Réaumur scale

Instrument-makers generally chose different liquids, and then used 80 °Ré to signify the boiling point of water, causing much confusion.

He found that thermometers made using mercury allowed the closest fit to his expectation of linearity.

[4] The Réaumur scale was used widely in Europe, particularly in France, Germany and Russia, and was referenced in the works of Thomas Jefferson, Thomas Mann, Fyodor Dostoevsky, Gustave Flaubert, James Joyce, Leo Tolstoy, and Vladimir Nabokov.

[5][6][7][8] For example, in Query VII of Notes on the State of Virginia, Jefferson converts readings from the Fahrenheit thermometer at Williamsburg to the Réaumur scale.

At the beginning of Book X of The Brothers Karamazov, the narrator says, "We had eleven degrees of frost", i.e. −11 °Ré, equivalent to −14 °C or 7 °F.

Its main modern uses are in some Italian and Swiss factories for measuring milk temperature during cheese production,[11] and in the Netherlands for measuring temperature when cooking sugar syrup [citation needed] for desserts and sweets.

Uses outside of Europe include a Mexican colonel in Santa Anna's army in San Antonio, Texas in 1836 recording the night's temperature as 34 °F and 1 °Ré.