Alcohol thermometer to give a background for reading the scale. The range of usefulness of the thermometer is set by the boiling point of the liquid used. In the case of the ethanol-filled thermometer, the upper limit for measurement is 78 °C (172.4 °F), which makes it useful for measuring daytime, nighttime and body temperatures, although not for anything much hotter than these. Ethanol-filled thermometers are used in preference to mercury for meteorological measurements of minimum temperatures and can be used down to −70 °C (-94 °F). The physical limitation of the ability of a thermometer to measure low temperature is the
Medical thermometer is placed properly. Allbutt, T.C., “Medical Thermometry”, "British and Foreign Medico-Chirurgical Review", Vol.45, No.90, (April 1870), pp.429-441; Vo.46, No.91, (July 1870), pp.144-156. Medical thermometer A medical thermometer (also called clinical thermometer) is used for measuring human or animal body temperature. The tip of the thermometer is inserted into the mouth under the tongue ("oral" or "sub-lingual temperature"), under the armpit ("axillary temperature"), or into the rectum via the anus ("rectal temperature"). The medical thermometer began as an instrument more appropriately called a water thermoscope, constructed by Galileo Galilei circa 1592–1593. It lacked an accurate scale with which to measure temperature