BiCKERTON. — On the Genesis of Worlds and Systems. 195 



collision a second time, and, even as an extreme possibility, more than 

 twice ; and it does not appear unlikely that this is really the case with 

 Tycho Brahe's temporary star. There is one thing that makes it likely. 

 All the text-books speak of it as a possible variable with a period of 313 

 years. Now, it appeared absolutely certain that if such a thing as consecu- 

 tive collision did happen, it would be longer between the first pair of impacts 

 than between the second pair of impacts ; and, on taking the dates given by 

 Herschel, it was found that the first interval was 319 and the second 308 

 years, thus adding another to the very remarkable series of coincidences 

 Avhich have been found in working out this hypothesis. 



But people are never satisfied without trying to ride a hobby to death ; 

 and really it does seem going rather to extremes to suggest, as has been 

 done, that nearly all we see in the heavens — all the millions of suns, aU the 

 nebulae — are parts of one great system produced by the impact of two 

 stupendous bodies meeting in fi'ee space — a system so extensive, that it 

 would probably take light at least a hundred years to pass through the 

 mass ; while of the bodies themselves, some are so big that the number of 

 times our sun would be required to measure their volume must be reckoned 

 by thousands. Thus has the hobby been goaded on, and it is not absolutely 

 certain that it has thrown its riders yet. It is true Proctor has been for 

 years carefully laying down a veritable railroad for just such a hobby ; when 

 he was working out his great research on the visible universe, so that it was 

 easy work for it, it ran like a snowball down a hill, gathering speed and 

 proportion as it went. But I must tell you how Proctor did this work. He 

 collected statistics of the number of stars and nebulfe, of star-clusters and 

 star-motion. He and his friends placed all these on charts, and when they 

 were finished, a single undoubted system was seen, which he describes 

 roughly as a ring or spiral of stars, with our solar system at or about the 

 centre, and with two caps of nebula covering the poles of this ruig. So 

 when the picture of the visible universe, given by Proctor, came to be 

 examined, it was found to be so like that which had been suggested as 

 likely to result from "partial impact," that it was felt the visible universe 

 itself must be one of its numerous offspring. 



But what does such an idea of the origin of the universe suggest to our 

 mind of the contents of space generally ? Clearly, that if two such bodies, 

 why not many, some almost infinitely large compared to them ? Why not 

 go with Kant, and think that as the earth and its moon are part of the Solar 

 System, as this system is part of the galaxy, why not the galaxy a part of a 

 still more imposing system ? Anyhow, the idea of space, suggested by this 

 theory, is that it contains an infinite number of masses, varying in size 

 from the particle of hydrogen to the stupendous mass which physicists look 

 forward to as the final condition of the visible universe, 



