Chapter II: Introduction: General Properties of Bodies. Impenetrability

Extension. Figure. Divisibility. Inertia. Attraction.
Attraction of Cohesion. Density. Rarity. Heat. Attraction of
Gravitation.

CONVERSATION II.

ON THE ATTRACTION OF GRAVITY. 22

Attraction of Gravitation, continued. Of Weight. Of the Fall of
Bodies. Of the Resistance of the Air. Of the Ascent of Light
Bodies.

CONVERSATION III.

ON THE LAWS OF MOTION. 32

Of Motion. Of the Inertia of Bodies. Of Force to produce
Motion. Direction of Motion. Velocity, absolute and relative.
Uniform Motion. Retarded Motion. Accelerated Motion. Velocity
of Falling Bodies. Momentum. Action and Reaction equal.
Elasticity of Bodies. Porosity of Bodies. Reflected Motion.
Angles of Incidence and Reflection.

CONVERSATION IV.

ON COMPOUND MOTION. 46

Compound Motion, the result of two opposite forces. Of
Curvilinear Motion, the result of two forces. Centre of Motion,
the point at rest, while the other parts of the body move round
it. Centre of Magnitude, the middle of a body. Centripetal
Force, that which impels a body towards a fixed central point.
Centrifugal Force, that which impels a body to fly from the
centre. Fall of Bodies in a Parabola. Centre of Gravity, the
point about which the parts balance each other.

CONVERSATION V.

ON THE MECHANICAL POWERS. 54

Of the Power of Machines. Of the Lever in general. Of the Lever
of the first kind, having the Fulcrum between the power and the
weight. Of the Lever of the second kind, having the Weight
between the power and the fulcrum. Of the Lever of the third
kind, having the Power between the fulcrum and the weight. Of
the Pulley. Of the Wheel and Axle. Of the Inclined Plane. Of
the Wedge. Of the Screw.

CONVERSATION VI.

ASTRONOMY.

CAUSES OF THE MOTION OF THE HEAVENLY BODIES. 70

Of the Earth's annual motion. Of the Planets, and their motion.
Of the Diurnal motion of the Earth and Planets.

CONVERSATION VII.

ON THE PLANETS. 80

Of the Satellites and Moons. Gravity diminishes as the Square
of the Distance. Of the Solar System. Of Comets.
Constellations, signs of the Zodiac. Of Copernicus, Newton, &c.

CONVERSATION VIII.

ON THE EARTH. 91

Of the Terrestrial Globe. Of the Figure of the Earth. Of the
Pendulum. Of the Variation of the Seasons, and of the Length of
Days and Nights. Of the Causes of the Heat of Summer. Of Solar,
Siderial, and Equal or Mean Time.

CONVERSATION IX.

ON THE MOON. 108

Of the Moon's Motion. Phases of the Moon. Eclipses of the Moon.
Eclipses of Jupiter's Moons. Of Latitude and Longitude. Of the
Transits of the inferior Planets. Of the Tides.

CONVERSATION X.

HYDROSTATICS.

ON THE MECHANICAL PROPERTIES OF FLUIDS. 118

Definition of a Fluid. Distinction between Fluids and Liquids.
Of Non-Elastic Fluids, scarcely susceptible of Compression. Of
the Cohesion of Fluids. Of their Gravitation. Of their
Equilibrium. Of their Pressure. Of Specific Gravity. Of the
Specific Gravity of Bodies heavier than Water. Of those of the
same weight as Water. Of those lighter than Water. Of the
Specific Gravity of Fluids.

CONVERSATION XI.

OF SPRINGS, FOUNTAINS, &c. 128

Of the Ascent of Vapour and the Formation of Clouds. Of the
Formation and Fall of Rain, &c. Of the Formation of Springs. Of
Rivers and Lakes. Of Fountains.

CONVERSATION XII.

PNEUMATICS.

ON THE MECHANICAL PROPERTIES OF AIR. 136

Of the Spring or Elasticity of the Air. Of the Weight of the
Air. Experiments with the Air Pump. Of the Barometer. Mode of
Weighing Air. Specific Gravity of Air. Of Pumps. Description of
the Sucking Pump. Description of the Forcing Pump.

CONVERSATION XIII.

ON WIND AND SOUND. 146

Of Wind in General. Of the Trade Wind. Of the Periodical Trade
Winds. Of the Aerial Tides. Of Sound in General. Of Sonorous
Bodies. Of Musical Sounds. Of Concord or Harmony, and Melody.

CONVERSATION XIV.

ON OPTICS. 157

Of Luminous, Transparent, and Opaque Bodies. Of the Radiation
of Light. Of Shadows. Of the Reflection of Light. Opaque Bodies
seen only by Reflected Light. Vision Explained. Camera Obscura.
Image of Objects on the Retina.

CONVERSATION XV.

OPTICS--_continued._

OF THE ANGLE OF VISION, AND REFLECTION OF MIRRORS. 168

Angle of Vision. Reflection of Plain Mirrors. Reflection of
Convex Mirrors. Reflection of Concave Mirrors.

CONVERSATION XVI.

ON REFRACTION AND COLOURS. 179

Transmission of Light by Transparent Bodies. Refraction.
Refraction by the Atmosphere. Refraction by a Lens. Refraction
by the Prism. Of Colour from the Rays of Light. Of the Colours
of Bodies.

CONVERSATION XVII.

ON THE STRUCTURE OF THE EYE, AND OPTICAL INSTRUMENTS. 195

Description of the Eye. Of the Image on the Retina. Refraction
by the Humours of the Eye. Of the use of Spectacles. Of the
Single Microscope. Of the Double Microscope. Of the Solar
Microscope. Magic Lanthorn. Refracting Telescope. Reflecting
Telescope.

GLOSSARY, 205

CONVERSATION I.

ON GENERAL PROPERTIES OF BODIES.