Romer to Newton

The Rømer scale was created by Danish astronomer Ole Christensen Rømer around 1701. Rømer is also famous for being the first person to measure the speed of light quantitatively in 1676, determining it by observing time variations in the eclipses of Jupiter's moon Io from different positions of Earth in its orbit.

Rømer set 0°Rø below the coldest temperature he expected in Denmark so that all practical outdoor measurements would be positive. This was a common design principle for early thermometric scales — avoiding negative values in everyday use. The 7.5 value arose from his calibration methodology using two fixed reference points and dividing the interval into 52.5 equal parts.

Normal body temperature (37°C) is approximately 22.5°Rø on the Rømer scale. Rømer himself used body temperature as one of his calibration reference points, which Fahrenheit later borrowed when constructing the Fahrenheit scale — translating Rømer's body temperature reference into his own 96°F calibration point.

Daniel Gabriel Fahrenheit visited Ole Rømer in Copenhagen in 1708 and observed his thermometers and calibration method. Fahrenheit adopted Rømer's idea of using two fixed reference points and the principle of avoiding negative temperatures in common conditions. He then redesigned the scale — multiplying Rømer's degrees by approximately 4 and shifting the zero — to achieve finer graduation and a different zero point.

Unlikely. Rømer's scale had an awkward 7.5°Rø freezing point and a 52.5-degree span — not easy to memorize or subdivide cleanly. Celsius's 0-to-100 design was simpler, aligned with the decimal metric system sweeping Europe, and gained powerful institutional backing from Swedish and French academies. Fahrenheit's scale — partly derived from Rømer's — won in the English-speaking world largely due to British imperial reach. Rømer's real legacy is indirect: inspiring Fahrenheit, who then dominated for 250 years.

Isaac Newton proposed the scale in 1701 in his paper "Scala Graduum Caloris", published anonymously in Philosophical Transactions of the Royal Society. He used a linseed oil thermometer and calibrated it against the freezing point of water and body temperature as fixed reference points.

0°N is the freezing point of water and 33°N is the boiling point of water, giving a 33-degree range. Newton also used body temperature (approximately 12°N) and "the greatest summer heat" as intermediate calibration points. These are the same two endpoints used by later scales, just with different degree spans.

Newton chose 33 because it factors neatly: 33 = 3 × 11, and one-third of 33 (11°N) corresponds approximately to body temperature in his calibration. The choice reflects his preference for divisions into thirds and twelfths, common in pre-metric scientific notation, rather than the decimal basis used by Celsius.

Newton and Celsius share the same zero (freezing water = 0), but Newton's boiling point is 33°N versus 100°C. To convert: °N = °C × 33/100 (or × 0.33). Room temperature (20°C) is 6.6°N; body temperature (37°C) is 12.21°N.

No. The Newton scale was never widely adopted and fell out of use by the mid-18th century as Fahrenheit and Celsius became dominant. It survives today only in historical accounts of thermometry and in temperature conversion tools as an educational curiosity about the origins of quantitative temperature measurement.