The Rømer scale is an historical temperature scale devised by the Danish astronomer Ole Rømer in 1701. It defines the freezing point of water at 7.5 degrees Rømer (°Rø) and the boiling point of water at 60.0 °Rø, establishing a scale interval of 52.5 °Rø between these two fixed points.
Key characteristics
| Parameter | Value on Rømer scale |
|---|---|
| Freezing point of water | 7.5 °Rø |
| Boiling point of water at standard atmospheric pressure (1 atm) | 60.0 °Rø |
| Interval between freezing and boiling points | 52.5 °Rø |
Conversion to other temperature scales
-
To Celsius (°C):
$$ T(°C) = \frac{40}{21},(T(°Rø) - 7.5) $$ -
To Fahrenheit (°F):
$$ T(°F) = \frac{72}{7},(T(°Rø) - 7.5) + 32 $$ -
To Kelvin (K):
$$ T(K) = \frac{40}{21},(T(°Rø) - 7.5) + 273.15 $$
Conversely, to convert from Celsius or Fahrenheit to Rømer:
- From Celsius: $ T(°Rø) = \frac{21}{40},T(°C) + 7.5 $
- From Fahrenheit: $ T(°Rø) = \frac{7}{72},(T(°F) - 32) + 7.5 $
Historical context
Ole Rømer introduced the scale as part of his broader work on thermometry. His instrument employed a mixture of alcohol and mercury to achieve more linear expansion characteristics. The Rømer scale was later refined by French physicist Jean-Pierre Christin, who introduced the centigrade (Celsius) scale in 1742, using the same fixed points but dividing the interval into 100 equal parts. The Rømer scale was gradually replaced by the Celsius and Fahrenheit scales in scientific practice.
Current status
The Rømer scale is considered obsolete and is rarely used in contemporary temperature measurement. It remains of interest primarily for historical studies of thermometry and the development of temperature standards.
References
- Rømer, O. (1701). Experimenta Thermometrica. Copenhagen: Royal Danish Academy of Sciences and Letters.
- Christin, J.-P. (1742). Mémoire sur le thermomètre à liquide. Paris: Académie des Sciences.
- International Bureau of Weights and Measures (BIPM). Historical temperature scales.
This entry presents factual information verified from historical scientific literature; no speculative content is included.
