Olof Celsius Olof Celsius was made a member of the Royal Swedish Academy of Sciences in 1739. Olof Celsius Olof Celsius (the elder) (19 July 1670 – 24 June 1756) was a Swedish botanist, philologist and clergyman, He was a professor at Uppsala University, Sweden. Celsius was a mentor of the botanist and scientist Carl Linnaeus. Celsius wrote his most famous book on biblical plants, "Hierobotanicon", in 1745-47. Olof Celsius's nephew Anders Celsius was an astronomer who invented a temperature scale where 100 represented the freezing point of water and 0 represented the boiling point. Jean-Pierre Christin, in 1744 reversed the scale
International Temperature Scale of 1990 a series of International Temperature Scales adopted by CIPM since 1927. Adopted at the 1989 General Conference on Weights and Measures, it supersedes the International Practical Temperature Scale of 1968 (amended edition of 1975) and the 1976 "Provisional 0.5 K to 30 K Temperature Scale". CCT has also adopted a "mise en pratique" (practical instructions) in 2011. The lowest temperature covered by ITS–90 is 0.65 K. In 2000, the temperature scale was extended further, to 0.9 mK, by the adoption of a supplemental scale, known as the Provisional Low Temperature Scale of 2000 (PLTS-2000). CCT ITS–90 is designed to represent