Comprising of a blackened hollow hemisphere about 20cm diameter, fitted on a wooden board lines with tin, and a steam chamber above the hemisphere to measure them an uniform temperature by passing steam through it recorded by two thermometers. Heavy silver disc soldered a bottom to copper - Constantan thermocouple housed in ebonite tube with lid, ebonite tube engraved with disc constants, mass and area. Complete supplied with one extra similar thermocouple for calibration. For determination of stefan’s radiation Constant.