NEW YORK AND LONDON
HARPER & BROTHERS PUBLISHERS
MCMVIII

Copyright, 1908, by Harper & Brothers.
All rights reserved.
Published March, 1908.

TABLE OF CONTENTS

[I].VOLCANIC PHENOMENA AND EARTHQUAKES1
Destruction caused by volcanism and by earthquakes.—Differentkinds of volcanoes.—Vesuvius.—Products of eruption.—Volcanicactivity diminishing.—Structure of volcanoes.—Geographicaldistribution of volcanoes.—Temperaturein the interior of the earth.—Significance of waterfor volcanism.—Composition of the earth’s interior.—Geographicaldistribution of earthquakes.—Fissures in theearth’s crust.—Groups of earthquakes.—Waves in the seaand in the air accompanying earthquakes.—Their connectionwith volcanism.—Systems of fissures.—Seismograms.
[II].THE CELESTIAL BODIES, IN PARTICULAR THEEARTH, AS ABODES OF LIVING BEINGS39
Manifold character of the worlds.—The earth probably atfirst a ball of gases.—Formation of the earth crust and itsrapid cooling.—Balance between heat received and heatlost by radiation.—Life already existing on the earth fora milliard of years.—The waste of solar heat.—Temperatureand habitability of the planets.—Heat-preserving influenceof the atmosphere.—Significance of carbon dioxide in theatmosphere.—Warm and cold geological ages.—Fluctuationsin the percentage of carbon dioxide of the air.—Combustion,decay, and growth.—Atmospheric oxygen.—Vegetablelife more ancient than animal life.—The atmospheresof planets.—Chances of an improvement in the climate.
[III].RADIATION AND CONSTITUTION OF THE SUN64
Stability of the solar system.—Losses and possible gainsof heat by the sun.—Theses of Mayer and of Helmholtz.—Temperaturesof the white, yellow, and reddish stars, andof the sun.—Sun-spots and sun faculæ.—Prominences.—Spectra of the parts of the sun.—Temperature of the sun.—Theinterior of the sun.—Its composition according to themechanical theory of heat.—The losses of heat by the sunprobably covered by the enormous solar energy.
[IV].THE RADIATION PRESSURE94
Newton’s law of gravitation.—Kepler’s observation ofcomets’ tails.—The thesis of Euler.—Proof of Maxwell.—Theradiation pressure.—Electric charges and condensation.—Comets’tails and radiation pressure.—Constituentsand properties of comets’ tails.—Weight of the solar corona.—Lossand gain of matter by the sun.—Nature of meteorites.—Electriccharge of the sun.—Electrons drawn into thesun.—Magnetic properties of the sun and appearance of thecorona.—Constituents of the meteors.—Nebulæ and theirheat and light.
[V].THE SOLAR DUST IN THE ATMOSPHERE. POLARLIGHTS AND THE VARIATIONS OF TERRESTRIAL MAGNETISM118
The supply of dust from the sun rather insignificant.—Polarizationof the light of the sky.—The upper clouds.—Differentkinds of auroræ.—Their connection with thecorona of the sun.—Polar lights and sun-spots.—Periodicityof polar lights.—Polar lights and magnetic disturbances.—Velocityof solar dust.—Fixation of atmospheric nitrogen.—TheZodiacal Light.
[VI].END OF THE SUN.—ORIGIN OF NEBULÆ148
The extinction of the sun.—Collision between two celestialbodies.—The new star in Perseus.—Formation of nebulæ.—Theappearance of nebulæ.—The nebulæ catch wanderingmeteors and comets.—The ring nebula in Lyra.—Variablestars.—Eta in Argus.—Mira Ceti.—Lyra and Algol stars.—Evolutionof the stars.
[VII].THE NEBULAR AND THE SOLAR STATES191
The energy of the universe.—The entropy of the universe.—Theentropy increases in the suns, but decreases in thenebulæ.—Temperature and constitution of the nebulæ.—Schuster’scalculations of the condition of a celestial bodyconsisting of gases.—Action of the loss of heat on nebulæand on suns.—Development of a rotating nebula into aplanetary system.—The hypothesis of Kant-Laplace.—Objectionsto it.—The views of Chamberlin and Moulton.—Theradiation pressure balances the effect of Newtoniangravitation.—The emission of gases from the nebulæ balancesthe waste of heat characteristic to the solar systems.
[VIII].THE SPREADING OF LIFE THROUGH THE UNIVERSE212
Stability of the species.—Theory of mutation.—Spontaneousgeneration.—Bathybius.—Panspermia.—The stand-pointsof Richter, Ferdinand Cohn, and Lord Kelvin.—Theradiation pressure enables spores to escape.—The effect ofstrong sunlight and of cold on the germinating power.—Transportof spores through the atmosphere into universalspace and through it to other planets.—General conclusions.

EXPLANATION OF ABBREVIATIONS, ETC.

The temperatures are stated in degrees centigrade (° C.), either on the Celsius scale, on which the freezing-point of water is 0°, or on the absolute scale, whose zero lies 273 degrees below the freezing-point of water, at -273° C. The equivalent temperatures on the Fahrenheit scale (freezing-point of water 32° F.) are added in brackets (° F.).

1 metre (m.) = 10 decimetres (dm.) = 100 centimetres (cm.) = 1000 millimetres (mm.) = 3.28 ft.; 1 kilometre (km.) = 1000 metres (m.) = 0.62 miles; 1 mile = 1.6 kilometres (km.).

Light travels in vacuo at the rate of 300,000 km. (nearly 200,000 miles) per second.

ILLUSTRATIONS

FIG.PAGE
[1]. VESUVIUS, AS SEEN FROM THE ISLAND OF NISIDA, INMODERATE ACTIVITY2
[2]. ERUPTION OF VESUVIUS IN 18824
[3]. ERUPTION OF VESUVIUS IN 18726
[4]. PHOTOGRAPH OF VESUVIUS, 1906. CHIEFLY CLOUDS OFASHES8
[5]. BLOCK LAVA ON MAUNA LOA10
[6]. THE EXCELSIOR GEYSER IN YELLOWSTONE PARK, U. S. A.REMNANT OF THE POWERFUL VOLCANIC ACTIVITY IN THE TERTIARY AGE11
[7]. MATO TEPEE IN WYOMING, U. S. A. TYPICAL VOLCANIC"NECK"12
[8]. CLEFTS FILLED WITH LAVA AND VOLCANIC CONE OF ASHES,TOROWHEAP CAÑON, PLATEAU OF COLORADO13
[9]. THE KILAUEA CRATER ON HAWAII15
[10]. CHIEF EARTHQUAKE CENTRES, ACCORDING TO THE BRITISHASSOCIATION COMMITTEE22
[11]. CLEFTS IN VALENTIA STREET, SAN FRANCISCO, AFTER THEEARTHQUAKE OF 190625
[12]. SAND CRATERS AND FISSURES, PRODUCED BY THE CORINTHEARTHQUAKE OF 1861. IN THE WATER, BRANCHES OF FLOODED TREES27
[13]. EARTHQUAKE LINES IN LOWER AUSTRIA30
[14]. LIBERTY BUILDING OF LELAND STANFORD JUNIOR UNIVERSITY,IN CALIFORNIA, AFTER THE EARTHQUAKE OF 190632
[15]. EARTHQUAKE LINES IN THE TYRRHENIAN DEPRESSION34
[16]. SEISMOGRAM RECORDED AT SHIDE, ISLE OF WIGHT, ONAUGUST 31, 189835
[17]. PHOTOGRAPH OF THE SURFACE OF THE MOON, IN THE VICINITYOF THE CRATER OF COPERNICUS62
[18]. SUN-SPOT GROUP AND GRANULATION OF THE SUN74
[19]. PART OF THE SOLAR SPECTRUM OF JANUARY 3, 187275
[20]. METALLIC PROMINENCES IN VORTEX MOTION76
[21]. FOUNTAIN-LIKE METALLIC PROMINENCES76
[22]. QUIET PROMINENCES OF SMOKE-COLUMN TYPE77
[23]. QUIET PROMINENCES, SHAPE OF A TREE77
[24]. DIAGRAM ILLUSTRATING THE DIFFERENCES IN THE SPECTRAOF SUN-SPOTS AND OF THE PHOTOSPHERE78
[25]. SPECTRUM OF A SUN-SPOT, THE CENTRAL BAND BETWEENTHE TWO PORTIONS OF THE PHOTOSPHERE SPECTRUM78
[26]. THE GREAT SUN-SPOT OF OCTOBER 9, 190379
[27]. THE GREAT SUN-SPOT OF OCTOBER 9, 190380
[28]. THE GREAT SUN-SPOT OF OCTOBER 9, 190381
[29]. THE GREAT SUN-SPOT OF OCTOBER 9, 190382
[30]. PHOTOGRAPH OF THE SOLAR CORONA OF 190083
[31]. PHOTOGRAPH OF THE SOLAR CORONA OF 187084
[32]. PHOTOGRAPH OF THE SOLAR CORONA OF 189885
[33]. PHOTOGRAPH OF ROERDAM’S COMET (1893 II.), SUGGESTINGSEVERAL STRONG NUCLEI IN THE TAIL100
[34]. PHOTOGRAPH OF SWIFT’S COMET (1892 I.)101
[35]. DONATI’S COMET AT ITS GREATEST BRILLIANCY IN 1858102
[36]. IMITATION OF COMETS’ TAILS104
[37]. GRANULAR CHONDRUM FROM THE METEORITE OF SEXES.ENLARGEMENT 1 : 70109
[38]. ARCH-SHAPED AURORÆ BOREALIS, OBSERVED BY NORDENSKIOLDDURING THE WINTERING OF THE VEGA INBERING STRAIT 1879124
[39]. AURORA BOREALIS, WITH RADIAL STREAMERS125
[40]. AURORA WITH CORONA, OBSERVED BY GYLLENSKIÖLD ONSPITZBERGEN, 1883126
[41]. POLAR-LIGHT DRAPERIES, OBSERVED IN FINNMARKEN, NORTHERNNORWAY127
[42]. CURVE OF MAGNETIC DECLINATION AT KEW, NEAR LONDON,ON NOVEMBER 15 AND 16, 1905138
[43]. CURVE OF HORIZONTAL INTENSITY AT KEW ON NOVEMBER15 AND 16, 1905139
[44]. ZODIACAL LIGHT IN THE TROPICS146
[45]. SPECTRUM OF NOVA AURIGÆ, 1892154
[46]. DIAGRAM INDICATING THE CONSEQUENCES OF A COLLISIONBETWEEN TWO EXTINCT SUNS157
[47]. SPIRAL NEBULA IN THE CANES VENATICI159
[48]. SPIRAL NEBULA IN THE TRIANGLE161
[49]. THE GREAT NEBULA IN ANDROMEDA163
[50]. RING-SHAPED NEBULA IN LYRA164
[51]. CENTRAL PORTION OF THE GREAT NEBULA IN ORION165
[52]. NEBULAR STRIÆ IN THE STARS OF THE PLEIADES167
[53]. NEBULAR STRIÆ IN THE SWAN169
[54]. NEBULA AND STAR RIFT IN THE SWAN, IN THE MILKY WAY171
[55]. GREAT NEBULA NEAR RHO, IN OPHIUCHUS172
[56]. STAR CLUSTER IN HERCULES173
[57]. STAR CLUSTER IN PEGASUS175
[58]. CONE-SHAPED STAR CLUSTER IN GEMINI176
[59]. COMPARISON OF SPECTRA OF STARS OF CLASSES 2, 3, 4185
[60]. COMPARISON OF SPECTRA OF STARS OF CLASSES 2, 3, 4186