Bill Potts wrote in USMA 24400:
Centigrade was an naming anomaly, based on the division of an arbitrary range into hundredths. The other scale, Fahrenheit, was, like so many other units, based on the name of a scientist. As the "Centigrade" scale was developed by Anders Celsius, his name was chosen (from three in common use -- Centigrade, Celsius and Centesimal) as the definitive one to clarify which particular degree was being expressed. Because it isn't itself a unit (but a qualifier of another unit, the degree), it retains the initial capital letter.
Permit me to split a hair. Anders Celsius of Uppsala, Sweden, proposed in 1736 a temperature scale of 100 degrees between the freezing and the boiling points, but he put 0� at the boiling point and 100� at the freezing point. Our �C should more correctly be described as "degree Crispin". The centigrade temperature scale with the freezing point at 0� and the boiling point at 100� was proposed in 1743 by Jean-Pierre Crispin of the *Acad�mie des Beaux-Arts* of Lyon. -- Joseph B. Reid 17 Glebe Road West Toronto M5P 1C8 Telephone 416-486-6071
