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
Liquid crystal thermometer and it is put onto someone's forehead it will change colour depending on the temperature of the person. There are two stages in the liquid crystals: Liquid crystal thermometers portray temperatures as colors and can be used to follow temperature changes caused by heat flow. They can be used to observe that heat flows by conduction, convection, and radiation. In medical applications, liquid crystal thermometers may be used to read body temperature by placing them against the forehead. These are safer than a mercury-in-glass thermometer, and may be advantageous in some patients, but do not always give an exact result,