A medical thermometer (also called clinical thermometer) is a device which 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), into the rectum via the anus (rectal temperature), into the ear (tympanic temperature), or on the forehead (temporal temperature). History 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 and could be affected by changes in atmospheric pressure. Italian physician Santorio Santorio is the first known individual to have put a measurable scale on the thermoscope and wrote of it in 1625, though he possibly invented one as early as 1612. His models were bulky, impractical and took a fair amount of time to take an accurate oral reading of the patient's temperature. Two individuals switched from water to alcohol in the thermometer. The earliest is Ferdinando II de' Medici, Grand Duke of Tuscany (1610–1670), who created an enclosed thermometer that used alcohol circa 1654. Daniel Gabriel Fahrenheit (1686–1736), a Polish-born Dutch physicist, engineer, and glass blower, made contributions to thermometers as well. He created an alcohol thermometer in 1709 and later innovated the mercury thermometer in 1714. Mercury, he found, responded more quickly to temperature changes than the previously used water. Fahrenheit also created the temperature scale which is named after him, having recorded the system in 1724. The scale is still only mainly used for everyday applications in the United States, its territories and associated states (all served by the U.S. National Weather Service) as well as the Bahamas, Belize, and the Cayman Islands. Prominent Dutch mathematician, astronomer and physicist Christiaan Huygens created a clinical thermometer in 1665, to which he added an early form of the Celsius scale by setting the scale to the freezing and boiling points of water. By 1742 Swedish astronomer Anders Celsius created the Celsius temperature scale that was the reverse of the modern scale, in that 0 was the boiling point of water, while 100 was freezing. It was later reversed by Swedish botanist Carolus Linnaeus (1707–1778) in 1744. Working independently of Celsius, the Lyonnais physicist Jean-Pierre Christin, permanent secretary of the Académie des sciences, belles-lettres et arts de LyonFR, developed a similar scale in which 0 represented the freezing