Rømer is a disused temperature scale named after the Danish astronomer Ole Christensen Rømer, who proposed it in 1701.
In this scale, the zero was initially set using freezing brine. The boiling point of water was defined as 60 degrees. Rømer then saw that the freezing point of water fell at roughly one eighth of that value (7.5 degrees), so he used that value as the other fixed point. Thus the unit of this scale, a degree Rømer, is 40/21sts of a kelvin (or of a degree Celsius). The symbol is sometimes given as °R, but since that is also sometimes used for the Rankine scale, the other symbol °Rø is to be preferred. The name should not be confused with Réaumur.
Daniel Gabriel Fahrenheit learned of Rømer's work and visited him in 1708; he improved on the scale, increasing the number of divisions by a factor of eight and eventually establishing what is now known as the Fahrenheit scale, in 1724.
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