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
Miller-Casella thermometer the ocean was always warmer than that below. Scientists aboard the HMS Challenger later questioned this assumption and made temperature measurements with reversing thermometers instead which wouldn't require the coldest water to be at the ocean's bottom. Nature article - Miller Casella thermometer Miller-Casella thermometer The Miller-Casella thermometer was a Six's thermometer with a double bulb used extensively by the "Challenger" expedition during the late nineteenth century. The thermomemeter was used for water temperature readings along 360 different research stations around the world's oceans. The thermometer, about 9 inches in length, was enclosed in a copper case and filled with