Thermodynamics is an exact, macroscopic theory. One of the clearest developments of the axiomsRankine’s axioms of this science is presented by William Rankine[aut]Rankine, William (1820-1872) in his magisterial Outline of the Science of EnergeticsScience of energetics (1855). The complete natural philosophy of engineering thermodynamics is presented in this work. The deep discussion of both work and heat as processes remains the foundation of modern engineering practice. The precise relationships between measurable thermal properties are derived by Rankine. (Modern pedagogical presentations are “kindergarten” versions!) Truesdell[aut]Truesdell, Clifford (1919-2000) was proud of the work of Rankine and said so! No discussion of the history of Thermodynamics can ignore the work of Rankine.