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 Readers of my former papers will see that the term " universes " so often occcur- ring in them, has in this volume been replaced by "cosmic systems."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 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 THE END W. Jolly & Sons, Printers, Aberdeen. UNIVERSITY OF CALIFORNIA LIBRARY BERKELEY Return to desk from which borrowed. This book is DUE on the last date stamped below. LIBRARY USE CNLY SEP 2 6 198 CIRCULATION PERT, RECETvfD CIRCULATION D)EPT. LD 21-100m-ll,'49(B7146sl6)476 YB 17009 U.C. BERKELEY LIBRARIES BODllbElMO A 101899