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
Medical thermometer is less of a problem with a coloured liquid. In the 1990s it was decided that mercury-based thermometers were too risky to handle; the vigorous swinging needed to "reset" a mercury maximum thermometer makes it easy to accidentally break it and spill the moderately poisonous mercury. Mercury thermometers have largely been replaced by electronic digital thermometers, or, more rarely, thermometers based on liquids other than mercury (such as galinstan, coloured alcohols and heat-sensitive liquid crystals). Phase-change thermometers use samples of inert chemicals which melt at progressively higher temperatures from 35.5 °C to 40.5 °C in steps of 0.1 °C. They