CONTENTS.
| [CONVERSATION I.] | ||
| ON GENERAL PROPERTIES OF BODIES. | [9] | |
| 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.
INTRODUCTION. GENERAL PROPERTIES OF BODIES. IMPENETRABILITY. EXTENSION. FIGURE. DIVISIBILITY. INERTIA. ATTRACTION. ATTRACTION OF COHESION. DENSITY. RARITY. HEAT. ATTRACTION OF GRAVITATION.
EMILY.
I must request your assistance, my Dear Mrs. B., in a charge which I have lately undertaken: it is that of instructing my youngest sister, a task, which I find proves more difficult than I had at first imagined. I can teach her the common routine of children's lessons tolerably well; but she is such an inquisitive little creature, that she is not satisfied without an explanation of every difficulty that occurs to her, and frequently asks me questions which I am at a loss to answer. This morning, for instance, when I had explained to her that the world was round like a ball, instead of being flat as she had supposed, and that it was surrounded by the air, she asked me what supported it. I told her that it required no support; she then inquired why it did not fall as every thing else did? This I confess perplexed me; for I had myself been satisfied with learning that the world floated in the air, without considering how unnatural it was that so heavy a body, bearing the weight of all other things, should be able to support itself.
Mrs. B. I make no doubt, my dear, but that I shall be able to explain this difficulty to you; but I believe that it would be almost impossible to render it intelligible to the comprehension of so young a child as your sister Sophia. You, who are now in your thirteenth year, may, I think, with great propriety, learn not only the cause of this particular fact, but acquire a general knowledge of the laws by which the natural world is governed.