Figure 2.

Timeline comparing use of the Calorie (kg basis or kcal), g-cal, kcal and joule. MKS, m-kg-s system of units; CGS, cm-g-s system of units. First known usage of the Calorie in German was by Mayer in 1845 [29]. First known occurrence in English was when Adolphe Ganot's physics text [6] was translated in 1863.