General Outline, 419; Origin of its Power, 419; Scientific Principles involved in its Operation, 420; the Beginnings of Modern Science, 421; the Alexandrian Museum, 422; the Aristotelian Philosophy, 424; the Middle Ages, 426; Galileo's Work, 428; Da Vinci and Stevinus, 429; Kepler, Hooke, and Huyghens, 429; Newton and the New Mechanical Philosophy, 430; the Inception of the Science of Energetics, 483; the Persistence of Energy, 433; Rumford's Experiments, 434; Fourier, Carnot, Seguin, 437; Mayer and the Mechanical Equivalent of Heat, 438; Joule's Determination of its Value, 438; Prof. Rankine's Investigations, 442; Clausius-Thompson's Principles, 444; Experimental Work of Boyle, Black, and Watt, 446; Robison's, Dalton's, Ure's, and Biot's Study of Pressures and Temperatures of Steam, 447; Arago's and Dulong's Researches, 447; Franklin Institute Investigation, 447; Cagniard de la Tour--Faraday, 447; Dr. Andrews and the Critical Point, 448; Donny's and Dufour's Researches, 448; Regnault's Determination of Temperatures and Pressures of Steam, 449; Hirn's Experiments, 450; Résumé of the Philosophy of the Steam-Engine, 451; Energy--Definitions and Principles, 451; its Measure, 452; the Laws of Energetics, 453; Thermo-dynamics, 453; its Beginnings, 454; its Laws, 454; Rankine's General Equation, 455; Rankine's Treatise on the Theory of Heat-Engines, 456; Merits of the Great Philosopher, 456. CHAPTER VIII. THE PHILOSOPHY OF THE STEAM-ENGINE. ITS APPLICATION; ITS TEACHINGS RESPECTING THE CONSTRUCTION OF THE ENGINE AND ITS IMPROVEMENT 457 Origin of all Energy, 457; the Progress of Energy through Boiler and Engine, 458; Conditions of Heat-Development in the Boiler, 458; the Steam in the Engine, 458; the Expansion of Steam, 459; Conditions of Heat-Utilization, 460; Loss of Power in the Engine, 462; Conditions affecting the Design of the Steam-Engine, 466; the Problem stated, 466; Economy as affected by Pressure and Temperature, 467; Changes which have already occurred, 468; Direction of Changes now in Progress, 470; Summary of Facts, 471; Characteristics of a Good Steam-Engine, 473; Principles of Steam-Boiler Construction, 476. LIST OF ILLUSTRATIONS. FRONTISPIECE: The Grecian Idea of the Steam-Engine.