120 EVOLUTION 



have undergone remarkable changes. In the Middle 

 Ages they were dreaded as sources of every kind of 

 pestilence and tragedy. Nineteenth-century astronomy 

 calmed the fear it broke out in Russia and Mexico less 

 than fifty years ago and led to something like a 

 contempt for even the long-tailed comets. The tail 

 might be 100 million miles long, and was often over 

 fifty, it explained, but it was thinner than the thinnest 

 breath of air. Some said even that the whole material 

 of a hundred-million-mile comet might, if properly com- 

 pressed, be packed in a railway truck. One may still say 

 that of the tail of a comet, but its head consists of a swarm 

 of meteorites, sometimes several thousand miles in width, 

 the colliding elements of which are raised to white heat, 

 and give off the vapour which is shot out in a tail by the 

 action of the sun. Through this tail the earth may pass 

 and has passed with complete indifference. And 

 even if we ran into the " head," or the close swarm of 

 large meteorites, the earth's great torpedo-net (its 

 atmosphere) could be trusted to protect it. We should 

 be treated to a brilliant display of shooting-stars, and 

 most probably suffer no damage. 



Flammarion, in a little work called La Jin du monde, 

 has indulged his vivacious imagination on the subject, 

 and conceived the earth as running through a comet-tail 

 consisting of gases that poison the atmosphere and 

 nearly destroy the human race. Mr. Wells has turned 

 the idea round, and made the comet's tail act in such a 

 way on the atmosphere as to convert the whole human 

 race, physically, into angels and Socialists within the 

 space of a few hours. These are merely playful 

 manipulations of the very remote astronomical possibility 

 of a comet coming along that would interfere with the 

 oxygen in our atmosphere. The whole question is well 

 discussed in a little work (Weltuntergang) by the able 

 German astronomer, Meyer. 



