The Rømer scale (Danish pronunciation: [ˈʁœˀmɐ]; notated as °Rø), also known as Romer or Roemer, is a temperature scale named after the Danish astronomer Ole Christensen Rømer, who developed it for his own use in around 1702.
[1]: 365 There is no solid evidence as to why Rømer assigned the value of 7.5 degrees to water's freezing point.
This did not greatly change the scale but made it easier to calibrate by defining it by reference to pure water.
These documents demonstrate the important influence Rømer's work had on Fahrenheit, a young maker and seller of barometers and thermometers.
Rømer also told Fahrenheit that demand for accurate thermometers was high.