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
Wedgwood scale of temperature. He also determined the melting points of three metals, namely copper (27 °W or ), silver (28 °W or ) and gold (32 °W or ). All these values are at least too high. Louis-Bernard Guyton de Morveau used his pyrometer to evaluate the temperature scale of Wedgwood and came to the conclusion that the starting point should be significantly lower, at instead of , and that the steps should be nearly halved from to no more than . However, even after this revision the Wedgwood measurements overestimated the melting points of elements. Wedgwood scale The Wedgwood scale