454 THE POPULAR SCIENCE MONTHLY. 



stars, so swift that the up-rush must sometimes carry matter clear 

 away into outer space. Imagine such a mass consisting in part of 

 fixed gas and in part of condensable vapors ejected from some star. 

 As it travels forward the vapors cool into meteorites, while the fixed 

 gas spreads abroad like a great net, to entangle other meteors. In 

 some cases both might travel together ; in others the gaseous portion 

 would be retarded before it passed beyond the neighborhood of the 

 star, and the denser meteors would get ahead. But even so in the 

 lapse of ages other meteors would be caught, so that in any event a 

 cluster would at length be formed. Now, the reasonable suspicion 

 that this is the real origin of meteors has received striking confirma- 

 tion from the discovery of the late Professor Graham, that meteoric 

 iron contains so much hydrogen occluded within it as indicates that 

 the iron had cooled from a high temperature in a dense atmosphere of 

 hydrogen precisely the conditions under which the vapor of iron 

 would cool down while escaping from a large class of stars, including 

 our sun. 



We have now traced an outline of the marvelous history of these 

 Arabs of the sky. We have met with outbursts upon stars sometimes 

 of sufficient violence to shoot off part of their substance. We have 

 found the gaseous portion sweeping through space like a net, and the 

 vapors that accompanied it condensed into spatters that have consoli- 

 dated into meteorites. We have seen this system traveling through 

 boundless space, with nothing near it except an occasional solitary 

 meteor, and we have seen it in the long lapse of ages slowly augment- 

 ing its cluster of these little strangers. As it wandered on it passed 

 within the far-spreading reach of the sun's attraction, and pei'haps has 

 since been millions of years in descending toward him. Its natural 

 course would have been to have glided round him in a curve, and to 

 have then withdrawn to the same vast abyss from which it had come ; 

 but, in attempting this, it became entangled with one of the planets, 

 which dragged it out of its course and then flung it aside. Immedi- 

 ately, it entered upon the new course assigned to it, which it has been 

 pursuing ever since. After passing the planet the different members 

 of the group found themselves in paths very close to one another, but 

 not absolutely the same. These orbits differed from one another very 

 slightly in all respects, and among others in the time which a body 

 takes to travel round them. Those meteors which got round soonest 

 found themselves, after the first revolution, at the head of the group ; 

 those which moved slowest fell into the rear, and the comet was the 

 last of all. Each succeeding revolution lengthened out the column, 

 and the comet soon separated from the rest. Fifty-two revolutions 

 have now taken place, and the little cloud has crept out into an 

 extended stream, stretching a long way round the orbit, while the 

 comet has fallen the greater part of a revolution behind. We can 

 look forward too, and see that in seventeen centuries more the train 



