Abstract: A compensator system for a stringed instrument is disclosed. The system includes a plurality of compensator blocks selectively positionable on the fretboard of a stringed instrument between its transverse projections. The compensator blocks extend upwardly in contact with the strings of the instrument. The blocks have a generally rectangular lower planar surface of a first length and first width and an upper planar surface of a second length and a second width. The width of the upper surface of the blocks is less than the width of the lower surface of the blocks thus forming tapered side walls between the upper and lower surfaces to form a trapezoidally-shaped cross-sectional configuration. The length of the lower surface of each block is essentially equal to the length of the fretboard between adjacent projections of the instrument.

Abstract: A heat exchanger having a horizontally-disposed, elongate shell with a partition extending lengthwise of the shell and interiorly thereof to form upper and lower compartments therein. The shell has end closures with at least one end closure having a flow passage communicating with the lower compartment of the shell for flow of fluid therethrough. A fluid port communicates with the upper compartment for delivering fluid thereto and passages at the edges of said upper compartment permit fluid flow from the upper compartment along the length thereof to wet the interior of the shell wall in the lower compartment. Fluid conduit means is positioned on the exterior of the shell for substantially the entire length thereof to place fluid in the conduit means in heat exchange relation with said shell wall.