Blasco De Garay's Proposition to propel Vessels by a Machine 16 Solomon De Caus 17 Giovanni Branca proposes to work Mills by Steam 22 Marquis of Worcester 23 Mechanical Properties of Fluids 25 Elastic and Inelastic Fluids 25 Elasticity of Gases 28 Effects of Heat 29 Application of these Principles to the Engines of Hero, De Caus, and Lord Worcester 30 Sir Samuel Morland 34 Denis Papin 36 Atmospheric Pressure 38 Weight of Air 39 Pressure of Air 41 Barometer 41 Elastic Force of Air and Gases 42 Force obtained by a Vacuum 43 Common Pump 43 Rarefaction by Heat 44 Process of filling Thermometers 44 Papin's Method of producing a Vacuum 44 His Discovery of the Condensation of Steam 45 Thomas Savery 47 CHAP. II. ENGINES OF SAVERY AND NEWCOMEN. Savery's Engine 49 Boilers and their Appendages 50 Working Apparatus described 51 Mode of Operation 52 Defects of Savery's Engine 58 Newcomen's Engine described by Papin 62 Newcomen and Cawley obtain a Patent for Atmospheric Engine 65 Accidental Discovery of Condensation by Injection 69 Potter's Discovery of the Method of working the Valves 71 His Contrivance improved by the Substitution of a Plug Frame 72 Advantages of the Atmospheric Engine over that of Savery 72 The Power of Savery's Engine restricted 73 It contained no new Principle 73 Its practical Superiority 73 CHAP. III. EARLY CAREER AND DISCOVERIES OF JAMES WATT. Atmospheric Engine improved by Beighton 75 Smeaton's Improvements in the Atmospheric Engine 76 Brindley obtains a Patent for Improvement in 76 Invents the Self-regulating Feeder 76 Infancy of James Watt 77 His Descent and Parentage 77 Anecdotes of his Boyhood 78 His early Acquirements 79