Instrument for measuring relatively high temperatures, as in furnaces. Most pyrometers work by measuring radiation from the body whose temperature is to be measured (radiation devices have the advantage of not having to touch the material being measured). Optical pyrometers measure the temperature of glowing bodies by comparing them visually with an incandescent filament of known temperature whose temperature can be adjusted. In resistance pyrometers, a fine wire is put in contact with the object; the instrument converts the change in electrical resistance caused by heat to a reading of the temperature of the object.
Learn more about pyrometer with a free trial on Britannica.com.
Pyrometer is any non-contacting device that intercepts and measures thermal radiation. This measure is used to determine temperature, often of the object's surface.
The word pyrometer comes from the Greek word for fire, "πυρ", and meter, meaning to measure. Pyrometer was originally coined to denote a device capable of measuring temperatures of objects above incandescence (i.e. objects bright to the human eye).