Clausius and Lord Kelvin on the basis of "Carnot's principle" (1824), modified in expression so as to be consistent with the conservation of energy (see Energetics).
The object of the present article is to illustrate the practical application of the two general principles - (I) Joule's law of the equivalence of heat and work, and (2) Carnot's principle, that the efficiency of a reversible engine depends only on the temperatures between which it works; these principles are commonly known as the first and second laws of thermodynamics.
Application of Carnot's Principle.
It simply asserts that the efficiency function F'(t), which is known as Carnot's function, is the same for all substances at the same temperature.
Joule (1845) was the first to prove it approximately by direct experiment, but did not see his way to reconcile Carnot's principle, as stated by Clapeyron, with the mechanical theory.
Kelvin had previously proposed to define an absolute scale of temperature independent of the properties of any particular substance in terms of Carnot's function by making F'(t) constant.
He now proposed to define absolute temperature as proportional to the reciprocal of Carnot's function, so as to agree as closely as possible with the scale of the gas thermometer.
With this definition of temperature 0, if the heat H is measured in work units, the expression of Carnot's principle for an infinitesimal cycle of range do reduces to the simple form dW/d9=H/0.
In all such cases there is necessarily, by Carnot's principle, a loss of efficiency or available energy, accompanied by an increase of entropy, which serves as a convenient measure or criterion of the loss.
By Carnot's principle, in all irreversible processes, dH/0 must be algebraically less than do, otherwise it would be possible to devise a cycle more efficient than a reversible cycle.
"Carnot's principle" is fundamental in the theory of thermodynamics.
His labours were incessant; practically every military document in the archives of the committee was Carnot's own work, and he was repeatedly in the field with the armies.
When Carnot's arrest was demanded in May 1 795, a deputy cried "Will you dare to lay hands on the man who has organized victory?"
This "Carnot wall," and, in general, Carnot's principle of active defence, played a great part in the rise of modern fortification.
In May 1894 he again became premier and minister of the interior; and he was by President Carnot's side when the latter was stabbed to death at Lyons in June.
Such an arrangement may be put through a cycle of operations as in Carnot's engine (see Thermodynamics) and all the laws of reversible engines applied to it.
(See Thermodynamics and Steam-Engine.) In Carnot's cycle the substance takes in heat at its highest temperature, then passes by adiabatic expansion from the top to the bottom of its temperature range, then rejects heat at the bottom of the range, and is finally brought back by adiabatic compression to the highest temperature at which it again takes in heat, and so on.
When the Wilson scandals occasioned the downfall of Grevy in December 1887, Carnot's high character for integrity marked him out as a candidate for the presidency, and he obtained the support of Clemenceau and of all those who objected to the candidatures of men who have been more active in the political arena, so that he was elected by 616 votes out of 827.
President Carnot's ostensible part during this agitation was mainly confined to augmenting his popularity by well-timed appearances on public occasions, which gained credit for the presidency and the republic. When early in 1889, Boulanger was finally driven into exile, it fell to President Carnot's lot to appear at the head of the state on two occasions of especial interest, the celebration of the centenary of 1789 and the opening of the Paris Exhibition of that year.