In which class and book the reaumur temperature scale is explained?

Réaumur temperature scale, scale established in 1730 by the French naturalistRené-Antoine Ferchault de Réaumur(1683–1757), with its zero set at the freezing point of water and its 80° mark at the boiling point of water at normal atmospheric pressure. Use of the Réaumur scale was once widespread, but by the late 19th century it had been supplanted by other systems.
conversion:-[°C]=[°Ré]×5⁄4
t [°F]=[°Ré]×9⁄4+32

i think this knowledge is enough