LE PLAY, PIERRE GUILLAUME FREDERIC (1806-1882), French engineer and economist, was born at La Riviere Saint-Sauveur (Calvados), on April 11, 1806, the son of a custom-house official. He was educated at the Ecole Poly technique at Paris, and from there he passed into the State De partment of Mines, where his powers of observation won him rapid promotion. In 1832, he became co-editor of the Annales des Mines, two years later he was appointed head of the perma nent committee of mining statistics and in 1840 engineer-in-chief and professor of metallurgy at the School of mines, where he became inspector in 1848. As a representative of the French Government, he reported on the steel and cutlery exhibited in London at the great exhibition of 1851, and at the Paris exhibi tions of 1855 and 1862 he was placed in charge of the arrange ment and classification of the products. On being created a sena tor in 1867, he made a brief entry into politics, but after the fall of the senate in 1870, he made no further attempt to re-enter parliament. During his long vacations, which he had systematic ally spent in travelling in Europe and Asia, Le Play had closely observed the social and economic conditions of the people, and on his retirement in 1870, he devoted himself to the study of similar questions in France. After investigating minutely the economic circumstances of about 30o families, he tabulated the facts with a view to discovering the bases of the welfare of the family, and in 1855 published a selection of 36 of these monographs in "Les Ouvriers Europeens" (6 vols.). Technically his work in classifying and tabulating family budgets is excellent. The con clusions at which Le Play arrived relate mainly to the morals of industry, and are of greater value to the statesman than the economist.
For his work in this sphere Le Play was awarded the Monthyon prize of statistics, by the Academie des Sciences. In 1856, Le Play founded the Socieete internationale des etudes pratiques d'Economie sociale, which has devoted its energies to forwarding social studies on lines laid down by its founder. The two basic contributions of Le Play and his continuators, are their insistence on, and treatment of, primary occupations, and their elaboration of the formula "place, work and folk." In opposition to the school of Comte, they approach sociological questions from physi cal science and industry, and depend on direct observation of representative families and of communities. In La Science Sociale, the main organ of the society, have been published a series of social monographs, which are invaluable both to the economist and sociologist. (See SOCIOLOGY.) By his work, therefore, Le Play has become the originator of one of the main schools of sociology. He died in Paris on April 5, 1882.