ABSTRACT
From the eighteenth century onward the efficiency of steam-engines was measured by the work they could do per given weight—usually a bushel—of coal burned. The establishment, within a few years after 1850, of the science of thermodynamics on the basis of the dynamical theory of heat through the geniuses of Joule, Rankine, Clausius and Thomson, marked a dramatic reversal in the comparative states of science and technology. The point about thermodynamics, and particularly Rankine's thermodynamics, is that it cleared the way ahead for designers of engines, particularly marine engines. In the 1850s the steam-engine was therefore the only feasible way of approaching the thermodynamic conditions for maximum efficiency. The acceptance of the principles of thermodynamics meant therefore new techniques in engine design, new standards of efficiency and new and exact measurements of the various significant processes in the steam-engine.
