Inertia.--Matter Incapable of spontaneous Change.--Impediments to Motion.--Motion of the Solar System.--Law of Nature.--Language used to express Inertia sometimes faulty.--Familiar Examples of Inertia. 27 CHAP. IV. ACTION AND REACTION. Inertia in a single Body.--Consequences of Inertia in two or more Bodies.--Examples.--Effects of Impact.--Motion not estimated by Speed or Velocity alone.--Examples.--Rule for estimating the Quantity of Motion.--Action and Reaction.--Examples of.--Velocity of two Bodies after Impact.--Rule for finding the common Velocity after Impact.--Magnet and Iron.--Feather and Cannon Ball impinging. --Newton’s Laws of Motion.--Inutility of.--Familiar Effects resulting from Consequences of Inertia. 34 CHAP. V. COMPOSITION AND RESOLUTION OF FORCE. Motion and Pressure.--Force.--Attraction.--Parallelogram of Forces. --Resultant.--Components.--Composition of Force.--Resolution of Force.--Illustrative Experiments.--Composition of Pressures.-- Theorems regulating Pressures also regulate Motion.--Examples.-- Resolution of Motion.--Forces in Equilibrium.--Composition of Motion and Pressure.--Illustrations.--Boat in a Current.--Motions of Fishes. --Flight of Birds.--Sails of a Vessel.--Tacking.--Equestrian Feats. --Absolute and relative Motion. 48 CHAP. VI. ATTRACTION. Impulse.--Mechanical State of Bodies.--Absolute Rest.--Uniform and rectilinear Motion.--Attractions.--Molecular or atomic.--Interstitial Spaces in Bodies.--Repulsion and Attraction.--Cohesion.--In Solids and Fluids.--Manufacture of Shot.--Capillary Attractions.--Shortening of Rope by Moisture.--Suspension of Liquids in capillary Tubes.-- Capillary Siphon.--Affinity between Quicksilver and Gold.--Examples of Affinity.--Sulphuric Acid and Water.--Oxygen and Hydrogen.--Oxygen and Quicksilver.--Magnetism.--Electricity and Electro-Magnetism.-- Gravitation.--Its Law.--Examples of.--Depends on the Mass.-- Attraction between the Earth and detached Bodies on its Surface.-- Weight.--Gravitation of the Earth.--Illustrated by Projectiles.-- Plumb-Line.--Cavendish’s Experiments. 63 CHAP. VII. TERRESTRIAL GRAVITY. Phenomena of falling Bodies.--Gravity greater at the Poles than Equator.--Heavy and light Bodies fall with equal Speed to the Earth. --Experiment.--Increased Velocity of falling Bodies.--Principles of uniformly accelerated Motion.--Relations between the Height, Time, and Velocity.--Attwood’s Machine.--Retarded Motion. 84 CHAP. VIII. OF THE MOTION OF BODIES ON INCLINED PLANES AND CURVES.