In this paper, we present a brief history of the development of mechanics and mechanical machines theory (particularly in Lazare Carnot) and consequently the birth and advanced studies in thermodynamics and heat machines (particularly in Sadi Carnot) that influenced science & technology (as technoscience) in Western society between the eighteenth and nineteenth centuries. We focus on theoretical aspects of thermodynamics efficiency—for improvements of practical studies from cannons to civil steam engines. Considerations on mechanical and thermodynamic machines and correlated topics like the role played by the impossibility of perpetual motion in mechanical and heat machines are discussed.