Swell.
1. (Music.) a. A contrivance for giving a gradually increasing and diminishing sound to a wind-instrument by varying the volume of air which passes to the pipes or reeds. This is accomplished by varying the size of the blast aperture, by a knee-stop, as in the parlor organ, or by a pedal in the church organ. b. One of the three aggregated organs which are combined in an instrument of large power. The other two are the great organ and the choir organ. The key-boards form three banks; the swell above, the great organ, the choir organ below. The swell consists of an organ shut up in a box on three sides, and on the other side inclosed by louvres, which are opened and shut by a pedal, so as to give a crescendo and diminuendo effect. The great organ has the most important and powerful stops. The choir organ has light and solo stops.
2. (Ordnance.) An enlargement of a gun near the muzzle. It is now suppressed in many forms of ordnance. 3. An enlarged or thickened portion of a gunstock.
