454 



KNOWLEDGE. 



December, 1911. 



David Gill that the great nebula of Andromeda (see 

 Frontispiece) is a distant Sidereal system not unlike 

 the Galactic system. This opinion of Sir David Gill is 

 shared b\' other astronomers, who believe that in this 

 beautiful oval patch of light we are looking upon 

 an orderly system of millions of suns. I'roni the 

 brilliant centre it possesses it is probahh' in an 

 earlier stage of e\(ilution than is our own Sidereal 

 Universe. 



The cxfjuisite photographs of the Magellanic 

 Clouds suggest that each of these twt) gigantic 

 systems is an independent double-spiral Sidereal 

 universe, for spread through each of them we 

 have star clusters, double, and wonder stars, just as 

 in the belt of the Milky Way. Their appearance 

 suggests that they are not much more distant than 

 some parts of the Milky Way itself. Hence. the\- 

 may at one time ha\'e been subsidiar\- parts of our 

 great Stellar system. The Pleiades also seem to be 

 somewhat independent in character, both from their 

 position as well as their appearance, as shown in 

 Figure S. There are other minor systems that 

 also suggest independence. Everv star in the 

 entire heavens seems to be mo\ing. The name 

 Proper Motion is given to this indei)endent travel 

 of the stars. It seems to have a mean value of 

 something less than twenty miles a second, but 

 some of the stars rise to speeds of some hundretis 

 of miles a second : " runawa\- stars " these are 

 sometimes called. 



The motion of the stars is not indiscriminate : 

 most of the stars appear to be moving in two stateh' 

 jirocessions in opposite directions. The distances 

 they are apart are so enormous as to suggest that 

 they do not often collide, but impact is undoubtedh' 

 a law of nature, and a surprising number of agencies 

 have already been found that, in spite of the 

 enormous distance of the stars from one another, 

 must tend to produce impact. In addition to these 

 two stately streams a number of minor drifts occur. 

 This, then, is rouglily the character of our Sidereal 

 Universe. It will now be our task to attempt to 

 show the mode of its origin. I sjjeak of it as an 

 attempt, but it is more of the character of an induc- 

 tion that has been demonstrated to be true b\- the 

 fulfilment of endless anticipations based on 

 dynamical deductions. The able mathematician 

 Clifford says : " It has many of its predictions 

 verified by subsequent discoveries in a manner as 

 striking even as the fulfilment of the predictions 

 of Mendelieff, based on the periodic law." 



The Oki(;in of thk Galactic Universk. 



The character of the .Milky ^^■ay. as seen in the 

 Southern Hemisphere, is much more suggestive of 

 the mode of its origin than the portion we can see 

 here in England. .\ centrifugal tendency is most 

 strikingly exhibited. Lateral streamers seem to 

 travel away from the main drift, suggesting the 

 sprays of splashes left by a twirling mop. 



It was in the Southern Hemisphere that, 



probably for this reason, some thirt\-two years ago, 

 a study of a beautifully clear sky suggested that the 

 Milky Wa\- was the result of the whirling coa- 

 lescence of two previously existing independent 

 cosmic SN'stems. A careful stud\' of Proctor's book 

 on " The Universe " aided b}- Sidne\- Walter's 

 exquisitel}' coloured charts of the two hemispheres, 

 quickh- convinced me that the induction was right : 

 and every disco\-er\- made by astronomers since that 

 time has tended to strengthen the conviction, and 

 nothing more strikingly than the concluding remarks 

 of Professor Kapte\'n, before the Dutch Science 

 Congress, on the Cosmic Cycle, which are quoted in 

 the last section of this article. 



The Dynamics of Coalescing Cosmic 

 Systems. 



Let us try and imagine the dynamical conditions 

 that could bring about a configuration and distribu- 

 tion of material similar to the contrasted system 

 that forms the Galactic Universe. 



Later on in this article, the mode of formation of 

 primordial cosmic systems will be described. It is 

 deduced that they must consist chieflN- of the lighter 

 elements, taken by the high kinetol of the atoms out 

 of cosmic systems. Through this ))rimordial matter 

 denser material is somewhat S[)arsel\- distributed. 

 We have already seen there is a continuous tendenc\' 

 during the whole existence of Sidereal s\stems for 

 light elements to be expelled. The many different 

 processes are debated in the article of the Septetnber 

 number of Harper's Mas^azijic. " On the Cycle of 

 the Eternal Hea\ens." The\' are also discussed in 

 some fulness in the " Birth of \\'orlds and S\-stems," 

 Harper's Library of Living Thought. Hence 

 decadent cosmic systems tend tt) consist of com- 

 pact suns, chiefiy of heav\' elements. Many of these 

 bodies are dark stars, commonly known as dead 

 suns. Thus we have two classes of cosmic s}-stems, 

 the incipient ones, consisting chiefiy of light gas. 

 and the decadent, consisting largel)' of compact 

 masses of heavy elements. 



Imagine two such systems to have come within the 

 sphere of one another's attractions. Lateral attrac- 

 tions would prevent the encounter being quite centre 

 to centre. Thus it is a case of whirling coalescence. 

 As the two svstems close in, the one upon the other, 

 an immense friction ensues. The mutual attraction 

 of the advancing suns, aided by this resistance, 

 would cause collisions: a vast central furnace would 

 thus grow up. The field of collision must for ages 

 have gone on increasing both in density and- dimen- 

 sions. The furnace is walled around by the advanc- 

 ing material in all directions in the plane of impact. 

 Presently, as temperature and density increase, the 

 pressure becomes enormous. This explosive matter 

 can find no relief in the plane of impact, for, as 

 alread\- shown, the material of the two \ast sj'stems 

 is crowding in all around it and walling it in. But 

 axially there is a chance of escape. The material is 

 ejected towards both poles, and this action goes on 



