| PAGE |
| INTRODUCTION | 1 |
| CHAPTER I. | |
| The bases of modern astronomy. Their late formation | 18 |
| Instruments and measures used by ancient astronomers | 19 |
| Weights and measures sought out by modern astronomers | 20 |
| Means employed to discover the density of the earth. | |
| Measuring by means of plummets not sufficiently exact | 20 |
| Measurements with torsion and chemical balances more accurate | 21 |
| Sir George B. Airy’s theory, and experiments at the Harton colliery | 22 |
| Results of experiments not reliable. Theory contrary to the Law of Attraction | 23 |
| Proof by arithmetical calculation of its error | 24 |
| Difficulties in comparing beats of pendulums at top and bottom of a mine | 26 |
| The theory upheld by text-books without proper examination | 27 |
| Of a particle of matter within the shell of a hollow sphere. | |
| Not exempt from the law of Attraction | 28 |
| A particle so situated confronted with the law of the | |
| inverse square ofdistance from an attracting body. Remarks thereon | 29 |
| It is not true that the attraction of a spherical shell | |
| is “zero” for a particle of matter within it | 31 |
| CHAPTER II. | |
| The moon cannot have even an imaginary rotation on its axis, | |
| but is generally believed to have. Quotations to prove this | 33 |
| Proofs that there can be no rotation. The most confused | |
| assertion that there is rotation shown to be without foundations | 35 |
| A gin horse does not rotate on its axis in its revolution | 37 |
| A gin horse, or a substitute, driven instead of being a driver | 38 |
| Results of the wooden horse being driven by the mill | 38 |
| The same results produced by the revolution of the moon. | |
| Centrifugal force sufficient to drive air and water away from our side of the moon | 39 |
| That force not sufficient to drive them away from its other side | 40 |
| No one seems ever to have thought of centrifugal force in connection with air and water on the moon | 41 |
| Near approach made by Hansen to this notion | 41 |
| Far-fetched reasons given for the non-appearance of air and water | 42 |
| The moon must have both on the far-off hemisphere | 44 |
| Proofs of this deduced from its appearance at change | 44 |
| Where the evidences of this may be seen if looked for at the right place. | |
| The centrifugal force shown to be insufficient to drive off even air, | |
| and less water, altogether from the moon | 45 |
| The moon must have rotated on its axis at one period of its existence | 47 |
| The want of polar compression no proof to the contrary | 48 |
| Want of proper study gives rise to extravagant conceptions, | |
| jumping at conclusions, and formation of “curious theories” | 48 |
| CHAPTER III. | |
| Remarks on some of the principal cosmogonies. Ancient notions | 49 |
| The Nebular hypothesis of Laplace. Early opinions on it. | |
| Received into favour. Again condemned as erroneous | 50 |
| Defects attributed to it as fatal. New cosmogonies advanced | 51 |
| Dr. Croll’s collision, or impact, theory discussed | 53 |
| Dr. Braun’s cosmogony examined | 59 |
| M. Faye’s “Origine du Monde” defined | 61 |
| Shown to be without proper foundation, confused, and in some parts contradictory | 65 |
| Reference to other hypotheses not noticed. All more or less | |
| only variations on the nebular hypothesis | 70 |
| Necessity for more particular examination into it | 71 |
| CHAPTER IV. | |
| Preliminaries to analysis of the Nebular hypothesis | 72 |
| Definition of the hypothesis | 73 |
| Elements of solar system. Tables of dimensions and masses | 75 |
| Explanation of tables and density of Saturn | 78 |
| Volume, density and mass of Saturn’s rings, general remarks | |
| about them, and satellites to be made from them | 79 |
| Future of Saturn’s rings | 79 |
| Notions about Saturn’s satellites and their masses | 80 |
| Nature of rings seemingly not well understood | 81 |
| Masses given to the satellites of Uranus and Neptune. Explanations of | 81 |
| Volumes of the members of the solar system at density of water | 82 |
| CHAPTER V. | |
| Analysis of the Nebular Hypothesis. Separation from the nebula | |
| of the rings for the separate planets, etc. | 83 |
| Excessive heat attributed to the nebula erroneous and impossible | 84 |
| Centigrade thermometer to be used for temperatures | 85 |
| Temperature of the nebula not far from absolute zero | 86 |
| Erroneous ideas about glowing gases produced by collisions of their atoms, | |
| or particles of cosmic matter in the form of vapours | 86 |
| Separation of ring for Neptune. It could not have been | |
| thrown off in one mass, but in a sheet of cosmic matter | 87 |
| Thickness and dimensions of the ring | 88 |
| Uranian ring abandoned, and its dimensions | 89 |
| Saturnian ring abandoned, and its dimensions | 90 |
| Jovian ring abandoned, and its dimensions | 91 |
| Asteroidal ring abandoned, and its dimensions | 93 |
| Martian ring abandoned, and its dimensions | 94 |
| Earth ring abandoned, and its dimensions | 95 |
| Venus ring abandoned, and its dimensions | 96 |
| Mercurian ring abandoned, and its dimensions | 97 |
| Residual mass. Condensation of Solar Nebula to various | |
| diameters, and relative temperatures and densities | 98 |
| Unaccountable confusion in the mode of counting absolute temperature examined and explained. | |
| Negative 274 degrees of heat only equal 2 degrees of absolute temperature | 100 |
| The Centigrade thermometric scale no better than any other, and cannot be made decimal | 103 |
| The sun’s account current with the Nebula drawn up and represented by Table III. | 104 |
| CHAPTER VI. | |
| Analysis continued. Excessive heat of nebula involved condensation only at | |
| the surface. Proof that this was Laplace’s idea | 108 |
| Noteworthy that some astronomers still believe in excessive heat | 109 |
| Interdependence of temperature and pressure in gases and vapours. | |
| Collisions of atoms the source of heat | 110 |
| Conditions on which a nebula can be incandescent. Sir Robert Ball | 110 |
| No proper explanation yet given of incandescent or glowing gas | 112 |
| How matter was thrown off, or abandoned by the Jovian nebula | 115 |
| Division into rings of matter thrown off determined during contraction | 116 |
| How direct rotary motion was determined by friction and collisions of particles | 117 |
| Saturn’s rings going through the same process. Left to show process | 118 |
| Form gradually assumed by nebulæ. Cause of Saturn’s square-shouldered appearance | 120 |
| A lens-shaped nebula could not be formed by surface condensation | 120 |
| Retrograde rotary motion of Neptune and Uranus, and revolution of their satellites | |
| recognised by Laplace as possible | 121 |
| Satellites of Mars. Rapid revolution of inner one may be accounted for | 123 |
| Laplace’s proportion of 4000 millions not reduced but enormously | |
| increased by discoveries of this century | 124 |
| CHAPTER VII. | |
| Analysis continued. No contingent of heat could be imparted to any planet by the parent nebula | 126 |
| Only one degree of heat added to the nebula from the beginning till it had | |
| contracted to the density of 1/274th of an atmosphere | 127 |
| Increase in temperature from 0° to possible average of 274° | |
| when condensed to 4,150,000 miles in diameter | 127 |
| Time when the sun could begin to act as sustainer of life and light anywhere. | |
| Temperature of space | 128 |
| The ether devised as carrier of light, heat, etc. What effect it might have on the nebula | 129 |
| First measure of its density, as far as we know | 130 |
| The estimate too high. May be many times less | 133 |
| Return to the solar nebula at 63,232,000 miles in diameter | 134 |
| Plausible reason for the position of Neptune not conforming to Bode’s Law. | |
| The ring being very wide had separated into two rings | 134 |
| Bode’s law reversed. Ideas suggested by it | 135 |
| Rates of acceleration of revolution from one planet to another | 137 |
| Little possibility of there being a planet in the position assigned to Vulcan | 138 |
| Densities of planets compared. Seem to point to differences | |
| in the mass of matter abandoned by the nebula at different periods | 138 |
| Giving rise to the continuous sheet of matter separating into different masses. | |
| Probably the rings had to arrive at a certain stage of density before contracting circumferentially | 139 |
| Possible average temperature of the sun at the present day. | |
| Central heat probably very much greater | 140 |
| Churning of matter going on in the interior of the sun, caused by unequal | |
| rotation between the equator and the poles | 140 |
| CHAPTER VIII. | |
| Inquiry into the Interior Construction of the Earth. | |
| What is really known of the exterior or surface | 142 |
| What is known of the interior | 143 |
| Little to be learned from Geology, which reaches very few miles down | 144 |
| Various notions of the interior | 145 |
| What is learnt from earthquake and volcanoes. Igno-aqueous fusion, liquid magma. | 146 |
| Generally believed that the earth consists of solid matter to the centre. | |
| Mean density. Surface density | 147 |
| More detailed estimate of densities near the surface | 148 |
| Causes of increased surface density after the crust was formed | 148 |
| Calculations of densities for 9 miles deep, and from there to the centre forming Table IV. | 150 |
| Reflections on the results of the calculations | 151 |
| Notion that the centre is composed of the heaviest metals. | |
| “Sorting-out” theory absurd | 151 |
| Considerations as to how solid matter got to the centre | 152 |
| Gravitation might carry it there, but attraction could not | 153 |
| How the earth could be made out of cosmic matter, meteorites or meteors | 154 |
| CHAPTER IX. | |
| Inquiry into the Interior Construction of the Earth—continued | 165 |
| The earth gasiform at one period. Density including the moon may have been 1/10,000th | |
| that of air. Must have been a hollow body. Proofs given | 166 |
| Division of the mass of the earth alone into two parts | 169 |
| Division of the two masses at 817 miles from surface | 171 |
| Reasons why the earth cannot be solid to the centre | 172 |
| Gasiform matter condensing in a cone leaves apex empty | 172 |
| Proportions of the matter in a cone | 173 |
| Calculations of the densities of the outer half of the hollow | |
| shell of the earth. Remarks upon the condensation | 174 |
| Calculations of inner half of the hollow shell | 175 |
| Remarks upon position of inner surface of the shell | 177 |
| Calculations of the same | 179 |
| CHAPTER X. | |
| Inquiry into the interior construction of the Earth—continued | 184 |
| Density of 8·8 times that of water still too high for the | |
| possible compression of the component matter of the earth as known to us | 185 |
| Reasons for this conclusion drawn from crushing strains of materials | 186 |
| A limit to density shown thereby | 187 |
| The greatest density need not exceed 6·24 of water | 188 |
| Gases shut up in the hollow centre. Their weight must so | |
| far diminish the conceded maximum of 6·24 | 189 |
| Density of inner half of earth at 3000 miles diameter. | |
| Greatest density may be less than 5·833 of water | 190 |
| Supposed pressure of inclosed gases very moderate | 191 |
| Meaning of heat limit to density. Temperature of interior | |
| half of shell and inclosed gases must be equal | 193 |
| State of the hollow interior | 194 |
| Results of the whole inquiry | 195 |
| CHAPTER XI. | |
| The Earth. The idea entertained by some celebrated men, and others | 197 |
| Difficulties of forming a sphere out of a lens-shaped nebula | 199 |
| Various studies of the earth’s interior made for specialy purposes. Difficulty some | |
| people find in conceiving how the average density of little over 5·66 can be | |
| possible, the earth being a hollow sphere | 200 |
| What is gained by its being a hollow shell | 201 |
| Geological theories of the interior discussed. | |
| Volcanoes and earthquakes in relation to the interior | 202 |
| Liquid matter on the interior surface of the shell, and gases in the hollow, | |
| better means for eruptions than magma layers | 206 |
| Focal depths of earthquakes within reach of water, but not of lavas | 207 |
| Minute vesicles in granite filled with gases, oxygen and hydrogen, but not water | 209 |
| The Moon. A small edition of the earth | 211 |
| Rotation stopped. Convulsions and cataclysms caused thereby. Air, water, | |
| vapour driven off thereby to far-off hemisphere. Liquid matter in hollow | |
| interior would gravitate to the inside of the nearest hemisphere | 212 |
| Form and dimensions during rotation. Altered form after it stopped | 213 |
| Agreeing very closely with Hansen’s “curious theory” | 214 |
| CHAPTER XII. | |
| Some of the results arising from the sun’s being a hollow sphere | 215 |
| Repetition of the effects of condensation on the temperature of the nebula | 216 |
| Ideas called up by the apparently anomalous increase of temperature | 217 |
| How heat is carried from the sun to the earth | 218 |
| The sun supposed to radiate heat only to bodies that can receive and hold it, | |
| and not to all space. The heat of the sun accumulated in a | |
| hot box to considerably beyond the boiling point of water | 219 |
| The heat accumulated in this way supposed to be due to a peculiar function of the ether, | |
| as it is a fact that heat can be radiated from a cold to a hot body | 220 |
| The sun must be gaseous, or rather gasiform, throughout. No matter in it solid | |
| or even liquid. Divisions and densities of shell | 221 |
| The hollow centre filled with gases, whose mass naturally | |
| diminishes the mean density of the whole body | 222 |
| The amount of this reduction so far defined. The presence of gases or vapours | |
| in the hollow a natural result of condensation | 223 |
| The hollow centre filled with gases not incompatible with the sun’s being | |
| a hollow sphere. The temperature at the centre may be anything, | |
| not depending on any law of gases | 223 |
| Further exposition of hollow-sphere theory put off till after | |
| further development of the construction of the sun | 224 |
| CHAPTER XIII. | |
| The ether. Its nature considered. Behaves like a gas | 226 |
| Can be pumped out of a receive | 227 |
| Light and heat do not pass through a tube in vacuo. | |
| Laboratory experiments examined | 228 |
| Light and darkness in a partial vacuum, though high | 229 |
| Electricity not a carrying agent | 230 |
| Why there are light and dark strata in a high vacuum | 232 |
| The real carrying agent through a high vacuum is the residue | |
| of ether left in it. Digression to consider the aurora | 233 |
| How air may be carried to extraordinary heights. Zones of | |
| air carried up are made luminous by electricity | 234 |
| Comparison of this method with experiments quoted | 236 |
| Experiment suggested to prove whether light passes freely through a vacuum tube | 237 |
| The ether does not pervade all bodies freely | 238 |
| It must be renounced altogether or acknowledged to be a material body, | |
| subject to expansion, condensation, heating or cooling | 239 |
| How light and heat pass through glass | 239 |
| Temperature of the ether variable. Zodiacal light, cause of | 240 |
| CHAPTER XIV. | |
| The ether considered and its nature explained. Further proofs | |
| given by Dr. Crookes’s work, of its material substance | 244 |
| Highest vacuum yet produced. Absorbents cannot absorb the ether | 246 |
| Dr. Crookes’s definition of a gas. Not satisfactory. Why | 247 |
| A fluid required to pump matter out of a vessel | 248 |
| Gas as described by Dr. Crookes would not suit | 249 |
| The ether the only elastic fluid we have. The only real gas,if it is a gas | 250 |
| A possible measure of the density of the ether | 250 |
| Causes of dark and light zones in high vacua | 251 |
| The real conductor of light in a high vacuum | 252 |
| How a vacuum tube glows, when electricity passes through it | 254 |
| Conclusions arrived at through foregoing discussions | 255 |
| Some exhibitions of light explained | 256 |
| Gases can be put in motion, but cannot move even themselves | 257 |
| The ether shown to be attraction. And primitive matter also | 258 |
| All chemical elements evolved from it. Its nature stated | 259 |
| Action at a distance explained by the ether and attraction | |
| being one and the same | 259 |
| CHAPTER XV. | |
| Construction of the solar system. Matter out of which it was formed | 261 |
| Domains of the sun out of which the matter was collected | 262 |
| Stars nearest to the sun. Table VII. showing distances | 263 |
| Remarks on Binary Stars. Table VIII. showing spheres of | |
| attraction between the sun and a very few | 265 |
| Sirius actually our nearest neighbour. Form of the sun’s domains of a very jagged nature | 266 |
| Creation of matter for the nebulæ, out of which the whole universe was | |
| elaborated. Beginning of construction | 267 |
| The law of attraction begins to operate through the agency of evolution | 267 |
| Form of the primitive solar nebula. The jagged peaks | |
| probably soon left behind in contraction | 268 |
| How the nebula contracted. Two views of the form it might take. | |
| Comparison of the two forms, solid or hollow | 269 |
| The hollow centre form adopted. The jagged peaks left behind | 272 |
| The nebula assuming a spherical form. Shreds, masses, | |
| crescents separated from one side | 273 |
| Probable form of interior of nebula. Compared with envelopes in heads of some comets | 274 |
| Reflections on the nebula being hollow. Opinions of others quoted | 275 |
| The matter of a sphere solid to the centre must be inert there | 276 |
| Further proofs of the nebula being hollow | 277 |
| How rotary motion was instituted | 278 |
| Such a nebula might take one of two forms | 279 |
| The form depending on the class of nebula. Planetary in the case of the solar system. | |
| A similar conception of how rotary motion could be instituted | 280 |
| CHAPTER XVI. | |
| The sun’s neighbours still exercise their attraction over him | 282 |
| Regions of greatest density in the 9 nebulæ dealt with; compared with the | |
| orbits of the planets made from them | 283 |
| Results of comparison favourable to the theory | 287 |
| Differences of size in the planets have arisen from variations in the quantity | |
| of matter accumulating on the nebulæ | 289 |
| Causes of the retrograde motions in Neptune, Uranus, and their satellites | 290 |
| Probable causes of the anomalous position of Neptune | 292 |
| Rises and falls in the densities and dimensions of the planets explained | 293 |
| The form of the nebulæ must have resembled a dumb-bell | 295 |
| More about rises and falls in densities | 296 |
| Reason why the Asteroid nebula was the least dense of the system; | 297 |
| Not necessary to revise the dimensions given to the 9 nebulæ | 298 |
| Causes of the anomalies in the dimensions, densities, etc., of the Earth and Venus | 299 |
| The strictly spherical form of the sun accounted for. But it may yet be varied | 299 |
| Repetition that a spherical body could not be made from a lens-shaped | |
| nebula by attraction and condensation | 300 |
| CHAPTER XVII. | |
| Former compromises taken up and begun to be fulfilled | 301 |
| Estimates of the heat-power of the sun made only from gravitation hitherto | 302 |
| Contraction and condensation of a nebula solid to the centre. | |
| Heat produced from attraction as well as by gravitation | 303 |
| What quantity of heat is produced by a stone falling upon the earth | 304 |
| Showing again that there is a difference between attraction and gravitation | 305 |
| Contraction and condensation of a hollow-sphere nebula, in the same manner as the solid one | 305 |
| Differences of rotation would be greater in a hollow nebula; because a great deal of | |
| the matter would be almost motionless in a solid sphere; | 306 |
| In neither case could matter be brought to rest, but only retarded in motion. | |
| Different periods of rotation accounted for | 307 |
| Table of different rates explained | 309 |
| Heat produced by gravitation, attraction and churning, not all | |
| constituents of the heat-power of the sun | 310 |
| There can be no matter in the sun so dense as water | 311 |
| The hollow part of the sun acting as a reservoir of | |
| gases, heat and pressure | 312 |
| The behaviour of heat produced in the nebula, and its power | 313 |
| How sun-spots are produced | 314 |
| Cyclonic motions observed in sun-spots. Why not all in | |
| certain directions, and why only observed in a very few | 315 |
| Cyclonic motions in prominences treated of | 316 |
| Many other things might be explained, on some of which we | |
| do not dare to venture. Concluding observations | 317 |
| CHAPTER XVIII. | |
| Return to the peaks abandoned by the original nebula. An idea of their number | 319 |
| Example of their dimensions. What was made out of them | 320 |
| What could be made from one of them | 321 |
| How it could be divided into comets and meteor swarms | 322 |
| An example given. How a comet may rotate on its axis. And what might be | |
| explained thereby. Orbits and periods of revolution | 323 |
| Not ejected from planets. Their true origin | 324 |
| Study of the velocities in orbit of comets, and results thereof | 326 |
| How far comets may wander from the sun and return again | 327 |
| No reason why comets should wander from one sun to another. Confirmatory | |
| of the description, in Chapter XV. of the sun’s domains | 328 |
| Of the eternal evolution and involution of matter. | |
| The atmosphere and corona of the sun | 329 |
| Partial analogy between it and the earth’s atmosphere | 331 |
| The density of it near the sun’s surface cannot be normally less than 28 atmospheres, | |
| but might be so partially and accidentally | 332 |
| Probable causes of the enormous height of its atmosphere | 332 |
| The mass taken into account, but cannot be valued | 334 |
| Most probably no matter in the sun exceeds half the density of water. | |
| The unknown line in the spectrum of the corona belongs to the ether | 335 |