Front matter
'UNITED STATES OF AMKHICA.!
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1. Great Cluster of Stars in Hercules. 2. Whirlpool Nebula of Lord Rosse.
Chapter I
GENERAL FORM AND DIMENSION'S OF THE EARTH — THE DIURNAL MOTION — ARTIFICIAL GLOBES.
PAGE
Astronomy 13
Form of the earth 14
Proofs that it is globular 14
The words up and down 15
Size of the earth 16
Inequalities of surface 16
The diurnal rotation IT
The equator of the earth 17
Meridians ._ 17
Latitude and longitude 17
The terrestrial sphere 18
The celestial sphere 18
The horizon 18
The vertical circles 19
Altitude and azimuth 19
Celestial equator 19
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The ecliptic 21
Equinoxes 21
Solstices 21
The colures 21
Signs of the ecliptic 22
Right ascension and declination 22
Celestial longitude and latitude 22
Apparent daily motion of the heavens 23
Rising, setting, culmination 23
Diurnal circles and horizon 24
The right sphere 25
The parallel sphere 26
The oblique sphere 26
Artificial globes 27
Problems on the terrestrial globe 29
Problems on the celestial globe 30
Chapter II. Parallax — Atmospheric Refraction Twilight
Parallax 38
Diurnal parallax 33
Greatest at the horizon 35
Diminishes as distance increases 35
Horizontal parallax 35
Parallax of the moon 35
Atmospheric refraction 35
Its effect on rising and setting 36
Distortion of the sun's disk 37
Illumination of the sky 37
Twilight 38
Duration of twilight 39
CHAPTER IH.
ASTRONOMICAL INSTRUMENTS — THE EARTH S MOTION ABOUT THE SUN — THE SEASONS FORM OF THE EARTH'S ORBIT.
The equatorial telescope 40
The transit instrument 40
The astronomical clock 42
Sidereal time .- 42
To find right ascension 42
To find declination 42
The mural circle 43
The altitude and azimuth instrument 43
The sextant 44
Observations of the sun's place 45
The ecliptic and zodiac 46
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CONTENTS
PAGE
The tropics and polar circles 46
Terrestrial zones 47
The annual motion observed without
instruments 4S
A motion of the earth, not the sun.. . 48
Cause of the change of seasons 49
Causes of heat in summer and of cold
in winter 51
PAGE
Time of greatest heat and greatest cold 52
Effect of no obliquity on seasons 52
Obliquity of 90° 53
To find the form of the earth's orbit. . 53
Perihelion, aphelion, etc 54
Line of apsides 55
Effect of sun's distance on the seasons 55
Chapter IV. Sidereal Time — Mean And Apparent Solar Time The
CALENDAR.
The sidereal day 57
The mean solar day 57
The apparent solar day 53
Causes of unequal solar days 58
The equation of time 59
Civil and astronomical timer 59
The Julian calendar 60
The Gregorian calendar 60
Days of the month and of the week... . 61
Chapter V. Oblate Form Of The Earth Its Mass And Density
PROOFS OF ITS ROTATION ON AN AXIS.
Central forces 63
Illustrations 63
Loss of weight on the earth 64
Loss from a second cause 64
Oblate form of the earth 64
Equatorial belt 65
Weight and density of the earth. ..... 67
Proofs of the earth's rotation 67
Chapter VI
THE SUN — SOLAR SPOTS — CONDITION OF THE SUN'S SUR- FACE — THE ZODIACAL LIGHT.
The form of the sun 69
The sun's distance and size 69
The sun's mass and strength of gravity 70
Diurnal rotation of the sun 70
Its apparent time 71
Its real time 71
Appearance of solar spots 71
Their motions and changes 72
Their nature 73
Herschel's theory 73
The zodiacal light 73
Chapter VII. Gravitation — Kepler S Laws Motion In An Elliptical
ORBIT — PRECESSION OF THE EQUINOXES.
Gravitation . . : 75
First law of gravitation 75
Second law 76
Kepler's laws 76
The first law 76
The second law 77
The third law 78
Paths of projectiles 7S
Effect of increased velocity 78
Why a planet returns from aphelion . . 79 Why a planet departs from aphelion.. 80
Precession of equinoxes 81
Signs of ecliptic displaced 81
Motion of the poles 82
Cause of precession 82
The tropical year 83
The sidereal year 83
C ONTENTS.
IX
Chapter VIII. The Moon Its Eevolutions — Its Phases The Condition
OF ITS SUEFACE.
PAGE
Distance and size of the moon 84
Eevolution about the earth 84
Months 85
Nodes t 85
Conj unction and opposition 85
Quadratures 86
Octants 86
Form of orbit 86
Diurnal motion 86
Libration of longitude 87
Libration of latitude 87
Diurnal libration 87
Eevolution round the sun 88
Phases of the moon 88
PAGE
Moon running high or low 90
The harvest moon 90
Inequalities of moon's surface 91
Form of valleys 92
Volcanic appearance 92
Height of its mountains 93
No atmosphere or vapor 93
Changes of temperature on the moon. 94
View of the earth from the moon 94
As to magnitude 94
As to phase 94
As to position in the sky 95
As to surface 95
Chapter IX. Eclipses Of The Moon And Sun
General relations in eclipses 97
Eclipse months 98
Eclipse of the moon 99
Forms of shadows 99
Duration of eclipse 100
Appearance of moon 100
Eclipse of the sun 100
Total shadow and penumbra of the moon 101
Total and partial eclipses of the sun . 101
Annular eclipse 103
Velocity of the shadow 103
Eelative number of solar and lunar
Eclipses at the moon 104
True form of shadows 104
Chapter X. Longitude — Tides
Local time 105
Connection between longitude and
local time 105
Longitude by the chronometer 106
Longitude by a lunar eclipse 106
By eclipses of Jupiter's satellites 106
By a solar eclipse 107
By occupations of stars 107
By the lunar method 107
By the magnetic telegraph 108
Change of days in going round the
earth 109
Ambiguity as to days among the islands of the Pacific . >. 109
Tides, high and low water 110
Spring and neap tides Ill
Opposite tides Ill
Form of the water acted on by the
moon Ill
Direct and opposite tides 112
Tides by the sun 112
Joint action of sun and moon 113
Effect of inertia of water 113
Diurnal inequality 114
Effects of coasts 115
Cotidal lines 116
Tides in lakes 118
CONTENTS.
CHAPTER XL
THE PLANETS — TABULAR STATEMENTS — MERCURY — VENUS — MARS.
PAGE
Planetary bodies classified 119
Three groups 119
Inferior planets 120
Superior planets 120
Satellites 120
Table of distances 121
Table of revolutions 121
Table of magnitudes 122
Table of masses 122
Sun and planets compared 123
Diameters and distances compared. . 123
Direction of motions 123
Mercury — apparent motions 124
Modified by the earth's motions 125
Stationary points 127
PAGE
Form and position of Mercury's orbit 127
Phases of Mercury 127
Point of greatest brightness 128
Transits of Mercury 12S
Venus— its apparent motions 129
The phases and brightness of Venus. 129
Transits of Venus 129
Use made of them 130
Mars— its situation in the System... 130
Apparent motions 130
Phases and changes of apparent size. 132
Appearance of disk 132
Orbit and equator of Mars 133
Days on the small planets , 133
Chapter XII. The Planetoids Jupiter Saturn Uranus Neptune
DISTURBANCES OF THE PLANETS.
Space between Mars and Jupiter 134
The planetoids 134
When discovered — number 134
Characteristics 134
Jupiter — its magnitude 136
Its place in the System 136
Its form and orbit 136
Belts of Jupiter 137
Satellites of Jupiter 138
Eclipses of Jupiter and its satellites. 138
Saturn— its disk 140
Rings of Saturn 140
Disappearance of rings 140
Phenomena of rings at the planet. . . 142
Satellites of Saturn 143
Uranus — discovery 143
Place in the System 143
Satellites of Uranus 144
Neptune — its discovery 144
Motions of the planets disturbed 145
Nodes retrograde . 146
Apsides advance 146
Eccentricity changes 146
Stability preserved 146
Chapter XIII. Comets — Shooting Stars
Nucleus, coma, and envelope of a
comet 148
Number of comets 148
Eccentricity of orbit 149
Form and direction of tail 149
Dimensions of comets 150
Light of comets 151
Mass of the comets 151
Directions of their motions 152
To find a comet's orbit 152
Comets of known period 153
Halley's comet 153
Remarkable comets 15*3
Comet of 1680 153
Shooting stars 155
Gaseous meteors 155
Solid meteors 156
Aerolites 156
CONTENTS
XI
Chapter XIV. The Fixed Stars— Constellations
PAGE
The stellar universe 158
The fixed stars and their magnitudes 158 Number included in the several magnitudes 159
Cause of unequal brightness 159
Star catalogues 161
Descriptions of constellations 161
Constellations of the Zodiac described 161 Aries — Taurus — Gemini — Cancer —
Leo— Virgo— Libra 161-165
Scorpio — Sagittarius 165
Capricorn us— Aquarius— Pisces 166
Constellations north of the Zodiac. . . 168
Ursa Minor — Ursa Major 168
Draco — Cepheus — Cassiopeia — Camelopardalus 168-171
PAGE
Andromeda — Perseus 1T2
Auriga — Leo Minor — Canes Venatici
— Coma Berenices— Bootes 173
Corona Borealis — Hercules — Lyra. . . 174
Cygnus — Vulpecula 175
Aquila — Antinous 176
Delphinus— Pegasus 176, 177
Ophiuchus 177
Constellations south of the Zodiac. . . 177
Cetus — Orion 177
Lepus — Canis Major — Canis Minor. . 178
Monoceros— Hydra 180
Evening constellations of autumn.. . 181
Of winter 182
Of spring 183
Of summer 183
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