LIBRARY 
 
 OF THE 
 
 UNIVERSITY OF CALIFORNIA. 
 
 ClMS 
 
 GENERM- 
 
THE ROMANCE OF THE 
 HEAVENS 
 
THE 
 
 ROMANCE OF THE HEAVENS 
 
 BY 
 
 A. W. BICKERTON 
 
 Professor of Chemistry, Canterbury College, Christchurch 
 New Zealand University 
 
 AUTHOR OF " THE ROMANCE OF THE EARTH," ETC. 
 
 "The whole difficulty of Philosophy seems to me to He In inves- 
 tigating the forces of Nature from the phenomena of motion, and 
 in demonstrating that from these forces other phenomena will 
 ensue. " JYe wton. 
 
 R A 
 
 OF THF. 
 
 UNIVERSITY 
 
 LONDON 
 SWAN SONNENSCHEIN & CO., LIM., 
 
 PATERNOSTER SQUARE 
 IQOI 
 

 GENERM. 
 
P R E F A C E 
 
 A THEORY that finds Astronomy a chaos 
 of facts and converts it into a classified 
 system ; that finds no generally accepted 
 explanation of the genesis of a single 
 celestial body or system and leaves none 
 untold ; that also shows the mechanism by 
 which the Cosmos renews itself and ^ives 
 
 o 
 
 probability to the belief that it is infinite 
 and immortal, obviously trenches upon 
 ground not commonly trodden. Such a 
 theory must be of so comprehensive a 
 character that it cannot be supposed that a 
 small work like the present exhausts the 
 subject. Any one of its four main divisions, 
 if fully treated, would require a volume ; as 
 would the mathematical problems involved. 
 On the other hand the present volume, 
 although not strictly "popular," is such 
 that, with careful reading, any person with 
 
 101899 
 
Preface. 
 
 a good school knowledge of experimental 
 science should be able to follow the 
 argument. In fact, so obvious are the 
 main ideas, that, as deduction carries one 
 from simple celestial bodies, past complex 
 cosmic systems, to still more complex 
 systems, one feels the mechanism of 
 cosmic evolution to be the car of an intel- 
 lectual mountain motor. And so easily is 
 one carried past phenomenon after phe- 
 nomenon to the loftiest pinnacle of human 
 thought, that it is only by the variety of 
 the scene, and the expansive width of the 
 prospect that one realises the elevation to 
 which one has been taken. 
 
 Readers of my former papers will see 
 that the term " universes " so often occcur- 
 ring in them, has in this volume been 
 replaced by "cosmic systems." This was 
 done, because, as both Lord Kelvin and 
 Lord Rayleigh independently pointed out 
 to me, the term "universes" would be 
 liable to be misunderstood. 
 
CHAPTER I 
 
 PARTIAL IMPACT 
 
 CELESTIAL PHENOMENA VARIATION OF SPLENDOUR 
 INSIGNIFICANT SIZE OF THE EARTH. CELESTIAL 
 EVOLUTION SUGGESTED-A THEORY BLENDING PHIL- 
 OSOPHY WITH SCIENCE OTHER THEORIES UNSATIS- 
 FACTORY. COMPREHENSIVE SCOPE OF THE INQUIRY. 
 ASTRO-PHYSICS-HEAT A MODE OF MOTION ITS TWO 
 KINDS RADIANT ENERGY-THEORY OF HEAT AND 
 MATTER CONVERSION OF MOTION OF MASS INTO 
 HEAT HEAT RESULTS FROM IMPACTS HIGH TEM- 
 PERATURES AND HIGH VELOCITIES-CRITICAL VELO- 
 CITIES. POSSIBILITIES OF STELLAR COLLISION - 
 DIRECT COLLISIONS IMPROBABLE. THREE PHENO- 
 MENA ASSOCIATED WITH PARTIAL IMPACT A THIRD 
 BODY FORMED HIGH TEMPERATURE EVOLVED - 
 INSTABILITY OF THE NEW BODY. 
 
 INTRODUCTORY. 
 
 The phenomena of the heavens have ever 
 been matters of interest to historic man, and 
 doubtless his pre-historic ancestors also pon- 
 dered over these mysteries. They could not 
 fail to note the rising and setting of the sun 
 the moon, and the stars ; nor could they help 
 observing the phases of the moon and her 
 
10 PARTIAL IMPACT 
 
 periodic change of place with regard to the sun, 
 and the similarity of her phases with her similar 
 relative positions. They would detect that the 
 winter aspect of stellar distribution differed from 
 its summer aspect. The splendid genius of 
 the paleolithic artist, who, as proved by the 
 remnants of the past, could sketch with such 
 spirited fidelity the giant elk and hairy elephant, 
 would have forced upon his trained eye the 
 permanency of the pattern in the stars of the 
 celestial vault, and amidst that permanency he 
 would detect the planets by their erratic move- 
 ments. 
 
 As he noticed the permanence of the varied 
 glory of the stars, he would perceive in those 
 wandering lights not merely difference in splen- 
 dour, but that this splendour also varied periodi- 
 cally as did their place amongst the stars. The 
 observant eye of the artist would note not 
 merely the contrast of dark and gloomy Saturn 
 with brilliant Venus, but would also observe the 
 glowing effulgence of Venus at quadrature com- 
 pared to her aspect at other times. But if none 
 of these fixed and changing marvels attracted 
 him, the most stolid eye would be delighted, 
 when stretching from zenith to horizon, the 
 
PARTIAL IMPACT II 
 
 magnificent plume of some gigantic comet 
 swept with majestic grace across the whole 
 expanse of the heavens. And as he watched 
 these many marvels, his questioning mind 
 would ask, as we continue to inquire, Why? and 
 Whence ? 
 
 Both to primitive and to early historic men 
 alike, the vast earth upon which they lived 
 would occupy in their thoughts the place of 
 premier importance, so they would answer the 
 question Why? by assuming that all the celestial 
 glories were but ministering lights for man's 
 convenience and joy. 
 
 Not so can we now regard them. A speck of 
 cosmic dust, a mote in space, an insignificant 
 member of a solar system resembling hundreds 
 of millions of systems in our single universe 
 such is the astronomer's verdict as to the cosmic 
 importance of our world. And we members of 
 the human family, what are we compared in 
 size to a mountain range ? And what is the 
 mountain range relative to the earth, the vast 
 earth that it costs us months to circumnavi- 
 gate ? Yet a human being, with his thinking- 
 power, is marvellous. And marvellous is any 
 animal, any plant. A leaf is a laboratory built 
 
12 PARTIAL IMPACT 
 
 up of wonders, of cells whose complexity is only 
 now beginning to be unfolded to us. Then 
 every part of every cell is made up of myriads 
 of molecules, each molecule a regiment of 
 atoms ; whilst the spectroscope reveals to us 
 the incredible miracle of the complexity of 
 an atom. So that accompanying the loss of 
 our sense of self-importance comes so deep a 
 knowledge of miracles of structure, that a 
 reverential awe equally impresses us whether 
 Ave examine the complexities of the incon- 
 ceivably minute or the immensities of cosmic 
 extension, and the mystery and the sublimity 
 of our own existence only grows the greater. 
 
 But whilst the marvellous structure and 
 gigantic dimensions of cosmic bodies and 
 systems are revealed to us in their complex 
 grandeur, we hear little that we can accept 
 concerning their genesis. Much indeed have 
 astronomers made known to us of their ex- 
 quisite order, but little have they instructed 
 us in the mechanism of their evolution. 
 
 This attempt to fill this want, to describe 
 scientifically, yet in simple language, a gener- 
 alisation explaining the evolution of stellar 
 bodies and systems, apparently succeeds in 
 
PARTIAL IMPACT 13 
 
 carrying the principle of evolution beyond a 
 mere planet or even the solar system, and shows 
 that it is a universal law controlling the cosmos. 
 The theory shows not merely the mode of the 
 genesis of the universe in detail and as a whole, 
 but it also points out the possibility of the 
 immortality of the cosmos, thus solving the 
 problem which has been the great quest of the 
 thinker of all times, and blending philosophic 
 thought with scientific observation. 
 
 At a time when the once accepted theories of 
 the origin of the Solar System have passed 
 out of common acknowledgement, this generali- 
 sation gives an account of the genesis not 
 merely of the order, but also of the apparent 
 irregularities of the Solar System, and for the 
 first time in the history of Science offers an 
 intelligible account of the evolution of the galactic 
 system, consisting of the Milky Way and the 
 polar caps of nebulae, together commonly known 
 as the visible Universe ; and this account of its 
 origin is so consonant with its complex structure, 
 with its extraordinary contrasts and its definite 
 irregularities, that when understood, scepticism 
 seems almost impossible. 
 
 The correlation involves general thermo-dy- 
 
14 PARTIAL IMPACT 
 
 namics, the dynamical theory of gases, the doc- 
 trines of the indestructability of matter and 
 energy, and it also shows the great cosmic im- 
 portance of the diversity of the atomic weights 
 of the different elements. It makes use also of 
 such recent science that a few years ago the 
 conception could not be fully worked out, and 
 had to wait for facts since discovered. Many of 
 its results are based upon and strengthened by 
 the latest observations of the telescope and the 
 spectroscope, by photo-telescopy and spectro- 
 scopy. It uses such recondite phenomena as 
 Crooke's experiments in radiant matter. It was 
 incomplete until the discovery of the five mona- 
 tomic non-combining gases recently found in 
 the atmosphere by Lord Rayleigh arid Professor 
 Ramsay ; and it blends all these facts and ob- 
 servations into a perfect whole, there being ap- 
 parently not a single phenomenon that does not 
 fall naturally into its place, nor one observation 
 in opposition to its teaching. Every portion of 
 the subject has been tested by graphics, and 
 much of it confirmed by ordinary analytical 
 mathematics. A perusal of the following chapters 
 will show that although so far-reaching, the con- 
 ception is one of comparative simplicity and flows 
 
ASTRO-PHYSICS 15 
 
 naturally as deductions from the accepted laws 
 of matter and energy. In fact the whole state- 
 ment is but the application of chemistry and 
 physics to celestial phenomena. 
 
 ASTRO-PHYSICS. 
 
 A skilful smith will take a nail rod, and 
 hammer it until it becomes white hot ; and 
 when an emery wheel revolves against a saw in 
 the process of sharpening, a shower of sparks 
 flies off from the edge of the disc ; in the same 
 way when the break is put heavily on a rapidly 
 moving train, sparks issue from between the 
 rubbing surfaces. In all these cases we have 
 heat manifested or produced by the partial 
 stoppage of the motion of mass, and an im- 
 mense number of experiments have at length 
 demonstrated that heat is a mode of motion. 
 It is accepted in fact that heat is the inde- 
 pendent vibratory motion of the ultimate par- 
 ticles of matter. The mode of motion we 
 describe as heat may be of two kinds. It may 
 be an internal quivering of the atom or molecule 
 itself, or it may be the independent motion of 
 the atom or molecule in space as a whole. 
 
 Thus, to illustrate, if we have a spherical sheep- 
 
1 6 ASTRO-PHYSICS 
 
 bell and throw it against a wall, it bounds back 
 again and rings as it comes towards us. In this 
 act of coming towards us it has a motion as a 
 whole, and at the same time it has an internal 
 vibration manifested as sound. 
 
 This internal quivering usually dies down soon 
 after the encounter ; and the bell ceases to be 
 audible. When there is a similar internal quiver- 
 ing motion in atoms, they give off radiant energy 
 of definite rates of vibration, but in the case of 
 solids and liquids the molecules are so close to- 
 gether that practically there is but little interval 
 between the encounters, and consequently in the 
 case of solids and liquids the heat motion is 
 continuously of both kinds. When the vibratory 
 phenomenon occurs inside a Crookes' tube in 
 which there are but very few molecules, the 
 molecules seldom strike one another, and the 
 motion is very largely in free space. The 
 molecules first vibrate when they strike the 
 negative pole, and again vibrate on striking the 
 opposite end of the tube. In the interval between 
 the impacts they are moving freely but invisibly 
 in space ; and apparently their motion produces 
 no radiation or motion of the ether ; but when 
 they strike the surface of the tube, the vibration 
 
ASTRO-PHYSICS I/ 
 
 produced by the impact gives out that peculiar 
 radiation that is associated with the pheno- 
 menon of Rongten Rays. 
 
 In connection with the Theory of Constructive 
 Impact, the properties of the ultimate particles 
 of matter and the motion of molecules in free 
 space will form a very large part of the subject,, 
 and therefore we must devote some time to 
 the consideration of the atomic constitution of 
 matter. 
 
 The spectroscope, we have said, reveals to us 
 the complexity of atomic matter. As we examine 
 its lovely chromatic ribbon we are reading atomic 
 songs. The notes are too refined for the ear, the 
 vibrations too small, so we use the eye, and it is- 
 the music of colour we perceive. Our eyesight,, 
 however, is too gross for much of this atomic 
 music. The photographic plate is sensitive to 
 many of these more minute vibrations, and there 
 are substances exhibiting the property of fluores- 
 cence that accept the same minute vibrations 
 and transmute them into such as are visible. 
 In addition to this vibratory motion every atom 
 is a storehouse of complex forces ; though atoms 
 are so minute that were an orange magnified to 
 the size of the earth, the atoms of the orange 
 
1 8 ASTRO-PHYSICS 
 
 would range from shot to shell in dimension. 
 There are millions upon millions of atoms in a 
 drop of water. 
 
 Of these complex singing atoms the earth is 
 built Mostly the atoms are locked together in 
 attractive affinities that exist for ages. Some- 
 times they are changing partners at the rate of 
 the quickest of Scotch reels a million times 
 multiplied, but locked or free, they are always 
 vibrating. Not all the ingenuity of man, not all 
 his most refined machinery, can cause a single 
 atom to come to rest. Cailletet and Pictet have 
 produced such cold that the motion of the atoms 
 has been greatly reduced ; and the liquifaction 
 of hydrogen has enabled us to obtain a still 
 further reduction of the vibrations of the ultimate 
 particles of matter, but even with all these agents 
 the irrepressible atom still moves. 
 
 In a gas or vapour the particles are free, and 
 fly about, knocking one another and the sides of 
 the vessel containing them, thus exercising 
 pressures that may be enormous. They force 
 the pistons of giant engines to do the work of 
 thousands of horses ; rend immense rocks in 
 dynamite explosions ; and send the molten lava 
 of the volcano high into the air. Then we may 
 
ASTRO- PHYSICS 19 
 
 reduce the motion (cool and condense the vapour 
 we say), and the molecules cling together by 
 their mutual attraction ; but still they roll so 
 freely over one another, and slip about so easily, 
 that the liquid produced by the condensation 
 will find its level. Yet even in the liquid there 
 is still a great unrest. Drop a particle of soluble 
 crimson pigment into a tall jar of liquid, leave it 
 a few days, and the restless atoms carry the 
 colour, particle by particle, up the jar until the 
 whole is tinted. Again reduce the speed of the 
 molecules by further cooling, and another 
 attraction sets in ; the molecules as it were clasp 
 hands and are locked into a solid by the force 
 we call cohesion. Definite parts of one molecules 
 attract definite parts of others, and lovely forms 
 are produced. 
 
 The exquisite stellate snovvflake, the feathered 
 fern-like frost upon the window pane, and the 
 marvellous structure that salicine, soda, and many 
 other crystals exhibit under the polarising micro- 
 scope are examples of this force of cohesion. 
 
 On the earth we have the molecules in all 
 three states, tight locked in the granite rock and 
 the steel girder bridge, sliding freely over each 
 other in the waters of the great oceans, and free 
 
 ^N. 
 
 ff- \ 
 
 UNIVERSITY ) 
 
 OF - K J 
 
20 ASTRO-PHYSICS 
 
 to move in the atmosphere in the form of vapour 
 and gas. 
 
 This vibrating motion or heat that changes 
 solids into liquids and a liquid into a gas is a 
 form of an entity called energy, whilst the atoms- 
 in their varied forms are called matter. 
 
 These two indestructible entities : matter and 
 energy, are each capable of existing in many 
 forms, but the cosmic sum total of either is 
 apparently incapable of being lessened or 
 increased. 
 
 There is another entity called ether, that is 
 possibly made up of electricity in a medium. 
 Ether appears to fill all space, and is the carrier 
 of radiant energy. 
 
 Energy is always associated with matter or 
 ether and we have no conception of energy but 
 through the interposition of matter or ether ; 
 nevertheless, energy may pass from one body of 
 matter or ether into other bodies. 
 
 Heat is only one of the many forms of energy. 
 The motion of a projectile is another, and when 
 a projectile is suddenly brought to rest the 
 energy that it possessed as motion of mass 
 becomes largely converted into motion of its. 
 particles, or what we call heat. 
 
ASTRO-PHYSICS 21 
 
 If a body be perfectly elastic, it is distorted by 
 an impact, but recovers its shape directly after- 
 wards, and in doing so bounds back again. In 
 this case, no heat is produced. If, instead of 
 being elastic, the mass impacting be similar to 
 lead, the whole form may be changed by the 
 collision. The motion of the mass as a whole in 
 this case disappears, and the constituent atoms 
 quiver with the friction of the atoms sliding over 
 one another. So rapid may be their motion 
 that the internal vibrations may effect the ether 
 and produce a flash of light. It is in this way 
 that motion of mass changes into that motion 
 of the particles that we call heat. 
 
 Now the energy involved in the motion of a 
 ton weight moving at a certain velocity is 
 exactly the same whether the ton weight be a 
 single body or made up of bullets or shot. It is 
 quite easy to carry the conception still further 
 down until we imagine that the ton weight 
 consists of the separate ultimate particles of 
 matter, all moving together in the same direction, 
 but without independent internal motion. 
 
 Should an impact occur, this motion that was 
 formerly parallel becomes indeterminate, and 
 disregarding the internal vibration of the mole- 
 
ASTRO-PHYSICS 
 
 cules, we are justified in assuming that the 
 irregular motion of the molecules after the 
 impact will be of the same velocity as the motion 
 of the mass before the impact, provided of course, 
 that the whole of the motion of the mass is 
 converted into the indeterminate motion of the 
 molecules. 
 
 There is a definite general velocity in each 
 different kind of molecule that represents its 
 temperature. The higher the temperature the 
 faster the molecules move. If they move at 
 twice the speed the energy is four times 
 as great, and the temperature is four times as 
 high. The idea of one thing being hotter than 
 another is simple, and it is possible to say that it 
 is twice as hot, but on our thermometers if we 
 say that the temperature of a thing is twice as 
 hot if the temperature is 200 degrees, instead of 
 one hundred degrees, it is not true, because the 
 zero of our thermometers is not the zero of true 
 temperature. The Centigrade zero is the 
 freezing point of water, but there is heat, we 
 know in a snowball. It is said that an ingenuous 
 student once asked his professor how many 
 snowballs would be needed to cause a kettle to 
 boil. The answer is easy enough, for if the 
 
ASTRO-PHYSICS 23 
 
 kettle were filled with liquid hydrogen, or even, 
 with liquid carbonic acid, and if the snow ball 
 were big enough, it would easily cause either of 
 these liquid substances to boil, and the snow- 
 ball would be very much colder after the 
 operation. 
 
 But there is a temperature below which we 
 believe it is actually impossible to go, and this 
 point is 273 degrees below the zero on the 
 Centigrade scale. This temperature we call the 
 absolute zero. At this temperature the motion 
 of atoms and molecules would cease. If we 
 make this point the zero of our scale, than 200 
 degrees absolute would be twice as hot as 100 
 
 o 
 
 absolute. 
 
 Now 200 degrees absolute is probably about 
 the temperature of the outer regions of our 
 atmosphere, and there the velocity of molecules 
 is such that hydrogen would move at about a 
 mile a second and oxygen at a quarter of a 
 mile a second. Therefore, were oxygen moving 
 at the rate of a mile a second, the temperature 
 or energy would be as the square of the velocity. 
 So the temperature of the oxygen would be 
 sixteen times as great as it is at the surface of 
 the atmosphere ; in other words oxygen moving 
 
24 ASTRO-PHYSICS 
 
 at the rate of a mile a second would be 3200 
 degrees absolute, or taking off 273 degrees 
 to change it into the Centigrade scale, it would 
 be 2927 degrees Centigrade. 
 
 Now it is perfectly certain that in an impact 
 of cosmic bodies, a speed of one hundred miles 
 a second is comparatively a low velocity. 
 That is to say that the temperature of hydrogen 
 would be two hundred times ioo 2 , or 2,000,000 
 degrees of absolute temperature, and oxygen 
 would be sixteen times as hot as the hydrogen, 
 whilst the heavier metals would be heated in 
 proportion to their atomic weights. From this 
 it will be easily seen that an impact occurring 
 between bodies travelling at the rate of one 
 hundred miles per second would give temper- 
 atures, dependent on chemical constitution, that 
 would range above 100,000,000 degrees. Such 
 then are the temperatures that we shall have to 
 deal with in the investigation temperatures 
 from a thousand to hundreds of thousands of 
 times as great as the most fervent heat of our 
 hottest furnaces. 
 
 Our personal experience of motion only 
 extends to small velocities. We are appalled 
 at the falling avalanche ; we know well the 
 
ASTRO-PHYSICS 25 
 
 velocity of an express train and the disastrous 
 results of a collision on the railway. The sun 
 moves at the comparatively low cosmic velocity 
 of four miles a second, and were the colliding 
 trains moving at this velocity the energy 
 involved in the collision would be fifty thousand 
 times as great as it is at sixty miles an hour. 
 The Earth moves forward in its orbit at about a 
 velocity of twenty miles a second, that is with 
 an energy twenty five times as great as if it had 
 only the velocity of the sun. If we could shoot 
 a projectile from the surface of the earth at a 
 velocity equal to the velocity of the earth in 
 space, it would leave the sphere of the earth's 
 attraction and never come back again. In fact 
 there is a velocity connected with each cosmic 
 body that just permits a body to be shot away 
 from it so that it will not return, and this 
 velocity is called the critical velocity. This is a 
 conception of extreme importance to the theory 
 of Constructive Impact. The critical velocity as 
 regards the earth is seven miles a second, 
 but a projectile shot from the earth at a velocity 
 of seven miles a second, although it would leave 
 the earth, would not leave the solar system. 
 The energy would require to be many times as 
 
26 ASTRO-PHYSICS 
 
 great. A body so shot from the earth would 
 acquire an orbital motion connected with the 
 sun, yet would pass through the very same spot 
 from which it was shot from the earth in its 
 annual revolution around the sun. Its year, 
 however, would not correspond with the year of 
 the earth, but would be near it in length of 
 duration. 
 
 For a body to be shot away entirely from the 
 surface of the sun, it would require to have a 
 velocity of 378 miles a second, and this conse- 
 quently is the velocity that a small planetary 
 body, placed at the extreme limit of the sun's 
 gravitating power would acquire were it to fall 
 into the sun. 
 
 Were two suns similar to our own to fall 
 together by mutual gravitation, the distance 
 that each would have to fall would only be half 
 that of a small body falling to the sun, because 
 each would travel towards the other through 
 half the separating distance, and if they re- 
 mained spheres when the surfaces touched each 
 other, only half the energy would be developed 
 in the velocity, compared with what would be 
 developed if the centre of one of the masses, 
 instead of being at radius distance, were on the 
 
ASTRO-PHYSICS 
 
 surface of the other sun. Each of these agents 
 would halve the energy and consequently the 
 total energy would be just a quarter of the 
 greatest possible for a particle, or equivalent to 
 the energy involved for half the velocity, that is 
 a little less than 200 miles a second. 
 
 It is in the highest degree improbable that 
 any particular pair of suns should come into 
 collision, their proper motion in space preventing 
 it. Should, however, any pair of equal bodies 
 collide, it is very much more probable that the 
 collision shall be of a grazing character rather 
 than that the bodies should approach one another 
 centre to centre and collide directly. The case 
 resembles the respective probabilities of a blind 
 rifleman striking the centre of the bull's eye, 
 hitting the target anywhere, or shooting hope- 
 lessly wide of the mark altogether. 
 
 But in these cosmic collisions the agency of 
 attraction comes into play, and the pull of the 
 one body upon the other considerably increases 
 the chance of a collision. Now a collision that 
 is thus produced by deflection cannot under any 
 possible circumstances be directly centre to 
 centre ; the conditions of orbital motion render it 
 impossible. Thus then, between fairly equal 
 
28 PARTIAL IMPACT 
 
 stars or dead suns the probability of a grazing 
 impact is very much greater than the chances of 
 a complete collision centre to centre, whilst the 
 study of the modes of grazing impact introduces 
 such an immense number of possibilities, that 
 its detailed study is well worthy of being regarded 
 as a new cosmic philosophy. 
 
 PARTIAL IMPACT. 
 
 In partial impact, in the first place, if the 
 graze be slight, the two bodies will not be stopped 
 in their way. The two parts that graze will 
 mutually destroy each other's motion of mass, 
 and standing in each other's way, will be cut 
 from the main masses of the colliding bodies, 
 and will approximately come to rest. Such an 
 impact as this has been called a " partial impact." 
 
 A partial or grazing impact of two suns will 
 produce three phenomena. In the first place, 
 as we have seen, a slight graze will not stop the 
 main portions of the colliding stars, nor appreci- 
 ably affect their velocities. The grazing parts 
 will simply be sheared off; will largely destroy 
 each other's momentum and convert this 
 energy of mass-motion into heat ; and by the 
 
PARTIAL IMPACT 29 
 
 coalescence of the sheared parts a third body 
 will be produced between the two original bodies. 
 
 Secondly, the temperature of the third body 
 will not depend upon the amount of the shear 
 but simply on the velocity transmuted into 
 heat, and on the chemical composition of the 
 mass ; that is to say a hundredth part cut off 
 will be as hot as a tenth. 
 
 Thirdly, the stability of the coalesced body 
 will depend on the amount of the graze. If the 
 graze be small, the temperature, that is the 
 molecular velocity, will be the same as with a 
 complete collision ; but the attractive power of 
 the third body will depend on the mass, and 
 obviously will be less than if the two stars had 
 coalesced completely. The attraction may 
 easily be so small that each molecule as it 
 reaches the surface of the newly formed third 
 body will start on a journey never to return, 
 being endowed with a velocity of greater than 
 the critical velocity required to escape the mass. 
 The sheared -off mass consequently expands 
 with a great temporary increase of light, but 
 after a time the nebula produced will become so 
 rarefied as to give but little light, because the 
 molecular encounters will be increasingly fewer. 
 
3O PARTIAL IMPACT 
 
 It will in fact expand into a hollow shell of gas, 
 or become as it is called, a " planetary nebula," 
 and finally, it will often dissipate into space. 
 Hence there is produced suddenly, a very brilliant 
 body that loses its light, not because it has cooled, 
 but because it was too hot to hold together. 
 
 These three phenomena are involved in every 
 case of partial impact, but scores of new con- 
 ditions come crowding on that complicate the 
 results. These will be studied in detail in 
 future chapters under their respective headings. 
 
CHAPTER II 
 
 TEMPORARY STARS 
 
 TEMPORARY STARS THEIR SUDDEN APPEARANCE, 
 EXTREME BRILLIANCY AND BRIEF INTENSITY- 
 ANCIENT AND MODERN RECORDS TEMPORARY STARS 
 ASSOCIATED WITH LUMINOUS GASES AND INCAN- 
 DESCENT SOLIDS. HYPOTHESIS OF STELLAR COLLISION 
 DEFECTS OF OTHER HYPOTHESES. MARVELLOUS 
 STORY OF NOVA AURIGA. PROOF THAT DEAD SUNS 
 EXIST-PROBABILITY OF THEIR COLLISION. PENE- 
 TRATING POWER OF PROJECTILES. HYPOTHETICAL 
 RESULTS OF STELLAR COLLISION TRANSFORMATION 
 OF MASS-MOTION INTO MOLECULAR MOTION - 
 INTENSE HEAT - GASIFICATION- EXPANSION- ROTA- 
 TION-DISSIPATION. 
 
 In November, 1572, Tycho Brahe, the Danish 
 astronomer, was unspeakably astonished to 
 behold a new star of extraordinary brilliancy in 
 the constellation Cassiopeia. It must have 
 appeared quite suddenly, for, Tycho Brahe tells 
 us, he believed it was not visible an hour before 
 he noticed it ; and indeed coach-drivers and 
 country people also observed it at the same 
 time. When first seen it was very brilliant 
 It soon became more brilliant than Sirius ; it 
 
32 TEMPORARY STARS 
 
 rivalled Jupiter ; it was even brighter than Venus 
 at quadrature, and it grew to be so bright it 
 could be seen at noonday. The fact that it was 
 fixed in space showed that it was at true 
 stellar distance, and therefore it was the most 
 brilliant body in the entire heavens. Probably 
 it gave off over a hundred thousand times as 
 much light as our sun. Then in a short time it 
 began to diminish in intensity ; in a few months 
 it was only a star of the second magnitude ; 
 and in seventeen months the Pilgrim, as it was 
 called, had faded away completely. 
 
 Kepler also describes a very similar star that 
 lasted about a year. 
 
 These evanescent stars are recorded all 
 through history both in China and Europe. 
 The Chinese record gives us a long list of 
 strange stars, many of which were doubtless 
 true temporary stars. They record such 
 phenomena in B.C. 134, in A.D. 173, and in 
 ion. On many occasions they have been 
 observed in Europe. Possibly the most remark- 
 able temporary star recorded was in B.C. 125, 
 which was visible in the daytime and is said to 
 have attracted the attention of Hipparchus, and 
 led him to draw up a catalogue of the stars, which 
 
TEMPORARY STARS 35 
 
 is the earliest on record. Other temporary 
 stars are recorded in A.D. 389, and in the years 
 945 and 1264. In 1572 occurred the brilliant 
 phenomenon described by Tycho Brahe. 
 
 Fully twenty such sudden appearances of 
 stars are recorded, some within the last few 
 years ; but these later ones were not prominent 
 objects, telescopes being needed to observe 
 them properly. Yet so marvellously have 
 photography and the spectroscope added to the 
 power of the telescope, that these points of light 
 have given us stellar information which the 
 brilliant visitants of the past never afforded 
 us. 
 
 The first star to which powerful modern 
 astronomical instruments were applied was the 
 new star in the Crown which appeared in 1866. 
 The spectrum of this star, when examined,, 
 appeared to be continuous, with bright lines 
 upon it, showing the presence of luminous 
 gases, and incandescent solids, but much in- 
 formation as to its nature was not obtained. 
 
 It was the appearance of the new star in the 
 Swan in the year 1877 that first directed my 
 attention to the stupendous nature of these new 
 stars, and to the fact that astromoners were 
 
34 TEMPORARY STARS 
 
 entirely at a loss for a sufficient explanation to 
 account for their extraordinary brilliancy and 
 rapid disappearance ; the current theories of the 
 time being both inconsistent with the modern 
 conception of energy, and utterly insufficient to 
 account for their peculiarities. In casting about 
 for an explanation of the almost unthinkable 
 acquisition of heat necessary to account for such 
 an extreme and evanescent luminosity, the 
 possibility suggested itself that the phenomenon 
 was due to a collision that had transformed the 
 darkness of dead stars into the brilliancy of a new 
 born sun. 
 
 All observations of temporary stars tell the 
 same story of sudden appearance ; temporary 
 increase of brilliancy ; rapid and generally 
 complete disappearance, sometimes leaving a 
 planetary nebula. 
 
 A new star is a giant sun that has been sud- 
 denly born ; a body of surpassing brilliance and 
 inconceivable size ; appearing all at once in the 
 universe, to fade away again in a few months. 
 
 It was quickly apparent, as already shown, 
 that in the majority of cases such collisions 
 would not involve the impact of the bodies as a 
 whole, but would be generally of a grazing 
 
TEMPORARY STARS 35 
 
 character, producing two wounded stars, and a 
 third intensly heated unstable body. Flint and 
 steel, as it were, had met one another, and struck 
 off an inconceivably brilliant spark. 
 
 The stupendous velocity acquired by dense 
 cosmic bodies falling towards one another, would 
 suffice, in the generality of cases, to carry them 
 through one another in a period of considerable 
 less than an hour. 
 
 What other explanation than that just 
 indicated can there be of such a stupendous 
 event? Suggestions there are, startling in 
 their insignificance : the sudden combustion of 
 hydrogen in a dead sun ; the bursting out 
 of a volcano, or the plunging of a planet 
 into a dead sun ; the passage of a meteoric 
 train through the atmosphere of a dead 
 sun ; the collision of meteoric swarms ; the 
 tidal disturbance of two dead suns passing 
 near one another, and so on. Think of a 
 bonfire or a volcano ten thousand times the 
 size of our own sun ! Suppose we even imagine 
 such a mass of heated matter to be produced, 
 how long would it take to cool ? Our particle 
 of cosmic dust the Earth probably took 
 hundreds of thousands of years. Our sun has 
 
36 TEMPORARY STARS 
 
 taken tens of millions, and will probably take 
 more than ten million years longer to cool. 
 Yet a body ten thousand times his brilliancy 
 vanishes in a year ! 
 
 How easy to imagine such a disappearance on 
 the theory of partial impact ? According to 
 this theory the disappearance is not suggested 
 as in the faintest degree to be due to cooling, 
 but to be due to such stupendous heat and of so 
 high a temperature that most of the molecules 
 of the body are above the critical velocity, and 
 thus they dissipate until finally they wander 
 alone in space. 
 
 If the information available at the time of the 
 development of this theory was not sufficient to 
 demonstrate it in its entirety, such was not the 
 case after the star Nova Aurigae appeared in 
 December, 1891. The history of this star is 
 most interesting and extraordinary. Between 
 December 8 and 10 a star made its appear- 
 ance where no trace of a star had before existed. 
 It was not there on the 8th, but was in evidence 
 on the loth, and there were two intervening 
 days when clouds prevented observation ; yet 
 for many weeks after its actual appearance no 
 eye perceived it. It was, however, writing its 
 
TEMPORARY STARS 37 
 
 record on the plates of the photographer. It 
 was first seen in February, 1892, by Mr. 
 Anderson. He wrote an anonymous letter, 
 asking if the star were not a new one. Such 
 indeed it proved to be, and soon telescopes all 
 over the world were scanning the face of the 
 stranger. Step by step observation proved that 
 its phenomena were of an amazing character. 
 The star was found to be double, and its two 
 parts were moving at a relative velocity of more 
 than 700 miles a second. Then a third body 
 was detected to be moving at the rate of some 
 23 miles a second. The character of this 
 third body was long in doubt. At length it 
 expanded into an undoubted and undeniable 
 planetary nebula, and Professor Barnard of the 
 Lick Observatory, by means of his magnificent 
 telescope, succeeded in measuring its disc. The 
 light of the combined bodies fluctuated greatly, 
 but these fluctuations were not due to the 
 nebula that produced the bright lines in the 
 spectrum, but to solid matter. So greatly was 
 scientific attention drawn to this star, that Mr 
 Alfred Taylor, F.R.A.S., himself examined the 
 work of 85 observers, and stated that the 
 material from which he abstracted his report 
 
38 TEMPORARY STARS 
 
 would be equal in volume to that of an immense 
 book. His summing up of this enormous mass 
 of recorded observations was to the effect that 
 there was no doubt that the new star consisted 
 of three separate bodies. Since the finding of 
 Nova Aurigse several other stars have appeared, 
 the spectra of which correspond very closely to 
 it in character. 
 
 The suggestion made in this cosmic theory is 
 that all temporary stars result from the grazing 
 impact of stellar bodies, and in those cases 
 where the temporary star has appeared where 
 no star before existed, the colliding bodies were 
 non-luminous or dead suns. 
 
 The variable star, Algol, demonstrates that 
 there is such a thing as a dead sun, and over 
 thirty years ago Dr. Johnstone Stoney suggested 
 that they existed, while Sir Robert Ball believes 
 that they are probably more numerous than the 
 stars that give out light, or what we call fixed 
 stars. 
 
 Collisions between suns will have their pro- 
 bability increased by their mutual gravitation, 
 and when suns approach one another it is ad- 
 mitted generally by astronomers that a tidal 
 action will distort the stars, dragging out 
 
TEMPORARY STARS 39 
 
 portions egg-ways towards one another, and it 
 would be these protruding parts that would tend 
 to collide. It may be thought that there would 
 not be energy enough to cut parts from the 
 solid masses of the suns, but a few minutes' con- 
 sideration will show that the energy available 
 is absolutely millions of times greater than that 
 necessary. It might also be thought that if the 
 bodies grazed at all, a complete coalescence 
 \vould ensue, due to their mutual attraction. A 
 few more minutes' consideration will show, in 
 the first place that not merely is a cosmic body 
 easily cut, but that no coalescence will take place 
 unless a comparatively large mass is struck 
 from both. 
 
 I shall show later on, that when a third of the 
 bodies are struck off, and the sheared -off masses 
 coalesce, that the great additional attraction 
 exercised by it upon the retreating bodies will 
 in most cases cause a " whirling coalescence " of 
 the bodies ; but the assumption that we are 
 making now, is that a small fraction, say a 
 tenth or a fiftieth part, is struck off from each of 
 the two bodies, the two small fragments coal- 
 escing to form a third body. 
 
 The penetrating power of projectiles from 
 
4O TEMPORARY STARS 
 
 modern guns, and the colliding powers of express 
 trains represent our terrestrial idea of impact, but 
 we speak of these bodies moving at so many feet 
 per second or miles an hour ; but there is more 
 than 27 million times the energy when moving a 
 mile a second than when moving a foot a second, 
 for the energy developed is in proportion to the 
 square of the velocity, for since there are 5,280 
 feet in a mile, the square of this number is 
 27,878,400. In the case of an express train we 
 speak of a velocity of sixty miles an hour, or a 
 mile a minute. Compared with this velocity, 
 that acquired by comparatively small suns of 
 100 miles a second gives us 60 squared, or 3,600, 
 multiplied by 100 squared, or 36,000,000, so 
 that an express train moving at the velocity of 
 100 miles a second would develop an energy 36 
 million times that involved in a speed of a mile 
 a minute. We have also to take into consider- 
 ation the relative masses of the train and the 
 star in order to be able to estimate the shearing 
 force available. Not only would these con- 
 siderations show that the force available is 
 enormously greater than is necessary to produce 
 the shear, but it also indicates the amount of 
 energy available in order to account for the 
 
TEMPORARY STARS 4! 
 
 temporary escape of the bodies from each other's 
 gravitating attraction. 
 
 It is clearly demonstrable therefore, that, 
 were two dead suns to strike off a small fraction 
 from each other, the two colliding bodies, in a 
 wounded condition, would pass on their way, 
 because neither body would exercise a sufficient 
 attraction to produce coalescence unless the 
 graze was considerable. The phenomena of these 
 wounded stars and this attraction will be debated 
 in the chapters on variable and double stars 
 respectively. For the present we are only 
 considering the characteristics of the new body 
 formed by the collision of the two stars and 
 the combined influence of the three bodies upon 
 the light of the complex spectrum produced. 
 
 A great increase in the complexity of the 
 problem produced in such a case of impact would 
 be introduced by the variety of chemical com- 
 position of the substances of which the temporary 
 star is built up, for as we have already shown, if 
 the star consisted of lead, it would be 207 times 
 hotter than if it consisted of hydrogen. But, 
 although there is this very great difference in the 
 temperature resulting from the collision, there is 
 no difference in the molecular velocity produced, 
 
 3 
 
42 TEMPORARY STARS 
 
 assuming that the whole of the star be made up 
 of a single chemical element. Thus with a star 
 of lead or of hydrogen, the molecular motion 
 that would be produced by the transformation 
 of the motion of the stars into molecular motion 
 in free space would be identical. Hence to 
 lessen the complexity of the consideration of 
 the subject of temporary stars, we will disregard 
 the chemical composition until the time comes 
 to deal with the subject under the heading of 
 selective molecular escape in Chapter V. 
 
 Were I to enter mathematically into the 
 problem, (which is not desirable in this pre- 
 liminary statement) I could show that were two> 
 equal gaseous suns to fall upon one another,, 
 without having originally any proper motion, 
 that the heat produced by the collision would be 
 exactly sufficient to form a new body at the 
 same temperature and of a diameter the sum of 
 their diameters, the whole of the energy of their 
 heat being transmuted into the energy of 
 expansion ; and 1 could also show that this 
 condition would be one in which the molecules 
 would be in equilibrium. In other words the 
 energy of the impact of two similar gaseous 
 suns would just suffice to make a new mass 
 
TEMPORARY STARS 43 
 
 of four times of volume of both, and this 
 new sun would be in equilibrium when it was 
 neither hotter nor colder than the two original 
 suns. The impact of two suns consequently does 
 not possess sufficient energy to transform a gase- 
 ous sun into a nebula, unless, like 1830 Groom- 
 bridge, they had great original proper motion. 
 
 Let us suppose our two suns that grazed each 
 another to be dark, hot-centered bodies. Let us 
 suppose a tenth be cut from each ; the shear will 
 not stop them, their acquired speed is so 
 stupendous. The wounded suns go on ; but the 
 parts in each other's way must stop each other. 
 A spinning motion will be present, but almost 
 all that violent onward rush will be converted 
 into motion of the particles, that is, into heat. 
 Of course it is impossible to imagine the 
 temperature produced ; but, given the chemical 
 composition and the velocity destroyed, what 
 cannot be imagined as already shown can be 
 calculated. The temperature may be a hundred 
 million degrees Centigrade. 
 
 The intensely hot coalesced mass struck from 
 the two suns is of course converted into gas. It 
 is too hot to be stable, and the great mass 
 expands at an incredible speed generally the 
 
44 TEMPORARY STARS 
 
 giant blazing globe would increase more than a 
 score of millions of miles per day. There is no 
 fancy in any of these statements, they are all 
 plain matters of fact, deductions from the known 
 laws of matter and energy ; they assert exactly 
 what would happen were a pair of suns to come 
 into partial impact. 
 
 Therefore, if two dark suns did graze and cut 
 off a tenth of each, it is absolutely certain a new 
 star would appear in the universe. Calculation 
 demonstrates that such graze occupies less than 
 an hour. Singularly enough, with bodies of 
 equal density, the size does not influence the 
 time, because they get up commensurate speed. 
 In this short time, then, a new sun is born. The 
 tremendous expansion and increase in brilliancy 
 sometimes last for days, then a new action sets 
 in. 
 
 Temporary stars disappear, not by cooling, 
 but because they are two hot to hold together. 
 All have read of Jules Verne's Columboid, the 
 wondrous-chambered shot that quitted the earth ; 
 and, such is human daring, I have known some 
 ardent souls that long to make a similar journey. 
 But not so can we visit the moon ; we have 
 neither the explosive nor the material to bear 
 
TEMPORARY STARS 45 
 
 the strain. About a thousand times the energy 
 of an ordinary shot would be needed to get up 
 speed sufficient. As already stated, a shot hurled 
 with a velocity of seven miles a second would 
 leave the earth and not return. All the particles 
 of the new star are moving with inconceivable 
 speed hundreds of miles a second. The 
 velocity to allow of bodies escaping from suns 
 of similar density is higher in proportion to the 
 mass of the suns. So the less the mass of the 
 new star, the less the speed required to escape 
 from it. 
 
 Imagine that all the molecules are shots above 
 the critical velocity ; when any come to the 
 surface they travel straight on and leave the 
 mass. Hence, the mass expands in two ways : 
 it expands by the tremendous pressure exercised 
 by the molecules striking one another, and also 
 expands because the molecules are always 
 escaping and flying away. Their speed may be 
 taken as a million miles an hour. After some 
 months nothing remains but an immense hollow 
 shell of gas aways expanding, in fact, one of 
 Herschel's planetary nebulae ; only such a 
 nebula as here described is not permanent it 
 continues to expand, and finally strews space 
 
46 TEMPORARY STARS 
 
 with countless wandering molecules, some of 
 which will in latter ages form material for the 
 origination of new universes. 
 
 So, that in whatever other ways temporary 
 stars may yet be explained, it is certain that a 
 comparatively small partial impact of dead suns 
 must produce a temporary star that will 
 suddenly blaze forth, increase in brilliancy for 
 a few days, then pass away by dissipation into 
 space. 
 
 When we come to spectroscopic evidence there 
 remains no room for doubt ; but this consider- 
 ation will be more appropriate in our study of 
 the two great dead suns flying from one another, 
 each bearing the scars of conflict in lakes of fire 
 hundreds of thousands of miles in diameter. 
 
4 8 
 
 DIAGRAM SHOWING AN IMPACT OF Two STARS OR DEAD SUNS, FORMING 
 A TEMPORARY AND Two VARIABLE STARS. 
 
 Fig. i Pair of stars distorted and coming into impact. 
 
 Fig. 2 Pair of stars in impact. 
 
 Fig. 3 Star? passing out jf impact, and formation 
 of third body. 
 
 Fig. 4. Showing entanglement of matter in each body. 
 
 Fig. 5 Two variables and a temporary star. 
 
CHAPTER III 
 
 VARIABLE STARS 
 
 MIRA, THE WONDERFUL STAR ALTERNATELY DARK AND- 
 BRILLIANT. VARIABLE STARS DUE TO COLLISIONS 
 SPECTROSCOP1C INVESTIGATIONS WHAT SHOULD,AND 
 WHAT DOES HAPPEN VARIABLE STARS FOUND IN 
 CLOSELY RELATED PAIRS ANTHELM'S STAR AND ITS 
 COMPANION VARIABLE. VARIABLES ASSOCIATED WITH 
 NEBULOSITY. AGENCIES AT WORK TO CONTINUE 
 VARIABILITY. INFINITE VARIETY OF CONDITIONS 
 AND PHENOMENA. 
 
 For just about four centuries astronomers 
 have known of an extraordinary star in the 
 constellation of the Whale Mira, or the Wonder- 
 ful, the older observers called it. Months elapse 
 without sign of a star ; then a faint light appears 
 that grows stronger and stronger for about three 
 months ; for a few weeks it remains brilliant ; 
 then during the next three months it fades 
 away again. This process is repeated year after 
 year, the period being computed at 331 days 
 16 hrs. 7 min. There are many scores, perhaps 
 hundreds, of stars that exhibit periodic fluctua- 
 
50 VARIABLE STARS 
 
 tions of intensity, though none are so remarkable 
 as Mira. 
 
 How are we to explain the peculiarities of 
 these stars ? 
 
 Suppose we were to hang a policeman's 
 lantern on a roasting-jack ; it would flash and 
 vanish, giving us an appearance similar to that 
 presented by Mira. But another explanation is 
 possible. Suppose we were to cut a large hole 
 in the side of a tin can, and hang it over a 
 lighted candle and let it spin, we should get the 
 same result. Hence we see that a variable star 
 may be a star with sides unequally illuminated 
 presenting these sides alternately to opposite 
 parts of the heavens. Or, there may be some- 
 thing that eclipses the star ; we know that the 
 short periodical eclipse of the Demon star 
 (Algol) is due to the passage of a dead sun 
 across its disc. The same is probably true of 
 several other stars. Of these two ideas the 
 revolving lantern theory best accounts for most 
 of the variable stars. 
 
 Let us return to the two colliding dead 
 suns we left receding from each other. Their 
 partial impact has taken a slice from each 
 and exposed the molten interior. As the 
 
VARIABLE STARS 51 
 
 two bodies fled from the flaming central mass, 
 their enormous attractive force, and the lack of 
 balance at each side of the colliding parts, would 
 cause huge tongues of fire to follow each re- 
 treating orb, heating the struck part intensely. 
 The heated centre would also be exposed, and 
 well up as the body resumed its spherical form. 
 The collision would also cause each of the two 
 colliding suns to spin, and to present alternately 
 a light and a dark face towards the same part of 
 space. Thus easily is the mystery of variable 
 stars explained. Deduction, therefore, from the 
 well-known laws of matter and energy demons- 
 trates that a partial collision of extinct suns 
 produces three bodies : an immense flaming ball 
 of fire, glowing and expanding at an enormous 
 rate, and 'two cosmic bodies flying from each 
 other at inconceivable velocities, each of these 
 bodies revolving and showing its unequally heated 
 surface. Presently, by mutual attraction, 
 the velocity of the two bodies becomes so much 
 reduced that the central expanding gaseous 
 body overtakes them and envelopes them, and 
 they become a double variable star within an 
 immense planetary nebula. 
 
 A number of recent temporary stars have 
 
52 VARIABLE STARS 
 
 been examined with the spectroscope, and 
 although the evidence of the subject is some- 
 what conflicting, there being no theory to guide 
 observers, yet the evidence on the whole is not 
 contradictory, and fortunately, there are sum- 
 maries by collectors of observations, one giving 
 the result of the work of over eighty observers, 
 and their summaries agree. The prismatic 
 light of these celestial visitants is very extra- 
 ordinary. Instead of the coloured lines that 
 usually represent the notes of the vibrating 
 atoms, the ribbon of light is crossed with broad, 
 indistinct bands, and on either side of the centre 
 of each of these bands is superimposed a line. 
 By the rainbow tinted ribbon the stars tell us 
 their story. How are we to read this stellar 
 message? 
 
 When a beam of white light falls upon a 
 prism it is bent to one side ; but white light is 
 made up of waves of many lengths, growing 
 shorter, from red, through all the colours of the 
 spectrum, to violet. Let us then imagine a 
 beam of white light to consist of long waves 
 striding onward and shorter waves running to 
 keep up, so that all travel at the same rate. 
 These waves meet the prism, and their directions 
 
VARIABLE STARS 53 
 
 are altered ; the shorter they are, the more they 
 are deflected ; so they accompany each other 
 no more ; they diverge, increasing the distance 
 from each other until the bright beam of white 
 light is coloured and fan shaped, and when it 
 falls on a white screen, it is a long coloured 
 streak. But the streak from the light of the 
 stars is uneven, in fact, sometimes broken ; there 
 is not a regular succession of waves of all lengths. 
 The coloured streak of light is largely modi- 
 fied by the characteristic waves corresponding 
 to the notes given out by the atoms. It is by 
 the period of the waves that we recognise the 
 atoms producing them. But in the spectra of 
 new stars the notes are out of tune, and by notes 
 being thrown out of tune we learn how the atom 
 is being treated, and how it is behaving itself. 
 The pitch of a tuning-fork alters if the fork is 
 made to travel rapidly. If it be approaching us, 
 the notes crowd upon one another, the waves 
 shorten and the pitch rises. If travelling away, 
 the waves lengthen out and the notes become 
 flatter. In the same manner light waves are 
 thrown out of tune by the travelling vibrating 
 atom. If it be moving away, then the coloured 
 line is displaced towards the red. If it be, 
 
54 VARIABLE STARS 
 
 approaching us, then the displacement is to- 
 wards the violet. When atoms are moving 
 in all directions, then the waves are displaced 
 both ways, and the line broadens out. 
 
 This is the reading of the beautiful cipher 
 message from our new stars. Broad bands, 
 indistinct at the edges, brighter in the middle, 
 are produced by atoms travelling from us, side- 
 ways, and towards us, at speeds of hundreds 
 upon hundreds of miles per second. In fact 
 they are the message of the flaming, expanding 
 orb that must result from the coalescence of the 
 two fragments ; clearly it would give us just such 
 bands. The two superimposed lines are telling 
 us of a body travelling hundreds of miles a 
 second towards us, and of another flying from 
 us. The lines are on the band because the atoms 
 forming the expanding nebula are travelling 
 faster than the giant orbs themselves. One of 
 the best determined measurements gave respec- 
 tively three hundred, and four hundred and 
 thirty miles a second, as the speed of the two 
 constituents of Nova Aurigae. Light and dark 
 bands are due to another cause. A dark band is 
 due to a bright light showing through a gas. A 
 bright line is due to an incandescent gas. Hence, 
 
VARIABLE STARS 55 
 
 in partial impact, if the molten sea of the sheared 
 sun shine through a hydrogen atmosphere, we may 
 have a dark band. If the star presents the edge 
 of the molten sea to us, it will be the gaseous 
 atmosphere we shall see, and the lines will be 
 bright. Obviously, whether going away or 
 approaching us, the star may be in any position 
 of rotation with regard to our earth, and in point 
 of fact in either star the bright line should slowly 
 fade and become dark and then bright again 
 Here, then, is the full reading of the beautiful 
 coloured cipher that came to us from that 
 marvellous star. It would not be unfair to ask 
 a student who knows nothing of impact to tell the 
 kind of spectrum such a set of bodies would 
 produce. There is but one correct answer ; and, 
 if a student cannot give it, he cannot read the 
 spectrum. Is not this piece of evidence of 
 impact most convincing? As we proceed proof 
 becomes overwhelming. On the theory of 
 partial impact variable stars are produced in 
 pairs. Are any such to be found ? I sought in 
 vain for an assertion of the fact ; then I plotted 
 some of these stars, and on the pair of ten inch 
 charts some were so close, that, in especial cases. 
 I could not put a needle through one without 
 
VARIABLE STARS 
 
 destroying another. " Can this be chance ? " I 
 asked my mathematical fellow-worker in cosmic 
 problems Mr. Beverley, of Dunedin. Chance ! 
 He calculated and answered, " Certainly there is 
 one chance in one hundred and sixty-two 
 sextillions." 
 
 Since I have been in London, from Mr. J. E. 
 Gore's list of suspected variable stars, I have 
 selected from four hours of Right Ascension, 
 such pairs of variables as seem distinctly to have 
 been formed by the same collision. The follow- 
 ing are their positions : 
 
 Declination. 
 
 6 9 
 
 6 27 
 
 13 33 
 13 20 
 
 22 28 
 
 22 43 
 
 3 32 
 
 3 27 
 
 The extraordinary coincidence that nine pairs 
 of variable stars as close as these should occur 
 
 R.A. 
 
 Declination. 
 
 R. 
 
 A. 
 
 h. in. 
 
 
 
 ' 
 
 h. 
 
 m. 
 
 3 38 
 
 23 
 
 59 
 
 6 
 
 33 
 
 3 39 
 
 23 
 
 34 
 
 6 
 
 35 
 
 4 H 
 
 19 
 
 3i 
 
 6 
 
 43 
 
 4 J 4 
 
 19 
 
 H 
 
 6 
 
 47 
 
 5 i 
 
 8 
 
 48 
 
 7 
 
 8 
 
 5 3 
 
 8 
 
 54 
 
 7 
 
 9 
 
 5 28 
 
 4 
 
 55 
 
 7 
 
 26 
 
 5 29 
 
 4 
 
 56 
 
 7 
 
 27 
 
 6 3i 
 
 18 
 
 33 
 
 
 
 6 32 
 
 18 
 
 8 
 
 
 
VARIABLE STARS 57 
 
 within so small an area in proportion to the 
 whole heavens, about one-thirtieth of the 
 celestial vault, is obviously not the result of 
 chance, and any sound theory of variable stars 
 must account for such a fact. 
 
 The really great distance that these stars are 
 from each other suggests that the condition of 
 variability is one that lasts a considerable time, 
 unless the proper motion of these stars is greater 
 than that of the average star in space, yet the 
 distances cannot be considered unreasonable. 
 It would be of extreme interest for the 
 astronomer to ascertain with accuracy the proper 
 motions of these pairs of variable stars. The 
 theory of impact suggests they are still increas- 
 ing their distance. 
 
 Assuming that a variable star is situated at 
 such a distance that its light would take ten 
 years to travel to us and that the stars are in- 
 creasing their visual distance from each other at 
 the rate of ten miles a second, then in one 
 hundred years the relative velocity would dis- 
 place it 12 of arc, as is shown in the following 
 calculation : 
 
 Light travelling at the velocity of 186,000 
 miles a second in ten years will travel 186,000 
 
 4 
 
58 VARIABLE STARS 
 
 x 10 x (60 x 60 x 24 x 365). The stars travelling 
 from each other at a velocity of ten miles a 
 second, in one hundred years will travel rox 100 
 x (60 x 60 x 24 x 365). Dividing the former by 
 latter gives us as I to 1860 as the relative 
 distances travelled by the star and the light. 
 Now a great circle of the celestial sphere is 
 made up of 360 degrees, and this divided by the 
 ratio of the radius to the distance travelled by 
 the star amounts to slightly less than 1 2 minutes 
 of arc. 
 
 If instead often miles they were separating at 
 the rate of sixty miles a second, that is to say 
 that each constituent of the pair had an apparent 
 proper motion of 30 miles a second, then the 
 distance they would travel in 100 years would 
 be i 9", that is an enormously greater distance 
 than any quoted in the list. 
 
 But a still more remarkable demonstration 
 occurs. Anthekn's temporary star of 1670, Nova 
 Vulpeculae, has near it a variable star. The 
 respective positions being as follow: R.A. iQh. 
 43m. 35., N.P.D. 27 2-6' ; and R.A. iph. 43m. 
 535., N.P.D. 27 0'8'. But there is in addition to 
 this a smaller star very close to the position of 
 Nova Vulpeculae that is also suspected to be 
 
VARIABLE STARS 59 
 
 variable. If really a variable star, this would be 
 an extraordinary confirmation of the theory. 
 We should have a temporary star appearing 230 
 years ago and its two variables still near the 
 position of the original impact and still variable ; 
 and yet not connected into a double star. 
 
 It is known to astronomers that variable stars 
 are sometimes associated with nebulae, as for 
 instance Hind's variable T Tauri. Might not 
 the nebulosity observed at the minimum of some 
 of the long period variable stars be always 
 present, but be overpowered at other times by 
 the greater brilliancy of the body ? We have 
 absolute evidence that Nova Aurigae did actually 
 appear suddenly in the heavens ; that the 
 spectrum of Nova Aurigae indicated two bodies 
 flying from one another with enormous velocities ; 
 that there were such fluctuations of light that 
 we should expect in the case of such revolving 
 bodies, and that they were associated with 
 luminous gas which, according to certain ob- 
 servers, did actually expand into a planetary 
 nebula ; and Professor Barnard succeeded in 
 measuring its disc. In Sir C. E. Peek's detailed 
 notes of variable stars frequent reference is also 
 made to observed nebulosity. 
 
60 VARIABLE STARS 
 
 Of course, a variable star, unequally heated, 
 tends to lose its variability by conduction, 
 convection, and all sorts of agencies. Still, I 
 have shown that quite a number of counteracting 
 agencies may possibly retard this equalisation of 
 temperature for perhaps thousands of years. In 
 consequence of this tendency to equality, I did 
 not expect to find numerous variable stars in 
 pairs ; but in fact I found more than I expected. 
 Therefore this indicates great permanence in the 
 inequalities. I have already discussed this high 
 probable permanency, and I will now attempt to 
 describe some of the agencies that cause stars to 
 retain their inequality of luminosity. 
 
 The equalisation of the temperature of any 
 heated star may come about by conduction, by- 
 ordinary convection of liquids, by radiation, and 
 also by the fact that there would be an 
 enormous atmospheric disturbance connected 
 with the highly heated scar that would be 
 surging in a most extraordinary way about this 
 huge molten lake of fire, as we see is -the case 
 even with a body of such equality of temperature 
 as the sun It is curious to note that each of 
 these agencies contains forces that are retarding 
 the production of an equalisation of temperature. 
 
VARIABLE STARS 6 1 
 
 Convection of heat is due to difference of 
 density. The denser material tends to sink and 
 the lighter to rise. Density itself may be due 
 to high specific gravity of material or to lower 
 temperature. It is almost certain that the 
 centres of all dark surfaced bodies are hotter 
 than the exterior. Hence if we cut one sixth 
 from the surface of a star it will expose its 
 heated interior. The wounded star of course 
 quickly regains its sphericity and the molten 
 interior now forms the surface. It is at an 
 enormously higher temperature than the rest 
 of the star, but it also consists of heavier mole- 
 cules. The consequence is that convection will 
 only go on until any difference of density due 
 to the combined causes has died out, and when 
 it has died out, the mass will still be hotter 
 than in any other part of the star. 
 
 Conduction, too, is exceedingly slo\v in a 
 liquid mass, and that the mass in this particular 
 case is liquid is undoubted. Consequently, the 
 attaining a common temperature by conduction 
 must be exceedingly slow, for this scar of fire 
 will often be as big as our sun. 
 
 In the case of radiation, the more highly 
 heated metallic surfaces will naturally radiate 
 
62 VARIABLE STARS 
 
 faster than the others or we should get no 
 variability in the star, but to attain equality of 
 temperature by the difference in the rate of 
 radiation would almost certainly take many 
 thousands of years. 
 
 We have now to take into consideration the 
 tremendous ae'riel disturbance that is produced 
 by this blazing lake of fire. We must examine 
 the motion of the atmosphere of a rotating star 
 with a lake of fire in the same way as we should 
 study a trade wind, and take into consideration 
 the fact that the vapour as it rises from the 
 surface would form saline and metallic rain 
 clouds in the higher regions of the atmosphere. 
 The examination of these two agencies shows 
 that a vast quantity of this material falls back 
 again as molten rain almost exactly on the edge 
 of the lake of fire. It would, however, gradu- 
 ally be carried farther and extend the size of the 
 lake and would be a large factor in producing 
 equality of temperature over the surface of the 
 star. 
 
 Is there any evidence of the lessening of 
 variability ? It is overwhelming. Some stars are 
 known to have been variable that are variable 
 no more, and the variability of very many stars 
 
VARIABLE STARS 63 
 
 has diminished greatly. Besides the types 
 described, there are all kinds of eccentric 
 variables, as, of course, we should expect, 
 for the field of possibilities of impact seems 
 infinite. 
 
 Sir C. E. Peek's recorded observations of 
 variable stars show a few cases of extreme 
 irregularity both of the variable period and 
 brilliancy, but since impact would result in two 
 variable bodies of different periods of rotation, 
 as well as a new star of ever decreasing brilliancy, 
 and of almost certain nebulosity, the total light 
 from a variable might be compounded of three 
 elements. The existence of these three sources 
 of light would alone account for irregularity, but 
 in addition each of the wounded stars would be 
 under the influence of a number of agencies all 
 struggling to produce irregularity of variability. 
 Thus it is probable that for some time after 
 impact there would be two rotations. There 
 would be a rotation of the shell or outer portion 
 of the stars as a result of the impact ; and there 
 would have been almost certainly a rotation 
 previous to the impact, and it might take many 
 years for these rotations to blend completely. 
 Then again, the large scar, the molten matter 
 
64 VARIABLE STARS 
 
 from the interior of the star, would overfill and 
 sink back rythmically for an indefinite period. 
 Think of the amazing variety of conditions ! 
 The impacting bodies may be of the same, 
 or of altogether different mass. They may 
 have every variety of density ; one may be 
 dense, the other rare. They may be as dead as 
 the moon, or as fiery as the sun. They may be 
 of totally different chemical composition, or 
 approximately the same. One may be a 
 star cluster, another a nebula, or star clusters 
 and nebulae may collide with one another. 
 Perchance a huge dead sun may recurrently 
 plunge through a group of dead suns and give 
 us the extraordinary Eta Argus. The bodies 
 may have every variety of impact, from a 
 meeting full face to face to the merest kiss. Is 
 there any end to the list of possibilities? I 
 think not, and hence, not to weary my readers, 
 I will pass to the next chapter and try to 
 describe the modus operandi by which that 
 fiery kiss weds two giant orbs into a union that 
 may last scores of millions of years. 
 
CHAPTER IV 
 
 DOUBLE STARS. 
 
 DOUBLE STARS RESULT FROM IMPACT-VIEWS OF SIR 
 ROBERT BALL AND PROCTOR-POSSIBILITIES OF STEL- 
 LAR WEDDINGS RECURRENT IMPACT RARE COLLI- 
 SIONS RESULTING IN PAIRS OF VARIABLES, BINARY 
 SYSTEMS OR COALESCENCE-WHIRLING COALESCENCE. 
 EVOLUTION OF AN ELLIPTICAL ORBIT. FACTS ABOUT 
 DOUBLE STARS THEIR VARIABILITY, COLOUR, CON- 
 NECTION WITH NEBULA AND POSITION IN THE MILKY 
 WAY. OTHER WAYS OF WEDDING. CONSTRUCTIVE 
 POWER OF PARTIAL IMPACT. 
 
 In 1877 the star appeared that sent my mind 
 in quest of the stupendous agencies that must 
 be working in the cosmos thus suddenly to 
 produce a sun which in a year faded to a cloud 
 of fire-mist. It did not cost an hour to learn 
 what a scientific El Dorado I had struck upon. 
 I saw that a graze was a force sufficient to- 
 cause burnt-out suns, Phoenix-like, to rise in 
 wondrous glowing systems from the ashes of 
 their dead past. 
 
 But not without long study were all the 
 consequences of the graze revealed to me in the 
 
66 DOUBLE STARS 
 
 richness and the complexity, the power and the 
 perfection of their action. So one must not 
 wonder that the first thoughts of astronomers 
 on these phenomena , should be somewhat 
 vague. The following extract from Sir Robert 
 Ball's article on "Double Stars," published in 
 the Melbourne Argus > will show that the idea of 
 impact is gaining ground, although students of 
 constructive collision will see by the extract 
 how very imperfect the conception still remains 
 even in the mind of so great an astronomer : 
 
 He says " Let us suppose that two of these 
 globes, when bent on their voyages through 
 immeasurable space, should happen in the 
 course of events to cross each other's tracks and 
 to be hurled each against the other in a mighty 
 collision. No doubt, I freely admit that such 
 incidents must be extremely infrequent in 
 comparison with the number of globes for which 
 such a disaster would be possible. But these 
 objects exist in such myriads that ever and 
 anon the chapter of accidents will suffice to 
 bring some pair of globes into collision, though 
 as regards any two particular globes the im- 
 probablity of their striking together would be 
 quite as great as the improbability of the 
 
DOUBLE STARS 67 
 
 striking together of two specified rifle bullets 
 in the air as they flew over a battle-field. But 
 no one can deny that if, in the course of the 
 battle, sufficient cartridges are discharged from 
 both sides, this excessively unlikely thing to 
 happen in the case of any particular pair of 
 bullets may yet happen in the case of some pair. 
 We have the best reasons for knowing that 
 throughout the length and depth of the universe 
 it has sometimes occurred that globes, hurrying 
 along with a speed far swifter than that of any 
 rifle bullet, perhaps, indeed, a hundred times 
 as quickly, have thus been brought into 
 collision. One effect of such a collision is 
 amenable to calculation. There is not the 
 slightest doubt that it must be accompanind 
 with the evolution of a stupendous quantity of 
 heat. In fact, it is known that if a globe 
 moving with the velocity which this earth 
 possesses, were to come into direct collision 
 with an obstacle equally massive, the quantity 
 of heat that should be produced by the impact 
 would be so vast that each of these mighty 
 globes would not only be heated red hot, but 
 would actually be transferred into what we 
 may describe as a fire cloud. Under ordinary 
 
68 DOUBLE STARS 
 
 circumstances the two stars would not come 
 from exactly opposite directions, and thus strike 
 each other directly ; the blow must usually 
 rather be described as a. very serious graze. In 
 such a case there would be an evolution of heat 
 often sufficient to raise the whole globe from the 
 extremely low temperature of space up to a 
 state of vivid incandescence. After the collision 
 the two objects would separate, each having 
 conferred upon the other the glory of a brilliant 
 star. The law of gravitation under all circum- 
 stances must assert itself. These two objects, 
 deprived of a large part of their original motions 
 by the collision, would assume movements of a 
 new kind, the guiding power of which would be 
 found in their mutual attraction. Under such 
 circumstances each of the globes would revolve 
 around the other, just in the same manner as a 
 planet revolves around the sun. It may certainly 
 be admitted that we have never up to the 
 present actually been witnesses of the process 
 by which a pair of glowing suns have been 
 brought into such remarkable association. But 
 it will hardly be doubted that such collisions 
 must have occasionally produced the results 
 above described when we note the fact that 
 
DOUBLE STARS 69 
 
 there are in the heavens thousands, I might 
 doubtless say many thousands, of pairs of stars, 
 each of which revolve around the other, just as 
 if their origin had been that which we have 
 described." 
 
 Sir Robert Ball refers. to rifle bullets meeting. 
 I have seen the photograph of a pair of bullets 
 fused together by such actual collision. What 
 Sir Robert says is very satisfactory as far as it 
 goes, but he does not seem to realise the very 
 slight effects of the graze upon the remainder of 
 the orb. I have shown, by several lines of 
 reasoning, that if the orbs were as hard as 
 adamant their energy is a million million times 
 in excess of the shearing force that is necessary 
 to cut them ; so that, wonderful as it may seem, 
 the parts not impacting would not be greatly 
 heated by the collision. 
 
 It will also be observed that Sir Robert Ball 
 says such collisions have not been positively 
 seen. But it has been shown that the birth of 
 a new star almost certainly results from collision. 
 He says nothing of the middle body produced ; 
 yet without this middle body the stars would 
 collide again and again, ultimately coalescing. 
 
 When I spoke to Proctor on impact, he 
 
70 DOUBLE STARS 
 
 readily admitted most of my reasoning as to 
 what would result were a collision to occur, but 
 was very emphatic as to the entire improbability 
 of the event But, at that time, photography 
 had not revealed the amazing numbers of the 
 stars, and the idea of dead suns was very vague ; 
 nor did he estimate the enormous deflecting 
 power of the mutual attraction that suns would 
 exert upon each other, thus tending to produce 
 collision. Subsequently, in his Astronomy, he 
 discusses the possibility of double stars being 
 formed from collision, and points out this 
 difficulty of recurrent impact. He admits 
 the pair would be wedded ; but he imagines 
 that at each anniversary the gorgeous ceremony 
 would be repeated. If so, each impact would 
 necessarily use up some energy, until, instead of 
 marriage celebrations, the occasion became a 
 kind of battle royal, in which the blows would 
 continue to grow quicker until the great orbs 
 would coalesce into one huge nebulous bun- 
 shaped sun. 
 
 Let us examine the agencies that render 
 recurrent impact very rare. They are fully 
 debated in my papers in the New Zealand 
 Philosophical Transactions for 1880, under the 
 
DOUBLE STARS 
 
 headings "Double Stars" and "Agencies Tending 
 to Alter the Eccentricity of Planetary Orbits." 
 Much of the reasoning is very technical. How- 
 ever, we must consider some of these agencies. 
 
 We understand how a partial impact leaves 
 three bodies the vast flaming nebula and the 
 two scarred suns. We see how the nebula 
 expands, overtakes the suns, and envelopes 
 them. It overtakes them because they quickly 
 lose much of the velocity they had at impact. 
 The suns lose this velocity partly as they 
 gained it, by mutual attraction ; but the great 
 central nebula at first also exercised immense 
 retarding influence, so they do not retreat with 
 the velocity of their approach. 
 
 Suppose two equal suns to have lost a sixth 
 each, then each sun weighs f and the new body 
 f, but as the new body is standing still in space, 
 the time of the attraction is doubled ; hence the 
 total attractive energy after impact is f + 1 = f = 1|,. 
 the original attractive energy. If there were J 
 cut off we should get three equal bodies, each f 
 the mass of the original bodies ; the energy of 
 the total new attraction is now double the 
 original attraction and it is no longer a case of 
 partial impact but one of whirling coalescence. 
 
72 DOUBLE STARS 
 
 If the colliding pair had been swift suns be- 
 fore the attraction commenced, possessing a 
 great independent motion like the star 1830 
 Groombridge, they would still lose some of this 
 motion by the graze, but not enough to wed 
 them. Probably, as a rule, dead suns move 
 faster than brilliant ones, for, doubtless, the 
 brilliancy of suns is partly kept up by impacts, 
 which necessarily destroy some of their motion. 
 But if such a slow sun as ours were very slightly 
 to graze another such sun the pair would not 
 escape; the extra attraction of the nebula of 
 coalescence would wed them, and they would 
 come rushing back towards each other. Why, 
 then, would they not collide again ? 
 
 This is the reason : the nebula that entrapped 
 them would be outside their orbit on their re- 
 turn, and so, instead of being pulled back to 
 collide, they would keep at distances of millions 
 upon millions of miles from each other. What 
 would happen to the earth were our sun to lose 
 half its mass? It would speed away and its 
 orbit would be immensely enlarged. So it is 
 with double suns ; the central nebula loses its 
 mass, and so the pair enlarge their orbits and do 
 not collide again. This is not the only agency 
 
DOUBLE STARS 
 
 73 
 
 which prevents recurrent impact, but it is the 
 most important. 
 
 The accompanying diagram shows this agency. 
 The hyperbolic orbit becomes a long ellipse. 
 
 DIAGRAM SHOWING THE FORMATION OF THE ORBIT OF A DOUBLE STAR. 
 
 The dotted circle represents the nebula expanded beyond aphelion 
 distance. 
 
 The two continued hyperbolas represent the path of the two stars had 
 there have been no collision. The collision occuring, the orbit becomes a long 
 ellipse, that becomes of less eccentricity, because the nebula has expanded. 
 (See also page 133). 
 
74 DOUBLE STARS 
 
 When aphelion distance is reached, and it be- 
 gins to fall back, the attraction is less ; hence it 
 does not fall so quickly and the ellipse becomes 
 much less eccentric. At each approach amongst 
 the meteoric matter left at impact aphelion 
 distance is lessened and gradually the orbit 
 becomes as it is in nature. 
 
 Thus we have seen partial impact produce the 
 star that fades into star-mist and two rotating 
 wonder stars. We have also seen how the 
 central nebula weds the two stars, and then by 
 dissipating prevents their impacting again. We 
 have now to ascertain how the characteristics of 
 double stars correspond with the conditions 
 promulgated in these papers. Obviously, the 
 orbits would be highly eccentric. The stars 
 would often be associated with a nebula, and 
 sometimes for thousands of years one or both 
 would be variable ; also, from the fact that the 
 metallic interior would well up, and form a vast 
 molten lake, they would tend to be coloured 
 and have characteristic spectra. 
 . Such are some of the deductions imperatively 
 forced upon us if we consider that binary stars 
 have been associated by impact. All are borne 
 out by observation in a most remarkable manner. 
 
DOUBLE STARS 75 
 
 Yet it was not easy to find most of the evidence ; 
 I sought for more than two years before meeting 
 any statement as to the variability of double 
 stars. Then I came upon the work of the great 
 Struve, and all at once obtained proof that 
 variability is a remarkable characteristic of 
 binaries. Struve had verified this as to twenty- 
 five, and suspected forty more. Later observa- 
 tion shows the characteristic to be far from 
 uncommon. Mr. J. E. Gore, in Knowledge 
 September 1st, 1899, gives several examples, and 
 in a recent letter to myself has pointed out four 
 other cases. Colour and peculiar spectra are 
 also characteristic. As to the association of 
 nebulae and double stars the following extracts 
 from Herschel's "Outlines of Astronomy" will 
 show how remarkable they are. 
 
 " The connection of nebulae with double stars is 
 in many instances extremely remarkable. Thus 
 in R.A. iSh ;m is, N.P.D. 109 56'," occurs an 
 elliptic nebula having its longer axis about 50" 
 in which, symmetrically placed, and rather nearer 
 the vertices than the fociofthe ellipse, are the equal 
 individuals of a double star^each of the loth 
 magnitude." 
 
 In a similar combination noticed by M. Struve 
 
76 DOUBLE STARS 
 
 (in R.A. i8h 2501, N.P.D. 25 7'), the stars are 
 unequal and situated precisely at the two extre- 
 mities of the major axis. In R.A. I3h 4701 335, 
 N.P.D. 129 9', an oval nebula of 2' in diameter, 
 has very near its centre a close double star, the 
 individuals of which, slightly unequal, and about 
 the 9-10 magnititude, are not more than 2" 
 degrees asunder." 
 
 Herschel also says : " Nebulae of regular 
 forms often stand in marked and symmetrical 
 relation to stars both single and double. Thus 
 we are occasionally presented with the beautiful 
 and striking phenomenon of a sharp and brilliant 
 star concentrically surrounded by a perfectly 
 circular disc or atmosphere of faint light, in 
 some cases dying away insensibly on all sides, 
 in others almost suddenly terminated." He 
 also mentions a case of the nucleus of Messier's 
 64th nebula being " strongly suspected to be a 
 close double star," and states that many other 
 instances might be cited. Doubtless modern 
 astronomy would furnish other examples. 
 
 One has only to refer to any table of the 
 elements of binary stars to see the high order of 
 their eccentricity. Lastly, where stars are thick 
 we should expect to find a high ratio of double 
 
DOUBLE STARS 
 
 stars, and such is the case ; nearly all the binary 
 stars are confined to the Milky Way. 
 
 There are other ways besides impact by which 
 suns may become associated. Whenever three 
 cosmic bodies come near one another one of 
 them has its velocity lessened. Thus, a comet 
 approaching the sun may come near a planet, 
 say, Jupiter ; and if its line of direction towards 
 the sun causes it to be nearer Jupiter when it 
 has passed than when it was approaching him, 
 the comet will lose more velocity than it gains, 
 and travel more slowly. Hence it may not have 
 enough speed to get away from the sun again, 
 and will thus become orbitally connected. Such 
 occurrences would happen rarely with suns, but 
 mu^t have produced some binaries. The 
 acoompanying diagram of the approach of three 
 stars shows this action ; and this action is also 
 of great importance in causing the escape of 
 bodies from a condensing cosmic system. 
 
 Again, a star may plunge tangentially through 
 a nebula, and be retarded enough to be unable 
 to release itself ; hence it would revolve about 
 the nebula and plunge through it at each revolu- 
 tion. The friction would cause it to lose velocity 
 and this lessened velocity would make its orbit 
 
78 DOUBLE STARS 
 
 more and more circular ; until, when the nebula 
 shrank to be a sun, the two would form a binary 
 star. 
 
 Should the evidence hitherto offered that 
 
 DIAGRAM ILLUSTRATING CHANGES OF VELOCITY THAT MAY OCCUR WHEN 
 THREE STARS PASS NEAR ONE ANOTHER. 
 
 I 
 
 I 
 
 B C C 
 
 Fig. i. Fig. 2. 
 
 ^0 <j { 
 
 C ^ B 
 A A 
 
 No. 4. No. 3. 
 
 FIG. i represents two stars, B and C, about to pass each other. A, 
 another star, is about to pass between the other two. The velocities, as 
 represented by the arrows, are takep as about equal. 
 
 FIG. 2 represents C and B having passed each other. They have gained 
 and lost velocity, whilst A is still approaching, so has gained and is still 
 gaining velocity. 
 
 FIG. 3, The velocity of A is about the same as in fig. 2, the velocity 
 however, has been gained and lost, but B and Chave still further lost velocity. 
 
 FIG. 4. A has a much higher velocity than in fig. i, as B and C are 
 further from it in leaving than in approaching. Whilst B and C have a 
 lessened velocity, and hence may be orbitally connected into a double star, 
 whilst the high velocity of A may carry it out of the cosmic system. 
 
DOUBLE STARS 79 
 
 partial impact occurs, and that it is an agent of 
 tremendous constructive power, be insufficient to 
 convince the sceptical, I must ask such, of their 
 patience to pursue the subject further until their 
 scepticism turns to a delighted conviction of the 
 might of this constructive force. In order to do 
 this, I must ask them to travel with me into the 
 realms of selective molecular escape, to consider 
 the formation of stars clusters and meteroic 
 swarms, to investigate the evidence offered by 
 modern photographs of nebulae, to trace out the 
 origin of the order manifest in the universe 
 and solar system, and to glance at the wondrous 
 interacting agencies which suggest that our 
 universe is but one of many, and that the mighty 
 Cosmos, as a whole, is infinite and immortal. 
 
CHAPTER V 
 
 SELECTIVE MOLECULAR ESCAPE 
 
 THE ATOMIC THEORY-COMBINING AND NON-COMBINING 
 MOLECULES-VELOCITY OF MOLECULES DEPENDS ON 
 TEMPERATURE. CELIBATE MOLECULES AND COSMIC 
 PIONEERS. DYNAMICAL THEORY OF GASES-GASEOUS 
 EXPANSION-SORTING OF ATOMS AT HIGH VELOCITIES 
 VELOCITY DEPENDENT ON ATOMIC WEIGHT. GASES 
 EVOLVED BY IMPACT, EITHER EXCEED THE CRITICAL 
 VELOCITY, OR, ASSISTED BY ROTATION AND OXYGENA- 
 TION, MAY FORM STAR CLUSTERS, METEORIC SWARMS 
 OR SUNS. OXIDES ARE OF LOW VOLATILITY. SELEC- 
 TIVE ESCAPE TENDS TO FILL SPACE WITH WANDERING 
 MOLECULES. 
 
 Hitherto in these chapters the differences of 
 chemical composition have been almost ignored, 
 and this has been done in order that the ideas 
 involved, by being less complex might be more 
 easily appreciated ; but chemical constitution 
 lies at the very foundation of Cosmic Evolution, 
 and the details of chemical constitution must be 
 understood before the wide areas the subject 
 covers can be fully explored. 
 
 Dalton's far-reaching atomic theory has been 
 the basis of most of the greater conceptions and 
 
SELECTIVE MOLECULAR ESCAPE 8 1 
 
 discoveries of modern chemistry. That theory 
 is that all substances are made up of ultimate 
 indivisible particles of matter of extreme minute- 
 ness and known as atoms. There are altogether 
 between sixty and seventy different kinds of 
 substances known as chemical elements, the 
 atoms of each of these different elements being 
 assumed to be absolutely alike in weight and 
 other properties, whereas the atoms of the 
 different kinds of elements differ in these 
 respects. Thus all the atoms of oxygen are 
 assumed to be sixteen times as heavy as those 
 of hydrogen, and when a combination of any of 
 these elements occurs the product is found to be 
 composed of some multiple of their respective 
 atomic weights. Thus there are two combina- 
 tions of oxygen with hydrogen, known respec- 
 tively as water and peroxide of hydrogen. In 
 water the weight of the oxygen is eight times 
 that of the hydrogen, and hence we conclude 
 that the molecule or ultimate particle of water 
 consists of one atom of oxygen and two of 
 hydrogen, whereas in the case of the peroxide 
 the proportion is sixteen to one, and it is there- 
 fore concluded that the molecule is probably of 
 one atom of each. It is not, however, always 
 
S2 SELECTIVE MOLECULAR ESCAPE 
 
 the case that the final particles of a compound 
 are made up of the simplest number of atoms 
 that are capable of grouping together ; in fact it 
 is assumed that the molecule of peroxide of 
 hydrogen consists of two atoms of oxygen 
 united by affinity with two atoms of hydrogen. 
 
 There are two classes of these ultimate mole- 
 cules : the ultimate molecules made by the 
 combination of atoms of different elements and 
 molecules containing only one element. Thus 
 the conception of a free molecule of hydrogen is 
 that it is made up of two of its ultimate atoms, 
 and the free molecule of oxygen may be either 
 made up of two atoms as it is in common oxygen, 
 or of three atoms as it is in ozone, or oxygen 
 that has been subjected to electrical or other 
 agency. 
 
 Again, it may be assumed that if molecules 
 are moving with extraordinary velocity and 
 strike one another, that the molecule of hydrogen, 
 consisting of two atoms, may be broken up and 
 its molecules or ultimate particles may then 
 consist of single atoms. In the case of hydrogen 
 these separated atoms would tend to join again, 
 but it is probable that at exceedingly high 
 temperatures, that is at a high velocity, a very 
 
SELECTIVE MOLECULAR ESCAPE 83 
 
 large number of the molecules are thus broken 
 up, and there are many elements in which we 
 believe that the ultimate atom may be also the 
 molecule. This is especially the case with the 
 group of recently discovered elements : helium, 
 neon, argon, crypton and xenon elements that 
 have no affinities either for other elements or for 
 themselves. They are consequently monatomic 
 molecules without any apparent function in the 
 solar system; complete celibates in fact, but just as 
 human celibates make the best pioneers into 
 little known regions, so it is probable that the 
 function of these elements is to make their way 
 into those parts of space where matter is very 
 sparse. Hence I have called these elements 
 Cosmic Pioneers, for they play a large part in 
 the reconstruction of the systems in the scheme 
 of Cosmic Evolution. 
 
 Since Dalton brought out his atomic theory, 
 there have been a number of suggestions as to 
 the possibility of elements being built up of 
 more primitive material. The attempts, however, 
 have not been attended with any very great 
 measure of success ; and although I believe that 
 Professor J. J. Thompson's recent paper on 
 "" Particles Smaller than Atoms " is taking us in 
 
84 SELECTIVE MOLECULAR ESCAPE 
 
 the direction of a profound discovery in elec- 
 tricity or ether, yet I am not at present of 
 opinion that we have evidence that the elements 
 themselves ever disintegrate and give off minute 
 particles of their own material, and in these 
 papers I rigidly use Dalton's theory of the 
 absolute fixedness and indestructibility of the 
 ultimate atom. Whilst I hold these views it will 
 be well to mention that although it should be 
 proved that the atoms are capable of disruption, 
 it will in no sense affect the general argument of 
 this theory ; only it is well to clear the ground 
 that the reader may know that no hypotheses are 
 used in connection with this scheme of Cosmic 
 Evolution other than those which are absolutely 
 accepted laws of matter and energy. The 
 Dynamical Theory of Gases is treated as an 
 accepted truth. Atoms, then, to the student of 
 this system of Cosmic Evolution, are indivisible 
 minute particles, that enter into combinations and 
 pass out of such combinations that form mole- 
 cules and break away from these molecules, but 
 in themselves undergo no change. 
 
 We have spoken already of these molecules in 
 their various states of solid, liquid and gas, and 
 it is in connection with their condition as gas 
 
SELECTIVE MOLECULAR ESCAPE 85 
 
 that we have now to follow up their study. The 
 dynamical theory of gases tells us that at the 
 same temperature and the same pressure, a litre 
 of gas, no matter what its composition, will 
 always contain the same number of molecules, 
 whether these molecules be the lighest mona- 
 tomic molecules or the heaviest possible com- 
 pound gas. The reason why the light gas, and 
 it may be the smaller molecule, occupy the same 
 space as the larger, heavier kind, is on account 
 of the rapidity of their motion. The space in 
 which an ordinary gas exists is nothing like 
 completely rilled with the gaseous molecules, and 
 it is frequently easy to compress the gas into 
 one hundredth of its volume without compressing 
 the molecules themselves. The reason the gas 
 occupies so much space is that the motion of 
 the molecules in consequence of their velocity 
 forces other material out of the way, and what 
 the lighter molecules lack in mass, they make up 
 in velocity. In illustration of this, for instance, 
 oxygen weighs sixteen times as much as 
 hydrogen and moves one quarter as fast. It 
 consequently strikes one blow to every four 
 blows of hydrogen, but the hydrogen strikes not 
 merely four times as often but with four times 
 
86 SELECTIVE MOLECULAR ESCAPE 
 
 the swiftness. Hence hydrogen hitting four 
 times as frequently and moving four times as 
 fast gives a momentum of 16; while oxygen 
 with a velocity of I and a mass of 16 gives also 
 a momentum of 16; so that the pressure 
 exerted by either gas is equal. 
 
 This difference of the velocity of molecules is 
 of extraordinary importance in connection with 
 Cosmic Evolution. Years ago Clark Maxwell 
 suggested that without the interposition of 
 energy, but simply by an intelligent sorting of 
 the atoms, it was possible to overcome the pro- 
 cess of the dissipation of energy. Now the 
 different rates of the velocity of the molecules in 
 a free cosmic system will actually sort the atoms 
 by natural means. Let us assume that a body 
 similar to 1830 Groombridge, that is a star 
 moving with an enormous velocity, were to strike 
 another similar star, and that both of these stars 
 were made up of admixtures of cosmic elements. 
 If these elements were in detached portions of 
 the star, on the impact of the two stars all the 
 molecules would approximately have the same 
 velocity given them, but the oxygen molecules 
 having the same velocity as the hydrogen mole- 
 cules would be sixteen times as hot. The whole 
 
SELECTIVE MOLECULAR ESCAPE 87 
 
 would of course be converted into gas, and 
 consequently soon after the collision the tempera- 
 ture would become approximately equal through- 
 out the mass. Then the hydrogen would be 
 moving four times as fast as the oxygen. The 
 oxygen would have lost and the hydrogen 
 gained heat, that is the oxygen would have lost 
 and the hydrogen have gained speed. Thus 
 the lighter molecules will rob the heavier mole- 
 cules of their speed in attaining a common 
 temperature. With this velocity the hydrogen 
 would possess sixteen times the power of escape 
 from the general mass compared with the 
 oxygen, and consequently if the velocity of the 
 hydrogen be great enough, (and it will usually 
 be great enough), it will start from the mass on 
 a journey with a higher velocity than it is 
 possible for the attraction of the body to arrest ; 
 so that we see there is a tendency, in a free 
 gaseous cosmic sphere, at a very high tempera- 
 ture, for the molecules to escape from the surface 
 in the invers^ order of their atomic weights. 
 Hydrogen will have a velocity on the average 
 twice as great as the element next to it helium 
 (if it be in the monatomic condition) ; and so we 
 find, that as the atoms increase in weight, they 
 
SELECTIVE MOLCULAR ESCAPE 
 
 decrease in speed. Now it is clear that if a 
 molecule start from the surface of a body, at any 
 angle, after it has travelled a very great distance, 
 it will be approximately travelling radially. 
 Hence there is a tendency for the whole of the 
 molecules to start on journeys as they reach the 
 surface. The lighter molecules go with a higher 
 speed and the heavier molecules at a lower speed. 
 For a long time, of course, there is an admixture 
 of these elements, but ultimately the quicker ones 
 outrun their more leisurely companions and we 
 have the gases sorting themselves into layers 
 somewhat similar to those of a lily bulb, advanc- 
 ing in inverse order of their respective atomic 
 weights. This tendency to separation I have 
 called Selective Molecular Escape. Had the 
 molecules velocity enough, we should find that 
 the whole of them would arrange themselves (at 
 a great distance from the place of impact) into 
 approximately concentric layers ; but supposing 
 the energy were too small to permit of dissipa- 
 tion of the whole of the gas, we should have the 
 very lightest gases escaping the system alto- 
 gether ; the intermediate remaining for very 
 considerable periods at the limit of effective 
 gravitation ; whilst the heavier metallic gases 
 
SELECTIVE MOLECULAR ESCAPE 89 
 
 would gradually lose heat by radiation and be 
 re-attracted back to the centre, forming, accord- 
 ing to the amount of the rotation and the quantity 
 of oxygen present, star-clusters, suns or meteoric 
 swarms, 
 
 The reason oxygen is so important as to 
 deserve special mention is due to the fact that 
 this element in its combinations with other 
 elements tends to render them very much less 
 volatile than the simple elements are themselves. 
 This property is exactly the reverse of chlorine, 
 for the compounds of chlorine with non-volatile 
 metals are often volatile, whereas the metals 
 associated with non-volatile oxides are often 
 volatile, as is instanced in the pro- 
 duction of the remarkable oxide of zinc 
 known as " Philosopher's Wool." The con- 
 sequence is that if there be a considerable 
 quantity of oxygen present, the separate elements 
 tend to become non-volatile compounds that 
 aggregate into dust, and again when we have a 
 considerable rotation, there is a tendency for this 
 dust to aggregate into nuclei and become orbit- 
 ally connected with the general mass instead of 
 shrinking directly towards the centre and 
 becoming a sun, as would be the case were the 
 
90 SELECTIVE MOLECULAR ESCAPE 
 
 heavier metals in the centre of the mass free 
 from rotation and from oxygen. In that case 
 they would develop into a single body of the 
 nature of a dense nebula, ultimately becoming a 
 sun. A full description of this part of the 
 subject will be given in subsequent chapters. 
 
 The most important characteristic of selective 
 molecular escape is its tendendency to give 
 light molecules so high a velocity that they 
 escape all gravitating systems and wander free 
 in space. 
 
CHAPTER VI 
 
 PLANETARY NEBULA 
 
 HERSCHEL'S CONCLUSION THAT PLANETARY NEBULAE 
 ARE HOLLOW SHELLS OF GAS-THEIR HUGE DIMEN- 
 SIONS. RELATIVE DISTRIBUTION OF MATTER AND 
 ENERGY AT HIGH TEMPERATURES. HOW SLIGHT IM- 
 PACTS CAN PRODUCE A SHELL OF GAS ENDURING 
 CHARACTER OF SUCH SHELLS WHEN ENORMOUSLY 
 LARGE AND COMPOSED OF DENSE GASES. FURTHER 
 INVESTIGATION NEEDED. PROBABLY THESE NEBULA 
 ARE ALTERING THEIR DIMENSIONS. A STAR CLUSTER 
 WITHIN A NEBULA. 
 
 In the preceding chapter it has been 
 demonstrated, on the theory of Selective 
 Molecular Escape, that after an impact of two 
 stars of mixed chemical composition a gaseous 
 envelope may be formed, associated or not with 
 a central condensation, which central mass may 
 ultimately result either in a star cluster, a 
 meteoric s\varm or a solar nebula. The 
 existence of such a hollow gaseous sphere, in 
 Herschell's opinion, is the only reasonable 
 explanation of those extraordinary celestial 
 bodies known to astronomers as planetary 
 
92 PLANETARY NEBULA 
 
 nebulae and the following extract from the 
 " Outlines of Astronomy" 1 gives Herschel's own 
 account of them : 
 
 " Planetary nebulae are very extraordinary 
 objects. They have, as their name imports, a 
 near, in some cases a perfect resemblance to 
 planets, presenting discs round, or slightly oval, 
 in some quite sharply terminated, in others a 
 little hazy or softened at the borders. Their 
 light is in some perfectly equable, in others 
 mottled and of a very peculiar texture as if 
 curdled. They are comparatively rare objects, 
 not above four or five and twenty having been 
 hitherto observed, and of these nearly three 
 fourths are situated in the southern hemisphere. 
 On the disc of No. 3 (Herschel's list) and very 
 nearly in the centre of the ellipse, is a star gm 
 and the texture of its light, being velvety, or as 
 if formed of fine dust, clearly indicates its 
 resolvability into stars. The largest of these 
 objects (No. 5) is situated somewhat south of the 
 parallel of B Ursae iMajoris and about I2m 
 following that star. Its apparent diameter is 
 2' 40", which, supposing it placed at a 
 distance from us not more than that of 61 
 
 1 Page 644 seq. 1893 
 
PLANETARY NEBULA 93 
 
 Cygni would imply a linear one seven times 
 greater than the orbit of Neptune. The light of 
 this stupendous globe is perfectly equable, 
 (except just at the edge where it is slightly 
 softened,) and of considerable brightness. Such 
 an appearance would not be presented by a 
 globular space filled with stars or luminous 
 matter, which structure would necessarily give 
 rise to an apparent increase of brightness 
 towards the centre in proportion to the 
 thickness traversed by the visual ray. We might 
 therefore be induced to conclude its real con- 
 stitution to be either that of a hollow spherical 
 shell, or of a flat disc presented to us by a 
 highly improbably coincidence in a plane 
 precisely perpendicular to the visual rays. 
 
 Whatever idea we may form of the real nature 
 of such a body, or of the planetary nebulae in 
 general, which all agree in the absence of central 
 condensation, it is evident that the intrinsic 
 splendour of their surfaces, if continuous, must 
 be almost infinitely less than that of the sun." 
 
 Herschel urges the improbability of a single 
 disc being presented to us exactly perpendicular 
 to the visual ray. How infinitely improbable is 
 it then that some twenty of these bodies should 
 
94 PLANETARY NEBULA 
 
 be presented to us in this position. Hence there 
 can be no explanation of planetary nebula but 
 that they are hollow shells of gas. 
 
 It has been shown that if an impact be of a 
 very slight character, so that the third body pro- 
 duced is of small mass, the energy available will 
 dissipate the whole of it, and every molecule of 
 which it is composed will become independent 
 in free space. The consequences of this pos- 
 sibility will be considered presently in connection 
 with the formation of cosmic systems of the first 
 order. 
 
 Were the impacting stars homogeneous, con- 
 sisting of one chemical element only, dissipation 
 of the whole of the molecules would also occur, 
 even if a considerable portion say one fifth 
 were sheared off from the stars ; but when there is 
 varying chemical composition, this would not be 
 true of anything like so large a ratio, for 
 selective molecular escape would cause the 
 lighter molecules to rob the heavier of their 
 energy. It is true that the passing of the 
 lighter molecules out of the system leaves the 
 denser material remaining of less mass than 
 before, but the robbery of the energy is out of 
 all proportion to the lessening of the mass. 
 
PLANETARY NEBULA 95 
 
 The following numerical illustration shows 
 in the case of spheres assumed to consist wholly 
 of water, how great is the respective loss of 
 energy as compared with the loss of matter in 
 the case of a partial impact. 
 
 Water has the formula H 2 O. Its molecule 
 consists of one atom of oxygen and two of 
 hydrogen, and its composition is therefore eight 
 parts of oxygen to one part of hydrogen. 
 Assume that at first the energy is equally dis- 
 tributed throughout the mass ; then the oxygen is 
 sixteen times as hot as the hydrogen. Now let 
 the temperature become equalised ; then the 
 velocity of the hydrogen molecule will be four 
 times that of the oxygen molecule and the 
 energy of an equal mass of hydrogen will be 
 sixteen times that of oxygen. In other words 
 each atom will have an equal store of energy, so 
 that f of the mass that is the oxygen will 
 have J the energy, and -J- of the mass that is 
 the hydrogen will have f the energy ; that is 
 with the escape of hydrogen i of the mass 
 will be taken away and f the energy, and the 
 remaining oxygen will only possess f of the 
 average energy it would have had supposing the 
 mass colliding had been all oxygen instead of 
 
96 PLANETARY NEBULA 
 
 water. In equal masses at the same tempera- 
 ture the energy is inversely as the atomic weight. 
 That is at 1,000 degrees absolute, a ton of 
 hydrogen has sixteen times the energy of a ton of 
 oxygen, 56 times that of a ton of iron, and 207 
 times the energy of a ton of lead. 
 
 Thus great is the contrast of the distribution 
 of matter and energy in the case of elements so 
 nearly related as hydrogen and oxygen with 
 atomic weights in the proportion of I to 16. 
 When we come to elements having a mean 
 atomic weight of 200, as is the case with a very 
 large group of elements, the translation of the 
 energy in porportion to the mass dissipated 
 become a very large ratio indeed : in other words 
 in selective molecular escape the dissipation of 
 the energy is enormously greater than the dis- 
 sipation of matter ; so that even with a very 
 slight graze, the difference of chemical composi- 
 tion would not permit the complete dissipation of 
 the newly formed body. When the graze is 
 considerable the material constituting the third 
 body will divide, at all events temporarily, into 
 three portions. The lighter molecules, such as 
 hydrogen and helium will be dissipated com- 
 pletely into space beyond the limits of effective 
 
PLANETARY NEBULA 97 
 
 gravitation ; the intermediate weights will be 
 carried to its limits, and the heavy will be 
 attracted back ; but should the graze be less than 
 will dissipate hydrogen and helium only, some 
 of the heavier molecules will pass away as well. 
 
 Let us consider the case of a graze in which 
 the ratio is such that only the lightest elements 
 will be completely dissipated. Then there would 
 be a large number of the heavier molecules that 
 would travel outwards radially, until their velocity 
 was very small, the decrease of motion being due 
 to the attraction of the rest of the mass. If the 
 position where the molecules came almost to a 
 state of rest were very remote for the centre, as 
 is actually the case with planetary nebulae, and 
 were the amount of the material left at the 
 centre of mass small, it would take a very long 
 period before the attraction of the central mass 
 would cause the molecules in the shell to be 
 attracted back to the centre. In some case the 
 period would be certain to be some thousands of 
 years. For example, in the case of the enormous 
 planetary nebulae described by Herschel as 
 being in dimensions at least seven times the 
 diameter of the known solar system. 
 
 A planetary nebulae may consist of three 
 
98 PLANETARY NEBUL/E 
 
 different classes of elements. It may consist 
 of hydrogen and helium, but in this case so 
 great would be the central attraction that the 
 spherical shell of gases would be of transitory 
 duration. 
 
 Secondly, it may consist of nitrogen and 
 elements of approximate atomic weights, in 
 which case the central mass left behind would 
 not be of so large a ratio and the planetary 
 nebula would be of a kind that would probably 
 ultimately show something of the nature of a 
 star at the centre, and would be of considerable 
 duration ; but for a planetary nebula to persist 
 a very long time there could not be a very great 
 central attraction. Therefore in this case 
 either the impact should not cut into the dense 
 metals at the centres of the spheres, or the 
 planetary nebula would be largely made up of 
 the heavier elements. Possibly this may be 
 demonstrated to be the case in some instances 
 with further spectroscopic research. 
 
 In the case where the dissipation did not 
 extend so far as to carry off any considerable 
 quantity of oxygen, these heavier elements would 
 combine with the oxygen as already suggested, 
 and the compound molecules would aggregate 
 
PLANETARY NEBULA 99 
 
 into cosmic dust, and this would cause the 
 curdled appearance described by Herschel. 
 
 A persistent planetary nebula is probably one 
 that has been formed by bodies coming into 
 impact and striking off so small a mass as to 
 dissipate most of it into space. Most of the 
 lighter gases were so dissipated whilst the inter- 
 mediate and heavier materials were taken to the 
 limits of effective gravitation and sorted ac- 
 cording to velocity, whilst, as a rule, the amount 
 left at the centre was small. It would be well 
 to measure again those planetary nebula which 
 have stars at their centres to ascertain if they 
 have sensibly diminished in volume since the 
 time when Herschel made his records. 
 
 However, it is probable, although it may be 
 slowly, that all planetary nebula are altering 
 their dimensions. If young, in relation to cosmic 
 existence, they would probably slowly increase 
 in size ; if a little older they would be, as it 
 were, at a comparatively steady condition, but 
 as they grow old the pace of their diminution 
 would usually accelerate. 
 
 The star that Herschel describes as having a 
 velvety texture, is probably, as indicated by 
 him, a star cluster, as the next chapter will 
 
100 PLANETARY NEBULA 
 
 show. A star cluster must at all events in many- 
 partial impacts, be a transitory condition before 
 the central condensation of the mass. 
 
CHAPTER VII 
 
 STAR CLUSTERS 
 
 STAR CLUSTERS THEIR BEAUTY, PROPORTIONS, COLOURS 
 AND PHENOMENA. SIR ROBERT BALL ON SELECTIVE 
 MOLECULAR ESCAPE-RESULTS OF THE PROCESS-THE 
 LIGHTER MOLECULES ESCAPE FIRST OXYGENATION 
 FORMATION OF DUST GLOBES CONDENSATION OF 
 SUNS INFLUENCE OF ROTATION WHIRLING COALES- 
 CENCE AND THE EVOLUTION OF CLUSTERS PER- 
 TURBATION WITHIN THE GROUP VARIABLES WITHIN 
 THE CLUSTERS-THEY EXIST AND SHOULD EXIST 
 LOCALISATION OF VARIABLES IMPACTS WITHIN A 
 CLUSTER ENTRAPPING POWER OF NEBULOUS MAT- 
 TER-DOUBLE STARS MORE PERMANENT THAN VARI- 
 ABLES-DOUBLE STARS WITHIN CLUSTERS.-CLUSTERS 
 DEVELOP INTO PLANETARY SYSTEMS. 
 
 Marvellous as is the beauty of Saturn's Rings, 
 of Venus in quadrature, of those lovely cosmic 
 flowers the glowing nebulae, yet according to 
 astronomers, the wondrous star clusters surpass 
 everything else for brilliant magnificence. These 
 groups of celestial gems may sparkle like 
 diamonds of the first water, or they may shine 
 with many a varied tint, some blue beyond the 
 Oriental sapphire, some vivid green, or red, or 
 purple. Some of the groups are all white ; 
 
102 STAR CLUSTERS 
 
 some, as in the constellation of the Southern 
 Cross, are white, interspersed with red, blue and 
 green stars ; while the most wonderful of all the 
 clusters, that in the Toucan, is of an exquisite 
 rose tint. Then, the number of component stars 
 is wonderful ; in most clusters they may be 
 counted by hundreds, in some there are many 
 thousand independent points of light, every point 
 of light a sun perchance bearing a planetary 
 system with it. What possibilites unfold them- 
 selves ! Think of any one of these Solar 
 Systems threading its way through the maze of 
 the other suns ! What vicissitudes it must 
 encounter ! For hundreds of years it might 
 revolve amongst the densities of star distribution 
 at the centre of the system ; then its orbit might 
 be deflected, and for thousands of years it might 
 travel towards the exterior of the cluster. 
 
 As for the sudden adaptations that would be 
 brought about by natural selection on such a 
 sun and its satellites, the changes from tropic 
 to arctic during the great glacial epochs of the 
 earth would be nothing in comparison. Then, 
 again, how the heavens must alter in aspect 
 within those wondrous coloured clusters, where 
 in one part the emerald and the ruby enhance 
 
STAR CLUSTERS 1 03 
 
 their mutual beauty, and in another the topaz 
 and the sapphire outglow each other! Imagine 
 oneself the inhabitant of a planet lit by a ruby 
 sun and an emerald sun ! Consider the bril- 
 liant pictures and the shadows every shadow 
 chromatic, and every shadow double, one 
 coloured red and the other green ! But if these 
 wonders seem too much for human imagination, 
 we need not try to conceive the effects for the 
 inhabitants of a planet within a coloured star 
 cluster ; only an infinity of omniscience could 
 accomplish the task. 
 
 The great Humboldt asked this most sug- 
 gestive question : " How can these systems be 
 maintained how can the suns, crowding at the 
 interior of star clusters, fulfil their revolutions 
 freely and without clashing ? " Do they revolve 
 without clashing ? The answer is : Almost cer- 
 tainly not. One of the latest new stars was in 
 a cluster, and the brilliant point of light often 
 noticed in such groups is doubtless the heated 
 wreck of colliding suns. Every such impact 
 strews the centre with gas which exercises a re- 
 tarding effect upon the suns passing through it ; 
 every such collision lessens the motive energy 
 of the cluster and helps to weld it together. 
 
104 STAR CLUSTERS 
 
 But this action is discussed in the latter part of 
 this chapter. The history of clusters is a long 
 and difficult matter, which must be told slowly 
 a.nd systematically. We ask : How did these 
 galaxies of suns originate, and what force united 
 all these giant orbs into magnificent concordant 
 groups ? My fellow-students must enlarge their 
 patience, for I want to trace complex agencies, 
 to follow the flights of varied molecules, and to 
 contemplate protean interchanges of matter and 
 energy. As we ascend in the research of grazing 
 impact, we look out upon a series of problems 
 so fertile in result, so infinite in potentialities, 
 that our feelings are exactly the reverse of 
 Alexander's : the student of impact will shed 
 no tears over a conquered world ; his sphere is 
 boundless ; in every direction new avenues of 
 investigation are found and new fields of obser- 
 vation expand before his delighted vision. And 
 although vicious specialisation will doubtless in- 
 vade its domain, yet so wide is the basis of 
 experimental science required for preliminary 
 comprehension that this particular disease will 
 have but slight scope, or effect. 
 
 If the original proper motions of the colliding 
 pair forming Nova Auriga? were small, the pair 
 
STAR CLUSTERS 1 05 
 
 must have been respectively four thousand and 
 eight thousand times the mass of our sun. A 
 grazing impact of such a pair of orbs would 
 consequently possess enough matter to make a 
 cluster of stars, and if we can show that the 
 conditions for their formation are present, the 
 problem is solved. I have suggested reasons 
 for supposing that dark suns may have a higher 
 average independent velocity than luminous orbs. 
 Imagine that two such dead suns, with inde- 
 pendent velocities, were to collide deeply. The 
 nebula produced would be intensely heated, 
 and wruld rotate. If two bodies like our own 
 sun were to collide completely, the impact would 
 not convert them into a nebula ; but our sun 
 is made up of different chemical elements, from 
 the very light atoms of helium and hydrogen to 
 the heavy ones of lead, gold and platinum. The 
 collision turns the forward motion of the mass 
 into a motion of the particles, that is, into heat. 
 It would not matter whether the mass were all 
 hydrogen or all lead, the rate of the molecular 
 motion would be the same ; but the lead mole- 
 cules of the same speed as hydrogen would be 
 more than two hundred times as hot. So, in 
 a sun of mixed elements, immediately after im 
 
 7 
 
IO6 STAR CLUSTERS 
 
 pact the speed of the atoms would be the same 
 and the temperature different. But mixtures 
 tend to equalise temperature. Then the cool 
 hydrogen gains and the hot lead loses heat 
 until they have equal temperature. Now comes 
 into play the wonderful principle described under 
 the heading of selective molecular escape. We 
 understand that a body which travels fast enough 
 may leave a cosmic mass and entirely escape. 
 Hence, when at the same temperature, light 
 atoms may leave the mass and the heavy ones 
 may not be able to do so. But if the central 
 mass be very small then every molecule may 
 leave the body. 
 
 All who have studied partial impact know the 
 fundamental thought of the whole theory is : 
 A small ratio graze would be as hot as a large 
 ratio graze ; the grazed parts would coalesce, 
 and the velocity ot the molecules would be so 
 high that, if the graze were slight, the attraction 
 of the mass would not prevent their escape and 
 entire dissipation throughout space. This idea 
 of gaseous escape, discussed in its many modi- 
 fications, in papers published nearly a score 
 of years ago, is now taking its place in literature. 
 Sir Robert Ball, who has succeeded Proctor as a 
 
STAR CLUSTERS IO/ 
 
 popular exponent of astronomy, deals with the 
 subject of molecular escape in a recent article on 
 Mars. He says : " But the chief interest that 
 the principle we have laid down possesses is 
 found in the explanation which has been given 
 of it. That explanation is both so recent and 
 so remarkable, that I am glad to have the oppor- 
 tunity of setting it forth, as it has an important 
 application to Mars. The view of the subject 
 here given is due to Dr. G. Johnstone Stoney, 
 F.R.S., who recently communicated it to the 
 Royal Dublin Society. Modern research has 
 demonstrated that what we call a gas is in truth 
 a mighty host of molecules far too small to be 
 perceptible in the most powerful microscope. 
 Each of these molecules is animated by a rapid 
 movement, which is only pursued for a short 
 distance in one direction before a rencontre takes 
 place with some other molecule, in consequence 
 of which the directions and the velocities of the 
 individual molecules are continually changing. 
 For each gas the molecules have, however, a 
 certain average pace, which is appropriate to 
 that gas for that temperature, and when two or 
 more gases are blended, as in our atmosphere, 
 then each molecule of the constituent gases con- 
 
108 STAR CLUSTERS 
 
 tinues to move with its own particular speed. 
 Thus, in the case of the air, the molecules of 
 oxygen, as well as the molecules of nitrogen, are 
 each animated by their characteristic velocity; 
 and the same may be said of the molecules of 
 carbonic acid, or of any other gas which, in more 
 or less abundance, may happen to be diffused 
 through our air. For two of the chief gases the 
 average velocities of the molecules as as follows : 
 oxygen, a quarter of a mile per second ; hy- 
 drogen, one mile per second. In each case the 
 temperature is taken to be 64 C. below zero, 
 being, presumably, that at the confines of the 
 atmosphere. It will be noticed that there is a 
 remarkable difference between the speeds of the 
 two molecules here mentioned. That of hy- 
 drogen is by far the greatest of any gas. We 
 may now recall a fundamental fact in connection 
 with any celestial body, large or small. It is 
 well known, that with the most powerful pieces 
 of artillery that can be forged a projectile can 
 be launched with a speed of about half a mile 
 a second. If the canon were pointed upwards 
 the projectile would soar to a great elevation, 
 but its speed would gradually abate, the summit 
 of its journey would be duly reached, after which 
 
STAR CLUSTERS IO9 
 
 it would fall back again on the earth. Such 
 would undoubtedly be the case if the experiment 
 were made on a globe resembling our own in 
 size and mass. But on a globe much smaller 
 than the earth, not larger, for instance, than are 
 some of the minor planets, it is certain that a 
 projectile shot aloft from a great Armstrong- 
 gun would go up, and would never return. The 
 lessening gravitation of the body would fail to 
 recall it." 
 
 Thus has the idea of Selective Molecular 
 Escape become public property. 
 
 An obvious result of this selective action is 
 that the coalesced mass is robbed of its light 
 gases. Thus, at the same temperature, the 
 mean speed of hydrogen is four times that of 
 oxygen, about seven times that of iron and 
 fourteen times that of lead. So, after a time, 
 the elements, helium, hydrogen and other light 
 gases will be rushing on into space, speeding 
 ahead ; whilst the lithium, nitrogen, oxygen, 
 neon and others are following in the order of 
 their atomic weight. But oxygen, although not 
 heavy, has great affinity for silicon and many 
 metals, forming with them non-volatile and 
 coalescent molecules. Hence oxygen is largely 
 
110 STAR CLUSTERS 
 
 entrapped, and, as the mass expands, this 
 chemical action sets in ; and a very rare, very 
 stupendous rotating luminous dust globe or, 
 perchance, dust shell is formed. Gradually, 
 as with rain and hail, coalescence of particles 
 takes place. If there were no rotation, this 
 dust would coalesce into a sun ; but, with 
 rotation, such is not necessarily the case. 
 The particles will be attracted to the centre, 
 but their tangential motion will make each 
 move in an orbit. The particles will con- 
 tinually cross each other's paths, coalescing and 
 growing larger and larger ; but, as selective 
 escape has taken everything of the nature of 
 nebulous matter out of the system, there is no- 
 thing to offer resistance to these growing 
 particles ; they become fewer in number as they 
 increase in size, and the huge mass of glowing 
 dust is slowly converted into a star cluster. It 
 is possible that a very deep case of whirling 
 coalescence may form a star cluster, for nearly 
 all the conditions required would be present. 
 But the subject is one of great complexity. 
 
 It is scarcely likely that there can be any 
 definite order as to the orbits of stars in a 
 cluster. The perturbations throughout the group 
 
STAR CLUSTERS III 
 
 must be so tremendous that impacts should be 
 frequent ; and it is possible that in star clusters 
 we might thus study every peculiarity of impact 
 were it not for the difficulty in getting detached 
 spectra. 
 
 In some star clusters variable stars exist in 
 considerable numbers, and in portions of other 
 star clusters variable stars seem to have con- 
 centrated themselves ; whilst a great number of 
 star clusters that have been examined appear to 
 have certainly not a greater proportion of 
 variable stars than are to be found in other parts 
 of the heavens. 
 
 On the Theory of Partial Impact, a variable 
 star is a star that has come into a grazing 
 collision with another star, and has had a 
 portion struck from it. This scarred portion 
 becomes in this way highly heated and the body 
 has been set rotating, and thus showing alter- 
 nately the heated and the cooler sides, gives a 
 variation of light. Consequently in attempting 
 to account for the localisation of variable stars 
 in special clusters and in parts of clusters, the 
 subject we have to study is the cause of a series 
 of impacts occurring in a comparatively short 
 time and in approximately near vicinity. 
 
112 STAR CLUSTERS 
 
 The stars of a star cluster are probably 
 smaller than the average independent star, and 
 are possibly, also, of higher average temperature. 
 
 Being associated into a group connected by 
 gravitation, the velocity of the stars in their 
 orbits is probably greater than the mean proper 
 motion of other stars. 
 
 From their relative nearness compared with 
 other stars, it is probable that impacts would 
 occur more frequently in star clusters than be- 
 tween a similar number of independent stars. 
 In a star cluster also it is probable, that the 
 variability that would be produced by a grazing 
 impact would not be of so long a duration as 
 would be be the case with stars of greater mass 
 and lower temperatures ; the heated portion 
 produced in probably gaseous bodies certainly 
 tending to diffuse itself over the general surface 
 of the body rather than to remain in a single 
 position as would be the case with a dark body 
 such as Mira, which has a lake of fire en one 
 side. 
 
 It is an uncontested fundamental principle 
 of the Theory of Partial Impact that if the 
 mutual velocities destroyed in the coalesced 
 part be above a given speed, proportionate to its 
 
STAR CLUSTERS 113, 
 
 mass, a nebula must be produced, and this in 
 spite of any difference of chemical composition. 
 Thus a lead or platinum globe would, in such 
 circumstances, become a nebula just as certainly 
 as a sphere of hydrogen, the temperature pro- 
 duced by the impact being proportional to the 
 atomic weight, and the molecular velocity and 
 consequent power of diffusion being equal in 
 all elements. 
 
 In star clusters partial impacts tend to dis- 
 tribute gas, and this tendency is aided by the 
 high temperature of the stars in the cluster and 
 the high velocity of their motion. If the im- 
 pact of stars take place near the centre of the 
 cluster, the gas will tend to be distributed com- 
 paratively equally on all sides of the disturbance. 
 This gas will retard the stars that pass through 
 it, and will tend to produce other impacts. This 
 again will result in more gas being distributed,, 
 leading to other collisions and consequently to 
 other variable stars. Moreover, we must re- 
 member that no internal disturbance will lessen 
 the general rotation of the mass, and con- 
 sequently the number of stars that will come 
 into impact has a distinct limit. Possibly some- 
 thing of this sort may occur ; a single impact 
 
114 STAR CLUSTERS 
 
 happens that distributes gas and causes another 
 impact. More gas and other impacts follow. 
 Presently those stars that can possibly be so 
 entangled diminish in number and after a time 
 we have a cessation of impacts, leaving a dis- 
 tribution of variable stars. 
 
 As already shown, if the original impact take 
 place near the centre, this distribution of variable 
 stars will tend to be through the whole star 
 cluster. If the original impact take place on 
 one side of the cluster, the fresh impacts pro- 
 duced by the retarding gas generally occur in 
 the same vicinity. As the variability would pro- 
 bably die down in star clusters more quickly than 
 elsewhere, although the impacts would be more 
 frequent, the number of variable stars would not 
 on an average be greater than amongst other stars. 
 
 Although it is reasonable to suppose that 
 variability will die down quickly in star clusters, 
 this does not apply to the entrapping of stars to 
 form double stars, for a pair of stars, once en- 
 trapped, save under very unusual circumstances, 
 remain as a double star until fusion into a larger 
 system occurs, so it is possible that there may be 
 a considerable number of double stars in any 
 given star cluster. 
 
STAR CLUSTERS 115 
 
 There would probably be an immense number 
 of double stars were it not that another factor 
 comes into play. The greater the original 
 motion of the stars before mutual attraction 
 commences, the greater is the probability of 
 escape after the impact. If the stars were at 
 rest when they were first attracted towards each 
 other, the smallest graze would inevitably blend 
 the pair. With a star of the character of 1830 
 Groombridge, it is almost certain that were more 
 than half the mass cut from the star the re- 
 maining portion would pass off into space and 
 would not be entrapped. Hence it would only 
 be in the case of a considerable graze in a star 
 cluster that double stars would be produced ; 
 but taking the sum of the actions there seems 
 reason to suppose that as a whole we should 
 expect star clusters to be richer in double stars 
 than a similiar number of stars in ordinary star 
 distribution. 
 
 As to 'the future of star clusters, almost cer- 
 tainly impact will cause the central condensa- 
 tions to increase until the temperature will 
 volatilise some of the suns, and this vapour will 
 be a retarding trap for those suns that pass 
 through the centre. Ultimately, this centre will 
 
 UNIVERSITY 
 
Il6 STAR CLUSTERS 
 
 become a huge flaming sun, with a vast system 
 of associated dead suns, that will one day be 
 giant planets 
 
 How rich are the possibilities of the Cosmos ! 
 The pendulum of Eternity sways, and a pair of 
 dead suns collide each, possibly, with innumer- 
 able satellites, that, after the collision, revolve 
 in orbits around a huge fire-mist. Then the fire- 
 mist cools and coalesces, and becomes a star 
 cluster. The stars of the cluster collide, again 
 volatilize, again coalesce and become one vast 
 sun, with the cooling outer suns now planets 
 teeming with such lofty life as evolution may 
 produce on their immensities during the thou- 
 sands of millions of years of action that but 
 complete this swing of Eternity's pendulum ! 
 
 We have considered impacts that may pro- 
 duce star clusters. It is easy to realise smaller 
 collisions producing the dust swarms, which* 
 under the influence of heat, of internal friction, 
 of reflection of solar light, and of electricity, 
 occasionally adorn the sky with the waving 
 plumes of our beautiful cometic visitants. The 
 discussion of these erratic but wondrously 
 attractive wanderers we will discuss with other 
 related marvels in Chapter X. 
 
CHAPTER VIII 
 
 THE SOLAR SYSTEM. 
 
 IMMENSITY OF THE SUN ITS CYCLONIC SPOTS, ROTATION 
 AND PROPER MOTION. THE PLANETS AND PLANE- 
 TOIDSTHEIR RELATIVE MOTION, ROTATION AND IN- 
 CLINED AXES. LAPLACE'S NEBULAR THEORY ITS 
 WEAK POINTS. PLANETARY SEASONS, DAYS, MOONS, 
 ECLIPSES AND TIDES. WHY THE MOON PRESENTS 
 ONE FACE TO THE EARTH. THE SUN'S FAMILY. 
 
 The sun the chief controlling power of the 
 system that bears his name is a huge ball of 
 fire more than a million times the volume of the 
 earth ; a seething, flaming, stormy mass of such 
 magnificent dimensions, that, in point of 
 distance alone, we could not discern a body of 
 the earth's size at the sun's centre, and the orbit 
 of the moon would be a comparatively small circle 
 on his disc. Were -the earth the centre of the 
 sun, the circumference of the sublime orb would 
 be twice as distant as the moon is from us now. 
 The cyclones on its face, which we call spots, 
 tell us that our parent globe is rotating 
 in about twenty-six of our days ; and it is 
 thought, such is the|] tremendous nature of its 
 
Il8 THE SOLAR SYSTEM 
 
 tumult, that the polar regions whirl round at a 
 different rate from the equatorial. Certainly 
 this is not impossible ; nay, it is even probable. 
 
 The sun travels in space taking his family 
 with him at the rate of about four miles a 
 second, in a direction slightly inclined to his 
 own polar axis. As stellar motions go, the 
 sun's rate is distinctly leisurely. Some of the 
 stars fly at the rate of hundreds of miles a 
 second ; and, when they get up speed for a 
 stellar encounter, the evidence proves that they 
 may strike one another with the inconceivable 
 swiftness of thousands of miles a second. It is of 
 no use to try to realise astronomic numbers ; we 
 can calculate them and talk about them ; 
 we can never appreciate them. Four 
 miles a second, although a small cosmic 
 velocity is a tremendous speed as we know 
 motions. When we look at an express train 
 running along creating a whirlwind of dust^ 
 paper, leaves and other debris a dozen yards on 
 either side of its mile-a-minute course, we have 
 a feeling of the irresistible ; yet had the train the 
 sun's speed it would possess 57,000 times the 
 energy it has at a mile a minute. The sun's 
 motion, combined with planetary revolution,. 
 
THE SOLAR SYSTEM 119 
 
 causes the earth and all the other planets to 
 move in sloping spirals. Of the sun's motion 
 in space, however, we need say little at present. 
 We will consider him as at rest, with the planets 
 revolving round him, and the moons around the 
 planets. There are eight planets ; four small 
 dense inner planets, and four outside large 
 planets of less density. A great gap occurs 
 between these two series, and therein revolve 
 many hundreds upon hundreds of minute planets, 
 or planetoids, as they are called. " Bode's Law " 
 describes a rough order in the position of the 
 planets, and, according to this order, a planet 
 was missing, for which a society of astronomers 
 was constituted to search. On the first day of 
 the last century Ceres was found in the gap ; 
 the following year Pallas; then Juno, then 
 Vesta, and so on and on, till nearly 460 tiny 
 planetary spheres are either named or numbered. 
 The two groups into which the planetoids 
 divide the planets are: the inner group, Mercury, 
 Venus, Earth, Mars ; the outer, Jupiter, Saturn, 
 Uranus, Neptune. 
 
 The nearer to the sun, the more quickly the 
 planet travels ; thus Mercury travels at about 
 ten times the speed of Neptune, and completes 
 
120 THE SOLAR SYSTEM 
 
 its circuit in eighty eight days, while Neptune 
 takes more than sixty thousand days to com- 
 plete one revolution. All the planets revolve, 
 roughly speaking, in one plane. All but one 
 rotate in the same direction that they revolve in. 
 It was this wonderful order that led Laplace to 
 his exquisitely beautiful theory. His nebular 
 hypothesis of the origin of systems has, doubt- 
 less, a good deal of truth in it ; but his theory 
 that planets and moons originate by the release 
 of rings has, I am afraid, to be given up. Any- 
 way, the planets' axes being at all angles, and 
 Uranus even believed to go the wrong way, makes 
 the theory difficult to the accept in its entirety. 
 
 Of the origin of planets, I shall hope to show 
 something presently, far less fascinating than the 
 ring theory, but one that accords with many of 
 the peculiarities of the system. 
 
 Thus then the planets are a series of eight 
 globes divided by the belt of planetoids into 
 two groups of four each. All the planets and 
 planetoids speed on in their course around the 
 sun in one direction ; and all, save the planetoids, 
 roughly speaking, in the same plane. All but 
 one are spinning in the same direction that they 
 revolve in, but the axes of their rotation are 
 
THE SOLAR SYSTEM 121 
 
 inclined very differently. Jupiter, the giant 
 planet, is nearly upright, whilst Uranus has its 
 axis almost in the plane of its orbit. Venus is 
 inclined more than an angle of 4$ deg. ; whilst 
 the earth, Mars, and Saturn are all tipped a 
 little more than the fourth of a quadrant. The 
 tipping of the axes produces the seasons. So it 
 is always spring-time in Jupiter ; whilst poor 
 Uranus presents one pole to the sun for about a 
 quarter of a century ; then spring comes, and 
 for twenty-five years he is side on to the sun, 
 gradually presenting the other pole. So roughly 
 for twenty-five of our years Uranus has a day 
 and night corresponding with his winter and 
 summer; when autumn and spring come the 
 days and nights correspond with his rotation. 
 If there are inhabitants they must lead a strange 
 kind of life. I suppose they travel with the 
 summer and chase it round the globe. Venus 
 has tremendous seasons, twice as acute as those 
 of the earth ; and there the sun is about twice as 
 hot. The seasons of Mars and Saturn are 
 similar to the earth's, only Saturn's year is 
 about thirty times as long as ours. 
 
 The days of Mercury, Venus and Mars are 
 
 about the same length as the earth's ; whilst 
 
 8 
 
122 THE SOLAR SYSTEM 
 
 Jupiter and SaturrThavefdays less than half as 
 long. 
 
 Most of the planets have attendant satellites ; 
 generally, these revolve roughly in the same 
 plane as the equators of the planets to which 
 they belong, our moon being about five degrees 
 out ; so that the apparent path of the moon in 
 in the heavens does not correspond with that of 
 the sun. As far as the moon is concerned, what 
 is called the harvest moon is the only charac- 
 teristic of seasons. The moon rotates once a 
 month ; and so always keeps the same face to us. 
 As the sun sometimes shines on the other side of 
 the moon, the face we know is then in the dark ; 
 and when by accident the moon gets fairly in 
 front of the sun we have an eclipse. But as the 
 disc of the moon, owing to altered distances, 
 appears sometimes smaller and sometimes larger 
 than the sun, we get different kinds of eclipses, 
 annular when the disc is not large enough to 
 cover the sun, total when it is. The eclipse of 
 the moon is due to its getting into the earth's 
 shadow. That the moon always presents the 
 same face to us is probably due to an interesting 
 tidal action. Both the sun and moon cause 
 tides on the earth ; but, owing to the nearness 
 
THE SOLAR SYSTEM 123 
 
 of the moon, the action is chiefly lunar. When 
 both act together we get the spring tides. The 
 so-called tidal waves are generally volcanic in 
 origin, due to the earth shivering when internal 
 contraction causes the surface to crush. The 
 tides bulge up on both sides of the earth ; away 
 from, and towards the moon. She attracts the 
 near ocean more than the earth ; she attracts 
 the body of the earth more than the distant 
 ocean. Thus one side bulges up because it is 
 pulled away from the earth ; the other side 
 because it is left behind. But if the moon pro- 
 duces such tides on the broken-up ocean, what 
 must it have done when all the earth was fluid ? 
 And what must have been the tides in the moon 
 produced by the earth fifty times as big and 
 twice as dense ? The earth is nearly a hundred 
 times as heavy as the moon. Probably the 
 moon does not possess the earth's proportion of 
 gold and platinum at her centre. However that 
 may be, the tidal action of the earth on the moon 
 when she was liquid must have been enormous. 
 Tides act as a brake and stop rotation ; so if we 
 were to put up water-power engines and use the 
 estuaries as mill ponds we should, as it were, 
 utilise the brake that is stopping the earth. Just 
 
124 THE SOLAR SYSTEM 
 
 as sparks fly out of a railway brake because of 
 the change of motion into heat, so the tides 
 warm the water of the oean. Were we to inter- 
 cept the water and do work by tidal engines, 
 there would be just the same amount of heat 
 produced finally. 
 
 The tremendous earth tides on the fluid moon 
 acted as a brake on the moon's rotation, and so 
 slowed it down until it presented the same face 
 to the earth. But the younger Darwin has 
 demonstrated that not all this energy went to 
 warm the moon. It was converted into potential 
 energy, and sent the moon to a distance, much 
 farther from the earth than it formerly had ; and 
 probably the nearer planets have had their 
 distances from the sun increased in the same 
 way. Of course, when the moon was nearer, 
 the earth tides were higher, and, incidentally, 
 the atmospheric geological agencies were greater 
 than they are to-day. 
 
 The moon probably belongs to the sun's true 
 family, as do also another set of far smaller 
 bodies, the meteors that constitute the zodiacal 
 light ; whilst the periodic comets and meteoric 
 swarms are adopted children, and the errant 
 comets only passing visitors. 
 
THE SOLAR SYSTEM 125 
 
 The zodiacal light described on page 141, is a 
 huge, bun-shaped, luminous mass, often to be 
 seen after the sun has set, sticking up aslant 
 to the horizon in the plane of the ecliptic. I 
 hope further to show that, in one state of the solar 
 system, much of its matter consisted of countless 
 myriads of millions of meteoric masses coalesced 
 molecules, and cosmic dust generally, all whirl- 
 ing in an atmosphere of rare gas. The zodiacal 
 light may possibly be the remains of this debris, 
 not yet absorbed by the sun. Those bodies 
 that revolve near the sun must move with a 
 velocity of over three hundred miles a second, 
 and if a large one met a dense errant body 
 visiting the sun from an opposite direction 
 there would be a collision that would easily 
 account for the brilliant solar flashes, and for 
 that particular one that produced a few years 
 ago such a violent magnetic storm that upset 
 our telegraphic instruments and culminated in 
 the most beautiful series of aurorse at both poles 
 of the earth. 
 
 The sun, planets, moon, and zodiacal light are 
 possibly legitimate relations united into a group 
 during the great collision that wedded the two 
 pre-solar masses from which I imagine the 
 
126 THE SOLAR SYSTEM 
 
 system originated. The members of the family 
 adopted since would not weigh very much. 
 There are a few comets and meteoric swarms 
 that we know of; there may be an infinity of 
 meteoric swarms we do not know of; because 
 only those that intersect the earth's orbit, and 
 sometimes plunge into our atmosphere, are 
 visible to us. There may be myriads of bodies 
 other than comets revolving in our system that 
 we do not see. We see comets because of their 
 physical condition. Comets are probably swarms 
 of particles orbitally connected. When these 
 get near the sun a tremendous tidal action sets 
 up, that makes the constituent bodies rub one 
 another and collide in various ways, producing 
 luminosity by impact and electricity by friction ; 
 and so our dust visitor lights up and becomes 
 visible. Were he solid we should not see him. 
 The zodiacal light, comets and meteors are 
 treated in detail in Chapter X. 
 
 Such then is our solar system, and in the 
 next chapter an attempt will be made to give a 
 definite account of its genesis. 
 
CHAPTER IX 
 
 THE ORIGIN OF THE SOLAR SYSTEM 
 
 AN INCIPIENT SOLAR SYSTEM DEDUCED FROM IMPACT. 
 HYPOTHESES OF LAPLACE, LOCKYER, AND PROCTOR 
 NOT ACCEPTABLE TIME RIPE FOR A NEW HYPOTHESIS. 
 FUSION OF TWO SUNS THE PLANETS REGARDED AS 
 STEP CHILDREN TWO GROUPS OF PLANETS IN THE 
 SOLAR SYSTEM THE SOLAR SYSTEM POSSIBLE AS THE 
 RESULT OF THE COLLISION OF PRE-EXISTENT SYSTEMS 
 OF SUNS AND PLANETS. EFFECTS OF GRAVITATION. 
 IRREGULARITIES OF THE SOLAR SYSTEM STEPS IN ITS 
 GROWTH-WHY THE INNER PLANETS ARE DENSER 
 THAN THE OUTER-JUPITER'S UPRIGHT AXIS AC- 
 COUNTED FOR MOONS ARE ENTRAPPED BODIES- 
 EFFECTS OF TIDES UPON THEIR ORBITS. ORIGINAL 
 AND ACQUIRED QUALITIES THAT HAVE LED TO THE 
 SYMMETRY OF THE SYSTEM-ASTRONOMY AND GEO- 
 LOGY CONSONANT. 
 
 We have seen how a star cluster may originate 
 and may become an incipient sun with satellites, 
 whose orbits are at all angles. It is also easy to 
 realise how a nebula may entrap bodies which, 
 on the shrinking of the nebula into a sun, may 
 become planets revolving in all directions. But 
 without the idea of impact to originate a common 
 
128 THE ORIGIN OF THE SOLAR SYSTEM 
 
 rotation, it is difficult to understand the evolu- 
 tion of systems such as the one of which our 
 earth is a member a. system in which the sun 
 and almost all of its satellites rotate, and all the 
 planets revolve, in the same direction and roughly 
 in one plane. 
 
 The exquisitely ingenious hypothesis of 
 Laplace, of the release and coalescence of nebular 
 rings, has fascinated mankind for generations ; 
 and although it is no longer fully accepted, it 
 leaves much fertile thought. The same may be 
 said of the meteoric hypothesis of Lockyer and 
 Proctor. The insuperable difficulties afforded 
 by the dynamical theory of gases as against 
 Laplace's theory does not apply to the meteoric 
 idea ; but, amidst the wondrous order of the 
 system, the irregularities in the directions and 
 orbits of the moons and planets, and of their 
 axes, are too great to be accounted for on the 
 meteoric hypothesis, so that although it was 
 once fairly well known, it has almost passed out 
 of literature. The ground is, therefore, clear for 
 a new hypothesis, could a reasonable one be 
 found. 
 
 It is possible, that the sun is the result of the 
 collision of two bodies that have fused and 
 
THE ORIGIN OF THE SOLAR SYSTEM 1 2Q< 
 
 coalesced, whilst the planets existed before the 
 collision occurred. The union of the two bodies 
 that made up our sun was probably a case of 
 whirling coalesence in which the two became one. 
 
 The planets are not the offspring of the union;, 
 they are stepson^ and daughters. Whether all 
 belonged originally to the one, or were divided 
 between both parents, it were hard to tell, per- 
 chance we may never know. Possibly the four 
 inner planets may have belonged to the one, and 
 the four outer to the other. They each form a 
 set, the members of which have a close resem- 
 blance to each other ; each group is so unlike 
 the other group, that the two groups may not be 
 related. Still, when we come to consider the 
 evolution of such a system, it seems almost 
 inevitable that some of this contrast of character 
 between the inner and outer planets must have 
 come about during their later evolution ; so that 
 much latitude of conjecture remains which further 
 research may narrow. Thus, in a general way 
 we may imagine the birth of the solar system. 
 
 Two vast globes are rushing in upon one 
 another, one or both attended by satellites. Any 
 of these satellites that plunge deeply into either 
 body are at once burnt up as the meteors of a 
 
I3O THE ORIGIN OF THE SOLAR SYSTEM 
 
 November shower are dissipated by our atmos- 
 phere but all do not so plunge. As the great 
 globes impinge upon one another some of the 
 satellites are carried forward and escape the 
 general conflagration. 
 
 The solar system does not look as if it were 
 produced by a partial impact in which a portion 
 of each globe passed forward into space. The 
 orbs, probably, plunged deeply into one another, 
 and the parts not actually meeting were carried 
 forward as huge tongues of fire that whirled 
 around the general mass and were absorbed 
 into it All the agencies of an impact would be 
 at work intense heat, axial escape, selective 
 escape and rotation. But the enormous attrac- 
 tion modifies all these agencies. The gravitating 
 power is not small as it would be were a portion 
 .struck from each body. Both the entire bodies 
 have coalesced, and the mutual attractive power 
 neutralised the expansive effect of heat, and 
 stopped the escape of molecules, except the 
 lightest and those favourably situated. Doubt- 
 less there never has been a cosmic impact that 
 did not strew space with countless wandering 
 molecules. But in the origin of the sun this 
 was not a large factor. The impact caused a 
 
THE ORIGIN OF THE SOLAR SYSTEM 131 
 
 whirl that swung the materials of the bodies 
 into a huge bun-shaped rotating nebula, possibly 
 always dense at the centre, but very rare at 
 the exterior, and probably extending beyond 
 Neptune ; at least, the very circular orbit of 
 that planet suggests that it was so, although 
 this is not necessarily the case. The tidal 
 stoppage of its rotation may have greatly 
 enlarged its orbit, for we must remember that 
 although tidal action would be very small at 
 Neptune's distance, yet it would not take much 
 work to push the planet further away from the 
 sun. Anyway, that is a question mathematicians 
 may probably answer. Certainly, if the solar 
 system was formed in this way, the outer margin 
 of the nebula extended to an enormous distance. 
 I have spoken above of axial escape. This 
 action is especially characteristic of a case of 
 whirling coalescence such as probably originated 
 the Solar System. It is of especial interest in 
 the case of the origin of the universe and will 
 there be described in detail. It suggests that at 
 the centre of two coalescing bodies a tremendous 
 pressure is produced that can find no relief save 
 axially and in this line in both directions 
 material is shot out of the system. 
 
132 THE ORIGIN OF THE SOLAR SYSTEM 
 
 Let us now gather up our ideas. Two bodies 
 with satellites have collideJ, have coalesced, the 
 non-coalescing parts swirling around each other ; 
 and this onward motion, combined with the 
 expansive effect of heat, and its other result 
 molecular escape has converted the two bodies 
 into a nebula. The original satellites that 
 formerly revolved without any order are swung 
 forward by the onward rush of their parent 
 orbs. Some are disintegrated ; but some escape ; 
 some cannot fly away entirely the attraction is 
 too strong ; hence they revolve in highly 
 eccentric orbits. Had they been originally at 
 rest they would have been thrown into a single 
 plane and would all revolve one way ; and in 
 their passages through the nebula would all 
 tend, as Laplace has shown, to rotate in the 
 same direction. But they were not at rest 
 around their central body ; they revolved, and 
 probably .rotated. All these motions would 
 tell in the final result, and fully explain all the 
 irregularities of the system. 
 
 This, then, is an account of the possible union 
 of the two bodies that formed the system. The 
 final evolution of the planets is a matter of 
 some difficulty. Much of their development 
 
THE ORIGIN OF THE SOLAR SYSTEM 133 
 
 has already been discussed in detail in earlier 
 papers. But the complexity of the process 
 tends to become bewildering, so we will only 
 give a very general glance at some of the 
 agencies that have converted that apparently 
 
 DIAGRAM OF THE OKBIT OF A PLANET. 
 
 S represents the sun and A the earth. In equal times it should fall to 
 D and be carried by its velocity to B ; the position it attains is C. Again, 
 in equal times it would fall to Q and be carried by its onward motion to P, 
 it consequently reaches M. The same agencies take it to Z. Clearly in 
 the next revolution when it reached A, if the sun now disappeared, there 
 would be no fall, hence it would reach B. If the sun were lessened it is 
 clear the earth would pass between B and C, and consequently at the 
 opposite end of the major axis it would be further from the sun, and the 
 o:bit would be more circular. Hence as seen in diagram page 73, the 
 perihelion distance will be increased and the stars not impact again, and in 
 the case of the oibits of the planets, all material lost before aphelion distance 
 is reached will make the orbit more circular. 
 
134 THE ORIGIN OF THE SOLAR SYSTEM 
 
 awful chaos of fire and conflict into the order 
 and method that now remain. 
 
 The accompanying diagram of the orbit of a 
 planet illustrates the interaction of the centri- 
 petal and centrifugal actions. 
 
 In the eye of the mind we watch the flight 
 from the central fire of the planets and, per- 
 chance, countless smaller bodies. We watch 
 the gigantic fire-mist whirling and expanding 
 until it is many hundreds of millions of miles 
 in diameter. We see the planets gradually 
 lessening the speed of their flight, and presently 
 commence their fall back towards the centre. 
 They plunge deeper and deeper into the fire- 
 mist, and all the gas outside their orbits has 
 no influence in causing their return. Hence the 
 orbits become more circular. But in the nebula 
 the body becomes heated and expands, gathering 
 the gas of the nebula towards itself. The 
 bodies cross one another's path, and will often 
 coalesce. Almost every such coalescence will 
 tend to make the orbits more circular, to cause 
 the rotation of all the planets to agree in 
 direction, and the axes to become more per- 
 pendicular to the plane of the orbit It would 
 also bring this orbit into the plane of the general 
 
THE ORIGIN OF THE SOLAR SYSTEM 135, 
 
 rotation of the nebula. Any planet that came 
 near the centre would be intensely heated, and 
 hence there would be a tendency to lose light 
 molecules ; whilst, on the other hand, this body 
 would tend to pick up the heavy molecules that 
 selective escape would have left near the centre 
 of the nebula. Thus, the inner planets would 
 tend to be small, and to consist of dense 
 material, and the outer planets large and less 
 dense, exactly as we find them in the solar 
 system. Selective escape would probably dis- 
 sipate much hydrogen, helium, neon, nitrogen 
 and argon but the energy proportionate to mass 
 would not be great enough to do this at all 
 effectively. 
 
 The giant planet Jupiter has probably been 
 largely formed by impact and accretion, owing 
 to its being in the centre of the storm of 
 meteors that would be produced by coalescing 
 molecules, and hence its axis is very up- 
 right. I think Proctor was the first to point 
 this factor out. The moons were probably 
 bodies entrapped by the planets when nebulous. 
 The orbits of the moons have probably increased 
 by tidal action ; much of their potential energy 
 of expansion would become energy of rotation,. 
 
136 THE ORIGIN OF THE SOLAR SYSTEM 
 
 and this by tidal action would turn into 
 potential energy of distance from their planet. 
 I cannot believe that the belt of the minor 
 planets, or the meteors constituting Saturn's 
 Rings, could have been present when either the 
 solar nebula extended beyond the planetoids, 
 or Saturn's volume extended beyond his rings. 
 I believe in one case a planet, and in the other 
 case a moon, has been blown to pieces by a 
 body plunging into their mass. Those who 
 have argued against this origin by explosion, 
 have overlooked a number of agencies that have 
 been effective in giving the present orbits to the 
 planetoids. 
 
 Of the origin of the very imperfect order of 
 the distances of the planets, called Bode's Law, 
 I have given a full account in former technical 
 papers, but my space does not permit me to dis- 
 cuss it here. Enough has been said to show 
 that there was a vast series of agencies at work, 
 tending to give the wonderfully majestic order 
 to the system of which our earth is a member. 
 
 It may reasonably be asked why the solar 
 system did not develop into a meteoric swarm, 
 and then a small star cluster, before its final 
 condition as a sun. I believe the answer to this 
 
THE ORIGIN OF THE SOLAR SYSTEM 137 
 
 to be, that it was not a case of partial impact, 
 and consequently, as already suggested, only 
 part of its gaseous constituents were sent out by 
 molecular selective escape. Therefore the 
 meteors, as they formed, revolved in a nebula that 
 all the time lessened their velocity and en- 
 trapped them. 
 
 It would seem, then, that there would be a 
 tendency for the contracting nebula to entrap 
 all but the larger bodies. But these larger bodies 
 would also possess an entrapping action. The 
 planets in their intermediate state would pro- 
 bably have associated with them a large nebulous 
 atmosphere, that the extreme tenuity of the 
 solar nebula would not be able to sweep away. 
 Such atmospheres would readily entrap bodies 
 moving through them at approximately the 
 same velocity, and such bodies would become 
 moons. In other words, the contracting solar 
 nebula would tend to entrap all but large 
 masses. And the nebulous planets, in the same 
 way, would tend to entrap and absorb all but 
 masses relatively large to the mass of the planet. 
 
 We must remember there is an area even about 
 a small planet, where the planet's gravitation is 
 greater than the sun's gravitation from the same 
 
 9 
 
138 THE ORIGIN OF THE SOLAR SYSTEM 
 
 spot in space. Thus it seems probable that the 
 planets might entrap moons. And in all these 
 cases we must also keep in mind the fact that 
 the orbits were probably much smaller, and have 
 increased in size by tidal action, converting their 
 energy of rotation into potential energy of dis- 
 tance, the same agency applying, of course, both 
 to the planets and their satellites. Some other 
 agencies regarding the atmosphere of the planets, 
 the zodiacal light, the planetoids, Saturn's rings, 
 and comets, are discussed elsewhere; and some 
 only hinted at. In a preliminary treatise like 
 the present, too great a detailed definition 
 would obviously be out of place. 
 
 We have glanced at the apparent chaos of 
 original and acquired motions from which, as a 
 skilful potter gives symmetry and beauty to a 
 shapeless mass of clay, the ruling power of the 
 Cosmos has given life and rhythm to our system. 
 The storms have been subdued, and the flames 
 quenched which gave the planets their long 
 baptism of fire, and sorted the materials for their 
 constitution. It is like a fairy tale to trace from 
 the original terrestrial ball of fire the wondrous 
 agencies that selected its material, wrinkled its 
 solidified crust, laid its surface down in layers, 
 
THE ORIGIN OF THE SOLAR SYSTEM 139 
 
 kneaded and crushed those layers into mountain 
 chains and immense valleys gradually to be 
 rilled with liquid as the cooling earth allowed 
 the acid vapours and steam to condense as salt 
 water ; then to watch the altered eccentricity of 
 the earth's orbit putting into play the physical 
 forces that, during the great glacial periods, 
 alternately covered each hemisphere with a vast 
 ice cap extending far down into temperate 
 regions. Then, again, it is a poem to trace the 
 gradual absorption of the poisonous gas, carbonic 
 acid, and see its carbon combine with other 
 elements and clothe the earth with verdure, 
 whose extent is revealed to us in the vast 
 carboniferous beds of stored energy that we now 
 use to drive our mighty engines. 'Tis indeed a 
 story of wonders to see that verdure partly give 
 place to animal life, and trace the long line of 
 evolution that has culminated in man. But all 
 this I have tried to tell in " The Romance of 
 the Earth." It does not belong to the story of 
 the wondrous stars that is at present being told. 
 
CHAPTER X . , 
 
 METEORIC PHENOMENA 
 
 THF, ZODIACAL LIGHT PROBABLY A PORTION OF THE 
 ORIGINAL METEORIC SWARM THAT FORMED THE 
 SOLAR NEBULA. THE PLANETOIDS PORTIONS OF 
 AN EXPLODED PLANET PLANETS EASILY BLOWN TO 
 PIECES-PLANETOID ORBITS DISCUSSED. SATURN'S 
 RINGS A COMPLEX PROBLEM. COMETS-ROTATING 
 MASSES OF PARTICLES ASSOCIATED BY GRAVITATION. 
 THEIR LUMINOSITY INCREASES ON NEARING THE SUN. 
 SPLITTING UP OF SWARMS-PERTURBING ACTION OF 
 PLANETS-SWARMS NOT OF SMALL MASS COMETS 
 TAILS DUE TO ELECTRIC INDUCTION. 
 
 The zodiacal light is a large lenticular or bun- 
 shaped mass of matter, the medial section of 
 which is coincident with the plane of the sun's 
 equator. It extends to a distance almost as far as 
 the earth's orbit, and reaches, in an axial direc- 
 tion, considerably beyond the body of the sun. 
 The zodiacal light is probably a portion of the 
 original meteoric swarm that constituted a large 
 part of the solar nebula, the smaller bodies 
 revolving in the outer regions of the nebula, and 
 consequently this cosmic dust did not suffer such 
 retardation as to be absorbed into the general 
 
METEORIC PHENOMENA 141 
 
 body of the sun, the velocity being sufficient 
 to keep the particles in orbits about the sun. 
 
 The whole of the material constituting this 
 vast appendage to the sun is probably com- 
 posed of independent masses, varying in weight 
 from tons to ounces, and in all probability they 
 are revolving in the same direction as the sun, 
 that is, if they are made up of the original 
 material of the sun. If on the other hand, as 
 some astronomers suggest, they have been 
 brought into the system by being swept from 
 comets in some such way as the meteoric swarms 
 that occasionally pass through the earth's atmos- 
 phere have been, then their direction about the 
 sun would be retrograde as well as direct. But 
 if they were thus swept from comets, and con- 
 sisted solely of meteoric swarms that passed 
 into our system, there seems to be no good 
 reason why they should lie chiefly in the plane 
 of the sun's equator. One sees no reason why 
 they should not be situated in all directions 
 equally about the sun. Therefore from their 
 equatorial position they are probably a portion 
 of the original bun-shaped nebula, or meteoric 
 swarm, that gave rise, by contraction, to the 
 sun itself. 
 
142 METEORIC PHENOMENA 
 
 It is probable that some of these small bodies 
 do actually revolve in different directions, for we 
 have reasons to suppose that occasionally col- 
 lisions of considerable masses occur among these 
 meteors. Such was probably the case in the 
 excessively brilliant light that was seen some 
 years ago and was accompanied by a violent 
 magnetic all storm over the world, and was fol- 
 lowed by magnificent displays of the Aurora 
 Borealis the evening afterwards. 
 
 Possibly it is the light reflected from this dust 
 swarm that surrounds the sun, that is the cause 
 of the corona seen during a total eclipse, because 
 by the study of a large number of drawings of 
 the corona, there can be but little doubt that it 
 extends much further equatorially than it does 
 axially. If this be so then the sun spots are also 
 in some way related to this zodiac light. This 
 is suggested by the fact that when an eclipse of 
 the sun is seen during a maximum sun spot 
 period, there is a much greater equality in the 
 distribution of the luminosity around the sun. 
 If it is true that in some way or other the corona 
 is due to the zodiacal light, then it is also con- 
 nected with the sun spot period. Possibly the 
 bat's wing form of the corona as seen at times 
 
METEORIC PHENOMENA 143 
 
 on both sides of the sun in the equatorial 
 direction, may be due to some order in the orbits, 
 of many of these meteors, as we have order in 
 the meteors that constitute Saturn's Rings. 
 
 THE POSITION OF THE PLANETOIDS. 
 
 Although I thus believe the zodiacal light to 
 be a portion of the original meteoric matter 
 
144 METEORIC PHENOMENA 
 
 of the solar system, I cannot believe that this is 
 the case with the planetoids, or with Saturn's 
 Rings. The resistance of the contracting nebula 
 in which they must have been revolving seems to 
 me to render the retention of the planetoids an 
 impossibility, and I cannot but think that Olbers, 
 the original discoverer of the planetoids Pallas 
 and Vesta, was right in his suggestion that these 
 bodies are portions of an exploded planet. 
 
 A planet may so easily be blown to pieces. 
 It is probable that the average velocity of bodies 
 at impact is some hundreds of miles a second. 
 With such a velocity the gas produced would 
 have an expansive force that would possess at 
 least from 10 to 50 thousand times the explosive 
 power of an equal mass of dynamite. Con- 
 sequently were a body of sufficient mass, and 
 endowed with anything like these velocities, to 
 .plunge into a planet, the pressure produced 
 would be such that the planet would inevitably 
 be blown to pieces. 
 
 Now it has been assumed that if a planet were 
 blown to pieces, the spot where it exploded 
 would be a spot through which the orbits of the 
 bodies would all pass, consequently the idea 
 that they are parts of an exploded planet has 
 
METEORIC PHENOMENA 145 
 
 "been given up. But two circumstances at least, 
 and there are probably others, should be taken 
 into consideration, before we come to this con- 
 clusion, and these together seem to render the 
 idea untenable that there would remain a common 
 point for the many orbits. If the explosion 
 were instantaneous and the pressure acted 
 equally in all directions, it would be true of the 
 pieces on their first return, but gradually it 
 would be less true because of the extra- 
 ordinary perturbations that would be exercised 
 upon the orbits of the various fragments. It is 
 quite clear that in the case of an explosion with 
 the force acting in all directions, all those particles 
 that are on the advanced side of the planet 
 would be accelerated, and those parts that are at 
 the back of the planet's motion would be retarded, 
 whilst those particles at the side would be sent off 
 in such directions as would change the plane of 
 the orbits altogether. Thus those sent away in 
 front would be in the plane of the orbit and 
 would travel quicker, and those sent away be- 
 hind would be also in the plane of the orbit, 
 but slower. Therefore there would be very 
 different orbits, even in the case of those of the 
 exploded particles that: still remained in the 
 
146 METEORIC PHENOMENA 
 
 original plane of the orbit of the planet ; but the 
 rest that were sent in all directions, would be in 
 all azimuths. Now it. is known that perturbations 
 are sufficient to alter the eccentricity of the earth 
 fully twelve millions of miles, and it is extremely 
 probable that the perturbing influence of Jupiter 
 upon these much nearer bodies, would alter 
 their curves to a very much greater extent, and 
 consequently the perturbations would entirely 
 prevent the possibility of a common point of 
 intersection of the exploded particles. Al- 
 though the perturbations may be cyclic, yet the 
 cycle would be such that we could not possibly 
 trace the identity of the position where the 
 explosion occurred. 
 
 If the explosion occurred, the body that plunged 
 into the mass of the other body, and produced 
 the explosion, would not effect the whole of its 
 destructive work in a single spot, but the effect 
 of the explosion would be travelling partly with 
 the planet and partly in the direction of the 
 body itself. Nor would the pressure be over 
 instanteously. The pressure would be carrying 
 the bodies, and be acting upon them for some 
 time, and it must be remembered that every 
 agency that takes a definite time only leaves 
 
METEORIC PHENOMENA 
 
 an established orbit when that agency has ceased 
 to act. The orbits of the particles are influenced 
 by their own motion and the sun's attraction 
 alone. These two agencies alone suffice, in my 
 estimation, to prevent anything like an approxi- 
 mate position being found in the orbits of the 
 several fragments that would correspond with 
 the position of the original explosion. 
 
 THE PIANET SATURN AND ITS RINGS. 
 
 Exactly the same argument applies to Saturn's 
 Rings, which in the same way consist of particles 
 
148 METEORIC PHENOMENA 
 
 associated by gravitation, revolving in orbits 
 around Saturn, and which, in all probability were 
 -once a moon that has been blown to pieces by 
 an explosion. 
 
 In the first place, when originally formed, the 
 rings would have a very different appearance 
 from that they now present. They would seem 
 to radiate from a position that was near the area 
 over which the explosive force exercised itself, 
 and this would be a roughly radial position 
 from which the orbits would spread in every 
 direction, giving rise, as it were, to a double 
 plume that would meet on the opposite side of 
 the planet. A number of agencies would tend 
 to convert this irregular motion into a plane. 
 The minute particles into which the possibly 
 molten mass was blown, would be constantly 
 impinging on one another, as they passed the 
 plane of the original orbit, and would tend to 
 bring them into that orbit. 
 
 In the same way the impacts would tend to 
 make the orbits of each of the bodies more and 
 more circular. There would be greater resis- 
 tance at perihelion distance than at aphelion, 
 because perihelion distance would, to a large 
 extent, be the position of the original explosion. 
 
METEORIC PHENOMENA 149* 
 
 All the particles that have their velocity acceler- 
 ated would be sent further from Saturn, and 
 those that had it diminished would tend to 
 plunge upon the surface of Saturn, so that it 
 would be chiefly those that had an outward 
 direction that would be persistent, and hence 
 those particles that were driven outwards on 
 coming into the old position, would suffer 
 retardation, and this retardation at perihelion 
 would lessen aphelion distance, and would 
 actually tend to make the path of the orbit more 
 and more circular. There are still further 
 agencies at work in the perturbations of the 
 other moons, but these are of too complex a 
 character to discuss here. 
 
 COMETS 
 
 Comets are almost certainly dust swarms, and 
 dust swarms, as we have seen, may be produced 
 in a number of ways by collision. The collision 
 of whirling coalescence of two small bodies would 
 dissipate the lighter gas, and the diffused material 
 would become an orbitally connected dust 
 swarm, and the same may be still more frequently 
 the case with partial impact. In fact, all that 
 applies to the origin of star clusters (see Chapter 
 
ISO METEORIC PHENOMENA 
 
 VII) applies also to the formation of a dust 
 :svvarm, but on a smaller scale. 
 
 Possibly, besides these dust swarms visiting 
 our system, there may be meteoric bodies having 
 masses much greater than these dust swarms, 
 but the fact is these masses would almost 
 inevitably escape observation, whereas a dust 
 swarm produces a series of phenomena that 
 causes it to be easily detected. 
 
 A comet then is probably a rotating mass 
 of particles of various dimensions associated 
 by gravitation, and as a rule in a whirl of which 
 the motions of most of the constituents are 
 roughly in one direction. 
 
 Such a swarm, coming into the solar system, 
 even at considerable distance from the sun, must 
 have the motion of its constituents very much 
 perturbed, and this perturbation would become 
 greater and greater as it approached the sun. 
 The perturbation would occasion collisions, and 
 these collisions would in many cases smash the 
 particles to still finer dust and in some cases 
 convert the collided bodies into gas. In either 
 case they would increase the luminosity, the one 
 by increasing the surface of reflection and the 
 other by giving actual self-luminosity. As they 
 
METEORIC PHENOMENA 151 
 
 approached the sun this action would be 
 increased to a greater and greater extent, and 
 in addition to this the reflected light from the 
 sun would be more and more brilliant. When 
 very near the sun, the disturbing action would 
 be so great that the side of the dust swarm 
 constituting the comet that was nearer the sun, 
 would be swept forward with enormously in- 
 creased acceleration and the part more remote 
 from the sun would be left behind, so that the 
 comet would be stretched somewhat into a 
 spindle shape. Should this action be very 
 intense the distance of the parts may become so 
 remote from the general body, that the dust 
 swarm would lose its association with them. 
 These portions would then become a train of 
 meteors that may or may not be orbitally con- 
 nected permanently with the sun, but it would 
 tend to be connected with the sun, owing to the 
 resistance of the gaseous and other matter of the 
 zodiacal light. But if the perturbing action of 
 any great planet had caused the comet to become 
 orbitally connected with the sun, then we should 
 have a train of meteors that would revolve in 
 the comet's train, and the whole comet, if coming 
 very close to the sun, might be swept out into a 
 
152 METEORIC PHENOMENA 
 
 train of meteors. That this does not happen 
 with all comets, proves that the idea that they 
 are of exceedingly small mass, is untrue, for if 
 they were of exceedingly small mass, no dust 
 swarm could approach anything like near the 
 sun without being swept into a meteoric train. 
 
 A METEOR HEATED BY FRICTION OF THE ATMOSPHERE AND ITS 
 VOLATILIZED TRAIN. 
 
 With anything like a heavy mass of dust,, 
 long before the sun is able to tear it to pieces,, 
 the sun's perturbing action sets up such an 
 amount of internal disturbance, that the general 
 body of the comet becomes luminous, and 
 doubtless in addition to the two actions of the 
 smashing of the particles and the volatilisation 
 and heating, we have, with the friction of the 
 particles flying past one another, a tremendous 
 evolution of electricity. Now in an investiga- 
 
METEORIC PHENOMENA 153 
 
 tion, an account of which I contributed to the 
 " Philosophical Magazine" in Dec., 1873, 1 showed 
 that in certain conditions of excessively high 
 temperature, electrical disturbances have a 
 
 The above diagram illustrates a set of parallel meteors, a part of a train, 
 plunging into our atmosphere. The apparent radial direction is an effect of 
 spherical perspective as is also the increasing lengths of their curves, as they 
 increase in distance from the radial point. 
 
 tendency to cause particles of gas to carry the 
 positive electricity completely away from the 
 body, and therefore, if the body is a bad 
 
 conductor and of considerable dimensions, i; 
 
 10 
 
154 METEORIC PHENOMENA 
 
 might be left negatively electrified. I should 
 say that the reverse is the case with low 
 temperatures, for at low temperatures the 
 negative electricity escapes more easily than the 
 positive. 
 
 At high temperatures the positive electricity 
 escapes from that portion of the system where 
 the electrical disturbances are set up. The 
 consequence is that it is possible that the sun 
 and all heated bodies may be charged with 
 negative electricity. The positive electricity 
 developed in the meteoric swarm, would stream 
 in possibly more or less invisible form from the 
 near portion into the sun, whilst the negative 
 would be repelled from the sun, inducing a path of 
 electrical action directly outwards from the sun. 
 This induced electrical action would take 
 a sensible time to travel the many millions of 
 miles to which the tail of a moderately large 
 comet reaches, so that the form of a comet's tail 
 would not as a rule be straight, but would be 
 curved somwhat into the form of a plume, and 
 as the comet passed nearest to the sun, the 
 radial action would continue, and thus we should 
 have this induced electric phenomenon always 
 being directed from the sun as a centre, while the 
 
METEORIC PHENOMENA 
 
 155 
 
 curvature of the plume would be always back- 
 wards, due to the lagging action of the induction, 
 and consequently backwards from the motion of 
 the comet itself. The comet might vary with the 
 nature of the dust swarm which may readily have 
 subordinate centres of motion, and the electrical 
 
 DIAGRAM ILLUSTRATING THE PATH OF A COMF.T. 
 
 The dotted line represents the orbit of a comet. The diagram shows the 
 radial direction of the tail from the sun, and the retardation of its distant 
 part into a curve. 
 
 action that is produced would differ. Doubtless 
 many other agencies come into play in the 
 production of the luminous plume of the comet, 
 but one thing may be taken as being certain, 
 and that is, that it is not in any way materially 
 connected with the comet itself any more than 
 
156 METEORIC PHENOMENA 
 
 the motes lit up by the beam of a revolving 
 searchlight belong to the searchlight. The tail 
 of a comet is directly a phenomenon of the ether, 
 and possibly indirectly produces illumination of 
 the metoric dust that in all probability exists not 
 merely as far as the earth's orbit, but to a greater 
 or less extent in the whole of the solar system, 
 if not in the whole of space. 
 
 The whole of the phenomena of the zodiacal 
 light, the planetoids, Saturn's Rings, meteoric 
 swarms and comets, show in a marked manner 
 the dustiness of space, and give us reason to 
 accept the great Struve's conclusion that the 
 intensity of light coming from vast distances, 
 diminishes more rapidly than inversely as the 
 square of the distance, and if this is the case, 
 we are to a large extent justified in the con- 
 clusions we shall come to and discuss in 
 Chapter XIII on the Immortality of the Cosmos^ 
 that radiant energy is ultimately absorbed by 
 matter in space. 
 
CHAPTER XI 
 
 THE VISIBLE UNIVERSE 
 
 STELLAR DISTANCES HOW THEY ARE MEASURED TRIGO- 
 NOMETRY LIGHT YEARS. THE NEAREST FIXED STAR 
 FOUR LIGHT YEARS DISTANT. IMMENSE SIZE AND 
 NUMBER OF THE STARS. KINDS OF STARS-TEM- 
 PORARY VARIABLE DOUBLE-MULTIPLE. NEBULAE 
 THE MILKY WAY AND ITS POLES. MANY KINDS OF 
 NEBULAE. THE UNIVERSE THE RESULT OF IMPACT. 
 DISTRIBUTION OF STARS IN SPACE ORDER IN THE 
 UNIVERSE. CORRESPONDENCE OF FACTS WITH THE 
 THEORY. 
 
 Twinkle, twinkle, little star : 
 How I wonder what you are ! 
 
 Thus runs the old rhyme ; and, now that we 
 know so much about the stars, our wonder is 
 still greater, although of another kind. We are 
 amazed at the marvels unfolded to us, at the 
 majesty of the creation and the vastness of the 
 scale upon which it is built. The distances of 
 the stars from us, and from each other, are so 
 enormous, that double stars, which, a power- 
 
]6O THE VISIBLE UNIVERSE 
 
 ful telescope will not divide, when examined 
 by the spectroscope are found to be revolving 
 around each other in orbits that would take an 
 express train hundreds of years to traverse. How 
 are these distances measured ? By a property of 
 the triangle. Upon the same base, and upon 
 the same side of it, there cannot be two triangles 
 that have their sides which are terminated in 
 one extremity of the base equal to one another, 
 and likewise those which are terminated in the 
 other extremity, equal to one another (Euclid, 
 Book i, proposition vii.) by which the old 
 Greek means if the sides of a triangle are stiff, 
 you cannot alter its shape. You may carefully 
 make a five-barred gate, and nail it strongly ; but 
 unless you put a diagonal, the gate will sag. 
 The diagonal ties it into two triangles and then 
 it is rigid. So if we have a base line and a 
 distant point, the distance to the point from 
 each end of the line, and the angles the point 
 subtends to the line, are rigidly fixed. There- 
 fore, if we know the length of the lines, we can 
 calculate the angles ; and if we know the base, 
 and the angles at its ends, we can calculate the 
 distances. The art of doing this is called 
 trigonometry. So accurate is this triangle 
 
THE VISIBLE UNIVERSE l6l 
 
 method of measurement that surveys of hun- 
 dreds of miles are often but a few feet out. 
 
 This is how we measure astronomical dis- 
 tances. A base line on the earth is measured, 
 and a point on the moon's surface chosen ; and 
 by the length of the line and the angles at its 
 ends, we can measure the moon's distance. By 
 a somewhat more complex process, taking 
 advantage of the passage of Venus across the 
 sun's disc, we can measure the distance of the 
 sun. But we can check our solar measurement. 
 By experiment we can determine the speed of 
 light: it is over 186,000 miles a second, about 
 ten million times as fast as the quickest express 
 train. By the eclipses of the satellites of the 
 planets we can tell how long light takes to 
 travel from the sun ; and thus, by two methods, 
 we get the distance of the sun and the size of 
 the earth's orbit. Of course, the orbit is an 
 ellipse and does not measure the same in all 
 parts. To measure the distance of the stars we 
 use the earth's orbit as a base line. It is over a 
 hundred and eighty millions of miles in diameter. 
 At intervals of six months, the angle a star 
 makes is measured. The angle is so small that 
 only the most accurate workers and the most 
 
162 THE VISIBLE UNIVERSE 
 
 gigantic and exquisite instruments are able to 
 detect any difference. But year by year the 
 observations are compared and defects are 
 eliminated, until at length there is considerable 
 certainty as to the distance. And what a re- 
 velation it is ! It would take the swiftest express 
 train forty millions of years to get to the nearest 
 star. It takes light over four years to travel; 
 from it to the earth. This star, Alpha Centauri, 
 is not seen in England. It is the brightest star 
 of the constellation Centaur. 
 
 The stars move, and by their distances we can 
 calculate their speed across the line of vision. 
 But, wonderful to relate, without knowing their 
 distances, we can calculate their speed in the 
 line of vision by means of the spectroscope ; and 
 the revelations of the spectroscope only confirm 
 the calculations from telescopic observation.. 
 If light takes over four years to come from 
 the nearest star, how long does it take from 
 the most distant ? Probably thousands of years. 
 As far as I can judge by the data available, the 
 huge dead suns that in 1892 gave us the mar- 
 vellous Nova Aurigae probably crashed through 
 each other before the battle of Crecy was fought. 
 Then, for hundreds on hundreds of years, the 
 
THE VISIBLE UNIVERSE 163. 
 
 message of the vibrating atoms carved the ether 
 into ripples that told system after system 
 of the stupendous phenomenon which had 
 occurred ; then the vibrations reached the 
 earth just in time to be deciphered by astrono- 
 mers. Had the message come a few years be- 
 fore, it would have fallen on uninstructed 
 senses, and would have been quite lost to 
 humankind. Unfortunately, although the senses 
 were trained the intellect was not. The pro- 
 verb, " The eye is blind when the mind does not 
 see," is intensely true of telescopic observation. 
 Had the observers been aware that a new tem- 
 porary star must consist of three bodies, as I had 
 shown by reasoning, and illustrated by diagrams 
 nearly a score of years ago, the whole life 
 history of such stars would probably be known 
 to us now. Vogel's observing power is wonder- 
 ful ; whilst other observers suspected the exis- 
 tence of the broad middle band which told of 
 the brilliant grazed-off mass, he clearly identi- 
 fied it, and even measured its velocity in space. 
 In the cause of science, it is to be hoped that 
 the intellectual inhospitality which has so long 
 closed the doors of science to the theory of partial 
 impact may have passed before any other 
 
164 THE VISIBLE UNIVERSE 
 
 brilliant temporary star adds lustre to our 
 heavens. 
 
 Such, then, are the distances of the stars ; what 
 of their size? A million, ten millions, hundreds 
 of millions of times the volume of the earth are 
 common dimensions. Thousands and tens of 
 thousands, perchance hundreds of thousands of 
 millions of times the volume of the earth some 
 of them seem to be. I estimated that those two 
 dark clashing orbs that impacted in case of 
 Nova Aurigae were respectively four thousand 
 and eight thousand times the mass of the sun. 
 It is no use to try to picture these sizes ; we 
 .simply do not understand them. We can calcu- 
 late them perfectly, as we can calculate the heat 
 produced by impact ; but what is the use to say 
 it is a hundred thousand times as hot as a blast 
 furnace? Our intelligence does not reach such 
 intensities any more than it does such volumes, 
 such speeds or such numbers. Think of it! Over 
 a hundred million suns in our single universe, 
 .besides nebulae of all kinds, star clusters and 
 meteoric swarms ! We know they all exist, but to 
 conceive their greatness is beyond us altogether. 
 
 The stars then are suns, in absolutely incon- 
 ceivable numbers, spread chiefly in a giant ring, 
 
THE VISIBLE UNIVERSE 165 
 
 called the Milky Way, or Galaxy. In this same 
 ring are all kinds of marvels besides the stars. 
 There are gigantic cloud-like irregular masses,, 
 such as the great nebulae of Orion ; also, stu- 
 pendous disc-looking masses, called planetary 
 nebulae, which, Herschel says, are shells of gas 
 so gigantic that our solar system might be placed 
 edge on seven times within some of them. Then 
 there are temporary stars stars that flash 
 suddenly into sight, sometimes expanding till 
 they are the brightest bodies in the entire 
 heavens probably globes of fire as large as the 
 orbit of the earth, that go on expanding into 
 space, and finally disappear. Then variable 
 stars, that sometimes seem to go out for months 
 and then reappear or exhibit periodic differences 
 of luminosity. Mira, the Wonderful, I have sug- 
 gested to be a giant dark sun that has had a 
 portion struck off, and thus exposed its molten 
 interior. Doubtless every cosmic body of gigan- 
 tic dimensions is hot-centered. The tremendous 
 impact no doubt set Mira spinning ; and as it 
 goes on rotating it turns alternately its brilliant 
 and dark sides to us. Then we have the so- 
 called twin suns, of which there are many thou- 
 sands. 
 
166 THE VISIBLE UNIVERSE 
 
 There are also triple and quadruple stars ; 
 in fact, groups of every kind, up to immense 
 clusters of orbitally associated suns, many of 
 them so exquisitely coloured that in a good 
 telescope they look like a collection of variously- 
 tinted gems. Still there are more marvels in 
 the Milky Way dead suns, the existence of 
 some of which has been demonstrated. Algol, 
 the Demon star, consists of a dead and a lucid 
 sun, and the spectroscope has measured and 
 weighed that dead sun, has told its velocity and 
 the size of its orbit, and pronounces it almost 
 exactly the size of our own sun. Sir Robert 
 Ball lately expressed the opinion that there may 
 be more dead than luminous suns ; I have for 
 years thought this. In our slight glance at the 
 denizens of the Milky Way, what a vast series 
 of gems we behold 
 
 Studding so thick 
 
 The great galactic ring 
 
 Which forms the crown of God ! 
 
 Before we can realise the majesty of stellar 
 -space we have to make acquaintance with the 
 wondrous aggregation of nebulae at the poles of 
 the Galaxy ; then we may proceed to the mode 
 of stellar evolution. 
 
THE VISIBLE UNIVERSE l6/ 
 
 Let us suppose this Milky Way, this gigantic 
 irregular ring of stars, nebulae, and a great 
 variety of bodies, to be the rim of a wheel 
 or better still, imagine it to be a sort of huge 
 double-gerbed Catherine wheel in full display. 
 Our solar system possibly lies somewhere towards 
 the centre of the wheel ; while, if we continue the 
 wheel-axis in both directions we come to two 
 stupendous aggregations of gaseous bodies, each 
 cap consisting of thousands on thousands of 
 nebulae of definite and sometimes exquisitely 
 beautiful form. Taking a celestial globe, con- 
 ventionally, of course, the solar system occupies 
 the centre ; encircling the globe in a broad stream 
 runs the Milky Way; on either side of this stream 
 of stars are comparatively bare belts ; then, as we 
 travel towards the poles of the Milky Way, in- 
 stead of stars, and star-clusters, &c., we come 
 upon nebulae. Thicker and thicker swarm the 
 nebulae as we travel onward ; most of them 
 roughly spherical in form, altogether unlike the 
 nebulae to be found in the Milky Way. But 
 spread amongst them are a number of nebulae of 
 very wonderful shape double, triple and quad- 
 ruple nebulae ; nebulae just coming into impact ; 
 nebulae in impact ; nebulae passing out of impact 
 
 OF THE 
 
 UNIVERSITY 
 
l68 THE VISIBLE UNIVERSE 
 
 with a long spindle between them ; every variety 
 of form resulting from the impact of nebulae. 
 There are spindles; spindles with incipient spirals 
 at the centre, like that of the Lion ; fully developed 
 double spirals ; double spirals with associated 
 nebulae; dumb-bell and annular nebulae,and other 
 forms. 
 
 The Milky Way is not without order. We 
 have what Proctor calls star-drift, streams and 
 sprays of stars. I well remember, one clear winter 
 night, chatting on impact with a friend. We 
 were looking up into the heavens, and I noticed 
 these wonderful sprays. " Why," I said, " the 
 very universe looks like a case of impact ; 
 these streams of stars seem to be the result of a 
 whirl ! " Stream after stream we pointed out to 
 one another. I had very imperfect ideas of the 
 universe then ; Herschel's old cloven-disc theory 
 was in my mind, and this notion did not fit well 
 at all. I went to Newcomen's " Astronomy," and 
 soon saw I must reconstruct my ideas. Then 
 Proctor's wonderful book, " The Universe," fell 
 into my hands. As 1 studied it, [ saw more and 
 more clearly the marvellous coincidence between 
 the universe as Proctor's great observing power 
 had pictured it, and the result that would be 
 
THE VISIBLE UNIVERSE 169 
 
 produced by the grazing but coalescent impact 
 of two previously existing universes. It was clear 
 that a rough ring of double spiral character, with 
 sprays and streams of stars, must ensue. It was 
 clear that such an impact must cover the poles 
 with gaseous matter that in time, by the passage 
 of bodies through it, must become nebulae and 
 nebulous stars. 
 
 All irregularities in gravitating groups tend 
 to increase themselves ; thus, out of diffused 
 gas grows up cosmic dust ; from cosmic dust 
 comes star clusters, or solar systems, according 
 to circumstance. Yesterday, according to the 
 swing of eternity's pendulum, the universe as we 
 know it did not exist. Perhaps we should 
 say our universe ; for, though the word in its 
 original meaning applies to the entire con- 
 tents of all space, it has come to be associated 
 with the galactic system only ; there being 
 much reason to believe in the existence of other 
 corresponding systems, the collection of all 
 these universes making up the infinite cosmos. 
 The thought capacity of the human brain is 
 marvellous, but finite ; we speak of the infinite 
 of the eternal but we cannot conceive them. 
 We know what time, and space, and matter, and 
 
I/O THE VISIBLE UNIVERSE 
 
 energy are ; of their whence and of their whither 
 we cannot know. We look, as it were, through 
 a circular tunnel, in which the future is a repeti- 
 tion of the past ; what we see is simply one 
 phase of an eternal rhythm. But whence came 
 our universe ? And what existed before it was ? 
 Does the curve wherein we dwell permit reply 
 to these tremendous questions ? I believe it 
 does. With form so definite and arrangements 
 so orderly, we may trace some history of 
 the past and some promise of the future. 
 
 Space is probably very imperfectly filled. 
 In the distribution of matter our universe is 
 comparatively crowded ; yet think of the empti- 
 nesses within our solar system, and of the 
 distance between it and the nearest star ! 
 Gravitation tends to clear space of matter and 
 aggregate it ; the motion of wandering molecules 
 tends to take them to the empty parts of the 
 Cosmos which gravitation has drained, again to 
 occupy them, and again to initate the formation 
 of new cosmic systems perchance huge 
 agglomerations without any kind of arrange- 
 ment, systems of the first order, as I have called 
 them. I shall offer suggestions regarding these 
 vast shapeless masses in Chapter XIII. Our 
 
THE VISIBLE UNIVERSE 
 
 universe is of a higher evolution ; it is full of 
 order and symmetry. The system consists not 
 only of the immense belt of stars the Milky 
 Way but also of the two caps of nebulae which 
 as depicted on the celestial globe cover the 
 poles of the galaxy. But let astronomers speak 
 for themselves as to its constitution. Sir J. 
 Herschel, who has studied star distribution more 
 than any other man, says that the mass of stars 
 is generally flat, of small thickness. He also 
 says that the number of stars visible in his 
 telescope in the Milky Way amounts to about 
 eighteen millions, and about two millions in the 
 remainder of the celestial vault. Struve 
 published a list of stars in which he showed that 
 in equal areas there were 4^ at the poles of the 
 galaxy to 122 in the galaxy itself. Proctor, 
 who discusses the facts very fully, after showing 
 that star clusters essentially belong to the 
 galaxy, and that as we pass from that great 
 circle we go through regular stages of irresolva- 
 bility to the galactic poles, and there find the 
 nebulae are completely irresolvable, says : " I 
 believe that cause may be assumed not unreason- 
 ably to be the difference in the circumstances 
 under which the galactic and extragalactic 
 
1/2 THE VISIBLE UNIVERSE 
 
 nebulae have reached their present state." 
 Again, in respect to the nebulae at the poles of 
 the Milky Way, Proctor shows that every theory 
 of their existence is ridiculous, " unless we con- 
 cede that the nebulae belong for the most part 
 to our galactic system." The splendid charts 
 and sketches by Sydney Waters, as well as 
 those of Proctor and Newcombe, show strikingly 
 this most remarkable arrangement. 
 
 Sir William Herschel states that any sound 
 theory of the universe must account for the 
 peculiar arrangement of the nebulae. Proctor, 
 in speaking on grounds of probability, says : 
 " Where the results are in direct contact, the 
 rich regions for one order corresponding to the 
 poor regions for the others, and vice versa, the 
 two orders of objects belong to one system," 
 and again says that he knows of no single 
 reason for supposing these nebulae to be external 
 galaxies. That they are not external galaxies 
 is proved from the facts recorded by Schmidt, 
 Hind and others, that nebulae have been observed 
 to vary and disappear, which is clearly impossible 
 with a galaxy like our Milky Way. I will 
 give only one other extract from among a large 
 number. It is from Proctor on " The Universe," 
 
THE VISIBLE UNIVERSE 173 
 
 and is wholly devoted to demonstrate these 
 conclusions. " The phenomena I have been 
 discussing seem to point to conclusions very 
 different from those which have been usually 
 accepted respecting the visible universe. Instead 
 of separating the stars and nebulae into distinct 
 systems, or rather of looking on the stellar 
 system as a member of the system of nebulae, 
 we seem compelled to look on almost every 
 object visible, even in the most powerful 
 telescope, as a portion of one system, which 
 comprises within its range simple, multiple, and 
 clustering stars, irresolvable nebulae, gaseous 
 bodies of symmetrical and unsymmetrical 
 figure, and in all probability myriads of other 
 forms of matter as yet undetected." 
 
 Let us attempt to trace out the evolution of 
 such a system. Let us try to realise how two 
 vast globular systems might plunge through 
 one another, and by a centrifugal motion pro- 
 duced by their opposing onrush, be swung into 
 an irregular ring of double spiral character. 
 The two primitive systems were possibly more 
 compact than our own system is now, although 
 there was probably much irregularity in dis- 
 tribution. There would be suns, nebulae, star 
 
1/4 THE VISIBLE UNIVERSE 
 
 clusters and other systems ; but they would 
 probably contain much more helium, neon, 
 argon, hydrogen and other gaseous elements 
 than our galaxy does at present. Whilst the 
 two gigantic masses closed in upon each other 
 during millions of years, impacts between the 
 various nebulae, the suns and other systems, 
 would be of increasing frequency. The centre 
 of coalescence would thus gradually become 
 gaseous, and the average temperature of this 
 part would steadily increase and produce great 
 pressure. This pressure would tend to expand 
 the gas. Let us try to understand with what 
 result. The two cosmic systems are each moving 
 forward, and are partially in impact, whilst the 
 remainder of each travels on, not, however, 
 parting company, but extending vast distances 
 into space. Yet the increased attraction result- 
 ing from coalescence will not permit more than 
 a few suns and other bodies with high original 
 motion to escape altogether. Hence, the lead- 
 ing parts travel in a curve. Thus we should 
 have a universe roughly double spiral in 
 character, hot and condensed in the centre, and 
 tending to a general rotation ; whilst all the 
 original motion of suns and systems would tell 
 
THE VISIBLE UNIVERSE 175. 
 
 as factors in the resultant motion. But groups 
 of stars similarly situated would tend to take a 
 common direction, and produce the streams and 
 sprays of stars and the community of motion of 
 adjacent stars that have been pointed out by 
 astronomers as so very characteristic of our 
 universe. The impact producing the universe 
 would not necessarily be in the least degree 
 paroxysmal to any of the outer suns and 
 systems ; they would not even tend to be 
 heated ; dead suns would remain so, and other 
 suns would lose heat and grow old. But at the 
 centre of the vast system everything would 
 tend to become gas under pressure pressure 
 acting in all directions, but finding relief most 
 easily axially to the general motion. This 
 outrush would cover the polar regions with 
 wide nebular caps. The motion commences by 
 pressure, but is continued by radial molecular 
 activity, to be gradually stopped by the attrac- 
 tion of the whole cosmic system. But another 
 remarkable principle comes in : The pressure at 
 the centre gradually lessens by the escape of 
 material, yet the remainder is still hot, whilst 
 the central attraction has lessened greatly ; 
 consequently, molecular escape may permit 
 
THE VISIBLE UNIVERSE 
 
 every molecule to follow the polar nebulae, 
 .and leave the central mass almost bare of 
 matter. 
 
 It is probable that originally the polar caps 
 were of continuous nebular matter, that became 
 .aggregated into globular nebulae by the passage 
 of errant bodies through the gas. Much of this 
 diffused gas may still remain, invisible to the 
 telescope ; but possibly to be detected by a very 
 powerful photospectroscope. Proctor, discussing 
 the origin of the polar nebulae, says : " They 
 may have been formed through the influence of 
 the same principle which makes the centrifugal 
 force near the poles of a rotating globe less than 
 that at the globe's equator," 
 
 It will be observed that both regarding the 
 solar system and the galaxy, coalescent impact 
 of two complex bodies has been suggested. In 
 the case of the galaxy, an axial pressure has 
 been assumed as accounting for the polar 
 nebulae ; yet, in the case of the solar system, no 
 such suggestion has been made. Probably, 
 however, gaseous matter did once so cover the 
 poles of the solar system ; but a large number 
 of agencies are at work tending to produce 
 modifications in every occurrence of impact, and 
 
THE VISIBLE UNIVERSE 
 
 it will be for future mathematical physicists to 
 determine where one tendency stops and 
 another begins. It may not be out of place, 
 even in this popular account, to give some 
 mathematical conclusions regarding impact. It 
 is demonstrable that an infinitely diffused 
 nebula, condensing into two solid bodies at 
 infinite distance, has lost half its potential 
 energy : exactly as much energy as is available 
 by their attraction bringing the two bodies into 
 impact ; therefore, this attraction, in a complete 
 impact of dense bodies, is only half the energy 
 necessary to make a nebula. Secondly, with a 
 pair of bodies such as the sun, it can be 
 shown that the energy of their attraction is only 
 sufficient to expand them to the sum of their 
 diameters. Hence it will be seen that an 
 ordinary complete impact of suns cannot 
 produce a nebula, while partial impact can do 
 so. 
 
 Let us retrace our steps. Two cosmic systems 
 roughly spherical in form, consisting of nebulae, 
 suns, etc., come into grazing impact and whirl 
 around each other : all the original motion of 
 each system as a whole, and also of all the 
 constituent members, tending to give irregularity 
 
1/8 THE VISIBLE UNIVERSE 
 
 to the final result. The parts coming into 
 actual impact are gradually volatilised, and, by 
 the pressure, the gas is projected axially, and 
 covers the poles of the galactic ring with 
 nebulous matter. It would seem probable that 
 the onrush of the stars from each of the 
 original systems would furnish two condensed 
 regions. In accordance with this view, Proctor 
 says : " The stars of the first six orders are 
 gathered into two definite regions a northern 
 and southern so markedly that the dis- 
 tribution of stars within these regions is richer 
 than the distribution over the rest of the 
 heavens in the proportion of five to two." 
 
 Does not the constitution of the galaxy, 
 given by astronomers as the result of their 
 observations, agree in a most remarkable 
 manner with that deduced from an assumed 
 grazing coalescence of two previously existing 
 systems ? All through our universe the 
 spectroscope reveals identity of matter and 
 community of motion. Observers find a most 
 wonderful contrast of character in different parts 
 of the heavens ; yet, they say, the contrasting 
 objects are related. The mode of evolution 
 suggested by a partial impact shows the nature 
 
THE VISIBLE UNIVERSE I/O/ 
 
 of this relationship ; shows why there is 
 community of motion in adjacent stars or star 
 drifts ; why there are streams and sprays of 
 stars ; shows the origin of the galactic belt, 
 why temporary, variable and double stars, why 
 star clusters and planetary nebulae are there, 
 whilst other regular nebulae are mostly at the 
 poles of the ring. Whence comes such amazing 
 correspondence between the constitution of the 
 universe as given by astronomers, and this series 
 of clear deductions from a probable cosmic 
 occurrence ? Does it not seem to suggest that,, 
 just as natural selection including sexual and 
 intellectual selection is the agent of organic 
 evolution, so impact, in its many varieties, is the 
 agent of cosmic evolution ? It may be that the 
 theory of impact is indeed what a critic has- 
 styled it : "A master-key to the mystery, the 
 greatness, the splendour, the multitudinousness. 
 and the variety of the heavens." 
 
CHAPTER XII 
 
 NEBULA 
 
 VARIETY OF NEBULA KINEMATIC DEDUCTIONS OF THEIR 
 BEAUTIFUL GEOMETRIC FORMS THESE STRUCTURAL 
 NEBULA FOUND AT THE POLES OF THE MILKY WAY. 
 EXTRUSION OF MASSES OF DIFFUSED GASES. AG- 
 GREGATION OF THESE GASES INTO GLOBULAR NEBU- 
 LA-IMPACTS AMONGST THE NEBULAE EXPANDING 
 DOUBLE SPIRALS DOCTOR ROBERTS' OBSERVATIONS- 
 RING NEBULA-FURTHER STUDY NEEDED. THE MA- 
 GELLANIC CLOUDS PROBABLY DETACHED COSMIC 
 SYSTEMS THEY CONTAIN ALL STAR PHENOMENA. 
 CONSTRUCTION AND DISSIPATION OF SYSTEMS. 
 
 Leaving the Milky Way, with its hundreds of 
 millions of blazing suns, its crashing orbs, its 
 multiple stars and its gem-like clusters, we pass 
 through vast spaces of comparative emptiness. 
 Then, as we approach the poles of the galaxy, 
 fresh objects become visible. These are the 
 glowing nebulae commonly revealed by the 
 great telescopes of our astromers as spherical 
 masses of luminous cloud. Sometimes they 
 show shapes of exquisite symmetry; and, as the 
 power of observation increases, so the number of 
 
NEBULA l8l 
 
 nebulae showing structure increases also. The 
 forms thus made manifest are very varied : long, 
 delicate spindles ; shorter spindles with spirals 
 at their centre ; exquisitely perfect double 
 spirals ; nebular rings, sometimes with light,, 
 gauze-like caps at the poles of the rings. Then, 
 there are double and multiple nebulae, double 
 nebulae associated with spindles, and many other 
 combinations ; whilst, besides these nebulae at 
 the poles of the Milky Way, there are the planet- 
 ary nebulae and the huge irregular nebulae of the 
 Milky Way itself. 
 
 When I first commenced the study of impact, 
 I thought chiefly of impacting suns dark or 
 luminous and of the results of such impacts : 
 temporary, variable, and double stars ; planetary 
 nebulae, and system clusters, Presently I began 
 to think of the mechanism of such impacts ; I 
 treated the subject kinematically, as scientists 
 would say. Then grew up ideas of lovely 
 forms spindles, spirals, rings and all the beauti- 
 ful forms of the known nebulae. All at once I 
 thought of the explosion of impact, of the awful 
 outrush of expanding gas that must result from 
 the collision of suns. Oh, the horror of it ! All 
 my lovely shapes blown to the four winds ! I 
 
1 82 NEBULA 
 
 don't often remember unpleasant things, but 
 writing this recalls that mauvais quart d'heure. 
 Then, again, I thought: "But the forms are 
 there, and the mechanism is there to produce 
 the forms. What does it mean ? " I asked 
 myself. 
 
 All at once the impact of nebulae occurred to 
 me. The kinematics would be the same, but 
 the outrush nothing to speak of in comparison. 
 I knew where the globular nebulae were spread 
 in the heavens ; but everything of interest I had 
 worked out yet had been in the Milky Way. 
 The planetary nebula were there, and I thought 
 these beautiful nebulae were there also. Had I 
 made a wrong assumption ? I tried to borrow 
 a celestial globe, but failed ; then, throwing 
 economy to the winds, I bought one, took the 
 bearing of these celestial flowers, and plotted 
 them. My surmise was right ; they were not 
 in the Milky Way, but amongst the globular 
 nebulae at the poles of the Milky Way. 
 
 In all probability, then, impacting stars cannot 
 produce these lovely forms, but impacting nebulae 
 can ; and where the nebulae are thick giving 
 us the probability of impact of nebulai there 
 we find these forms ; and in the Milky Way, 
 
NEBULA 183 
 
 where the stars are thick, we find the wonders 
 that may be deduced as resulting from the 
 impact of stars. 
 
 Let us now try to imagine the origin of these 
 huge globular nebulae, and of some of the 
 varieties of forms possible to be produced by 
 their coming into contact with one another. In 
 the chapter on the origin of the visible universe, 
 I have tried to show that at one time both of 
 the galactic polar regions were continuous masses 
 of nebulae of extreme tenuity. 
 
 Any cosmic body that passed through such 
 gas might be entrapped ; the heat produced by 
 friction would tend to volatilize it ; the heavier 
 molecules of the diffused gas would be attracted 
 towards the body ; thus as the body travelled, it 
 might leave an expanding train that would make 
 a cometic nebula, although cometic nebulae may 
 be formed in other ways. All irregularities in 
 gravitating matter tend to accentuate them- 
 selves ; hence, the volatilized body gradually 
 attracts nebulous matter about it, and a globular 
 nebula results. Attraction acts everywhere; and, 
 where there is no counteracting agency, it gener- 
 ally welds matter into a sphere. Molecular 
 attraction unites the particles of water into the 
 
1 84 NEBULA 
 
 dew-drop, the form of the transparent liquid tears 
 to pieces the interwoven colours of the sunbeam, 
 and sends them forth in wondrous tinted shreds. 
 Attraction makes the solid earth a sphere,, 
 slightly flattened by its own counteracting 
 spinning motion. So attractive action on 
 diffused nebulous matter aggregates it into 
 gigantic roughly-rounded masses, the original 
 motion modifying its form. 
 
 Doubtless, all these nebulae retain some of 
 the motion of the original body that commenced 
 their formation, and are consequently travelling 
 in space. Sometimes they must be in one 
 another's path, whilst their own gravitating force 
 urges them towards one another. Thus they 
 collide. The agencies that apply to the impact 
 of stars apply also to nebulae, but are much 
 modified. 
 
 Herschel compares nebulae and stars in the 
 following passage from his " Outlines " : 
 
 " Double nebulae occasionally occur, and when 
 such is the case the constituents commonly 
 belong to the class of spherical nebulae, and are 
 in some instances undoubtedly globular clusters. 
 All the varieties of double stars, in fact, as to 
 distance, position, and relative brightness, have 
 
NEBULA 185 
 
 their counterparts in double nebulse ; besides 
 which the varieties of form and gradation of 
 light in the latter afford room for combinations 
 peculiar to this class of objects. Though the 
 conclusive evidence of observed relative motion 
 be yet wanting, and though the vast scale on 
 which such systems are constructed, and the 
 probable extreme slowness of the angular 
 motion, it may continue for ages to be so, yet it 
 is impossible when we cast our eyes upon such 
 objects to doubt their physical connection. 
 The argument drawn from the comparative 
 rarity of the objects, in proportion to the whole 
 extent of the heavens, so cogent in the case of 
 double stars, is infinitely more so in the case of 
 double nebulae. Nothing more magnificent can 
 be presented to our consideration than such 
 combinations. Their stupendous scale, the 
 multitude of individuals they involve, the per- 
 fect symmetry and regularity which many of 
 them present, the utter disregard of complication 
 on thus heaping together system upon system, 
 and construction upon construction, leave us 
 ost in wonder and admiration at the evidence 
 they afford of infinite power and unfathomable 
 
 design." 
 
 12 
 
1 86 NEBULA 
 
 I had to ask your patience when we traced 
 the flight of various molecules but in con- 
 sidering the origin of nebulae we enter on a new 
 series of motions. We are not considering how 
 the individual atoms sort themselves ; we are 
 following the transformation of enormous masses 
 of luminous gas into the beautiful celestial fire 
 flowers that compose the bouquets of the 
 universe. 
 
 Our two globular fire clouds are impinging 
 upon one another. The cooler outer portions 
 inter-penetrate, the encounter of the molecules 
 makes them vibrate, and the waves so set up in 
 the ether give us increased luminosity. The 
 nebulae may move many hundreds of times 
 faster than a rifle ball ; yet so enormous are 
 these bodies that the impact may take hundreds, 
 perchance many thousands, of years. As they 
 pass each other the colliding gas forms a 
 luminous spindle between ' the two nebulae. 
 Herschel has given us drawings of these vast 
 globes, with spindles between them in all stages 
 of formation. In every case the rare outer 
 atmosphere of each nebula plunges deeply 
 through the other mass, and there is a lack of 
 balanced momentum on either side ; so that, as 
 
NEBULA 
 
 .87 
 
 the colliding nebulae go on their way, trailing 
 the spindle behind, they leave the centre of the 
 spindle in a state of whirl. And so, as each of 
 the ends of the spindle travels after its retreating 
 nebula, gradually the motion of the centre 
 converts it into an expanding double spiral. 
 
 The accompanying sketch shows one of these 
 spirals. 
 
 SPIRAL NERULA. (LORD ROSSE). 
 
 Although the life of a man may not permit 
 him to trace in its full history such a wondrous 
 .nebular evolution, yet, so rich is the mighty 
 
188 NEBUL/E 
 
 cosmos that, by means of photography, every 
 stage may be studied simultaneously. 
 
 Think of a sensitive photograph plate being 
 presented for many hours to the same object 
 a plate that, in a thousandth of a second, would 
 photograph a flash of lightning! Imagine this 
 plate fixed in the focus of one of our great 
 light-gathering telescopes, kept by accurate 
 clockwork, following the apparent motion of the 
 nebula ; then some idea may be formed of the 
 tremendous power of our modern research ! 
 
 The great nebula of Andromeda is a spiral ; 
 that of the Lion shows the spiral at the centre ; 
 then in gradually developing spirals we have 
 that of Pegasus, of Virgo, of Canes Venatici. 
 The "Photographic Annual" for 1895 (pages 
 234-235) describes Dr. Roberts' discoveries of 
 spiral structure of nebulae where the visual 
 observation of Lord Rosse and Sir John Herschel 
 entirely failed to discern any such structure. It 
 also describes new spiral nebulae of great beauty, 
 and other structures never even suspected before 
 in nebulae. But now comes the part interesting 
 to students of impact. Dr. Roberts, at the 
 meeting of the Royal Astronomical Society in 
 May, 1894, suggests, in explanation of these 
 
NEBULA 189 
 
 convolutions, that the nebulae were formed by 
 streams of meteors which came in contact whilst 
 travelling from opposite quarters of space, the 
 collisions of their margins producing the spiral 
 motion. Again, he says of another nebula : 
 " There is a considerable amount of structure in 
 the nebula, which seems to be assuming the 
 spiral form, as if there had been a collision in 
 one half, which had the effect of closing together 
 the nebulous mass and distorting its form." 
 Thus, although but few astronomers have had 
 the leisure to read any of my papers carefully 
 enough to grasp the deeper principles pro- 
 mulgated in them, there is growing up a belief 
 in the occurrence of Partial Impact, and a 
 superficial appreciation of some of its effects. 
 
 But we must leave the spiral nebulae and pass 
 on to the wonderful ring nebulae, which, from 
 their analogy to our visible universe, has led us 
 to the most important and far-reaching of all the 
 many subjects the theory covers. Hitherto we 
 have dealt with impacts in which, as a rule, the 
 original bodies have separated after the impact ; 
 but, obviously, bodies may plunge so deeply into 
 one another that they never part again, and to 
 a collision of this kind I believe that annular 
 
190 NEBULA 
 
 nebulae owe their existence. It is not to be 
 imagined that a solitary worker in the vast field 
 of impact can think of all the conditions of such 
 complex phenomena; all the agencies set at work 
 by such conflict of forces. Still, I will at least 
 try to tell of some of the forces rendered active 
 by a grazing but almost complete impact of 
 nebulae. 
 
 Instead of two cosmic systems imagine two 
 huge gaseous globes plunging through each 
 other ; as they close in from opposite directions 
 we realize that a stupendous whirl must be set 
 up. But the action of axial extrusion is to be 
 traced. Obviously, the mere closing-in of the 
 colliding nebulae must produce pressure ; but 
 compression produces heat, and this in its turn 
 produces more pressure ; so that at the centre 
 of the mass there is an enormous expanding 
 force. Where in this whirling mass can it find 
 relief? Certainly not in the directions in which 
 the two nebulae' are closing in upon one another, 
 not in the plane of rotation ; but there is no 
 opposing force in the direction of the axis, and 
 in this direction the pressure produces motion. 
 The coalesced bodies are now a kind of huge 
 mortar open at both ends, from which are pro- 
 
NEBULA 
 
 jected in either direction torrents of gas. Pressure 
 commences the outrush of gas and molecular 
 escape finishes it. Thus is the centre cleared 
 out of the huge, bun-shaped rotating nebula, and 
 it becomes a ring ; so that annular nebulae should 
 for a time be accompanied by a gauze-like mate- 
 rial that, seen endways, seems to stretch across 
 the ring ; seen edgeways, appears a diffusion 
 in the direction of the axis. 
 
 I would urge upon any one who is interested 
 in the evolution of nebulae to study the various 
 drawings in the light of this account of their 
 genesis. Every grade of the evolution, every 
 variety of collision seems to have , its repre- 
 sentation. And doubtless should the present be 
 compared with past drawings it may be possible 
 to trace the entire history of the evolution of 
 any form of nebulae. Do not the possibilities of 
 even a section of the subject seem almost 
 limitless, whilst this much is manifest the 
 wonder and beauty of the fields of research are 
 as sublime as their expanse is magnificent. 
 
 I have tried to give an idea of our universe, 
 very brief and imperfect, but the best I 
 can accomplish without tending to become 
 wearisome. But there are wonders in the 
 
NEBUL/E 
 
 heavens that seem not to belong to our universe 
 at all ; stars that appear to be visitants from 
 other cosmic systems, perchance there are such 
 systems actually apparent to us, though I 
 suppose the dust of space cuts from our sight 
 most of such systems or universes that prob- 
 ably make up the mighty Cosmos as a whole. 
 The two Magellanic clouds probably are inde- 
 pendent systems. Mr. H. C. Russell's remarkable 
 photographs show gigantic spiral structures, with 
 stars, star clusters and every variety of denizen 
 that people our own universe. Is it possible 
 that these are two systems on the way to form, 
 by mutual coalescence, a system of a higher 
 order ? Later on I hope to show how primitive 
 systems may form systems of the first order ; 
 then, by coalescence, systems like our own, of 
 more complex structure and higher order, are 
 formed, partially to dissipate and help to form 
 systems of a lower order again. 
 
 Thus in the Cosmos we have birth and 
 death ; construction and dissipation of worlds, 
 solar systems and cosmic systems. Everywhere 
 rhythm and order ; everywhere majesty and 
 law. Of marvel and beauty there is no end, 
 whether it be of the stupendously great or of the 
 
NEBULA 193 
 
 infinitesimally minute. We dissect a flower, 
 marvelling at its loveliness. Through a lens we 
 see the structure of its parts, its spirals, its 
 delicate reticulations. With a compound 
 microscope we look into the complexity of its 
 cells. Chemically we pull the cells to pieces and 
 get molecules, we analyse the molecules and 
 sort the constituent atoms. Then we apply the 
 spectroscope, and the atoms reveal themselves 
 in song, and tells us of structures so marvellous 
 that our hearts beat with delight in such 
 adaptation of means to ends, and in recognition 
 of the object of creation. 
 
 Joy is God's index of a rightful act, 
 Pain is the signal telling man he errs, 
 Dire misery points out deep social wrong. 
 
 Was Beethoven at fault when he gave us his 
 weird dissonances ? Do not the succeeding 
 phrases ring out the more harmoniously ? Shall 
 we blame the Creator for the present dissonant 
 conditions of life ? Nay, let us learn the lesson 
 and help to bring about the consonance that is 
 so attainable would we but learn the lesson. But 
 all in good time ; well it were we had learned 
 it before. To educate to the careful uses of 
 wondrous fire the burn must be keen and long. 
 
194 NEBULA 
 
 To me, the richness of human life rendered pos- 
 sible by the applications of science is so mar- 
 vellous that blended with the present paroxysm 
 of hate, I seem to hear the first chords of that 
 sublime music which is, I believe, to be heard in 
 the immediate future of the race. It may be, 
 that still further wrenching dissonances have to 
 be heard for the full appreciation of the grand 
 harmony in store. 
 
 We have, glanced at a picture of that portion 
 of the mighty cosmos it is granted us to know 
 about. We have now by deduction but to apply 
 our reasoning power to trace out the remaining 
 portion of a cosmic cycle, and our task is 
 finished. Yet gigantic as is the portion of the 
 creation our enquiry has revealed to us, it is 
 probably but a peep into the infinite. 
 
 The theory of impact furnishes a clue to the 
 mystery of cosmic evolution ; by its aid we can 
 trace the stages in the history of the earth, the 
 sun and the universe, and learn that the present 
 is no other than a phase of the eternal. Quota- 
 tion may here be permitted from a very succinct 
 statement of cosmic evolution on the basis of 
 impact given by the Bradford Daily Argus : 
 
 " Shall we have to recast our notions as to the 
 
NEBULAE 195 
 
 scheme of the universe? It almost seems so. 
 Hitherto it has been an accepted belief that 
 planets and suns and systems are all hastening 
 to one endless death, and the blackness of ever- 
 lasting night. But from a transplanted Briton 
 in New Zealand Professor Bickerton, of Canter- 
 bury College, Christchurch comes a newer and 
 more hopeful faith. He has evolved a theory of 
 'Constructive Impact' which, whilst it offers a 
 plausible explanation of the astronomical pro- 
 blems presented by variable stars, and the new 
 stars which flare into startling brilliance for a 
 few brief astronomical hours, to subside again 
 into obscurity or disappear entirely, also provides 
 for an endless cycle of birth, maturity and death 
 on the part of stars, akin to that which we see 
 around us in organic life. . . . There are 
 other directions in which Professor Bickerton's 
 theory fits into ascertained phenomena, but we 
 have said sufficient to indicate its ingenuity and 
 plausibility. The matter is certainly one which 
 deserves the close attention of astronomers, and 
 it is interesting to the general public as another il- 
 lustration of the truth underlying the old proverb, 
 that there is nothing new under the sun. Even the 
 sun and the stars may not be new for aught we 
 
196 NEBULA 
 
 know, but may have gone through endless cycles, 
 beginning with the nebular condition as chaotic - 
 masses of heated gas, and passing through all 
 phases until the condition of passive death as 
 shown by our moon is reached, to be again 
 revivified, reduced to the nebular condition again 
 by other stars with which they have collided. 
 There is nothing inherently improbable in the 
 theory, and no substantial reason why the same 
 birth, growth and death of planets should not go 
 on for all eternity. But how immeasurably does 
 the apparent length of eternity extend when 
 aeons represented by the birth and life and death 
 and re-birth of solar systems are the ticking of 
 its pendulum ? " 
 
 We have now but to study the details of the 
 complex series of agencies that seem to permit 
 the possibility of an immortal cosmos, and our 
 task of sketching a picture of the field of con- 
 structive impact is finished. 
 
CHAPTER XIII 
 
 THE IMMORTALITY OF THE COSMOS 
 
 THE INDESTRUCTIBILITY OF MATTER AND CONSERVATION 
 OF ENERGY. DISSIPATION OF MATTER AND ENERGY 
 -SPACE IS DUSTY WHY LIGHT IS LOST ABSORPTION 
 OF RADIANT ENERGY. IT BECOMES VELOCITY OF 
 MOLECULES. HIGH-VELOCITY MATTER PASSES TO 
 WHERE MATTER IS SPARSEST. AGGREGATIVE HIGH 
 POTENTIAL AND GRAVITATION. FORMATION OF A 
 COSMIC SYSTEM. COSMIC EVOLUTION. A CYCLIC 
 PROCESS. 
 
 Towards the close of the i8th century 
 Lavoisier's brilliant investigations demonstrated 
 the indestructibility of matter. The great 
 Frenchman proved by the application of the 
 balance that nothing material can be lost ; that, 
 for instance, fire may cause apparent annihilation ; 
 but the atoms which existed before exist still, 
 locked in new combinations. For fifty years this 
 scientific achievement outshone all others, so 
 that immaterial nature passed almost unnoticed, 
 until our English Joule measured the changes of 
 working power energy we call it. Then an- 
 other fundamental truth revealed itself. Energy, 
 
200 IMMORTALITY OF THE COSMOS 
 
 the imponderable entity of the cosmos protean 
 as thought was found to be as indestructible 
 as matter. In the face of this discovery the 
 materialism of science was vanquished for ever. 
 
 Then the quantity of this energy pouring in 
 ceaseless torrent from the sun was measured, 
 and its origin was investigated. Answers more 
 and more satisfactory were given, and, lastly, it 
 was shown that the heat developed by the con- 
 traction of the sun suffices to account for solar 
 radiation for tens of millions of years. Next 
 the questions arose : Where is all this energy 
 speeding to ? Even that which falls upon the 
 earth escapes again into outer space. Will the 
 sun send forth all his heat to the dust of infini- 
 tude ? And, while cooling with fleeting flashes, 
 as planet after planet falls towards him what 
 evil fate is in store when he shall have devoured 
 all his children ? Will everlasting night encom- 
 pass the burnt-out orb ? It has seemed it must 
 be so that even collision with another sun will 
 only postpone the period of death. Here let us 
 try to understand Lord Kelvin's great generalisa- 
 tion, called the Dissipation of Energy. The laws 
 of heat suggest that every hot body in the 
 Cosmos is cooling, and, the lost heat will warm 
 
IMMORTALITY OF THE COSMOS 2OI 
 
 the cool bodies until all matter is at one 
 temperature. In like manner the laws of gravi- 
 tation suggest that all bodies will aggregate 
 into one vast orb, thus reaching a state in which 
 life, as we know it, will be impossible. The 
 universe, probably having begun as diffused gas 
 will end as solid matter. 
 
 Is there any mode of escape from this con- 
 clusion of universal death ? Rankine and 
 Clausius have pointed out possibilities that seem 
 to promise a less melancholy result, but Lord 
 Kelvin has demonstrated their insufficiency. 
 Herbert Spencer in a magnificent passage in 
 his " First Principles " shows how impact may 
 revivify ; but the method he suggests fails on 
 the score of equivalent energy, and physicists 
 consider it no longer. Possibly there is no 
 single physicist of eminence that does not 
 willingly or unwillingly admit the logic of 
 Lord Kelvin's argument. But it may be that 
 in coming to this belief in universal death some 
 agency has been overlooked. Is there any 
 means by which low temperature heat may 
 become energy of a higher order? Are there 
 any forces at work to diffuse as well as to 
 concentrate matter ? I believe both these 
 
 13 
 
202 IMMORTALITY OF THE COSMOS 
 
 questions may be answered affirmatively. The 
 road of reply is definite and unmistakable, but 
 entangled and circuitous ; those, however, who 
 will take the trouble to follow it will find it as 
 beautiful and as wondrous as it is complex. 
 
 Space is dusty ; it is a fog of wandering 
 meteors, errant comets, extinct planets, and dead 
 suns, with free molecules of gas travelling in all 
 directions between the denser matter. Light 
 penetrates this fog for millions upon millions of 
 miles, but in time it is stopped. Thus all radia- 
 tion may fall upon the dust of space and warm 
 it. Heat is a motion of molecules. Gradually 
 cool a gas, and its molecules lose speed. Let 
 molecules travel from bodies, the attraction of 
 the bodies make the molecules travel slower 
 in other words, it cools them. Let a slowly mov- 
 ing molecule of hydrogen or helium touch a w r arm 
 particle of cosmic dust, it will bound off again 
 carrying away the heat, exactly as molecules 
 bound from the blackened heated vane of a 
 radiometer : the heat of the solid body is changed 
 into motion of the molecules, giving the gas a 
 fresh start on its journey. 
 
 The farther a molecule is from cosmic matter 
 the slower it travels ; it is slowest of all in the 
 
IMMORTALITY OF THE COSMOS 203 
 
 most empty parts of space that is, it lingers 
 longer there than anywhere else. If particles 
 are moving indiscriminately in all directions, and 
 tend to linger anywhere, in that place they will 
 accumulate. I have called this action the 
 aggregating power of high potential. It is a 
 very important principle. To illustrate its 
 nature let us imagine a number of persons 
 moving at the rate of four miles an hour across 
 a field. Let us assume them to be blind and 
 moving quite indiscriminately whilst directly 
 they reach the edge of the field they start back 
 again. Within the field there is a ploughed area, 
 an acre in extent, across which people must 
 move four times as slowly, or at the rate of a 
 mile an hour. If this action goes on indefinitely, 
 it is quite easy to see that there will be on the 
 average four times as many persons within the 
 ploughed area as on an equal area in other parts 
 of the field. 
 
 Thus there exists an aggregating tendency 
 the reverse of gravitation, and it also acts in 
 a general way on different kinds of matter. 
 Gravitation tends to select as its especial media 
 heavy atoms, infusible and non-volatile matter, 
 and elements of high affinity. High Potential 
 
204 IMMORTALITY OF THE COSMOS 
 
 tends to select light atoms, volatile substances 
 and especially monotomic non-combining ele- 
 ments. The field of the one is where matter is 
 richly distributed. The field of the other where 
 it is rarest. Therefore, freely moving gas tends 
 to accumulate in the empty parts of space, and 
 this gas may originate new universes cosmic 
 systems of the first order. This is the especial 
 function of such light gases as hydrogen and 
 helium, and perchance of gases lighter still. 
 These minute molecules these projectiles that 
 selective escape has set free from impacting 
 bodies to travel with incredible velocities are 
 cosmic pioneers, filling the parts of space left 
 empty by shrinking cosmic systems. There is 
 this difference between these two actions. The 
 cause of gravitation is still an unsolved mystery ; 
 on the other hand the aggregating power of high 
 potential is a physical deduction based on a 
 mathematical conceptions, and explains itself. 
 
 Hydrogen, which has the lightest known 
 atom, will at any given temperature, have the 
 highest velocity, and in passing out of the 
 cosmic system is the most likely to reach a 
 position of highest potential and should its 
 velocity be more than sufficient to carry it 
 
IMMORTALITY OF THE COSMOS 2O5 
 
 across this space and take it to other cosmic 
 systems, it will move slower and obviously be 
 retarded in the position of highest potential 
 where matter is rarest. 
 
 As hydrogen accumulates there, the potential 
 of this portion of space will sink and it will be 
 less difficult for other molecules to reach the 
 place. Of course, any molecule, whether hydro- 
 gen or otherwise, that is above the critical 
 velocity of the cosmic system it is leaving, will 
 be able to pass this portion of space, but it will 
 be chiefly hydrogen and helium that will be the 
 first in the field. As these lighter gases ac- 
 cumulate, it will be easier for others to get there 
 and slowly we shall get up to atomic weights 
 corresponding to those of oxygen, nitrogen and 
 neon. This part of space being the position 
 where molecules have a lowest mean velocity 
 will be the coldest part of space and would 
 be coldest of all in its rarest stages. Thus, with 
 this lowest mean velocity oxygen reaches this 
 position sixteen times as hot as hydrogen 
 Hence the temperature of this part of space 
 rises as the gravitating power increases. Ulti- 
 mately there is a considerable distribution of 
 gaseous matter, in fact, the tendency to aggregate. 
 
206 IMMORTALITY OF THE COSMOS 
 
 will continue until the potential sinks to equality 
 with the rest of space. 
 
 Should any high velocity mass plunge through 
 this accumlation, it may become heated to in- 
 candescence and bring about a combination of 
 oxygen with the light elementary substances 
 such as boron, lithium, sodium, magnesium, 
 aluminium, carbon and hydrogen. This com- 
 bustion would give rise to solid and liquid 
 nuclei, which would condense into cosmic dust, 
 and thus it would be possible that this portion 
 of space would become aggregated into dense 
 bodies. This is not possible with the cosmic 
 pioneers, helium, neon, argon, crypton and 
 xenon ; for these substances are permanent 
 monatomic non-combining elements remaining 
 permanently gaseous. It is quite possible that 
 at the low temperature of cosmic maximum 
 potential, many of these cosmic pioneers might 
 become liquid, but after material has begun to 
 accumulate the mean temperature of the space 
 would be above the point of liquifaction, and 
 hence these elements are permanently gaseous. 
 
 We must remember that not only do mole- 
 cules travel quickly ; cosmic bodies sometimes 
 do so likewise. The star 1830 Groombridge is 
 
IMMORTALITY OF THE COSMOS 2O/ 
 
 flying through the universe at the inconceivable 
 speed of two hundred miles a second, whilst if 
 the calculated parallax of Arcturus is correct it 
 has the tremendous velocity of at least 376 
 miles a second, and Mu Cassiopeia^ shows a 
 velocity of 302 miles a second. Such velocities 
 will probably carry these stars completely through 
 our universe the chance of their striking another 
 star is exceedingly small and they will pro- 
 bably travel into those vast gas-filled regions 
 where friction will slowly stop them, heat them,, 
 and entrap them. 
 
 Thus, gas-filled space is a trap for wandering 
 bodies. Gradually the mutual attraction of the 
 entrapped bodies tends to coalesce them, to 
 condense the gas about them, to diminish the 
 volume and increase the density of these in- 
 cipient universes. Such masses I call primitive 
 cosmic systems of the first order. They are 
 nebulous aggregations, made up largely of light 
 molecules, continually entrapping bodies made 
 up of heavier molecules. Then, by mutual 
 attraction, these primitive systems collide ; and, 
 as a result, selective escape sends some of the 
 light molecules on their journey again, once 
 more to play the part of pioneers, whilst the 
 
208 IMMORTALITY OF THE COSMOS 
 
 dense elements aggregate into suns and systems. 
 Continually are the older cosmic systems thus 
 drained of the light gases. But another remark- 
 able principle comes into operation. As already 
 mentioned, three bodies never pass near each 
 other without a permanent relative change of 
 velocity. One may gain speed sufficient to 
 send it out of the universe it belonged to. If 
 two primitive cosmic systems collide and become 
 one, before that one reached its densest state, it 
 would probably by many agencies have sent 
 half its matter wandering into outer space, free 
 from its own gravitating force. 
 
 It is certain that our universe is not a primitive 
 cosmic system. Its parents were probably not 
 of the first order, but had already collided and 
 attained definite form. The evidence suggests 
 that our universe, as such, is in its infancy ; and 
 that probably its parents were of the second 
 order. Possibly, when more is known of its 
 'character, later thinkers may be able to speak 
 more decidedly regarding its antecedents. 
 
 Has this series of agencies been made clear ? 
 If so, the reader can perhaps picture the 
 innumerable wandering molecules set free by 
 cosmic bodies the dust of space the move- 
 
IMMORTALITY OF THE COSMOS 2O9 
 
 ments of radiant energy constantly pouring into 
 space tending to warm that dust ; the slowly 
 moving molecules being struck by the vibrations 
 of heated molecules and bounding off again to 
 lose motion by further travel. He will realise 
 the crowding of molecules in those empty high 
 potential spaces where molecules linger, and the 
 gaseous nebula so formed being a trap for 
 wandering bodies set free by the interactions of 
 three bodies ; the attraction, the shrinkage, the 
 final coalescence into primitive cosmic systems 
 in which there is practically no definite structure, 
 no recognisable order ; then the grazing impact 
 that by the rotation set up would whirl the two 
 huge systems into one, with systematic structure 
 and order. I formerly imagined the Magellanic 
 clouds might be primitive cosmic systems but 
 the wonderful photographs of Mr. Russell have 
 clearly demonstrated such a definite spiral struc- 
 ture that it appears evident they are of a higher 
 order. Their very condensed character also 
 favours this view. 
 
 Thus, the theory of dissipation of energy is 
 seen to be a part of a large cyclic process of 
 which partial impact, molecular selective escape 
 and the aggregating power of high potential 
 
2IO IMMORTALITY OF THE COSMOS 
 
 are also parts and together all declare the Cosmos 
 as a whole to be immortal. A system equally 
 perfect in the marvellous forces within the 
 minutest atom, the complex structure of organic 
 molecular groupings, the infinity of cosmic 
 dimensions, and the eternity of cosmic duration. 
 There is no flaw in the vast design. Atoms 
 clash, combine, and form molecules ; and these 
 break up again. Organisms are born and die. 
 Worlds, systems, universes are evolved, play 
 their part, disintegrate and disperse ; only to 
 reappear in new and complex relationships. 
 The mighty cosmos remains ever rhythmic in 
 its glorious energies. 
 
 Man's mind reels on the brink of the un- 
 fathomable when he tries to grasp the mystery 
 even of his own being. Everything impresses 
 him with a feeling of profound humility in his 
 own insignificance. At the same time his sur- 
 roundings force upon him the most absolute 
 faith in the perfection of the great whole of which 
 he is so minute a part. In contemplating this 
 perfection one feels certain that the present dis- 
 order and misery of the world are merely that 
 brief paroxysm of apparent chaos from which 
 order will issue. Is it credible that the evolution 
 
IMMORTALITY OF THE COSMOS 211 
 
 of mental power which enables man to appreci- 
 ate the superb grandeur of the infinite, which 
 enables him to harness the forces of nature 
 to serve his neecls shall cease with material 
 success. Is it credible that he will remain 
 content to see supine indifference and selfish- 
 ness destroy all that is lovely in life? Such 
 ideas are incredible. One glimpse of the eternal 
 assures us that the tangled affairs of human life 
 will yet be unravelled fully. May it not be that, 
 just as the burnt child dreads the fire, so 
 the awful effect of the selfishness which 
 has produced the present misery amongst 
 mankind may burn its lesson so deeply as to be 
 ineffaceable in human history ? Darwinism 
 clearly shows that pleasurable emotion alone 
 can be persistent, and that pain and misery are 
 indications of decadence. If this be so, what a 
 marvellous gospel of hope is contained in the 
 religion of science ! And should the theory of 
 Constructive Impact this unpractical theory of 
 cosmogony so awaken intelligence that the 
 perfection of evolutionary methods may be 
 learned, and the lesson acted upon in daily 
 affairs, then such an unpractical theory will 
 prove richer than commerce or business or any 
 
212 IMMORTALITY OF THE COSMOS 
 
 of the material achievements so lauded by 
 practical men. When the absolute beauty of the 
 Cosmos is realised by mankind, pain and. misery 
 will be suffered . only till the alterations that are 
 necessary for their removal can be ascertained ; 
 joy will be recognised more and more fully 
 throughout the rolling aeons whose infancy we 
 dwell in joy will be known as the true, the 
 inalienable birthright of humanity. 
 
CHAPTER XIV 
 
 DEMONSTRATION OF THE THEORY 
 DEDUCTIONS AND EVIDENCES 
 
 FIVE QUESTIONS TO BE ANSWERED. THE ANSWER TO 
 EACH QUESTION NATURALLY DIVIDES INTO FOUR 
 PARTS, NAMELY, PARTIAL IMPACT, SELECTIVE MOLE- 
 CULAR ESCAPE, AXIAL EXTRUSION, AND THE AGGRE- 
 GATE POWER OF POSITIONS OF HIGH POTENTIAL. 
 THE FIVE QUESTIONS IN EACH OF THEIR FOUR SEC- 
 TIONS ANSWERED IN DETAIL. AFTER WEIGHING 
 THESE ANSWERS SCEPTICISM IMPOSSIBLE. 
 
 The preceding chapters have given a general 
 idea of the scope and character of the theory of 
 constructive collision. The conception is simple 
 and not without interest. But the question to 
 be asked is not, is this theory interesting or in- 
 genious? The all important point is, Does 
 this generalisation of cosmic evolution represent 
 the truth ? 
 
 Answers to the following questions seem 
 to demonstrate it absolutely : 
 
214 DEMONSTRATION OF THE THEORY 
 
 1. Is Constructive Impact based upon sound 
 deductions ? 
 
 2. Are there facts available that correspond 
 with the deductions. 
 
 3. Is this evidence capable of being explained 
 by any other known theory ? 
 
 4. Has it shown the power to anticipate the 
 discovery of phenomena ? 
 
 5. Is it able to guide research ? 
 
 When we make an attempt to answer these 
 questions, an examination of theory suggests 
 that although it is highly correlated, being not 
 merely continuous but cyclic, yet the scope as 
 well as the character of its thought divides quite 
 naturally into four parts : 
 
 A. A "Partial Impact" of stars or dead suns, 
 producing 
 
 (a) Temporary stars, 
 
 ($) Two variable stars, 
 
 (V) Double stars. 
 
 (The fundamental thought of this section is 
 the formation of a third body of unstable 
 character.) 
 
 B. "Selective Molecular Escape" accounting 
 for the origin of 
 
 (a) Planetary nebulae, 
 
DEMONSTRATION OF THE THEORY 21 5 
 
 (b) Meteoric swarms, 
 (V) Star clusters, 
 (d) Solar systems. 
 
 (The fundamental thought of this section is 
 the sorting of atoms by their varying velocity.) 
 
 C. "Axial Extrusion," accounting for the form of 
 (a) The Galactic System, 
 
 (#) The position of the nebulae at the poles 
 
 of the Milky Way. 
 
 (The fundamental thought in this section is 
 the enormous pressure produced that has no 
 position of relief save in the axis of the whirl of 
 coalescence.) 
 
 D. " The Aggregative Power of High Poten- 
 tial : " That is the power of retardation which 
 positions of high potential, exercise upon mole- 
 cules and other bodies passing through them 
 .and the suggestion of the existence of 
 
 (a) Cosmic Systems or Universes of three 
 orders, 
 
 () The cyclic character of the Cosmos. 
 The agencies in this action are too complex 
 to be expressed in a phrase. 
 
 Let us now attempt to answer the questions 
 enumerated in regard to each of these four 
 .sub-divisions. 
 
2l6 DEMONSTRATION OF THE THEORY 
 
 I 
 
 First: Are the deductions true ? 
 
 PARTIAL IMPACT. 
 
 A. Is the idea that a third body will be formed 
 as the result of a grazing impact a reasonable 
 suggestion ? 
 
 Let us examine it in the supposed case of the 
 impact of two bodies similar to our sun. The 
 bodies will be at a velocity of almost exactly 200 
 miles a second. To give an idea of the nature of 
 the energy involved, an express train travelling 
 at the rate of a mile a minute would have to have 
 its energy increased by 200- x 6o' 2 or 144 
 million times. But compare the mass of the 
 Sun with that of the train. Obviously, without 
 attempting to calculate, it runs beyond trillions 
 into sextillions. By considering this fact alone, 
 it has not entered into the mind of any scientific 
 thinker of any standing to doubt the possibility 
 of portions being sheared from the colliding 
 masses and coalescing to form a third body. 
 
 (a) Would this third body be unstable ? 
 In other words would the motion of 
 the molecular velocity be sufficient to 
 carry away every impacting particle 
 
DEMONSTRATION OF THE THEORY 2I/ 
 
 into space ? Oxygen at about 200 
 absolute, moves a quarter of a mile 
 a second. When it moves a mile 
 a second its temperature is 3,200. 
 When the molecular velocity is 200 
 miles a second the temperature will be 
 128 millions of Centigrade degrees on 
 the absolute scale. At such a temper- 
 ature everything is dissociated and 
 volatilised, and if only the graze be 
 small enough, it is obvious that every 
 molecule is above the critical velocity. 
 Obviously the mass expands ; and 
 obviously, also, it dissipates into space. 
 Consequently a brilliant body is 
 suddenly produced, becoming in a 
 short time supremely brilliant, and 
 then quickly fading away. This is 
 the Temporary Star. 
 
 } As to the two cut bodies, it is clear that 
 there is an unbalanced momentum in 
 the deeper part of the cut. Conse- 
 quently a portion of the third body will 
 become entangled, and this highly 
 heated matter will produce a scar of 
 greater luminosity than the rest of the 
 
218 DEMONSTRATION OF THE THEORY 
 
 body. It is clear also that this en- 
 tanglement will retard the motion of 
 this side of the body and will give rise 
 to rotation. The stars thus present 
 periodically their heated highly lumin- 
 ous scars to different parts of the 
 heavens, and each body appears as a 
 Variable Star. Hence variable stars 
 should appear in pairs ; and although 
 one may lose its variability quicker 
 than the other, some variable stars 
 should still be found in pairs. 
 (c) Is it not certain that the coalesced mass 
 tends to add to the attraction exercised 
 upon each other by the retreating 
 scarred bodies, and that such additional 
 attraction may wed them, and convert 
 them into a physical pair ? If before 
 the pair reached aphelion distance the 
 central body has dissipated, is it not 
 also clear that the perihelion distance 
 will be increased ? Thus the pair of 
 stars may be orbitally connected ; that 
 is, we have a Double Star. 
 
 SELECTIVE MOLECULAR ESCAPE. 
 B. Accepting similarity of state, square root 
 
DEMONSTRATION OF THE THEORY 2IQ 
 
 of mean square etc., etc. ; the following are re- 
 cognised laws of Thermo-dynamics : 
 
 1. The specific heat of an element varies in- 
 versely as its atomic weight. 
 
 2. With the same quantity of heat equal 
 masses will be heated in the proportion of their 
 atomic weights : that is an equal mass of oxygen 
 will be 1 6 times, and lead will be 207 times as 
 hot as hydrogen. 
 
 3. At the same temperature, molecular velocity 
 is inversely proportional to the square root of 
 the molecular weight. Hence at the same 
 temperature the molecule of hydrogen moves 
 four times as fast as oxygen ; and since the 
 energy of a body varies as the square of the 
 velocity, at the same temperature, hydrogen has 
 sixteen times the tendency to escape that 
 oxygen 'has, and it escapes with four times the 
 velocity. 
 
 Hence it is surely sound to assume that when 
 moving in free space, molecules endowed with a 
 momentum above the critical velocity will tend 
 to sort themselves, and will escape in the inverse 
 order of their atomic weight. This sorting 
 process I have called Selective Molecular Escape. 
 (a) It is obviously likely that in many im- 
 
220 DEMONSTRATION OF THE THEORY 
 
 pacts some molecules will have velocity 
 enough to get away from the mass,, 
 while others will not be able to over- 
 come the attraction of gravitation. 
 There will be intermediate molecules 
 that will neither have energy enough to 
 get away, yet will have too great a 
 velocity to be quickly attracted back. 
 In other words, they will approximately 
 reach a position of maximum potential, 
 and will possess no appreciable velocity 
 when in the vicinity of that position. 
 After being for a time approximately at 
 rest, they will slowly acquire a new 
 motion in the direction of the central 
 mass. Clearly it follows that such a 
 set of molecules may form more or less 
 temporarily a hollow shell of gas, or in 
 other words, a Planetary Nebula. 
 () A rotating mass of matter that contains 
 in it solid or liquid particles and in 
 which there is no gas to produce re- 
 tardation, is obviously an orbitally con- 
 nected mass, but since these particles 
 will be continually crossing one another's 
 paths, there will be impacts and pos- 
 
DEMONSTRATION OF THE THEORY 221 
 
 sibly coalescence between the members ; 
 and even if the general temperature be 
 high, when there is a considerable 
 quantity of oxygen present, the non- 
 volatility of the oxides formed will 
 tend to cause fusion on impact, and 
 coalescence rather than volatilisation, 
 Hence the rotating mass of non-vola- 
 tile material becomes converted into a 
 meteoric swarm, possibly of a very 
 high temperature. 
 
 (c) If it continues to coalesce, such a swarm 
 
 becomes a star cluster, and ultimately, 
 by the further collision of the masses, 
 tends to become a group of bodies 
 associated around a central sun. 
 
 (d) Two such systems as these latter com- 
 
 ing into whirling collision, would, in 
 the manner already minutely detailed, 
 give rise to some system of free bodies, 
 constituting planets on the outer regions 
 of the original system. 
 
 AXIAL EXTRUSION. 
 
 C. A case of whirling coalescence of vast cosmic 
 systems, such as the Magellanic Clouds, will be 
 
222 DEMONSTRATION OF THE THEORY 
 
 associated at one period of its existence with 
 great pressure in the particular parts that have 
 actually come into collision. A kinematic con- 
 sideration will show that this pressure can find 
 no path of escape save in both directions along 
 the axis of the whirl. Hence matter will be shot 
 upwards and downwards from this whirl-axis, 
 and may very readily be sent to a very consider- 
 able distance. In fact, it is probable that in 
 most cases some of the material will be endowed 
 with a velocity higher than the critical velocity, 
 whilst an immense quantity will reach a position 
 at which the attraction of the mass is very much 
 weakened, and the return journey will be one of 
 extreme slowness. A whirling collision between 
 two such systems will therefore produce a sort 
 of rough double spiral with two polar caps of 
 nebulous matter in a more highly gaseous state 
 than those portions of the systems that have not 
 actually come into direct impact, and thus we 
 have deducibly possible from the theory of con- 
 structive impact a state of things resembling the 
 visible universe. 
 
 (a) Thus there would be to an observer 
 within the whirling systems, a ring of 
 stars all around, consisting of the two 
 
DEMONSTRATION OF THE THEORY 223 
 
 -5 ~~ 
 
 parts whirling around each other, such 
 as is the case with the Milky Way 
 and 
 
 (b) There would also be as a result of the 
 axial pressure gaseous matter extruded 
 from the whirling systems in the form 
 of nebulous caps such as exist at the 
 poles of the Milky Way. 
 
 AGGREGATIVE POWER OF POSITIONS OF HIGH 
 POTENTIAL. 
 
 D. The reader will have observed that, as we 
 passed onwards from Section A, the nature of the 
 deductions increased in complexity, also introduc- 
 ing gradually an increase of speculative ideas into 
 the problem. Yet in no case is there an hypo- 
 thesis of any new force or new property of 
 matter, the whole of the deductions being 
 absolutely based on scientific fact. Nevertheless 
 the increase in complexity carries with it a 
 certain air of speculativeness. In this section 
 we are treating of the aggregating power of high 
 potential exerted upon bodies originally at a 
 high velocity. This action stands absolutely in 
 contrast with the aggregative power of gravitating 
 masses in trapping bodies of low velocity. Here 
 
224 DEMONSTRATION OF THE THEORY 
 
 we trench upon such unworked scientific ground, 
 that although the deduction appears perfectly 
 straight-forward, and by no means difficult to 
 comprehend ; yet it were better that this part of 
 the subject should stand alone. Its final non- 
 acceptance would not in the faintest degree 
 carry with it disproof of the prior propositions. 
 
 The farther we get from a cosmic body, the 
 lower will be the average velocity of associated 
 bodies, including elementary molecules. The 
 stupendous velocity that may occasionally be 
 .acquired by hydrogen, amounting almost cer- 
 tainly to thousands of miles a second, suggests 
 emphatically, that such a velocity is capable of 
 carrying it beyond the universe ; or in other 
 words as regards the galactic system, hydrogen 
 can attain a velocity above the critical velocity. 
 If there be in space other systems similar to our 
 galactic system, and should hydrogen pass out 
 of one of them, between these systems there will 
 be a position of highest potential with regard to 
 both, and it is there that the hydrogen will move 
 the slowest. Where the hydrogen tends to 
 move slowest, it tends to accumulate. All bodies 
 including molecules that have been sent out of 
 systems and are moving indiscriminately in all 
 
DEMONSTRATION OF THE THEORY 225 
 
 directions, will in the same way tend to be 
 retarded in positions o high potential. When 
 the accumulation of hydrogen becomes consider- 
 able, it is still in a position of high potential, 
 but its potential is lessened by the accumulations. 
 It was its high original velocity that enabled it 
 to reach a position where the molecules could 
 thus accumulate, and since any other material 
 that will reach this aggregating position must 
 have been originally of high velocity, there is a 
 tendency for this portion of space to contain 
 matter consisting of light atoms and also of such 
 elements that do not easily aggregate. It is 
 not here necessary to recapitulate the argument 
 as to the function of the cosmic pioneers and 
 the trapping action that these elements must 
 possess, but it will be seen on a review of the 
 former chapter that a large set of interacting 
 agencies are at work, that suggest that in this 
 way cosmic systems of a different character to 
 our own galactic system will be formed, and 
 that the collisions of two such primary systems 
 may produce a system somewhat similar to our 
 own. 
 
 The essential point to be considered is that 
 there are two modes by which matter can 
 
226 DEMONSTRATION OF THE THEORY 
 
 aggregate : the first being that of gravitation by 
 causing attraction of matter towards matter^ 
 consisting of dense and non-volatile material ; and 
 the second being the fact that bodies of high 
 velocity, consisting chiefly of atoms of light gas, 
 tend to accumulate in the sparsest portions of 
 space, and are thus in a position of maximum 
 potentiality. 
 
 This then represents the more important of 
 the -series of deductions that give rise to the 
 theory of constructive impact. We now pro- 
 ceed to consider if there are any facts that 
 correspond with these deductions. 
 
 II. 
 
 CORRESPONDING FACTS. 
 
 A. (a) In the case of temporary stars, of 
 which over a score have been recorded, 
 most of these stars have been almost 
 at their brightest when first seen. 
 Some few were of extreme brilliancy 
 at first, but others to which attention 
 was directed in their earliest stages, for 
 some days increased in brilliancy 
 increased enormously. The whole of 
 these stars have rapidly dissipated into 
 space ; yet some were of such intensity 
 
that it is almost certain that they must 
 have been thousands of times more 
 brilliant than our sun. Very few of 
 these temporary stars have lasted more 
 than a year. 
 
 (b) The theory suggests that variable stars 
 
 should be produced at the same time as 
 temporary stars, and that they shall be 
 in pairs. It is a remarkable confir- 
 mation of this that Nova Vulpeculae 
 (Anthelm's Star), of 1670, has, near its 
 position, a known variable star, and a 
 suspected variable. The figures from a 
 small area of the heavens have been 
 given in the chapter of variable stars. 
 The great number of variables that 
 occur in pairs, but too distant from 
 each other to be associated by gravita- 
 tion, cannot be the result of chance. 
 
 (c) Many double stars are variable. This 
 
 fact was pointed out by Struve in an 
 article published in The Intellectual 
 Observer for 1862, in which he says 
 definitely that some twenty-three 
 double stars are variable, and he sus- 
 pected some forty more. 
 
228 DEMONSTRATION OF THE THEORY 
 
 In Knowledge for September ist, 1899, Mr. 
 J. E. Gore points out the variability of 
 some well-known binaries and in a 
 subsequent letter to myself he has 
 added four more to the list. It is also 
 known, as the theory suggests, that 
 both double and variable stars are 
 associated with nebulae. 
 
 B. (a) Herschel gives an account of hollow 
 shells of gas as being the only possible 
 explanation of planetary nebulae. It 
 seems difficult to conceive of any other 
 way in which shells of gas can originate 
 except in the case of the peculiar sorting 
 action of Selective Molecular Escape. 
 Moreover, temporary stars have been 
 known to become planetary nebulae, 
 and in the case of Nova Aurigae, Pro- 
 fessor Barnard has even succeeded in 
 measuring its apparent disc. 
 
 (U] That meteoric swarms exist is demon- 
 strated by the phenomena associated 
 with comets, some of which have been 
 torn to pieces by their near approach 
 to the sun, and some pass through the 
 orbit of the earth. The disseminated 
 
DEMONSTRATION OF THE THEORY 22C/ 
 
 portions of the comets, when crossing 
 the orbit of the earth, occasionally 
 become visible to us as a swarm of 
 shooting stars, the dust becoming in- 
 candescent while passing through our 
 atmosphere. 
 
 (r) The star clusters exist in such numbers 
 that reference to the facts concerning 
 them that support the deductions need 
 not be made. 
 
 (ff) As regards the solar system there is an 
 extraordinary coincidence between it 
 and the deduced results of the whirling 
 collisions debated so fully in Chapter 
 IX., that it would be waste of time to 
 do more than point to the facts re- 
 corded. 
 
 C. With regard to the coincident facts con- 
 nected with the appearance of the Cosmos and 
 the polar caps of nebulae, I cannot do better than 
 refer the reader to those works on the character 
 of the universe that have been written by Proctor 
 and Gore, and the magnificent charts of Sidney 
 Walters published in the transactions of the 
 Royal Astronomical Society. 
 
 D. We have no evidence of the existence of 
 
230 DEMONSTRATION OF THE THEORY 
 
 systems of the primary cosmic character sug- 
 gested by the theory, or that they are in process 
 of formation, but were they forming, and were 
 the formation to reach up to the outposts of our 
 own universe, I cannot see that there is any 
 possible mode by which we could become aware 
 of their existence, unless it be that wonderful 
 spectroscopes may be built that may suggest 
 that such a system is forming, but this in the 
 highest degree is an improbable suggestion. 
 
 III. 
 
 Is there any satisfactory explanation of tempo- 
 rary stars that is so simple as to have passed 
 into common science ? Is there any explanation 
 of the fact that variable stars appear so frequently 
 in pairs ; that double stars are frequently vari- 
 able ; that both are often associated with nebulae ? 
 Is there any reason why variable stars are left 
 where temporary stars have before existed ? Is 
 there any explanation that gives a coherent 
 account of the origin of planetary nebulae and 
 why planetary nebulae should sometimes have 
 stars at their centres and should be where 
 temporary stars have once appeared ? 
 
 Does any explanation exist as to why the 
 
DEMONSTRATION OF THE THEORY 231 
 
 planets nearest the sun should be small and 
 dense, and their axes tip over so as to make 
 large angles with the ecliptic ; why the outer 
 planets are large and rare ; and why Uranus 
 rotates in a direction the opposite to the other 
 planets ? 
 
 Has any suggestion yet been made as to why 
 the universe should consist, roughly speaking, of 
 a double spiral or ring of stars, and two polar 
 caps of nebulae, and why there should be streams 
 and sprays of stars in the system ? 
 
 In no case do I know of any explanation 
 that fits in with the apparent facts, except the 
 deductions that have been made from the 
 Theory of Constructive Impact. 
 
 IV. 
 
 Are the deductions of this theory able to anti- 
 cipate phenomena ? 
 
 One half of the facts with which the Theory of 
 Constructive Impact is concerned were unknown 
 to me until I had sought for them, in many cases, 
 for years. An immense number of facts, such 
 .as that of the existence of pairs of variable stars, 
 the existence of variable stars near where a 
 temporary star had been formerly, and many 
 
232 DEMONSTRATION OF THE THEORY 
 
 other points of the theory are, I believe, still un- 
 known to the ordinary astronomer. 
 
 The most remarkable of any of these anticipa- 
 tion of facts is the case of Nova Aurigae. The 
 diagram illustrating the impact of two dead 
 suns facing Chapter III. was first printed in 
 1879, thirteen years before Nova Aurigae ap- 
 peared. The following is a list of predictions 
 made before the year 1880, and verified by actual 
 observations of astronomers since 1 892 : 
 
 PREDICTIONS. DEMONSTRATIONS 
 
 MADE A SCORE OF MADE RECENTLY BY 
 YEARS AGO. ASTRONOMERS. 
 
 I. The theory required I. Shown by the as- 
 that a new star tronomers of 
 
 should consist of Europe and 
 
 three bodies. America of Nova 
 
 Aurigae. 
 
 2. That two of these 2. The velocities mea- 
 bodies should be sured were 400 
 
 flying from each and 320 miles per 
 
 other at stupen- second, respec- 
 
 dous velocities. tively. 
 
 3. It predicted that the 3. Vogel's estimate was 
 middle body 23 miles a second, 
 
 should be moving 
 slowly. 
 
DEMONSTRATION OF THE THEORY 233 
 
 4. This middle body 4. Several astronomers 
 should become a observed this ne- 
 
 planetary nebula. bula ; Professor 
 
 Barnard measur- 
 ed its disc. 
 
 5. That there should 5. One fluctuation was 
 be fluctuations of observed and was 
 
 light in the two so striking as to 
 
 retreating bodies. be spoken of as a 
 
 "re- appearance. " 
 S ir Norman 
 Lockyer says it 
 was not the light 
 of the nebula 
 that increased. It 
 must consequent- 
 ly have been, ac- 
 cording to pre- 
 diction, the light 
 of the other 
 bodies. 
 
 6. These three bodies 6. This was the first 
 (one being nearly we 11 -ascertained 
 
 at rest, one flying fact that so sur- 
 
 one way, the other prised astro- 
 
 in the opposite nomers all over 
 
 direction) must the world. Alfred 
 
 produce a triple Taylor, after 
 
 lined spectrum. studying the 
 
 work of 85 obser- 
 vers, summed up 
 with "there is no 
 doubt of this 
 fact." 
 
 15 
 
234 DEMONSTRATION OF THE THEORY 
 
 7. The theory required 7. This was the exact 
 
 that one of these character of the 
 
 lines should be spectrum as ob- 
 
 bright and broad tained from a 
 
 with indistinct mean of all the 
 
 edges, and on this observations, 
 line should be the 
 two lines either 
 bright or dark. 
 
 8. Finally it was pre- 8. And it has done so. 
 dieted that the 
 temporary star 
 should disappear. 
 
 Such are some of the remarkable verified 
 anticipations of Partial Impact. Can many 
 cosmic theories show such results in the very 
 infancy of their acceptance ? 
 
 V 
 
 The last question is, Is the Theory of Con- 
 structive Impact likely to guide research ? 
 
 Reference has already been made to the many 
 facts that have been found only after much search- 
 ing for them, and that are even now unknown 
 generally to astronomers. 
 
 Doubtless had the astronomers of Europe been 
 aware that in Nova Aurigae they should have 
 looked, in the first place, for the characteristics 
 of a temporary star with its peculiar bright in- 
 
DEMONSTRATION OF THE THEORY 235 
 
 defined nebulous line ; secondly, for two variable 
 stars flying from one another at velocities of 
 hundreds of miles a second ; and thirdly, that 
 these two variable stars would show fluctuations 
 of light that would intermix with the light of the 
 temporary star, they might have ascertained by 
 more liberal and careful observation, the detailed 
 curve of light that the phenomena exhibited. 
 They would certainly have known that they had 
 to look for broad bands on the spectrum upon 
 which would be superimposed two other bands, 
 each of which would in all probability have 
 changed from dark lines to luminous ones. 
 Probably more confirmatory evidence of the 
 theory would thus have been forth-coming. 
 Astronomers should now search in the vicinity 
 of every variable star to ascertain if there is not 
 another in its near neighbourhood. They should 
 measure the distance of the present pairs to 
 ascertain if the distance is increasing. They 
 should search the position of every recorded 
 temporary star to ascertain if any variables are 
 near it. They should search in star clusters and 
 ascertain if any of the variables in the clusters 
 are in pairs, and if these pairs are wedded into 
 definite orbits. They should carefully be on the 
 
236 DEMONSTRATION OF THE THEORY 
 
 look-out for temporary stars of short duration 
 within these clusters, and especially in those star 
 clusters, or parts of star clusters, where a richness 
 of variable stars seems to suggest that the 
 paroxysms or series of encounters have not yet 
 died down. They should look for nebulae associ- 
 ated with variable stars, and especially in the 
 case of double stars that are at the present time 
 variable. They should compare the present dis- 
 tances of pairs of variables with earlier measure- 
 ments, and in the case where the former lists 
 only gives one of the two, they should ascertain 
 if its place has been moved in the direction that 
 tends to increase the distance from the other 
 star. 
 
 The forms of the nebulae should also be com- 
 pared with older drawings, and great pains 
 should be taken to produce the best possible 
 photographs of all existing nebulae showing 
 definite structure as contrasted with globular 
 nebulae. The old pictures should be compared 
 with the new to ascertain how far the spindles, 
 show incipient spirals, and spirals show further 
 development. Double nebulae should be care- 
 fully watched to see if there is a faint spindle 
 lying between the components. The centres of 
 
DEMONSTRATION OF THE THEORY 237 
 
 planetary nebulae should be examined for signs 
 of incipient star clusters and for faint aggrega- 
 tions of light of different charcter to that of the 
 nebula itself. The diameters of the discs should 
 be carefully measured. All double stars should be 
 carefully watched for intensity to ascertain if any 
 considerable number of them should prove to 
 be variable. The variable double stars should 
 further be investigated to ascertain if both the 
 stars are variable, or only one of the constituents 
 These are suggestions of a few of the directions in 
 which the theory of Constructive Impact will be 
 likely to guide research. 
 
 In face of the evidence presented, any doubt 
 of the collision of stars is as though a person 
 saw two locomotives up on end and entangled 
 with one another, all the carriages of the train 
 telescoped, death and destruction everywhere, 
 and were to say : " It cannot be a collision. 
 Our system of electric switches renders them 
 impossible. I own it looks like one, but it must 
 clearly be a delusion, for our system of signalling 
 is absolutely perfect. Besides I did not see the 
 collision, and seeing only is believing. You 
 must really seek some other explanation." 
 
 Scepticism of stellar impact is as though a 
 
238 DEMONSTRATION OF THE THEORY 
 
 man entered a shattered house and said : " It 
 is impossible a shell has exploded here, for 
 there is an armistice." 
 
 " But," says someone, " look at the dilapi- 
 dated house .; see the nature of the wounds and 
 smell the gunpowder ! " 
 
 " Yes ! If it were not for the armistice I should 
 certainly think that a shell had exploded, but 
 you see it cannot be so." 
 
 " But look at the pieces of iron sticking in 
 the walls, does not that prove it ? " 
 
 " I see the iron ; I admit the evidence is 
 plausible ; but we must not forget the armistice." 
 
 It is scarcely an exaggeration to say that the 
 evidence in these two similes is not more 
 striking than the evidence of stellar collision. 
 Only had we no such evidence, it is almost 
 certain that there must be collisions, for there is 
 no system of switches and rails to keep stars 
 apart, and no armistice to prevent them colliding ; 
 but on the contrary, there are actually mutual 
 attractions pulling them like mighty magnets 
 towards each other. 
 
 So when we see space strewn with star 
 wreckage, it seems incredible that anyone can 
 think stars do not collide. We stand in the 
 
DEMONSTRATION OF THE THEORY 239 
 
 presence of the actual facts, and we are forced 
 to believe in their encounters. 
 
CHAPTER XV 
 
 SYNOPTIC STATEMENT OF THE PRINCIPLES 
 AND PHENOMENA OF COSMIC IMPACT : 
 
 PREPARED FOR THE USE OF SCIENTIFIC 
 
 MEN AND SOCIETIES. 
 
 STELLAR COLLISION PARTIAL IMPACT NEW STARS AND 
 PLANETARY NEBULAE SELECTIVE MOLECULAR 
 ESCAPE FORMATION OF STAR-CLUSTERS AND METE- 
 ORIC SWARMS COMETS VARIABLE STARS-DOUBLE 
 STARS-NEBUL/E ORIGIN OF THE GALACTIC UNI- 
 VERSE-THE SOLAR SYSTEM MATHEMATICAL CON- 
 DITIONS OF THE FORMATION OF NEBUL/E THE 
 COSMOS POSSIBLY IMMORTAL-SEQUENCE OF AGEN- 
 CIESLIST OF PAPERS IN THE TRANSACTIONS OF 
 THE NEW ZEALAND INSTITUTE. 
 
 1. The new photographic charts have demon- 
 strated that there are over a hundred million 
 bright stars in the Milky Way. 
 
 2. The companion of Sirius and the dark com- 
 ponent of Algol prove the existence of dead suns. 
 These are possibly very numerous. Sir Robert 
 Ball thinks them more numerous than luminous 
 
STELLAR COLLISION 24! 
 
 ones : for other theoretical reasons than his I 
 believe him to be right. 
 
 3. Stars have an independent velocity or pro- 
 per motion of about ten miles a second upon an 
 average. Recent spectroscopic observations 
 seem to suggest a slightly higher velocity than 
 this. 
 
 4. This motion is apparently without much 
 order. It will alter the relative distance of stars, 
 and may bring them near each other, and pos- 
 sibly into impact. 
 
 5. If they are brought near each other their 
 mutual attraction will alter their velocity, and 
 curve their courses into hyperbolic orbits. If 
 they do not graze they will ultimately again 
 attain their original proper motion. 
 
 6. When stars are very near each other their 
 attraction will cause them to be distorted into an 
 egg-shape. 
 
 7. The tendency to collision will therefore be 
 increased by their mutual attraction in these 
 two ways, for it will cause them (i) to curve 
 their courses, (2) to be distorted when very near 
 each other. The chances of collision will there- 
 by be made one hundred times greater on an 
 average. In the case of two such bodies as our 
 
242 STELLAR COLLISION 
 
 sun the chances of collision would be about one 
 thousand times greater. 
 
 8. All impacts brought about in this way by 
 deflection will be of a grazing character ; con- 
 sequently nearly all stellar collisions of 
 approximately equal bodies will be of a grazing 
 character. 
 
 9. The average velocity of stars at impact will 
 be hundreds of miles a second, and in many 
 cases thousands. The average " proper motion " 
 will not appreciably affect the final velocity. 
 Thus a proper motion of ten miles will add less 
 than half a mile a second to a colliding velocity 
 (velocity acquired by attraction) of one hundred 
 miles a second. 
 
 10. A mere graze of the atmospheres of stars 
 obviously will not cause them to coalesce, nor 
 will a slight graze of the stars themselves. As 
 a mean result, when more than a third of each 
 of two equal bodies collide, coalescence will 
 ensue, but this will depend on the original proper 
 motion. Were nine-tenths of 1830 Groombridge 
 to collide with a similar star the remaining tenth 
 would not be stopped in its course ; it would pass 
 on in space, the bulk of the two stars tempo- 
 rarily coalescing and then dissipating into space. 
 
PARTIAL IMPACT 243 
 
 11. The effect of the collision will be to 
 intensely heat the colliding parts. Were the 
 surface of the sun composed of oxygen the 
 temperature produced by a slight graze would 
 be about 1 20,000,000 centigrade. 
 
 PARTIAL IMPACT. 
 
 12. The heating effect of a graze of two stars, 
 of two star-clusters, or of two nebulae, or even of 
 a star plunging through a star-cluster, will not 
 appreciably extend to the parts not colliding. 
 To emphasize this fact such impacts have beerk 
 called " partial." 
 
 13. " Partial impacts" of stars generally result 
 in the formation of three bodies. The fraction 
 of each star, lying in the path of the other, which 
 actually collides, and whose momentum will be 
 nearly or quite destroyed, will be cut off from 
 the rest of the star ; they will coalesce and 
 remain behind, whilst the two cut stars pass on 
 in space. 
 
 14. Partial impacts of a third of two equal 
 stars having considerable original proper motion 
 would make of the two impacting orbs three 
 equal bodies : two of them would travel on in 
 space in opposite directions ; the third would 
 
244 PARTIAL IMPACT 
 
 revolve and dissipate without any motion of 
 translation. If there had been no proper motion 
 the three bodies would have coalesced into a 
 whirling mass. If less than a third be cut off 
 from each, the two bodies become three bodies 
 orbitally connected. 
 
 15. The temperature produced by an impact 
 depends on the velocity destroyed and on the 
 chemical constitution of the colliding bodies. 
 High velocities and heavy molecules both tend 
 to produce high temperatures. Consequently the 
 temperature does not depend upon the amount 
 of the graze. Were one-tenth or one-hundredth 
 grazed off the impacting stars, the temperature 
 of the coalesced part would be the same. 
 
 1 6. Although the temperature will be the 
 same, the gravitating power of the coalesced part 
 will depend upon the mass and volume of that 
 part ; it will increase as the mass increases, and 
 diminish as the volume increases if the mass 
 remains constant. 
 
 17. There is a speed called the "critical 
 velocity " at which projectiles would permanently 
 leave cosmic bodies ; this velocity is seven miles 
 a second for the earth and 378 miles a second 
 for the sun. 
 
NEW STARS AND NEBUL/E 245 
 
 1 8. Heat is molecular motion. In a small 
 graze of any given pair of stars the molecules 
 will have the same velocity as in a large graze, 
 but the gravitating force holding the bodies to- 
 gether will be different. In a large graze the 
 body may be stable, the velocity of the 
 molecules not overcoming the attraction of 
 gravitation ; in a small graze the body will ex- 
 pand indefinitely in consequence of the small 
 attractive power of the coalesced mass, and 
 every expanding particle will have so high a 
 velocity that it will in general become an inde- 
 pendent wanderer in space, the velocity of the 
 molecules being above the critical velocity of the 
 mass. Consequently space will be spread with 
 free molecules. 
 
 NEW STARS AND PLANETARY NEBULA. 
 
 19. The mass of gas produced by such an 
 impact will obviously expand temporarily into a 
 hollow shell of gas. Herschel tells us this is the 
 condition of planetary nebulae. 
 
 20 A partial impact of stars will therefore 
 generally produce in less than an hour an in- 
 tensely heated body that will expand enormously 
 for a time, without much diminution of heat. 
 
246 NEW STARS AND NEBUL/E 
 
 It will consequently become very bright indeed, 
 after that it will continue to expand with di- 
 minishing intensity until it becomes a planetary 
 nebula, and will then often disappear by the 
 molecules dissipating completely into space. 
 
 21. Therefore in this time a new star has 
 l>een born that increases in intensity until the 
 general parallelism of motion of the molecules 
 causes a lessening number of impacts between 
 the molecules. As Sir William Crookes' experi- 
 ments in radiant matter prove that molecules only 
 radiate immediately after encounters, the lumin- 
 osity will diminish, and will go on diminishing 
 until the body disappears. In special cases the 
 planetary nebula may be fairly permanent. In 
 other cases a permanent star may appear in the 
 centre of the nebula. 
 
 22. The graze occupies less than an hour and 
 as with bodies of equal density the velocity 
 acquired is proportional to the diameter, all 
 grazing impacts of true stars or dead suns will 
 occupy about one hour. 
 
 23. The molecules on the far side of the 
 nebula (or third body formed by the two col- 
 liding stars) will be retreating from us ; those on 
 the near side will be advancing towards us. 
 
SELECTIVE MOLECULAR ESCAPE 247 
 
 The spectrum of such a body will consequently 
 be crossed by broad bright bands with a maxi- 
 mum in the centre and gradually dying 
 imperceptibly away. If this body has any 
 motion in space, as it probably will have when 
 the two colliding stars are unequal, the line of 
 maximum intensity, though in the centre of the 
 band, may be displaced from its true position. 
 
 24. Soon after impact the escaping molecular 
 velocity will be greater than the motion of 
 recession of the two cut stars, consequently the 
 displaced lines of these bodies will be on either 
 side of the centre of the broad band, but on its 
 .surface. 
 
 SELECTIVE MOLECULAR ESCAPE. 
 
 25. Immediately after the impact the tempera- 
 ture of different kinds of molecules will be very 
 different from one another. Were the two col- 
 liding spheres composed of oxygen, they would 
 be sixteen times as hot as if they were similar 
 spheres of hydrogen. The temperature at 
 impact will be proportional to the atomic weight 
 In a sphere of mixed elements these inequalities 
 of temperature would quickly equalize them- 
 selves. When this was the case the hydrogen 
 
248 SELECTIVE MOLECULAR ESCAPE 
 
 would be moving four times as fast as the 
 oxygen. The velocities would vary inversely as 
 the square root of the atomic weights. Whilst 
 their escaping energy will be inversely as their 
 atomic weight, that is hydrogen will have 
 sixteen times the chance of escape that oxygen 
 has. 
 
 26. This difference of velocity will tend to 
 sort the molecules into layers like those of a lily 
 bulb. The hydrogen on the outside will be 
 followed by helium, lithium and other elements 
 in the order of their atomic weights. 
 
 27. If there are elements lighter than hydrogen 
 or if as Prof. J. J. Thomson suggests there be 
 entities smaller than atoms, these will, of course, 
 precede hydrogen. In my lectures and papers 
 on this subject I have called this action " selec- 
 tive molecular escape." 
 
 28. Space will be thickly spread with free 
 molecules of the lightest elements. This fact is 
 important : it is one of the counteracting 
 agencies that prevent the theory of the dissipa- 
 tion of energy being of cosmic application. 
 
 29. A telescopic view of a new planetary 
 nebula produced by a partial impact, if seen 
 through a prism, should give a series of discs of 
 
STAR-CLUSTERS AND METEORIC SWARMS 249 
 
 diameters diminishing with increase of atomic 
 weight in its component elements. 
 
 30. This fact, taken in conjunction with the 
 broadening of the lines into bands, will enable us 
 to calculate the distance of such a body. It is 
 possible, however, that the parallelism of the 
 motion of the foremost molecules may prevent 
 encounters ; hence this layer of gas may not be 
 luminous. 
 
 FORMATION OF STAR-CLUSTERS AND 
 METEORIC SWARMS. 
 
 31. The hydrogen will rob the heavy mole- 
 cules of their energy : hence in any considerable 
 graze the heavy metals might not indefinitely 
 expand. They would lose their velocity by 
 radiation and by doing work against gravitation, 
 and they would be attracted back again, and 
 may form a star in the centre of the nebula. 
 Some nebulae have such stars. 
 
 32. In a partial impact the coalesced part will 
 not have all its motion converted into heat 
 The momentum on the two sides will not be ex- 
 actly balanced. The body will consequently 
 tend to spin. It is generic of partial impact that 
 
 it tends to cause rotation in all the bodies 
 
 16 
 
250 STAR-CLUSTERS AND METEORIC SWARMS 
 
 produced, and also that the rotation is all in the 
 same direction. 
 
 33. It is a peculiarity of oxygen that it tends 
 to render its compounds with metals less volatile 
 than are the metals themselves. Almost all 
 metallic oxides are less volatile than the metals 
 forming them. Consequently, when metallic 
 atoms and oxygen come together, they pro- 
 duce molecules that tend to coalesce. Thus 
 nuclei form in a nebula and it becomes 
 dusty. If the nebula be rotating this dust tends 
 to move in orbits, and it would be constantly 
 picking up other dust and molecules. Thus a 
 rotating metallic nebula, in which molecular 
 selective escape has dissipated the light mole- 
 cules, tends to aggregate, not necessarily into a 
 single body, but oftener into a number of bodies 
 orbital ly connected. If the mass be large it will 
 become a star-cluster, if small a meteoric swarm. 
 
 34. In star-clusters, impacts should be frequent 
 These groups should be photographically ob- 
 served to notice any sudden increase of intensity. 
 Then the pair of impacting stars should be 
 watched for nebulae and for variability. 
 
 35. Star-clusters would as a rule be very 
 deficient in helium and neon, and also have but 
 
COMETS 251 
 
 little uncombined hydrogen and not a large 
 quantity of hydrogen in any condition, otherwise 
 it would, except under special circumstances, 
 have become a single star. But partial impact 
 would make gas of the heavier elements and dis- 
 sipate such gas. This would produce resistance 
 arid cause other impacts; thus variable stars may 
 characterize some star-clusters, or special parts 
 of a star-cluster, as is the case. 
 
 COMETS. 
 
 36. Meteoric swarms when near the sun would 
 be distorted, and the constituent fragments 
 would impact with extraordinary frequency. 
 They would therefore become very brilliant, and 
 show as comets. The friction would produce 
 an enormous development of heat and elec- 
 tricity. 
 
 37. It is certain that the material of a tail of a 
 comet does not belong to the comet itself. It is 
 the dust of space lit up in some way like motes 
 in air illuminated by a search-light. The phe- 
 nomenon of the tail is almost certainly electrical. 
 In a paper " On a New Relation between Heat 
 and Electricity," I have discussed agencies that 
 may explain the phenomenon. 
 
252 VARIABLE STARS 
 
 38. Such a swarm, when close to the sun, 
 would have its near part drawn in advance of, 
 and its distant part left in the rear of, the general 
 swarm. Its weak attractive power would often 
 cause it to separate into a train. 
 
 The above are some of the phenomena that 
 may ensue in the coalesced mass. 
 
 VARIABLE STARS. 
 
 39. The two stars that grazed would have a 
 part cut out of each : this would expose the pro- 
 bably hot interior. Each star would entangle a 
 portion of the other. This would increase the 
 temperature and luminosity of the cut part of 
 each. 
 
 40. The stars after collision would recover 
 their sphericity chiefly by the molten interior 
 welling up. This by momentum would overfill 
 the space, and there would be a rhythmic tidal 
 action, the molten lake overfilling and then 
 sinking. 
 
 41. The retardation of the sheared stars by 
 the entangled material would cause them to 
 spin. This would act chiefly on the outer layers ; 
 the inside would tend to retain the original 
 rotation of the star. 
 
VARIABLE STARS 253 
 
 42. Thus in the sheared stars there are three 
 tendencies struggling with one another (i) the 
 original rotation, (2) the new rotation, (3) the 
 tidal action. 
 
 43. But the new rotation would be a large 
 component. We have therefore a star which 
 rotates and shows us alternately its hot and cool 
 sides. The old rotation and the tidal motion 
 produce other fluctuations of intensity, and also 
 inequalities of the rate of motion. 
 
 44. Evidently such a body as described would 
 be a variable star, and for a time such stars 
 would be in pairs. 
 
 45. Many variable stars are in pairs. It is so 
 striking a phenomenon that the probability is 
 one hundred sextillions to one against its being 
 the result of chance. 
 
 46. The stars of these pairs would have a 
 motion directed outward from each other. The 
 spectra might show displaced lines, if so the dis- 
 placement should be in opposite directions in the 
 two stars. 
 
 47. Conduction, convection, tidal motion, and 
 the contending rotations will tend to bring about 
 equality of temperature. This condition of 
 variability will consequently be a temporary 
 
254 DOUBLE STARS 
 
 one. The star will ultimately become of uniform 
 luminosity. These characteristics are all of 
 them known peculiarities of variable stars. 
 
 48. Convection is due to difference of density. 
 This difference may result from differences of 
 temperature, or of chemical composition or of 
 both. The lake of fire in the sheared star will 
 consist of heavier molecules than the remaining 
 surface, and it will also be at a higher tempera- 
 ture. These two will tend to neutralize each 
 other ; so that equality of temperature due to 
 convection will not be brought about quickly. 
 
 49. Therefore, although such variable stars 
 will doubtlessly become uniform, it is surprising 
 what a number of agencies there are tending to 
 retain this inequality of temperature. On 
 theoretical grounds it appears that this con- 
 dition of unequal heating may, as an extreme 
 case, last thousands of years. 
 
 DOUBLE STARS. 
 
 50. The work of cutting the stars will be 
 infinitesimal in relation to their available energy 
 before collision. It will not cause any appreci- 
 able lessening of the velocity of the escaping 
 stars. But the middle body will exert a power- 
 
DOUBLE STARS 255 
 
 ful attraction. It will exercise a retarding 
 influence, preventing the retreat of the two 
 bodies, equal to that of three times the mass 
 either body loses. Hence, when two equal bodies 
 lose a third of each by impact, the attraction 
 acting on each of the escaping bodies is doubled. 
 Therefore they do not as a rule become free from 
 the new central body unless the original proper 
 motion were large. 
 
 51. If however, the original proper motion 
 were large, and the graze small, the two stars 
 would escape each other. If the original motion 
 were small, and the graze, on an average, more 
 than a tenth, then the two stars would become 
 orbitally connected. 
 
 52. Such a pair, when thus connected, would 
 form a permanent double star. It is the opinion 
 of some astronomers that impacting stars becom- 
 ing orbitally connected could not make double 
 stars, as they think such stars would impact 
 again. But they overlook the fact that the 
 nebula that retarded their escape and formed 
 an important factor after the first impact, will 
 have dissipated before they return. 
 
 53. Hence the eccentricity will lessen greatly, 
 and, as a rule, instead of impacting again they 
 
256 DOUBLE STARS 
 
 will be scores of millions of miles away at 
 perihelion. In fact, they may have about the 
 eccentricity that double stars are known to 
 have. 
 
 54. There is a possibility of a second impact 
 when the graze has been a very small fraction, 
 or if one of the stars were multiple. But the 
 period of the subsequent recurrence of impacts, 
 after the first recurrence, would lessen in point 
 of time. On calculating the dates of the appar- 
 ently recurrent star, " The Pilgrim," viz., 945, 
 1264, and 1572, this is proved to be the case. 
 The dark bodies producing these impacts must 
 be of absolutely stupendous dimensions. The 
 dark bodies producing Nova Aurigae were pro- 
 bably 8,000 and 4,000 times the mass of the sun 
 respectively. 
 
 55. Double stars should be more often variable 
 than single stars. Struve has proved that they 
 are hundreds of thousands of times more vari- 
 able than ordinary stars. 
 
 56. We should expect them also to be more 
 frequently coloured. This, too, is most strikingly 
 the case. 
 
 57. We should look for them to be associated 
 with nebulae. Herschel says the association of 
 
NEBULA 257 
 
 nebulae and double stars is most truly remark- 
 able. 
 
 58. They should be highly eccentric. This is 
 also well known to be the case. 
 
 59. A large number of agencies tend to render 
 the orbit less eccentric. These are fully dis- 
 cussed in my papers of 1880. 
 
 NEBULA. 
 
 60. If stars come into partial impact, the 
 tendency to form nebulae of definite form, other 
 than planetary or cometic, seems to be entirely 
 destroyed by the outrush of the high-velocity gas. 
 This is not the case with the impact of nebulae. 
 
 6 1. Impact may take place between nebulae, 
 between star-clusters, between meteoric swarms, 
 and between any two similar or dissimilar 
 celestial bodies. The graze may be little or 
 large ; the original bodies may have had a small 
 or great proper motion ; and all these pecu- 
 liarities will tend to vary the results. 
 
 62. If two nebulae come into a slight grazing 
 impact there will result a double nebula, which 
 will show a spindle at the centre. As they are 
 parting company they may have temporarily a 
 dumb-bell appearance ; but, as the two sides of 
 
258 NEBULA 
 
 the coalesced nebula are moving in opposite 
 directions, a spiral begins to form at the centre 
 of the spindle. As the ends travel on in space 
 the spiral would increase, and ultimately a 
 double spiral would result 
 
 63. One or both of the original nebulae may 
 be entangled in the spiral. 
 
 64. If the impact be considerable, the two- 
 nebulae do not escape each other, and an annular 
 nebula results. It would have gauze-like masses 
 of nebulae at the poles of the ring, produced by 
 the outrush of gas during the impact. 
 
 65. There are nebulae corresponding to every 
 one of these conditions : nebulae coming into- 
 impact some in impact with the spindle show- 
 ing between them ; there are also spindle nebulae- 
 left alone ; others with an incipient spiral visible 
 at the centre ; others where the spiral is more 
 distinctly visible ; and others where the double 
 spiral is fully developed. 
 
 66. Finally there are annular nebulae with the 
 gauze-like caps referred to above. Thus at one 
 and the same time the evolution of nebulae at 
 any of its stages may be watched, and not 
 unlikely older drawings may show the less 
 advanced stages of the same nebulae. 
 
ORIGIN OF THE GALACTIC UNIVERSE 259- 
 
 THE ORIGIN OF THE GALACTIC UNIVERSE. 
 
 67. If two Cosmic systems such as the 
 Magellanic Clouds come into grazing impact, an 
 annular cosmic system will result, the poles of 
 which will be covered with nebulous matter 
 owing to the outrush of gas during the millions- 
 of years of the impact. 
 
 68. This principle of outrush needs some 
 explanation. As two globular masses close in 
 upon each other, the raotion will lie chiefly in a 
 plane which might be called the orbital plane. 
 It is obvious that the pressure of the heated gas 
 resulting from the impact, as the bodies close, 
 the gas in, can find no escape in this orbital 
 plane, but can only escape upwards and down- 
 wards. 
 
 69. Stars will pass into such caps of nebula, 
 as originally covered the galactic poles, and will 
 there be entrapped, and will attract nebulous 
 matter. They will thus become nebulous stars ; 
 or they may be volatilized altogether and become 
 globular nebulae. Such a distribution of nebulae 
 exactly corresponds with our universe. 
 
 70. Where globular nebulae are thick we should 
 expect double, spindle, and spiral nebulae. 
 These nebulae are actually found amongst the 
 
260 THE SOLAR SYSTEM 
 
 nebulae at the polar caps of the Milky Way. 
 Again, where stars are thick we should expect 
 planetary nebulae, double, temporary, and vari- 
 able stars, and star-clusters all the result of 
 the impact of stars. These, as the theory 
 requires, are almost entirely found within the 
 Milky Way. 
 
 71. If the universe were formed by such a 
 graze as we describe we should expect a greater 
 density of stars in those parts of space where 
 their motion chiefly directs the two original 
 cosmic systems. Proctor speaks of two such 
 clustering masses as striking features of our 
 universe. 
 
 72. If our galactic system were the result of 
 impact there would be much community of 
 motion in adjacent stars. This is a remarkable 
 peculiarity of the stars in the Milky Way. A large 
 number of further coincidences are debated in 
 my papers "On the Visible Universe," in the N.Z. 
 Phil, transactions, and in the body of the present 
 
 volume. 
 
 THE SOLAR SYSTEM. 
 
 73. Nebulae must tend to entrap bodies 
 passing through them. Such bodies would 
 frequently become orbitally connected with the 
 
THE SOLAR SYSTEM 26 1 
 
 nebula. Then, when the nebula, with these 
 bodies, became a sun, it would produce a system 
 with planets in all azimuths, in the same way as 
 the comets that our solar system has entrapped 
 are in all azimuths. 
 
 74.. Were a sun to impact with such a body 
 or with a dense star-cluster, and were the graze 
 considerable, all the planets would be whirled 
 roughly into one plane, and the central mass 
 would become a bun-shaped nebula. 
 
 75. It is not improbable that our sun was 
 formed by an incipient star-cluster impacting 
 with a nebulous sun, and that the present solar 
 system constitutes a large part of the whole 
 impacting mass. In other words, it is probable 
 that there was not a large ratio of the original 
 bodies dissipated into space during the impact, 
 but it is probable that the impact was a large- 
 ratio collision. 
 
 76. It is to be supposed that in every impact 
 much matter will leave the system. Some of 
 the gas extruded by the pressure acting along 
 the axis will be lost, with much of the hydrogen. 
 The attraction, therefore, on the return of the 
 planets may be so much lessened by these losses 
 that the orbits may be converted into an 
 
262 THE SOLAR SYSTEM 
 
 approximation to a circle. The nebula would 
 -expand enormously ; all the matter of it that 
 might pass outside aphelion distance would not 
 aid in attracting the planet back. Perihelion 
 distance would thus be increased by this 
 agency. 
 
 77. Of course, at first the rotation on their 
 axes of the newly-constituted planets would be 
 in all possible directions. Thus, the axes may 
 be in the ecliptic, or the motion may be retro- 
 -grade. The order observed in the rotation of 
 the inner planets will be established after- 
 wards, the outer planets largely escaping these 
 agencies. 
 
 78. Gaseous adhesion and many other agencies 
 are at work to cause apsides to rotate. Con- 
 sequently the larger nebular planets would 
 gradually pick up all matter within the 1 limits 
 of their orbits, thus giving the rough order to 
 the distance of the planets that is commonly 
 known as Bode's Law. 
 
 79. In a rotary nebula I have shown that 
 much matter will tend to become meteoric. 
 The absorption by a planet of every meteorite 
 will tend to cause the planet to rotate in the 
 -common direction of the nebula, and will cause 
 
THE SOLAR SYSTEM 263 
 
 the axis to tend to become upright on the axial 
 plane. This action will tell most with planets 
 near the centre of the series, such as Jupiter and 
 Saturn, because they will be largely gaseous and 
 in the thick of the meteoric matter. The outer 
 planets will necessarily be almost beyond the 
 region of such influence, while the near ones will 
 have but slight entrapping atmospheres, as ex- 
 plained hereafter. 
 
 80. All this exactly accords with the actual 
 inclinations of the axes of the respective planets. 
 
 8 1. It is probable that the orbits of the 
 planets were originally much smaller ; but much 
 of the potential energy of dimension would, as 
 they shrank, be converted into energy of 
 rotation, and this, by tidal action, into increased 
 distance from the sun. The same may also be 
 true of the moons. 
 
 82. As the volume of the nebula diminished 
 its temperature would increase. An increased 
 temperature would produce molecular exchanges 
 between the planets and the nebula, and this 
 would most affect the nearer bodies. Thus the 
 near planets would lose all their light atoms by 
 their escape into the surrounding nebula ; whilst, 
 oa the other hand, the low velocity of the heavy 
 
264 THE SOLAR SYSTEM 
 
 molecules of the nebula would allow these 
 molecules to be picked up by the planets. 
 
 83. Hence the near or inner planets would be 
 small and dense, as we find them in our solar 
 system, and the outer planets large and less 
 dense, as in reality they are. 
 
 84. The heat of the contracting nebula will 
 tend to increase the temperature of the planets,, 
 which would consequently expand. This would 
 lessen their hold upon their light matter in two 
 ways: (i) by the lessened attraction produced 
 by expansion, and (2) by the increased velocity 
 of the molecules themselves. The near planets 
 would consequently be composed almost wholly 
 of the heavy metals. The smaller and hotter 
 any planets were, the greater would be their 
 chance of being without atmosphere. The 
 absence of this and the small volume of the 
 planets would lessen their trapping action. 
 Consequently they would not be so upright in 
 their orbital planes as the middle planets. 
 
 85. The distant planets, being almost out of 
 the nebula, would not collect an appreciable 
 quantity of matter ; hence the original axes of 
 rotation may be at any angle, or even retro- 
 grade, as, in fact, they are. , 
 
THE SOLAR SYSTEM 265 
 
 86. As the nebula shrank within the orbits cf 
 the planets, the planets would again pick up light 
 molecules that would form an atmosphere ; but 
 the temperature of the planets would not allow 
 of much hydrogen being picked up unless it were 
 in combination. 
 
 87. The resistance and contraction of the 
 central nebula would clear space of all meteoric 
 dust unless such were orbitally connected with a 
 planet. The asteroids are probably parts of an 
 exploded planet. The impact of a rapidly- 
 moving body plunging into a planet could easily 
 blow it to pieces. It has been suggested that, if 
 so, such bodies would pass through the common 
 point of their explosion. This idea is an error, 
 as a planetary perturbation and other agencies 
 would prevent such coincidence. 
 
 88. The trapping of their moons by the 
 planets would probably occur when the planets 
 were nebulous, and before the central nebula had 
 attained to any great density. Hence they 
 would lie roughly on the planet's equatorial 
 plane. 
 
 89. Whilst a body of the mass of the earth 
 could pick up an atmosphere, the smaller 
 attractive power of the moon would not allow 
 
 17 
 
266 THE FORMATION OF NEBUL/E 
 
 this at the temperature it would be at when its 
 nebula contracted within its orbit. The moon 
 would probably be much nearer the earth at first, 
 but the stopping of its rotation by tidal action 
 would increase the distance. 
 
 90. Many other agencies that would convert 
 the system under discussion into one similar to 
 our own are treated of in my paper on " Causes 
 tending to alter the Eccentricity of Planetary 
 Orbits," in N. Z. Phil. Trans. 
 
 MATHEMATICAL CONDITIONS OF THE FOR- 
 MATION OF NEBULA. 
 
 91. It can be shown, that if two gaseous suns 
 impact completely, the suns having had no 
 original proper motion, and that were the whole 
 of the motion converted into heat, and this heat 
 into the potential energy of expansion, then the 
 new sun would have a diameter the sum of the 
 diameters of the original suns. It can also be 
 shown that such a condition is one of molecular 
 equilibrium. 
 
 92. Consequently the complete impact of two 
 gaseous suns not possessing much original 
 motion, and brought together by gravitation, 
 does not make a nebula of them ; but as soon as 
 
THE COSMOS POSSIBLY IMMORTAL 267 
 
 the paroxysm of the encounter is over they are 
 of the same temperature as before, having used 
 up all their energy in increasing to the sum of 
 their original diameters. This is a remarkable 
 and unexpected result. 
 
 93. Were there great original proper motion, 
 they might become a nebula by complete 
 impact ; but were the original velocity of the two 
 bodies very high, and the impact of very great 
 energy, then an indefinitely-diffused nebula 
 would result. Such a nebula, if hot, would be 
 unstable, and would indefinitely expand. Croll's 
 theory to account in this way for an increase 
 in the age of the sun's heat is therefore un- 
 tenable. 
 
 THE COSMOS POSSIBLY IMMORTAL. 
 
 94. If our universe be proved, from its con- 
 figuration and character, to have been formed of 
 two previously-existing cosmic systems as 
 appear probable from et seqq., then the entire 
 cosmos may be made up of an infinity of cosmic 
 systems. 
 
 95. Meteoric swarms prove space to be dusty 
 with wandering dark bodies, and " molecular 
 selective escape " proves it also to be spread with 
 
268 THE COSMOS POSSIBLY IMMORTAL 
 
 countless myriads of molecules of light gas. It 
 is probably due to the dust of space that we see 
 no distant cosmic system other than the Magel- 
 lanic Clouds. 
 
 96. If this be the case, radiation must all be 
 caught by the dust of space, and, unless some 
 agency be found to take this heat away, the dust 
 must be gradually increasing in temperature. 
 
 97. Bodies not in closed orbits when moving 
 at high velocities take but a short time to pass 
 over great distances ; they take longer and 
 longer periods as the velocity is reduced. Hence 
 the molecules of hydrogen and other light gases 
 when they have travelled into positions com- 
 paratively free from the influence of matter, will 
 be generally moving slowly. But such slowly- 
 moving molecules are cold : hence such gas may 
 be at a lower temperature than any other matter 
 in space. 
 
 98. Whenever by their mutual motions such 
 molecules strike cosmic dust, they will acquire 
 the temperature of the latter : that is, they will 
 increase their molecular velocity. They will 
 thus have a new start of motion. 
 
 99. It is evident that unless it strikes some- 
 thing the molecule can only lose this motion by 
 
THE COSMOS POSSIBLY IMMORTAL 269 
 
 radiation and by doing work. When it has 
 done work, it will be further from matter, or in a 
 position of higher potential, and Crookes' 
 experiments prove that molecules do not radiate 
 in free paths except immediately after en- 
 counters. 
 
 100. Moving matter not in orbits will tend to 
 move slowest where there is least matter that 
 is, where gravitation potential is highest be- 
 cause in these places it has done most work 
 against gravitation. Where bodies moving in- 
 discriminately move slowest they obviously tend 
 to aggregate : in other words the hydrogen and 
 other light gases of space tend to accumulate in 
 the sparsest portions of space. 
 
 101. Thus radiant energy falls upon the dust 
 of space and heats it. This heat gives motion 
 to molecules, and the molecules then tend to 
 use their new energy to pass to positions of high 
 potential, thus converting low-temperature heat 
 that is, dissipated energy into potential 
 energy of gravition that is, into the highest 
 form of available energy. 
 
 1 02. This action will tend to go on until 
 attraction is equal in different parts of space. 
 Thus we should have, if there were no counter- 
 
2/0 THE COSMOS POSSIBLY IMMORTAL 
 
 acting influence, in one part of space bodies in 
 mass, in another part diffused light gases. 
 
 103. But long before this equality of distribu- 
 tion can ensue another action is set up. The 
 mass of light gas will become a retarding trap 
 to indiscriminately-moving bodies. 
 
 104. Free bodies moving indiscriminately 
 will tend to pass through a group of masses 
 similar to our galactic system, through which 
 1830 Groombridge is passing now. But they 
 will tend to be trapped in any mass of gas they 
 encounter. Thus the place that was most void 
 of matter now begins to have more than a 
 regular distribution of matter. A new cosmic 
 system of the first order has begun to form. 
 
 105. The potential of this part of space lessens,, 
 and the work required to reach these positions 
 not being so great as at first, oxygen and other 
 heavier molecules get there, increasing the 
 density ; and oxygen also tends to produce 
 non-volatile compound molecules. Hydrogen 
 would form water molecules, these would 
 coalesce ; but helium and the other cosmic 
 pioneers do not combine, they remain perma- 
 nently gaseous. 
 
 106. Although dense bodies sent out of 
 
THE COSMOS POSSIBLY IMMORTAL 2/1 
 
 cosmic systems by the interaction of three 
 bodies would generally pass through old cosmic 
 systems where matter is in dense masses, they 
 evidently would not pass through such vast 
 gaseous aggregations as the incipient cosmic 
 systems. The bodies would be retarded by the 
 friction produced, and perchance volatilized, 
 forming nuclei in the general mass ; their 
 mutual attraction would cause denser aggrega- 
 tions to occur, and a cosmic system of the first 
 order would be produced. 
 
 107. Two such systems colliding produce a 
 system of the second order. The Magellanic 
 Clouds are probably systems of the second 
 order. This is suggested by their spiral form. 
 
 1 08. Such systems colliding with any other 
 cosmic system, produces a system of the third 
 order. Our own galactic system is very probably 
 a tertiary system. It is too orderly to be a 
 primary system and too irregular to be a 
 secondary system. 
 
 109. When three bodies pass near each other, 
 one at least has its velocity increased. In this 
 way it is possible to account for the enormous 
 velocity of 1830 Groombridge, although this 
 high velocity might also be due to the attraction 
 
2/2 THE COSMOS POSSIBLY IMMORTAL 
 
 of our universe, or of a near dead sun. The truth 
 of which latter idea could be ascertained by 
 observations of its regularity of speed. When- 
 ever the velocity is great enough to enable the 
 body to escape the attraction of the universe, 
 the body is lost to it, and the other two bodies 
 would be moving more slowly. If this should 
 occur only once in a thousand cases seeing 
 that when it does occur the body escapes given 
 time enough, much of the energy of any in- 
 dividual system must thus be used up in 
 allowing the escape of bodies. 
 
 1 10. If it could be shown that the impact of two 
 similar universes would result in the formation of 
 one which, in a similar stage, was of larger mass 
 than the larger of the originals, then impact 
 would be, on the whole, an aggregating agency, 
 and the permanent equilibrium of the cosmos 
 would be disturbed. 
 
 Hi. This is probably not the case, for during 
 the impact of the universes themselves much 
 matter would escape, and at every impact of in- 
 dividual bodies within the new universe light 
 molecules would be set wandering that would 
 ultimately leave the system. When the new 
 system has become more dense, during the 
 
THE COSMOS POSSIBLY IMMORTAL 2/3 
 
 approach of any three bodies one would 
 occasionally be sent out of the system. There 
 are other agencies that, together with these, 
 render it possible for two similar cosmic systems, 
 by coalescing to become one x which, when con- 
 tracted to the size of either of its components 
 retains no more matter than one of the original 
 systems. 
 
 1 12. We have in these phenomena a complex 
 series of agencies tending to overcome the 
 dissipation of energy and the aggregation of 
 matter. Impact developes heat, separates bodies, 
 and diffuses gas. Radiation falls on the matter 
 of space and heats it : this energy is taken up 
 by the hydrogen to increase its velocity. As 
 the hydrogen loses this new velocity it is carried 
 to positions of higher potential. It will tend to 
 linger in the empty parts of space, and it then 
 becomes a trap for wandering bodies. These 
 wandering bodies are separated from systems 
 by the mutual interaction of three bodies. 
 
 1 1 3. Thus, is suggested the possibility of an 
 immortal Cosmos, in which we have neither 
 -evidence of a beginning nor promise of an end. 
 The sequence of these agencies is as follows : 
 
 (a) Diffusion of heat by radiation. 
 
2/4 THE COSMOS POSSIBLY IMMORTAL 
 
 (b) This radiation, falling on the dust of space,. 
 
 heats it. 
 
 (c) The heat of this cosmic dust is taken away 
 
 by slowly moving light molecules having 
 their velocity increased. 
 
 d) Free molecules are also sent out of 
 systems by partial impacts, by selective 
 molecular escape, and other agencies. 
 
 (e) Free molecules will remain longest in the 
 position of maximum potential where 
 their motion is least, and will conse- 
 quently tend to aggregate in the empty 
 parts of space. 
 
 (/) By the interaction of three bodies the 
 velocity acquired by one sometimes takes 
 it out of the cosmic system. 
 
 (,) Hydrogen and the cosmic pioneers then 
 become a trap for wandering bodies that 
 tend to be stopped and converted into- 
 dense nebulae. 
 
 (//) These dense nebulae tend to attract 
 surrounding gas ; they cool and shrink,, 
 some ultimately forming solid bodies. 
 
 (i) These bodies, by mutual attraction, give 
 density to the new cosmic system. 
 
 (/) Such systems are of the first order. 
 
THE COSMOS POSSIBLY IMMORTAL 2/5 
 
 () The impact of systems of the first order 
 produces systems of the second order. 
 
 (/) Any other impacts produce systems of the 
 third order, of which our galactic system 
 is a type. 
 
 (;) The coalesence of two cosmic systems 
 does not necessarily, as a final result,, 
 produce a system of a larger mass than 
 one of the two original systems from 
 which it was formed, as many agencies 
 are tending to send matter out of the 
 coalesced mass. 
 
 () It is thus seen that dissipation of energy 
 is but a part of a complex cyclical 
 process ; and there is consequently the 
 possibility of an immortal cosmos in 
 which we have neither evidence of a 
 beginning nor promise of an end, the 
 present being but a phase of an eternal 
 rhythm. 
 
 The diagrammatic scheme of cosmic evolution 
 illustrates these agencies (page 198). It must be 
 noted that bodies and systems are printed in 
 italic capitals ; and where several such are one 
 above another it implies sequence of phenomena. 
 
2/6 LIST OF FORMER PAPERS 
 
 The following Papers on Constructive Collision 
 
 are to be found in the Transactions of the 
 
 N.Z. Institute. 
 ON TEMPORARY AND VARIABLE STARS. July 
 
 4th, 1878. 
 
 ON PARTIAL IMPACT, &c. August ist, 1878. 
 ON THE VISIBLE UNIVERSE. February i3th, 
 
 1878. 
 ON THE GENERAL* PROBLEM OF STELLAR 
 
 COLLISION. March i3th, 1879. 
 PRESIDENTAL ADDRESS ON THE GENESIS OF 
 
 WORLDS AND SYSTEMS. April 3rd, 1879. 
 
 CAUSES TENDING TO ALTER ECCENTRICITY 
 
 OF PLANETARY ORBITS. May 6th, 1880. 
 ON THE ORIGIN OF THE SOLAR SYSTEM, 
 
 August 5th, 1880. 
 THE ORIGIN OF DOUBLE STARS. August 5th, 
 
 1880. 
 
 SOME RECENT EVIDENCE IN FAVOUR OF 
 
 IMPACT. November ist, 1893. 
 
 THE IMMORTALITY OF THE COSMOS. Novem- 
 ber 7th, 1894. 
 
 SYNOPTIC STATEMENT OF THE PRINCIPLES 
 AND PHENOMENA OF COSMIC IMPACT. 
 Prepared for the criticism of Scientific Men 
 and Societies. November 7th, 1894. 
 
INDEX 
 
 ABSOLUTE ZERO, 23 
 
 AGGREGATIVE HIGH POTENTIAL, 
 203, 223 ; media of, 204 
 
 ALGOL, 166 ; a dead sun, 38 ; vari- 
 able, 50 
 
 ALPHA CENTAURI (nearest fixed 
 star), 162 
 
 ANDERSON (Mr.) and Nova Aurigae, 
 
 ANDROMEDA, nebula of, 188 
 
 ANNULAR NEBULAE, see NEBULAE 
 
 ANTHELM'S Variable (Nova Vul- 
 peculae), 58, 227 
 
 APHELION, attraction at, 73 
 
 APSIDES, 256 
 
 ARCTURUS, 207 
 
 ARGON, 83 
 
 ARGUS (TA), 64 
 
 ASTEROIDS, see PLANETOIDS 
 
 ASTRONOMICAL measurements, 161 
 
 ASTRO-PHYSICS, 15 
 
 ATMOSPHERE, of incipient planets, 
 137 ; oxygen and hydrogen in, 
 23 ; temperature, 23 
 
 ATOMIC THEORY (Dalton's), 80 ; see 
 also ATOMS, ELEMENTS and 
 MOLECULES 
 
 ATOMIC WEIGHTS, 81 ; importance 
 of, 14 ; and dissipation of gas, 
 96 ; and Selective Molecular 
 Escape, 87-8 
 
 ATOMS, Clark Maxwell on, 86 ; com- 
 plexity of, 12, 17 ; fixed and 
 ii. destructible, 84 ; movement of, 
 18 ; particles smaller than, 83 ; 
 size of, 17 ; spectra, 54 
 
 ATTRACTION, see GRAVITATION 
 
 AURORA BOREALIS, 125, 142 
 
 AXIAL ESCAPE, 131, 221 ; extrusion, 
 190 ; fundamental thought of, 
 215 
 
 Axis, planetary, 120-1 
 
 BALL (SiR ROBT.), on Impact, 66 ; 
 
 dead suns, 38, 166 ; Mars, 107 ; 
 
 Selective Molecular Escape, 
 
 107 ; speed of stars, 67 
 BARNARD (Prof. E. C.), measures 
 
 Nova Aurigae, 37, 59 
 BEVERLY (Mr.), 56 
 BINARIES, see DOUBLE STARS 
 BIRTH of Suns, 44 
 BODE'S LAW, 119, 136 
 Bradford Daily Argrts, quoted, 194 
 
 CAILLETET, 18 
 
 CANES VENATICI, 188 
 
 CASSIOPEIA (Mu), 207 
 
 CERES, 119 
 
 CELESTIAL phenomena, 10 ; cele- 
 bates, 83 
 
 CENTAUR, 162 
 
 CENTRIFUGAL FORCE, 134 
 
 CENTRIPETAL FORCE, 134 
 
 GET us, 49 
 
 CHADS and symmetry, 138 
 
 CHARTS, Proctor's, 172 ; New- 
 comen's, 172 ; Waters', 172 
 
 CHEMICAL ELEMENTS, 8x ; composi- 
 tion and impact, 80 
 
 CHLORINE, 89 
 
 CLAUSIUS, 201 
 
 CLUSTERS, 101 seq. ; see also STAR 
 CLUSTERS 
 
 COALESENCE, 29, 69 ; and comets, 
 149; and Solar System, 129; 
 condi* ions of after impact, 39* 
 energy involved, 71 ; of nebulae, 
 72 ; ot suns, 130 ; of suns cannot 
 produce nebulae, 177 ; whirling 
 and clusters, no; see also IM- 
 PACT 
 
 COHESION, 19 
 
 COMBUSTION, 206 
 
 COMETIC NEBULAE, 183 
 
 COMETS, 126, 149, 251 ; formed by 
 collision, 149 ; luminosity of r 
 152 ; masses of gravitating 
 meteors, 150 ; not of small mass, 
 152 ; path of, 155 ; perturbations 
 within, 150; produced in dif- 
 ferent ways, 149 ; retardation of, 
 77 ; tails due to electrical induc- 
 tion, 154 
 
 COMPOSITION, chemical and velo- 
 city, 42 
 
 COMPOUNDS, volatile, 89 
 
 CONDENSATION, 19 ; of clusters, 115 J. 
 of planetary nebulae, 98 
 
 CONDUCTION, 60; slow in liquids, 
 61 
 
 CONSTRUCTIVE IMPACT, see IM- 
 PACT 
 
 CONSTRUCTIVE POWER of the 
 Theory, 79 
 
 CONVECTION, 60 
 
 CORONA (SOLAR), and zodiacal light, 
 142 ; bat's wing form, 143 ; cause 
 of, 142 
 
278 
 
 Index 
 
 COSMIC DUST, formation of, 89 ; 
 and zodiacal light, 125. 
 
 COSMIC EVOLUTION, 192-4, 259 ; a 
 cyclic process, 210 ; agent of, 
 179; and accepted principles, 
 84 ; and monotomic elements, 
 (pioneers), 83 ; and oxygen, 89 ; 
 and velocity of molecules, 86 ; 
 diagram, 198 ; see also COSMIC 
 SYSTEMS 
 
 COSMIC PIONEERS, 83, 206 ; function 
 of, 204-6 ; see al>o ARGON, 
 CRYPTON, HELIUM, NEON, 
 XENON 
 
 COSMIC SYSTEMS, growth of, 207, 
 229 ; Mr. Russell's photographs, 
 192 ; of first order, 204-5 ; see 
 also COSMIC EVOLUTION and 
 MAGELLANIC CLOUDS 
 
 CosMOS, immortal, 13, 199, 210, 
 267 ; infinite, 79 ; possibilities 
 of, 116 
 
 COUNTERPARTS of stars and nebulae, 
 184 
 
 CRITICAL VELOCITY, 25; and tem- 
 perature, 36 ; of Earth, 25, 108 ; 
 of planetoids, 109; of Sun, 26 
 
 CROLL'S theory untenable, 267 
 
 CROOK ES' experiments, 14 ; tubes, 16 
 
 CROWN, new star in, 33 
 
 CRYPTON, 83 
 
 CRYSTALISATION, 19 
 
 CYCLES, cosmic, 210 
 
 CYCLONES on the sun, 117 
 
 CYGNI, (61), 93 ; see also SWAN 
 
 DALTON'S atomic theory, 80, 83 
 
 DAI:WIN, (Prof. G. H.), on the 
 Moon, 124 
 
 DARWINISM, 211 
 
 DATES of Temporary Stars, 32, 33, 
 36, 58 
 
 DAYS, length of, 121 
 
 DEAD SUNS, collision of, 105 ; de- 
 monstated in Algol, 38 ; Dr. 
 Johnsione Stoney on, 38 ; move 
 faster, 72 ; pre-existent, 175 ; 
 Sir Robert Ball on, 38 
 
 DEM IN STAR, see ALGOL 
 
 DENSITY, a factor of variability, 61 ; 
 of planets, 119; of planets ex- 
 plained ; 13 
 
 DIRECT IMPACT impossible, 28 ; see 
 also IMPACT 
 
 DISSIPATION, and atomic weights, 
 96 ; of matter and energy, 95 ; 
 of meteors, 130 ; of temporary 
 stars, 45 ; of Third Body, 30 
 
 DISSIPATION of ENERGY, 200 ; over- 
 coming, 86 ; theory confuted, 195 
 
 DOUBLE ROTATION of sun, 118; of 
 variables, 63 
 
 DOUBLE SPIRAL NEBUL.K, see 
 NEBULA; 
 
 DOUBLE STARS, (Chapter iv.) 65, 
 254 ; and nebula;, 75 ; caused 
 by gravitation, 68, 78 ; char- 
 acteristics, 74 ; eccentric orbits, 
 71, 73 ; entiapping action, 114; 
 lormed by a tangential approach, 
 77 ; Herschel on, 75 ; in clusters, 
 114; nearly all in the Milky 
 Way, 77 ; numeious, 69 ; Proc- 
 tor on, 70 ; orbits produced by 
 interaction, 77 ; revolution of, 
 69; Sir Robert Ball on, 68; 
 within nebula;, 76 ; see also 
 DOUBLE VARIABLE STARS, IM- 
 PACT, and VARIABLE STARS 
 
 DOUBLE VARIABLE STARS, 51 ; 
 Mr. J. E. Gore's records, 75 ; 
 Struvc's observations, 75 
 
 DUPLICATION of orbits after im- 
 pact, 72 
 
 DUST, formation of cosmic, 89 
 
 DU^T SWARM, formation of, no; 
 velocity of, 125 
 
 DUSTINESS of space, 202 
 
 DYNAMICAL THEORY OF GASES, 14, 
 84 ; and Nebular Hypothesis, 
 128; pressure and temperature, 
 85 
 
 EARTH, as a planet, 119; critical 
 velocity of, 25, 108 ; eclipses, 
 122; "Romance of the," 139; 
 size of, n ; size of orbit, 161 ; 
 velocity of, 25 
 
 ECCENTRIC orbits explained, 132 
 
 ECLIPSES of the moon, 122 ; of the 
 sun, 122, 142 
 
 ELASTICITY, 21 
 
 ELECTRICITY and comets, 152-3 ; and 
 ether, 84 ; escape of, 153-4 ; 
 negative, of the sun, 153-4 
 
 EL DORADO, a scientific, 65 
 
 ELEMENTS, 81 ; energy of, 96 ; oxen- 
 genation of, i TO ; volatile, 89 ; 
 see also NEW ELEMENTS 
 
 ENERGY, absorption of, 156 : and 
 matter, respective dissipation of, 
 95 ; and velocity, 40 ; associated 
 with matter, 20 ; available for 
 shearing, 39, 69 ; converted, on 
 moon, 124; dissipation of, 200; 
 heat, a form of, 20 ; indestructi- 
 bility of, 20, 200 ; involved in 
 impact, 27, 71 ; motion of mass 
 converted, 22 ; of coalescence, 
 71 ; of elements, 96; on moons, 
 136; transmutation of, 20, 142; 
 of Sun, 118 
 
 ENTRAPPING of molecules, 207 
 
 EPHEMERIDES of variable stars, 56 
 
Index 
 
 279 
 
 ESCAPE of electricity, 154; of gases, 
 (see SELECTIVE MOLECULAR 
 ESCAPE and AXIAL ESCAPE) 
 
 ETA ARGUS, 64 
 
 ETERNITY'S Pendulum, 116 
 
 ETHER and comets' tails, 156 ; and 
 electri.ity, 20, 84 
 
 Ev( LUTION, a universal law, 13; 
 (cosmic), agent of, 179 ; diagram. 
 198; of life, 139; of Milky Way, 
 174; of planetary life, 116; of 
 planets, 116; of clusters, 103; 
 of systems, 207 
 
 EXPLOSION of planets, 144 
 
 FLUORESCENCE, 17 
 FORCE, see ENERGY 
 
 GALACTIC POLES, 13, 167, 180 
 
 GALAXY, see MILKY WAY 
 
 GASES, compound, 85 ; compressible, 
 85 ; dynamical theory, 14, 84 ; 
 entrapping power, 207 ; expand 
 into nebula, 51 ; invisible masses, 
 176 ; monatomic, 14, 85 ; motion 
 of, 85, 107 ; nature of, 107- ; pres- 
 sure and temperature, 85 ; re- 
 tarding effects of, 113; sorting 
 of, 88 
 
 GASIFICATION after impact, 87 
 
 GEOLOGICAL agency, 124, 139 
 
 GLACIAL periods, 139 
 
 GLOBULAR NEBUL/K (Chapter xii.), 
 180; see also NEBULAE 
 
 GORE (Mr. J. E.) on double vari- 
 ables. 75; list of do., 56 
 
 GRAVITATION, and double stars, 68 ; 
 between two centres, 137; in- 
 creases force of impact,' 38 ; 
 irregularities of, 183 ; media of, 
 203 ; velocity of, 40, 71 
 
 GRAZING IMPACT, see IMPACT 
 
 GKKAT BKAR, 92 
 
 GROOM BRIDGE (1830), 43, 72, 86, [15, 
 206 
 
 HARVEST MOON, 122 
 
 HEAT, a form of energy, 20 ; a mode 
 of motion, 15 ; and motion of 
 mass, 15; conduction, 60; con- 
 vection, 60; degrees of, 22; 
 evolved by impact, 67, 87, 105 ; 
 of g.ises, 16 ; of liquids, 16 ; of 
 solids, 16; of temporary stars, 
 34 ; of two kinds, 15, 16 ; radia- 
 tion after impact, 61 ; see also 
 TEMPERATURE and THERMO- 
 METER 
 
 HELIUM, 83 ; dissipation, of, 96 ; 
 velocity of, 87 
 
 HERSCHEL (Sir J.) on shape of uni- 
 verse, 171 
 
 HERSCHEL (Sir WM.), drawings of 
 nebulae, .186: on nebuhe, 184; 
 on nebulae in relation to stars, 
 76 ; on planetary nebulae, 92, 
 165 ; on double stars and nebulae, 
 
 HIND, on the galaxy, 172 
 HIND'S variable (T Tauri), 59 
 HUMBOLDT quoted, 103 
 HYDROGEN, cosmic function of, 204 ; 
 
 dissipation of, 96 ; liquifaction 
 
 of, 18, 22 ; motion of, 68, 95 ; 
 
 peroxide, 81 ; velocity of, 87 ; 
 
 weight of, 81 
 HYPOTHESIS of Impact, 34 
 
 IMMORTALITY of the Cosmos, 
 (Cbapter xiii), 13, 199, 210, 267 
 
 IMPACT (Chapter i), 10, 240 ; ac- 
 counts tor Nova Aurigae, 55; 
 advice to students, 235; agencies 
 of, 130; agent of cosmic evolu- 
 tion, 179 ; " a master key " 179 ; 
 and chemical composition, 80 ; 
 and evolution of universe, 169, 
 174-5 ; and gaseous suns, 42 ; 
 and gasification, 87; and gravita- 
 tion, 38; author a solitary worker, 
 190 ; causes variable stars, 
 51, 56, 60 ; comprehensiveness 
 of the theory, 13, 79 ; demon- 
 stration of, 216; diffuses gas, 
 149 ; energy involved, 27, 39 ; 
 formation of double stars, 72 ; 
 formation of Jupiter, 135 ; forma- 
 tion of solar system, 129 ; forma- 
 tion of temporary stars, 38 ; 
 fo mation of planetary nebulae, 
 51, 94; fundamental thought of, 
 106,214; grazing, 34; growing 
 belief in, 66; heat evolved by, 
 67, 87, 105 ; hypothesis of, 34 ; 
 in clusters, 112, 116; list of 
 papers. 276 ; mathematics of, 
 42, 177 ; of dead suns, 105 ; of 
 nebulae, 182, 186, 189 ; other 
 theories insufficient, 35 ; partial, 
 28; possibility of, 27, 66; p'es- 
 sure of gas after collision, 191 ; 
 Proctor's views, 70 ; produces 
 comets, 149 ; produces nebulae, 
 30, 105 ; producing three bodies, 
 28, 51 ; question by Humboldt, 
 163; recurrent, rare, 70, 256; result 
 of, 41, 66 ; shearing energy, 69 ; 
 simplicity of theory, 14; tem- 
 perature of, 24 ; velocity con- 
 sidered, 22, 24, 51, 71, 87; will 
 not transform gaseous suns into 
 a nebula, 43 ; see also COALESC- 
 ENCE, PARTIAL IMPACT, THIRD 
 BODY, and VARIABLE STARS 
 
280 
 
 Index 
 
 INDESTRUCTIBILITY of energy, 200; 
 
 of matter, 199 
 INDUCTION causes comets' tails, 154 
 
 JOULE, 199 
 
 JULES VERNE, 44 
 
 JUNO, 119 
 
 JUPITER, 119 ; and comets, 77 ; and 
 
 perturbation, 146; formation of, 
 
 135; Proctor on, 135 
 
 KELVIN (Lord), on dissipation of 
 
 energy, 200 
 
 KEPLER'S temporary star, 32 
 KINEMATICS, 181 
 Knowledge, quoted, 75 
 
 LAKE OF FIRE, 62 ; tidal action, 63 
 
 LAPLACE'S NEBULAR HYPOTHESIS, 
 120 ; reasons against, 128 
 
 LAVOISIER, 199 
 
 LEO, 168, 188 
 
 LICK OBSERVATORY, 37 
 
 LIFE on planets, 116 
 
 LIGHT, analysis, 52 ; Irom travelling 
 bodies, 54 ; Struve's conclusion, 
 156; see also SPECTRUM AN- 
 ALYSIS 
 
 LOCKYKR, meteoric hypothesis of, 
 128 
 
 MAGELLAN ic CLOUDS, 192, 209 ; 
 
 Mr. Russell's photogiaphs, 192 
 MAGNETIC STORM, 125, 142 
 MATHEMATICS of impact, 42, 177, 
 
 267 
 MATTER, an indestructible entity, 
 
 20, 199 ; constitution of, 17; and 
 
 eneigy, respective di>sipation of, 
 
 95 
 
 MARS, 119; Sir Robert Ball on, 107 
 MAXWELL (CLARK), on atoms, 86 
 Melbourne Argus quoted, 66 
 MERCURY, 119 
 MESSIER'S 64th nebula, 76 
 METALLIC rain, 62 
 METEORIC HYPOTHESES, 128 
 METEORIC PHENOMENA (Chapter 
 
 x.), 140, 249 ; comets, 149, 251 ; 
 
 planetoids, 144 ; Saturn's rings, 
 
 147; solar corona, 142; zodiacal 
 
 light, 140 
 METEORS, 153; dissipation of, 130; 
 
 trains derived from comets, 151 ; 
 
 visible and invisible, 126, 150 
 MINOR PLANETS, see PLANETOIDS 
 MILKY WAY, 165 ; cloven disc 
 
 theory, 168 ; composition of, 
 
 167 ; disposition of components, 
 
 171 ; evolution of, 13, 174 ; 
 
 nebula; in, 182 ; not a primitive 
 
 system, 208 ; Proctor on, 171 ; 
 
 profusion of double stars, 77 ; 
 see also GALACTIC POLES 
 
 MIRA (the "Wonderful" Star), 49, 
 112, 165 ; period of, 49 
 
 MOON, a member ol the solar system, 
 124 ; harvest, 122 ; potential 
 eneigy, 124 ; Prof. G. H. Darwin 
 on, 124; tidal action and rota- 
 tion, 122-4 5 see a ' s SOLAR 
 SYSTEM 
 
 MOONS, and potential energy, 136; 
 entrapping ot, 137 ; explosion ot, 
 148 ; of planets, 122 ; orbits of, 
 145; oiigin of, 135; revolution. 
 of, 122 ; see also PLANETS 
 
 MOLECULAR ESCAPE and Cosmic 
 Kvolution, 94 ; see also SELEC- 
 TIVE MOLECULAR ESCAPE 
 
 MOLECULES, at low tcmperatuies, 
 18; equal velocities, 113; Inui- 
 gibility of, 82 ; free, 82 ; htat 
 after impact, 87 ; motion of gas, 
 107 ; travel radially, 88 ; two 
 kinds of, 82 ; velocity and tem- 
 perature, 22 ; escape of, see 
 SELECTIVE MOLECULAR ESCAPE 
 
 MONATOMIC MOLECULES, 83, see 
 also NEW ELEMENTS 
 
 Mu CASSIOPEIA, 207 
 
 MULTIPLE NEBULA, see NEBUL/E 
 
 NEBULAE (Chapter xii.), 180, 257; 
 action of, in coalescence, 72 ; and 
 cosmic dust, 90; and double 
 stars, 75 ; Andromeda, 188 ; 
 advice to students, 191, 235; at 
 Galactic Poles, 167 ; beauty of, 
 ipi ; cannot be produced by 
 coalescence ofsuns, 177 ; cometic, 
 183 ; comparison of drawings, 
 191 ; double nebula;, 184 j 
 double spiral, 181 ; Dr. 
 Roberts' investigations, 188 ; 
 entiappin? power, 127, 137 ; ex- 
 pansion of solar, 134 ; formed 
 by coalescence, 70 ; (galai tic), 
 'e-existent, 174 ; globular, 180 \ 
 erschel on, 75, 184, 186 ; in 
 relation to stars, 76 ; in the 
 Milky Way, 182 ; impacts be- 
 tween, 182, 186 ; kinds of, 767 ; 
 Lord Rosse on, 188 ; Messier's 
 64th, 76 : meteoric theory of, 
 189: multiple, 181; Nova Auri- 
 ga;, 59; of solar system, 131 ; 
 physical connection, 184; photo- 
 graphs of, 188 ; (polar) Proctor 
 on, 176 ; pressure after collision, 
 191 ; prevent recurrent impact, 
 72 ; produced by impact, 30 ; 
 retardation by, 78; rings, 181, 
 189; size of, 185; spindle, 181 ; 
 
 S' 
 
Index 
 
 281 
 
 spiral, 181, 187 : structure of, 
 189 ; symmetry of, 180 ; see also 
 PLANETARY NEBUL/E 
 
 NEBULAR HYPOTHESIS, 120; con- 
 futed, 128 
 
 NEBULOSITY of variable stars, 59 
 
 NEON, 83 
 
 NEPTUNE, 119, 131 ; circular orbit 
 of, 131 ; orbit of, and size of 
 planetary nebulae, 93 
 
 NEW BODY formed by Impact see 
 IMPACT, TEMPORARY STARS and 
 THIRD BODY 
 
 NEWCOMEN'S " Astronomy,'' 168 : 
 charts, 172 
 
 NEW ELEMENTS, 83; see also ARGON, 
 CKYPTON, HELIUM, NEON, 
 XENON 
 
 NEW STARS, see TEMPORARY STARS 
 
 NEW ZEALAND Philosophical So- 
 ciety, 70, 276 
 
 NITROGEN in planetary nebulae, 90 
 
 NOVA At, RIG.*:, 36, 232 ; accounted 
 tor by impact, 55 ; disc 
 measured, 37 ; expands into 
 planetary nebula, 59 ; mass 
 of, 105 ; motion of constituents, 
 54', Mr. Anderson di.-covers, 
 37 ; Mr. Taylor on, 37 ; size 
 of, 164 ; spectrum, 37, 54 ; 
 sudden appearance, 59; third 
 body demonstrated, 37, 54 
 
 NOVA VULPECUL^:, 227 ; a variable 
 star near it, 58 
 
 NUBECUL.E, see MAGELLANIC 
 CLOUDS 
 
 OLBERS on origin of planetoids, 144 
 
 ORBITS, circular, 135, 148 ; eccen- 
 tricity of, 71 ; enlargement of, 
 72, 138 ; hyperbolic, 73 ; of 
 comets, 155 ; of double stars, 
 71,78; of earth, 161 ; of moons, 
 I 35 '> of planets, how formed, 
 J 33 > of planetoids, 145 
 
 OKION, 165 
 
 OXYGENATION, 109 , within plane- 
 tary nebulae, 98 
 
 OXYGEN, energy of, 95 ; in cosmic 
 evolution, 89; motion of, 86; 
 weight of, Si 
 
 OZONK, 82 
 
 PAIRS of variable stars, 56, 57 
 PALLAS, 119 ; discovered by Olbers, 
 
 144 
 PARTIAL IMPACT, 28; see also 
 
 IMPACT 
 PEEK (Sir C. E.) on variable star 
 
 irregularities, 63 ; variable star 
 
 notes, 59 
 PEGASUS, 188 
 
 PERTURBATION of Jupiter, 146: of 
 planetoids, 145 ; within comets, 
 150 
 
 PHILOSOPHER'S WOOL, 89 
 
 Philosophical Magazine, 153 
 
 PHILOSOPHY and science, 13 
 
 Photographic Annual, 188 
 
 PICTET, 1 8 
 
 PILGRIM, temporary star, (1572), 32 ; 
 recurrent, 256 
 
 PLANETARY NEBULAE (Chapter vi), 
 91, 245 ; age of, 99 ; and nitrogen, 
 98 ; and Selective Molecular Es- 
 cape, 91 ; clusters and stars 
 within, 92 ; composition of, 98 ; 
 condensation, 98 ; formed by 
 impact, 45, 51 ; hollow shells of 
 gases, 93-4 ; in Nova Auri^ae, 
 37 ; persistent, 97 ; size of, 93, 
 97 ; transitory, 98 ; see also 
 NEBULAE 
 
 PLANETOIDS, acceleration of motion, 
 145 ; critical velocity of, 109 ; 
 discovered by Olbers, 144 ; 
 formed by explosion, 136 ; in- 
 tersection of orbits improbable, 
 147 ; not originally meteoric, 
 144 ; number of, 119 ; orbits of, 
 
 r 45 
 
 PLANETS, atmosphere of, 137; 
 Bode's Law, 119 ; characteristics 
 of, 129; circular oibits of, 135; 
 days, 121 ; density, 135; dis- 
 tances increased by tidal action, 
 124 ; explosion of, 144 ; groups 
 of, 119; inner, dense, 119; 
 moons, 122; motion of, 119; 
 nebulous, 137 ; outer, large, 119 ; 
 orbits of. 133 ; orbits, eccen- 
 tricity of, 71; orbits increased, 
 138 ; result from impact of pre- 
 existent systems, 116, 129; re- 
 volution of, 120, 127 ; rotation, 
 120; seasons, 121; years, 120; 
 see also SOLAR SYSTEM 
 
 POLES of the Milky Way, 180 
 
 PROCTOR, charts of, 172 ; meteoric 
 hypothesis of, 128 ; on double 
 stars, 70; on impact, 70; on 
 Jupiter, 135 ; on polar nebulae, 
 176 ; on probability, 172 ; on 
 star drift > 168 ; on the galaxy, 
 171 ; on the universe, 173 
 
 PROJECTILES, power of, 20, 40 
 
 RADIATION in Crookes' tubes, 16 
 
 RADIOMETER, 202 
 
 RALEIGH (LORD), and monatomic 
 
 gases, 14 
 RAMSAY (Prof. W.), and monatomic 
 
 gases, 14 
 RANKINE, 201 
 
282 
 
 Index 
 
 RECORDS of temporary stars, 32 
 RELIGION of Science, 211 
 RETARDATION due to gas, 113 
 RING NEBULA, see NEBUL.-K 
 ROBERTS (DR. IsAAc),on nebulae. 188 
 41 ROMANCE OF THE EARTH," 139 
 RONGTEN RAYS, 17 
 ROSSE(LORD), sketch of spiral nebu- 
 la, 187 
 
 ROYAL ASTRONOMICAL SOCIETY, 188 
 ROYAL DUBLIN SOCIETY, 107 
 ROTATION, and tidal action, 135 ; 
 double, 63 ; of pl.-tnets, 120 ; of 
 sun, 117 ; of temporary stars, 
 43 ; of variable stars, 51 
 RUSSELL (Mr. H. C.), on Magellanic 
 CLOUDS, 192 
 
 SATELLITES, see MOONS 
 
 SATURN, 119 
 
 SATURN'S RINGS, beauty of, 101 ; an 
 exploded moon, 136. 148 ; mete- 
 oric bodies, 136 ; order in, 143 ; 
 not originally meteoric, 144 ; not 
 pre-nebulous, 136 
 
 SCHMIDT, on the galaxy. 172 
 
 SCIENCE and philosophy, 13 ; special- 
 isation of, 104 ; religion of, 211 
 
 SEASONS, 121 
 
 SELECTIVE MOLECULAR ESCAPE 
 (Chapter v.), 80, 87, 247 ; and 
 compound bodies, 97 ; and 
 planetary nebulae, 91 ; funda- 
 mental thought of, 215 , of hy- 
 drogen, 97 ; Sir R. Ball on, 107 
 
 SOLAR SYSTEM (Chapter vii.), 117, 
 260 ; deduced from impact, 127 ; 
 evolution of, 132 ; expansion of 
 nebula, 134 ; its order and irregu- 
 larity, 13, 128, 136 ; original 
 nebula, 131; origin of (Chapter 
 be.), 127; planets, 129, theories 
 of, 13 ; true members of, 124 ; 
 results from impact, 125 ; see 
 also SUN, PLANETS, PLANE- 
 TOIDS and MOONS 
 
 SOUTHERN CROSS (cluster), 102 
 
 SPACE, dustincss of, 202 ; imperfectly 
 filled, 170 
 
 SPECTRUM ANALYSIS, 52 , atomic 
 motion, 54 ; New Star in The 
 Crown, 33 ; Nova Aurigae, 37 ; 
 of double variable stars, 75 ; of 
 temporary stars, 33, 41, 52 ; of 
 travelling bodies, 54 
 
 SPENCER (Mr. Herbert), 201 
 
 SPHERES, formation of nebulous, 183 
 
 SPINDLE nebulae, see NEBULA 
 
 SPIRAL nebulae at Galactic Poles, 
 182 ; see also NEBULAE 
 
 SPRING tides, 123 
 
 STABILITY of Third Body, 29 
 
 STARS, movement of, 162 ; nearest, 
 162 ; quadruple, 166 ; related to 
 nebulae of regular form, 76 ; 
 size of, 164 ; speed of, 67 ; 
 triple, 166 ; variability and 
 motion, 57; within planetary 
 nebulae, 92 ; see also STELLAR 
 PHENOMENA 
 
 STAR-DRIFT, 168, 175 
 
 STAR CLUSTERS (Chapter vii), 101, 
 249; and variable stars, 112; 
 beauty and colours of, 101, 103 ; 
 cessation of impacts, 113 ; con- 
 densation of, 115; double stars 
 within, 114; evolution of, 103, 
 no; evolution of planets. 116; 
 future of, 115 ; impacts within, 
 103, 112, 116 ; number and size 
 of components, 102, 112; per- 
 turbation within, no; Southern 
 Cross, 102 ; Toucan, 102 ; within 
 planetary nebulae, 92 
 
 STELLAR PHENOMENA, dimensions, 
 164; evolution, 13; movements, 
 162 ; velocities, 207 ; weddings, 
 70 ; see also STARS 
 
 STONEY (Dr. G. Johnstone), 107; 
 on dead suns, 38 
 
 STRUVE, on absorption of light, 156 ; 
 on double variables, 75 ; list of 
 stars, 171 
 
 SUN, composition of, 105 ; corona 
 of, 142 ; critical velocity of, 26 ; 
 cyclonic spots, 117 ; direction of 
 movement, 118 ; double rota- 
 tion, 118; eclipse of, 142; elec- 
 trical phenomena, 125 ; energy 
 of, 118; flashes on, 125; 
 negatively electrified, 153 ; pre- 
 existent conditions, 125 ; result 
 of fused and coalesced bodies, 
 129 ; size of, 117 ; sunspots, 117 ; 
 sunspots and zodiacal light, 142 ; 
 rotation, 117; velocity of, 25, 
 118 ; see also SOLAR SYSTEM 
 
 SUNS, brilliancy of, 72 ; coloured, 
 103 ; impact of gaseous, 42 ; 
 velocity of, 40 ; see also DEAD 
 SUNS 
 
 SWAN, New Star in, 33 
 
 SYNOPTIC STATEMENT, 240 seq 
 
 TAYLOR (Mr. Alfred), and Nova 
 Aurigae, 37 
 
 TEMPERATURE, and critical velocity, 
 36 ; atmospheric, 23 ; equalisa- 
 tion of, 60 ; freezing point, 22 ; 
 high, 24 ; molecular motion, 18 ; 
 molecular velocity, 22 ; of im- 
 pact, 24 ; of Third Body, 29 ; 
 p essure of gases, 85 ; see also 
 HEAT 
 
Index 
 
 TEMPORARY STARS, (Chapter ii.) 31, 
 245 ; at stellar distance, 32 ; 
 ancient and modern, 32 ; bril- 
 liancy and disappearance, 32 ; 
 composed of luminous gas and 
 incandescent solids, 33 ; dissipa- 
 tion of, 45 ; formed by impact, 
 38 ; gasification, 43 ; heat of, 
 34 ; in Cassiopeia (1572), 31 ; 
 in The Crown (1866), 33; in 
 The Swan (1877), 33; Nova 
 Auriga; (1891), 36 ; Nova Vul- 
 peculae (1670), 58 ; phenomena 
 of, 34 ; seen by Kepler, 32 ; 
 spectra, 33, 41, 52 ; sudden ap- 
 pearance of, 31 ; summaries ol 
 observations, 52 ; recurrent, 256 ; 
 rotation, 43 ; theories of, 35 ; 
 within a cluster, 103 
 
 THEKMO- DYNAMICS, 13 ; laws of, 219 
 
 THERMOMETER, 23 ; zero, 22 
 
 THIRD BODY, 69 ; becomes a nebula, 
 30 ; characteristics of, 41 ; dis- 
 sipation of, 30, 94 ; expansion 
 of, 43 ; formation of, 39, 43 ; in 
 Nova Auriga;, 37, 54 ; produced 
 by impact, 29 ; stability of, 29 ; 
 temperature of, 29 ; retarding 
 effects of, 45 ; rotates, 51 ; when 
 very small, 106 ; see also IM- 
 PACT and TEMPORARY STARS 
 
 THOMPSON (Pror. J. J.) on particles 
 smaller than atoms, 83 
 
 TIDAL ACTION, 38 ; and heat, 123 ; 
 and rotation, 135 ; and rotation 
 of moon, 122 ; on planetary 
 distances, 124 ; on variable stars, 
 63 
 
 TIDAL WAVES, 123 
 
 TIDES, spring, 123 
 
 TOUCAN, The (cluster), 102 
 
 TRANSMUTATION, of energy, 105 ; 
 of matter and energy, 109 
 
 TRIGONOMETRY, 160 
 
 TRIPLE STARS, 166 
 
 T TAURI, (Hind's variable), 59 ; 
 nebulosiiy of, 59 
 
 TYCHO BRAHE, 31 
 
 UNIVERSE, THE VISIBLE (Chapter 
 xi.), 159, 259 ; evolution of, 13 ; 
 Proctor on, 173 ; produced by 
 impact, 169 ; see also GALACTIC 
 POLES and MILKY WAY 
 
 URANUS, 119 
 
 URSA. MAJORIS, 92 
 
 VARIABLE STARS (Chapter iv.), 49, 
 252 ; Algol, 38, 50 ; Anthelm's 
 star (Nova Vulpecula;), 58 ; as- 
 sociated with nebulosity, 59 ; 
 atmospheric disturbance on, 62 ; 
 
 closely associated, 56 ; density, 
 61 ; diminish in intensity, 62 ; 
 double, 75 ; double rotation, 63 ; 
 double within a nebula, 51 ; ec- 
 centric, 63 ; ephemerides, 56 ; 
 equalisation of temperature, 60 ; 
 explained by impact, 51 ; factors 
 of variability, 60; formation of, 
 in ; Hind's variable, 59 ; in 
 clusters, in; inegularities ex- 
 plained, 63 ; lakes of fire on, 62 ; 
 long periods and nebulosity, 59 ; 
 loss of variability, 60, 62 ; Mira 
 (The " Wonderful "), 49 ; molten 
 interior, 50; Mr. J. E. Gore's 
 list of, 56 ; near Nova Vulpecu- 
 lae, 58 ; permanency of, 57 ; pro- 
 duced in pairs, 55 ; relative 
 movement of pairs, 57 ; rotation 
 of, 51 ; sides unequally illumin- 
 ated, 50 ; Sir C. E. Peek's notes, 
 
 50 ; Sir C. E. Peek's observations 
 of irregularities, 63; three sources 
 of light, 63 ; T Taui i, 59 ; see 
 also DOUBLE STARS 
 
 VELOCITY, 22 ; and chemical com- 
 position, 42 ; and energy, 40 ; 
 and gravitation, 71 ; and retar- 
 dation, 45 ; at impact, 24 ; 
 critical, 25; fixed for different 
 molecules and temperatures, 22 ; 
 independent of composition, 21 ; 
 loss after impact, 71 ; of cosmic 
 bodies, 35 ; of dust swarms, 125 ; 
 of Earth, 25 ; of impacted bodies, 
 
 51 ; of molecules after impact, 
 87 ; of Nova Aurigae, 37 ; of 
 stars, 907 ; of small suns, 40 ; of 
 Sun, 25 ; on approach of ihree 
 bodies, 78 ; overcomes gravita- 
 tion, 40 ; see also CRITICAL 
 VELOCITY 
 
 VELVETY STAR explained, 99 
 
 VENUS, 119; beauty of, 101 ; transit 
 of, 161 
 
 VERNE (JULES), 44 
 
 VESTA, 119; discovered by Olbers, 
 144 
 
 VIRGO, 188 
 
 VOGEL, 163 
 
 VOLATILITY of elements and com- 
 pounds, 89 
 
 WATER, composition of, 81 : dissi- 
 pation of molecules, 95 
 
 WATERS (Mr. SYDNEY), charts of, 
 172 
 
 WEDIMNGS, stellar, 70 
 
 WEIGHTS, atomic, 14 
 
 WHALE (1'he), 49 
 
 WHIRLING COALESCENCE, see COAL- 
 ESCENCE 
 
284 
 
 Index 
 
 WONDER STAR, no; see also MIRA 
 
 XENON, 83 
 
 X-RAYS, see RONGTEN RAYS 
 
 YEARS, planetary, 120 
 ZERO, see THERMOMETER 
 
 ZINC, oxide, 89 
 
 ZODIACAL LIGHT, 124; a mass of 
 meteors, 125 ; a meteoric swarm, 
 140 ; and solar corona, 142 ; and 
 sun spots, 142; brilliant, 142 ; due 
 to small bodies, 140 ; equatorial 
 position, 141 ; nature of, 140 ; 
 part of original solar nebula, 140 
 
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