Thermometer

An instrument used to measure temperature. A traditional clinical thermometer consists of a glass capillary tube (a tube with a very fine bore) that is sealed at one end and has a mercury-filled bulb at the other. Modern versions of the clinical thermometer include an electronic probe connected to a digital display, and an aural thermometer, which measures the temperature of the eardrum. Both versions give an almost instant reading. There are also disposable skin thermometers that employ heat-sensitive chemicals, which change colour at specific temperatures. These are not as reliable, however. Clinical thermometers may be calibrated in degrees Celsius (centigrade), degrees Fahrenheit, or sometimes both.