14 



CONTENTS OF VOLUME II. 



THE PULLEY PAGE 269 



Cord. Sheave. Fixed Pulley. Fire-Escapes. Single moveable Pulley. Systems of Pulleys. 

 Smeaton's Tackle. White's Pulley. Advantage of. Runner. Spanish Bartons- 



THE INCLINED PLANE, WEDGE, AND SCREW 281 



Inclined Plane. Effect of a Weight on. Power of. Roads. Power oblique to the Plane. Plane 

 sometimes moves under the Weight. Wedge. Sometimes formed of two inclined Planes. 

 More powerful as its Angle is acute. Where used. Limits to the Angle. Screw. Hunter's 

 Screw. Examples. Micrometer Screw. 



EBULLITION 295 



Process of boiling. Vaporization and Condensation. Latent Heat of Steam. Experiments of 

 Black. Effect of atmospheric Pressure on the boiling Point. Ebullition under increased Pressure 

 under diminished Pressure. Relation between the Barometer and boiling Point. Effect of the 

 Altitude of the Station of the boiling Point. Elasticity of Steam. Its Lightness. Sum of the latent 

 and sensible Heat always the same. Effect of the Compression of Steam without Loss of Heat. 

 Steam cannot be liquefied by mere Pressure. Boiling Points and latent Heat of other Liquids. 

 Condensation of Vapor. Principle of the Steam-Engine. Nature of permanent Gases. Examples 

 of the Application of the Properties of Steam. 



COMBUSTION 319 



Flame produced by chemical Combination. Supporters of Combustion and Combustibles. Oxygen 

 chief Supporter. Heat of Combustion. Flame. Its illuminating Powers. Combustion without 

 Flame. Property of spongy Platinum. Table of Heat evolved in Combustion. Theory of La- 

 voisier. Of Hook and others. Electric Theory. 



HOW TO OBSERVE THE HEAVENS 329 



Interesting Nature of the Subject. Diurnal Rotation. Circumpolar Stars. Ursa Major. Forms 

 of the Constellations. The Pointers. The Pole-Star. Cassiopeia. Capella. The Swan. 

 Equatorial Constellations. Orion. Sirius, or the Dogstar. Aldebaran. Procyon. Auriga. 

 Columba. Herschel's Observations on Sirius. Dr. Wollaston's Observations. Aspect of the 

 Heavens at different Seasons of the Year. Uses of the Celestial Globe. To Ascertain the 

 Aspect of the Heavens on any Night at any Hour. Effect of the Telescope on Fixed Stars. 

 Relative Brightness of the Stars. Theory of refracting and reflecting Telescopes, as applied 

 to the Stars. Manner in which Sir W. Herschel applied it. Method of estimating the Bright- 

 ness of small Stars. Method of observing variable Stars. Double Stars. Description of the Mi- 



THE STELLAR UNIVERSE FIRST LECTURE 355 



Range of Vision. Augmented by the Telescope. Periodic Stars. Examples of this Class. Vari- 

 ous Hypotheses to explain these Appearances. Their Insufficiency. Temporary Stars. Re- 

 markable Examples of this Class. These may possibly be periodic Stars. Double Stars Their 

 vast Number. They are physically connected. Telescopic Views of them. How they may in- 

 dicate the annual Parallax. Researches of Sir W. Herschel. Discovery of the orbitual Motions 

 of double Stars. Binary Stars. Extension of Gravitation to the Stars. Their elliptic Orbits dis- 

 covered. Effects of double and colored Suns. Proper Motions of the Stars. Probable Motion 

 of the Solar System. Analysis of its Effects. Suggestion of Mr. Pond. Independent Motions of 

 the Stars. Proper Motions of double Stars. Probable Amount of the real Motions of the Stars. 



THE STELLAR UNIVERSE SECOND LECTURE 375 



Form and Arrangement of the Mass of visible Stars. Sir W. Herschel's Analysis of the Heavens. 

 The Milky Way. The vast Numbers of Stars in it. Form and Dimensions of this Mass of 

 Stars. Nebulae and Clusters. Various Forms and Appearance of Nebulas. Great Nebula in 

 Orion. Megallanic Clouds. Planetary Nebulas. Vast Number of Nebulae. Herschel's Cata- 

 logue. Structure of the Universe. Laplace's nebular Hypothesis. Examination of its moral 

 Tendency. 



THE STEAM-ENGINEFIRST LECTURE 397 



The Steam-Engine a Subject of popular Interest. Effects of Steam. Great Power of Steam. 

 Mechanical Properties of Fluids. Elastic and inelastic Fluids. Elasticity of Gases. Effects of 

 Heat. Savery's Engine. Boilers and their Appendages. Working Apparatus. Mode of Op- 

 eration. Defects of Savery's Engine. Newcomen and Cawley's Patent. Accidental Discovery 

 of Condensation by Injection. Potter's Invention of the Method of working the Valves. His Con- 

 trivance improved by the Substitution of the Plug-Frame. 



THE STEAM-ENGINESECOND LECTURE 417 



Mechanical Force of Steam. Facts to be remembered. Watt finds Condensation in the Cylinder 

 incompatible with a due Economy of Fuel. Conceives the Notion of Condensing out of the Cyl- 

 inder. Discovers separate Condensation. Invents the Air-Pump. Substitutes Steam Pressure 

 for Atmospheric Pressure. Invents the Steam Case or Jacket. His first Experiments to realize 

 these Inventions. His Experimental Apparatus. His Models at Delft House. Difficulties of 

 bringing the improved Engines into Use. Watt employed by Roebuck. His Partnership His 

 first Patent. His Single- Acting Engine. Discovery of the Expansive Action of Steam Its Me- 

 chanical Effects. Its Variable Action. Methods of Equalizing it. Its extensive Application in 

 the Cornish Engines. Extension of the Steam-Engine to Manufactures. Attempts of Papin, 

 Savery, Hull, Champion, Stewart, and Washborough, W^att's second Patent. Sun-and-Planet 

 Wheels. Valves of Double- Acting Engine. 



