RÉAUMUR, (RENÉ-ANTOINE FERCHAULT DE). - THE RÉAUMUR TEMPERATURE SCALE.

Regles pour construire des Thermometres dont les Degres soient comparables, et qui donnent des idées d'un Chaud ou d'un Froid qui puissant être rapportés à desmsures connües.

Paris, L'Imprimerie Royale, 1732. 4to. Without wrappers. Extracted from "Mémoires de l'Academie des Sciences. Année 1730". Pp. 452-507 a. 1 folded engraved plate. With titlepage to Année 1730/1732. Titlepage with small tears to margins. Clean and fine.

First appearance of this importent paper in which Reaumur reveled how he constructed his invention of the thermometer scale, the scale which bears his name. The construction of the thermometer was based on alchohol, and the scaling bases on 0 degree for the freezing point of water and 80 degree for the boiling point of water.

"The one serious drawback to Réaumur’s thermometer was that different strengths of alcohol have different coefficients of dilation, so that while one type of alcohol might expand one degree after the application of a certain amount of heat, another might expand two degrees under the same conditions. It was vital that all thermometers scaled according to his system have the same grade of alcohol. Réaumur suggested that the alcohol used in his thermometers be of a type that would dilate 80 degrees - that is, 8 parts in 100 - between the temperature of ice and the temperature at which the alcohol began to boil in an open thermometer tube. Owing to an unfortunate confusion of language in his article on the thermometer, however, nearly everyone believed that 80° on his scale was the temperature of boiling water; and as a result, when so-called Reaumer thermometers began to be made by the artisans of Paris, they were nearly all scaled linearly with respect to two fiducial points, 0° for ice and 80° for boiling water." (DSB).

Parkinson "Breakthroughs" 1730 P.

Order-nr.: 46579