NAM.1977-10-32-1

Altimeter boiler tube, 1890 (c). Used by Col Sir Sydney Burrard, Royal Engineers. Engine turned brass with three active parts. Cylindrical brass with central thickened core drilled to receive thermometer. Felt insulation round bottom for handling when hot. Upon three brackets resting on burner housing with twelve holes for ventilation round bottom. Burner fits into housing at bottom, and is unused. Wick protected by brass cap. The whole fit into two interlocking cylinders, each likewise perforated and blackened, the upper cylinder with aperture to allow insertion of thermometer. Two rubber seals with central aperture for thermometer insertion at aperture. Contained in leather carrying case, with section for third thermometer. Operates by gauging the temperature at which water boils at differing altitudes.