Thermodynamics the work of French physicist Nicolas Léonard Sadi Carnot (1824) who believed that engine efficiency was the key that could help France win the Napoleonic Wars. Scots-Irish physicist Lord Kelvin was the first to formulate a concise definition of thermodynamics in 1854 which stated, "Thermo-dynamics is the subject of the relation of heat to forces acting between contiguous parts of bodies, and the relation of heat to electrical agency." The initial application of thermodynamics to mechanical heat engines was extended early on to the study of chemical compounds and chemical reactions. Chemical thermodynamics studies the nature of the role of
Christianity in the 19th century regulation of working conditions. "Rerum novarum" argued for the establishment of a living wage and the right of workers to form trade unions. Popes have always highlighted the inner link between the Virgin Mary as Mother of God and the full acceptance of Jesus Christ as Son of God. Since the 19th century, they were highly important for the development of mariology to explain the veneration of Mary through their decisions not only in the area of Marian beliefs (Mariology) but also Marian practices and devotions. Before the 19th century, popes promulgated Marian veneration by authorizing new Marian feast days,