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
Temperature it is often convenient to use the Celsius scale, in which corresponds very closely to the freezing point of water and is its boiling point at sea level. Because liquid droplets commonly exist in clouds at sub-zero temperatures, is better defined as the melting point of ice. In this scale a temperature difference of 1 degree Celsius is the same as a increment, but the scale is offset by the temperature at which ice melts (). By international agreement the Kelvin and Celsius scales are defined by two fixing points: absolute zero and the triple point of Vienna Standard Mean