a free or beating reed. 3. Diaphone pipes (rarely used), which produce sound by intermittent bursts of air introduced into the pipe. The flue pipe family encompasses many different popular types of pipes, including various flute, diapason, and violin varieties. Flue pipes, unlike reed pipes, require a minimum of attention and care and will stay in tune for relatively long periods of time at a given temperature. For this reason flue pipes (usually violin and flute) were the main types used in smaller styles of coin pianos and orchestrions.