In USMA 24398 Carl Sorenson wrote in reply to Matthew Zotter:
Where did Centigrade come from? Why was it changed to Celsius?
I don't really have sources for this, but this is what I assume. Centigrade
was defined in terms of the freezing and boiling points of water. Celsius
is (at least currently) defined in terms of Kelvin (which uses the triple
point). Thus, Celsius is tied to SI and centigrade is not, if this is
correct. In practical terms the difference negligible, but Celsius is the
term to use.
The centigrade scale was officially renamed Celsius by the 9th
*Conf�rence G�n�rale des Poids et Mesures* in 1948. The two terms
are completely equivalent although the definition of the scale was
modified by the CPGM in 1954.
I remember I found in Germany in 1935 that the scale was referred to
as Celsius.
The term "centigrade" describes the temperature scale, as distinct
from Fahrenheit. However centigrade also refers to an angular scale
with 100 division in a right angle. Celsius was the first to propose
a temperature scale with 100 degrees between freezing and boiling.
However,he proposed zero for the boiling point and 100 for the
freezing point. Almost contemporaneously Christin of Lyon proposed
zero for the freezing point and 100 for the boiling point. It would
be more correct to refer to "degrees Christin".
--
Joseph B. Reid
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