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 PHYSIOCRATS

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PHYSIOCRATS

troubled by the problem, which also arrested the at- tention of physicists; as in 1798 when Benjamin Thompson, Count Rumford (1753-1814), made ac- curate experiments on the heat evolved by friction, and, in 1799, when similar experiments were made by Sir Humphrey Davy (1778-1829). In 1803, beside the notes in which Laplace. announced some of the greatest conquests of the doctrine of caloric, Ber- thollet, in his " Statique chimique ", gave an account of Rumford's experiments, trying in vain to reconcile them with the prevailing opinion. Now these ex- periments, which were incompatible with the hypoth- esis that heat is a fluid contained in a quantity in each body, recalled to mind the supposition of Descartes and Newton, which claimed heat to be a very lively agitation of the small particles of bodies. It was in favour of this view that Rumford and Davy finally declared themselves.

In the last years of his life Carnot consigned to paper a few notes which remained unpublished until 1878. In these notes he rejected the theory of ca- loric as inconsistent with Rumford's experiments. "Heat", he added, "is therefore the result of motion. It is quite plain that it can be produced by the con- sumption of motive power and that it can produce this power. Wherever there is destruction of motive power there is, at the same time, production of heat in a quantity exactly proportional to the quantity of motive power destroyed; and inversely, wherever there is destruction of heat, there is production of motive power".

In 1842 Robert Mayer (1814-78) found the princi- ple of the equivalence between heat and work, and showed that once the difference in two specific heats of a gas is known, it is possible to calculate the me- chanical value of heat. This value differed little from that found by Carnot. Mayer's pleasing work exerted scarcely any more influence on the progress of the theory of heat than did Carnot's unpublished notes. However, in 1843 James Prescott Joule (1818-89) was the next to discover the principle of the equivalence between heat and work, and conducted several of the experiments which Carnot in his notes had requested to have made. Joule's work com- municated to the new theory a fresh impetus. In 1849 William Thomson, afterwards Lord Kelvin (1824-1907), indicated the necessity of reconciling Carnot's principle with the thenceforth incon- testable principle of the mechanical equivalent of heat; and in 1850 Rudolf Clausius (1822-88) accom- plished the task; thus the science of thermodynamics was founded. When in 1847 Hermann von Helmholtz published his small work entitled "Ueber die Erhal- tung der Kraft", he showed that the principle of the mechanical equivalent of heat not only established a bond between mechanics and the theory of heat, but also linked the studies of chemical reaction, electricity, and magnetism, and in tliis way physics was confronted with the carrying-out of an entirely new programme, whose results are at present too incomplete to be judged even by scientists.

AlmagiA, La dottrina delta marea nelV aniichita classica et net medio eiio, taken from Memorie delta Reals Accademia dei Lincei (Rome, 1905) ; Caver.ni, Gloria del metodo sperimentale in Italia (Florence, 1891-8); Duhem, Les theories de la Chaleur in Revue des Deux Mondes (189.5), CXXIX, 869; CXXX, 380, 851; Idem, L'tvotutidn de la Mecanique (Paris, 1903); Idem, Les origines de la Statique (2 vols., Paris, 1905-6); Idem, Etudes sur Leonard de Vinci, ceux qu'il a lus et ceux qui Vont lu (2 vols., Paris, 1906-9); Idem, La th^orie physique, son objei et sa structure (Paris, 1900); Idem, Sui^ei;' to fpaiv6ij.eva. Essai sur la notation de Theorie physique de Platan d Galilee (Paris, 1908) ; DChbino, Kritische Gesch. d. allg. Mechanik (2nd ed., Leipzig, 1877) ; Heller, Gesch. d. Physik w. Aristoteles bis auf d. neueste Zeit (2 vols., Stuttgart, 1882-4); Hellmann, Neudrucke von Schriften u, Karten Uber Meteorologie u. Erdmag- netisnus (15 vols., Berlin, 1893-1904); Jouquet, Lectures de Micanique, La Micanique enseignie par les auieurs originaux (2 vols., Paris, 1908-9); Klein, D. Principien d. Mechanik, kistorisch u. kritisch dargestellt (Leipzig, 1872); Lasswitz, Gesch. d. Atomistik vom Mittelalter bis Newton (2 vols., Hamburg and Leipzig, 1890); LlBltl, Hist, des Sciences math^matiques en

Italic, depuis la Renaissance des Letlres jiisqu'ii la fin du XVII' sihie (4 vols., Paris, 1838-41); Mach, U. Mechanik in ihrer Entwickelung, histor. — kritisch dargestellt (6th ed., Leipzig, 1908); Pascal, CEuvres, ed. Brunschvicq and Boutroux (3 vols., Paris, 1908); Rouse Ball, An Essay on Newton^s Principia (London and New York, 1893) ; Memoires sur V Electrodyna- mique in Collection de Memoires publics par la jSocieti franiaise de Physique, II-III (Paris, 1885-7); Sue Aine, Hist, du Galmnisme et analyse des differens outrages pubties sur celle dicouverte, depuis son origine jusqu'a nos jours (4 vols., Paris), an X (1802) — an XIII (1803); Thirion, Pascal, Vhorreur du vide et la pression atmosphSrique in Revue des Quest, scien., 3rd series; XII (1907), 384; XIII (1908), 149; XV (1909), 149; TnuROT, Recherches histor. sur le Principe d'Archimide in Revue Arch&ologique (new series, Paris), XVIII (1868), 389; XIX (1809), 42; III, 284, 345; XX (1869), 14; Todhunter, A Hist, of Mathematical Theories of Attraction and the Figure of the Earth from time of Newton to that of Laplace (2 vols., London, 1873); Todhunter and Pear- son, A Hist, of the Theory of Elasticity (2 vols., Cambridge, 1886- 93) ; Venturi, Commentari sopra la Storica e le Teorie dell* Oltica (Bologna, 1814); Verdet, Introduction aux (Euvres d'Aw gustin Fresnel, I (Paris, 1866-70), pp. ix-xcix; Weidemann, D. Lehre v. d. Elektricitat, 2nd ed. (3 vols., Brunswick, 1893-5); WoHLWILL, D. Entdeckung d. Beharrungsgesetzes in Zeitschrift f. Vdlkerpsychologie u. Sprachwissenschaft (Berlin), XIV (1883), 365; XV (1884), 70, 337; Idem, Galilei u. sein Kampf f. d. Copernicanische Lehre (Hamburg and Leipzig, 1909).

Pierre Duhem.

Physiocrats (vo-i.s, nature, KpareTv, rule), a school of writers on political and economic subjects that flourished in France in the second half of the eigh- teenth century, and attacked the monopolies, exclu- sive corporations, vexatious taxes, and various other abuses which had grown up under the mercantile sys- tem. Statesmen of the mercantile school in France and elsewhere had adopted a system of tutelage which often gave an artificial growth to industry but which pressed hardly upon agriculture. The physiocrats proposed to advance the interests of agriculture by adopting a system of economic freedom. Laissez faire et laissez passer was their watchword. Frangoia Quesnay (1694-1774), physician to Mine de Pompa- dour and Louis XV, founded the school (1758). The term "physiocracy" was probably used by Ques- nay to convey the idea that the new system provides for the reign of the natural law. Quesnay and hia disciples were called economisles by their contempo- raries ; the term physiocraies was not used until the beginning of the nineteenth century.

Political Philosophy. — In metaphysics Quesnay was a follower of Descartes and borrowed from him the mathematical method used in his "Tableau Econ- omique". He accepted a modified form of the natural rights theory which pervades eighteenth-century lit- erature and gave it an optimistic interpretation. He erajihasizes the distinction between the natural order (ordre nalurel) and the positive order {ordre posilif). The first is founded upon the laws of nature which are the creation of God and which can be discovered by reason. The second is man-made; when its laws coincide with those of the natural order the world will be at its best. He objected to the natural rights philosophers of his day that they concerned themselves only with the positive order to the neglect of the natural. He held that primitive man upon entering society does not give up any of his natural rights, thus taking issue with Rousseau's theory of the social contract. From his optimistic doctrines concerning the laws of the natural order he deduces his doctrine of laissez faire. Economic evils arise from the monop- olies and restrictions of the positive order; statesmen should aim to harmonize the positive order with the natural by abolishing these excrescences. The state should withdraw its support from the attempts of special interests to bolster up industry artificially. In the language of the physiocrats, "He governs best who governs least". Although ultimately their prin- ciples proved favourable to the Revolution, Quesnay and his disciples were in favour of an absolute mon- archy subject only to the laws of the "natural order". They considered that it would be easier to persuade a prince than a nation and that the triumph of their