The first known document reporting temperatures in this modern â forwardâ Celsius scale is the paper Hortus Upsaliensis dated 16 December 1745 that Linnaeus wrote to a student of his , Samuel NauclÃ r. In it , Linnaeus told the temperatures inside the orangery at the Botanical Garden of Uppsala University : The first known document reporting temperatures in this modern `` forward '' Celsius scale is the paper Hortus Upsaliensis dated 16 December 1745 that Linnaeus wrote to a student of his , Samuel NauclÃ r. In it , Linnaeus recounted the temperatures inside the orangery at the Botanical Garden of Uppsala University :