black bulb thermometer
Date: 1890-1910
Inventory Number: 1998-1-1261
Classification: Thermometer
Subject:
Maker: Henry J. Green (fl. 1885 - 1910)
User: Oak Ridge Station (1931 - 2005)
User: George R. Agassiz Station, Harvard (1951 - 1982)
User: Harvard College Observatory (founded 1839)
Cultural Region:
Place of Origin:
City of Use:
Dimensions:
5 x 43.8 x 5 cm (1 15/16 x 17 1/4 x 1 15/16 in.)
Description:
A thermometer consisting of a thin glass tube with a capillary that has a scale. Its mercury bulb is painted completely black and is in the shape of a sphere at the end of a cylindrical stem. The whole thermometer is kept inside a clear glass vessel with a large spherical bulb surrounding the thermometer's mercury bulb such that it is exactly at its center.
Signedon stem opposite scale, script: H. J. Green, Brooklyn, N.Y. 7017
FunctionThis is a thermometer for determining the amount of heat radiation (infrared light) in the environment at a certain moment. Its mercury bulb is isolated from contact with the ambient temperature by an evacuated glass vessel, and it is painted completely black so it will absorb the maximum possible heat radiation.
Heat radiation is an important meteorological reading as an indication of cloudiness and contributes to the subjective perception of ambient temperature in addition to the temperature of air.
Heat radiation is an important meteorological reading as an indication of cloudiness and contributes to the subjective perception of ambient temperature in addition to the temperature of air.
ProvenanceTransferred to CHSI, From the Agassiz Station, Harvard College Observatory, Harvard, Mass.