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SECTION XI.
Precession and Nutation-Their Effects on the Apparent Places of the
Fixed Stars
SECTION XII.
Page 74
Mean and Apparent Sidereal Time-Mean and Apparent Solar Time-
Equation of Time-English and French Subdivisions of Time-Leap
Year-Christian Era-Equinoctial Time-Remarkable Eras depending
upon the Position of the Solar Perigee-Inequality of the Lengths of
the Seasons in the two Hemispheres-Application of Astronomy to Chro-
nology-English and French Standards of Weights and Measures 77
SECTION XIII.
Tides-Forces that produce them-Three kinds of Oscillations in the Ocean
-The Semidiurnal Tides-Equinoctial Tides-Effects of the Declina-
tion of the Sun and Moon-Theory insufficient without Observation-
Direction of the Tidal Wave-Height of Tides-Mass of Moon obtained
from her Action on the Tides-Interference of Undulations-Impossi-
bility of a Universal Inundation-Currents
SECTION XIV.
85
Repulsive Force Interstices or Pores-Elasticity-Mossotti's Theory-
Gravitation brought under the same law with Molecular Attraction and
Repulsion-Gases reduced to Liquids by Pressure-Intensity of the Co-
hesive Force-Effects of Gravitation-Effects of Cohesion-Minuteness
of the ultimate Atoms of Matter-Limited Height of the Atmosphere-
Theory of Definite Proportions and Relative Weight of Atoms-Dr. Far-
aday's Discoveries with regard to Affinity-Composition of Water by a
Plate of Platina-Crystalization-Cleavage-Isomorphism-Matter con-
sists of Atoms of Definite Form-Capillary Attraction
SECTION XV.
96
Analysis of the Atmosphere-Its Pressure-Law of Decrease in Density-
Law of Decrease in Temperature-Measurement of Heights by the
Barometer-Extent of the Atmosphere-Barometrical Variations-Oscil-
lations-Trade Winds-Monsoons-Rotation of Winds-Laws of Hur-
ricanes-Water-Spouts
111
SECTION XVI.
Sound-Propagation of Sound illustrated by a Field of Standing Corn-
Nature of Waves-Propagation of Sound through the Atmosphere-
Intensity Noises A Musical Sound-Quality-Pitch-Extent of
Human Hearing--Velocity of Sound in Air, Water, and Solids-Causes
of the Obstruction of Sound-Law of its Intensity-Reflection of Sound
-Echoes-Thunder-Refraction of Sound-Interference of Sounds 122
SECTION XVII.
Vibration of Musical Strings-Harmonic Sounds-Nodes-Vibration of Air
in Wind Instruments-Vibration of Solids-Vibrating Plates-Bells-
Harmony-Sounding Boards-Forced Vibrations-Resonance-Speaking
Machines
134
SECTION XVIII.
Refraction-Astronomical Refraction and its Laws-Formation of Tables of
Refraction-Terrestrial Refraction-Its Quantity-Instances of Extraor-
dinary Refraction-Reflection-Instances of Extraordinary Reflection-
Loss of Light by the Absorbing Power of the Atmosphere-Apparent
Magnitude of Sun and Moon in the Horizon
SECTION XIX.
Page 147
Constitution of Light according to Sir Isaac Newton-Absorption of Light
-Colors of Bodies-Constitution of Light according to Sir David Brew-
ster-New Colors in the Solar Spectrum-Fraunhofer's Dark Lines-
Dispersion of Light-The Achromatic Telescope-Homogeneous Light-
Accidental and Complementary Colors-M. Plateau's Experiments and
Theory of Accidental Colors
SECTION XX.
153
Interference of Light-Undulatory Theory of Light-Propagation of Light
-Newton's Rings-Measurement of the Length of the Waves of Light,
and of the Frequency of the Vibrations of Ether for each Color-New-
ton's Scale of Colors-Diffraction of Light-Sir John Herschel's Theory
of the Absorption of Light-Refraction and Reflection of Light
SECTION XXI.
161
Polarization of Light-Defined-Polarization by Refraction-Properties of
the Tourmaline-Double Refraction-All doubly Refracted Light is
Polarized--Properties of Iceland Spar-Tourmaline absorbs one of the
two Refracted Rays-Undulations of Natural Light-Undulations ot
Polarized Light-The Optic Axes of Crystals-M. Fresnel's Discoveries
on the Rays passing along the Optic Axis-Polarization by Reflection 172
SECTION XXII.
Phenomena exhibited by the passage of Polarized Light through Mica and
Sulphate of Lime-The Colored Images produced by Polarized Light
passing through Crystals having one and two Optic Axes-Circular
Polarization-Elliptical Polarization-Discoveries of MM. Biot, Fresnel,
and Professor Airy-Colored Images produced by the Interference of
Polarized Rays 180
SECTION XXIII.
Objections to the Undulatory Theory, from a Difference in the Action of
Sound and Light under the same circumstances, removed-The Disper-
sion of Light according to the Undulatory Theory
SECTION XXIV.
190
Chemical or Photographic Rays of the Solar Spectrum-Messrs. Scheele,
Ritter, and Wollaston's Discoveries-Mr. Wedgewood and Sir Humphry
Davy's Photographic Pictures-The Calotype-The Daguerreotype-
The Chromatype-The Cyanotype-Sir John Herschel's Discoveries in
the Photographic or Chemical Spectrum-Mons. E. Becquerel's Discovery
of Inactive Lines in the Chemical Spectrum
193
SECTION XXV.
Heat-Calorific Rays of the Solar Spectrum-Experiments of MM. De
Laroche and Melloni on the Transmission of Heat-The Point of greatest
Heat in the Solar Spectrum varies with the Substance of the Prism-
Polarization of Heat-Circular Polarization of Heat-Transmission of the
Chemical Rays-Absorption of Heat-Radiation of Heat-Dew-Hoar
Frost-Rain-Hail-Combustion-Dilatation of Bodies by Heat-Propa-
gation of Heat-Latent Heat--Heat presumed to consist of the Undula-
tions of an Elastic Medium-Parathermic Rays-Moser's Discoveries
Page 206
SECTION XXVI.
Atmosphere of the Planets and the Moon-Constitution of the Sun-Esti-
mation of the Sun's Light-His Influence on the different Planets-
Temperature of Space-Internal Heat of the Earth-Zone of Constant
Temperature-Heat increases with the Depth-Heat in Mines and
Wells-Thermal Springs-Central Heat-Volcanic Action-The Heat
above the Zone of Constant Temperature entirely from the Sun-The
Quantity of Heat annually received from the Sun-Isogeothermal Lines
-Distribution of Heat on the Earth-Climate-Line of Perpetual Con-
gelation-Causes affecting Climate-Isothermal Lines-Excessive Cli-
mates-The same Quantity of Heat annually received and radiated by
the Earth 238
SECTION XXVII.
Influence of Temperature on Vegetation-Vegetation varies with the Lati-
tude and Height above the Sea-Geographical Distribution of Land
Plants-Distribution of Marine Plants-Corallines, Shell-fish, Reptiles,
Insects, Birds, and Quadrupeds-Varieties of Mankind, yet Identity of
Species
SECTION XXVIII.
262
Of ordinary Electricity, generally called Electricity of Tension-Methods
of exciting Bodies-Transference-Electrics and Non-Electrics-Law of
its Intensity-Distribution-Tension-Electric Heat and Light-Atmos-
pheric Electricity-Its Cause-Electric Clouds-Back Stroke-Violent
Effects of Lightning-Its Velocity-Phosphorescence-Phosphorescent
Action of Solar Spectrum-Aurora
SECTION XXIX.
271
Voltaic Electricity-The Voltaic Battery-Intensity-Quantity-Compari-
son of the Electricity of Tension with Electricity in Motion-Luminous
Effects-Decomposition of Water-Formation of Crystals by Voltaic
Electricity-Electrical Fish 290
SECTION XXX.
Terrestrial Magnetism-Magnetic Poles-Lines of equal and no Variation
-The Dip-The Magnetic Equator-Magnetic Intensity-Secular, peri-
odic, and transitory Variations in the Magnetic Phenomena-Origin of
the Mariner's Compass-Natural Magnets-Artificial Magnets-Polarity
-Induction-Intensity-Hypothesis of two Magnetic Fluids-Distribu-
tion of the Magnetic Fluid-Analogy between Magnetism and Elec-
tricity
300
SECTION XXXI.
Discovery of Electro-Magnetism-Deflection of the Magnetic Needle by a
Current of Electricity-Direction of the Force-Rotatory Motion by Elec-
tricity-Rotation of a Wire and a Magnet-Rotation of a Magnet about
its Axis-Of Mercury and Water-Electro-Magnetic Cylinder or Helix-
Suspension of a Needle in a Helix-Electro-Magnetic Induction-Tem-
porary Magnets-The Galvanometer
SECTION XXXII.
Page 314
Electro-Dynamics-Reciprocal Action of Electric Currents-Identity of
Electro-Dynamic Cylinders and Magnets-Differences between the Ac-
tion of Voltaic Electricity and Electricity of Tension-Effects of a Voltaic
Current-Ampère's Theory
SECTION XXXIII.
319
Magneto-Electricity-Volta-Electric Induction-Magneto-Electric Induc-
tion-Identity in the Action of Electricity and Magnetism-Description
of a Magneto-Electric Apparatus and its Effects-Identity of Magnetism
and Electricity
322
SECTION XXXIV.
Electricity produced by Rotation-Direction of the Currents-Electricity
from the Rotation of a Magnet-M. Arago's Experiment explained-
Rotation of a Plate of Iron between the Poles of a Magnet-Relation of
Substances to Magnets of three kinds-Thermo-Electricity 325
SECTION XXXV.
The Action of Terrestrial Magnetism upon Electric Currents-Induction
of Electric Currents by Terrestrial Magnetism-The Earth Magnetic by
Induction-Mr. Barlow's Experiment of an Artificial Sphere-The Heat
of the Sun the Probable Cause of Electric Currents in the Crust of the
Earth; and of the Variations in Terrestrial Magnetism-Electricity of
Metallic Veins-Terrestrial Magnetism possibly owing to Rotation-
Magnetic Properties of the Celestial Bodies-Identity of the Five Kinds
of Electricity-Connection between Light, Heat, and Electricity or Mag-
netism
329
SECTION XXXVI.
Ethereal Medium-Comets-Do not disturb the Solar System-Their
Orbits and Disturbances-M. Faye's Comet, probably the same with
Lexel's-Periods of other three known-Halley's-Acceleration in the
Mean Motions of Encke's and Biela's Comets-The Shock of a Comet-
Disturbing Action of the Earth and Planets on Encke's and Biela's
Comets--Velocity of Comets-The Great Comet of 1843-Physical Con-
stitution-Shine by borrowed Light-Estimation of their Number . 337
SECTION XXXVII.
The Fixed Stars-Their Numbers-Estimation of their Distances and
Magnitudes from their Light-Stars that have vanished-New Stars-
Double Stars-Binary and Multiple Systems-Their Orbits and Periods
-Orbitual and Parallactic Motions-Colors-Proper Motions-General
Motions of all the Stars-Clusters-Nebulae-Their Number and Forms
-Double and Stellar Nebula-Nebulous Stars-Planetary Nebulæ--
Constitution of the Nebula, and Forces which maintain them-Distribu-
tion-Meteorites-Shooting Stars
SECTION XXXVIII.
Page 361
Diffusion of Matter through Space-Gravitation-Its Velocity-Simplicity
of its Laws-Gravitation independent of the Magnitude and Distances of
the Bodies-Not impeded by the Intervention of any Substance--Its
Intensity invariable-General Laws-Recapitulation and Conclusion 386
NOTES
INDEX
391
445