Mercury-in-glass thermometer ushered in a new era of accuracy and precision in thermometry, and is still to this day regarded as one of the most accurate thermometers available. The thermometer was used by the originators of the Fahrenheit and Celsius scales. Anders Celsius, a Swedish scientist, devised the Celsius scale, which was described in his publication "The origin of the Celsius temperature scale" in 1742. Celsius used two fixed points in his scale: the temperature of melting ice and the temperature of boiling water. This wasn't a new idea, since Isaac Newton was already working on something similar. The distinction of Celsius
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