Medical thermometer (1836–1925) designed a medical thermometer that was much more portable, measuring only six inches long and taking only five minutes to record a patient's temperature. In 1868, German physician, pioneer psychiatrist, and medical professor Carl Reinhold August Wunderlich published his studies that consisted of over one million readings from twenty-five thousand patients' temperatures, taken in the underarm. With his findings, he was able to conclude a healthy human's temperature fell within the range of 36.3 to 37.5 °C (97.34 to 99.5 °F). Dr. Theodor H. Benzinger (13 April 1905 - 26 Oct 1999) invented the ear thermometer in 1964. Born
Thermometer required the user to leave the thermometer in the hot liquid until after reading it. If the non-registering thermometer was removed from the hot liquid, then the temperature indicated on the thermometer would immediately begin changing to reflect the temperature of its new conditions (in this case, the air temperature). Registering thermometers are designed to hold the temperature indefinitely, so that the thermometer can be removed and read at a later time or in a more convenient place. Mechanical registering thermometers hold either the highest or lowest temperature recorded, until manually re-set, e.g., by shaking down a mercury-in-glass thermometer, or