Kelvin Celsius, which has the same magnitude. The definition implies that absolute zero (0 K) is equivalent to . In 1848, William Thomson, who later was made Lord Kelvin, wrote in his paper, "On an Absolute Thermometric Scale", of the need for a scale whereby "infinite cold" (absolute zero) was the scale's null point, and which used the degree Celsius for its unit increment. Kelvin calculated that absolute zero was equivalent to −273 °C on the air thermometers of the time. This absolute scale is known today as the Kelvin thermodynamic temperature scale. Kelvin's value of "−273" was the negative reciprocal
Réaumur scale Réaumur scale The Réaumur scale (; °Ré, °Re, °r), also known as the "octogesimal division", is a temperature scale for which the freezing and boiling points of water are defined as 0 and 80 degrees respectively. The scale is named for René Antoine Ferchault de Réaumur, who first proposed a similar scale in 1730. Réaumur’s thermometer contained diluted alcohol (ethanol) and was constructed on the principle of using 0° for the freezing temperature of water, and graduating the tube into degrees, each of which was one-thousandth of the volume contained by the bulb and tube up to the zero mark.