METEORITES, METEORS, AND SHOOTING-STARS. 741 



active, and that when they were active they were more likely to have 

 been open seas of lava, not well fitted to shoot out such masses, the 

 idea of the lunar origin of the meteorites gradually lost ground. But 

 the unity of meteorites with shooting-stars, if true, increases a hun- 

 dred-fold the difficulty, and would require that the comets have the 

 same origin with the meteorites. No one claims that the comets came 

 from the moon. 



That the meteorites came from the earth's volcanoes is still main- 

 tained by some men of science, particularly by the distinguished astron- 

 omer royal for Ireland. The difficulties of the hypothesis are, how- 

 ever, exceedingly great. In the first place, the meteorites are not like 

 terrestrial rocks. Some minerals in them are like minerals in our rocks. 

 Some irons are like the Greenland terrestrial irons. But no rock in 

 the earth has been yet found that would be mistaken for a meteorite 

 of any one of the two or three hundred known stone-falls. The me- 

 teorites resemble the deep terrestrial rocks in some particulars, it is 

 true, but the two are also thoroughly unlike. The terrestrial volcanoes 

 must also have been wonderfully active to have sent out such a multi- 

 tude of meteorites as will explain the number of stone-falls which we 

 know and which we have good reason to believe have occurred. The 

 volcanoes must also have been wonderfully potent. The meteorites 

 come to us with planetary velocities. In traversing the thin upper air 

 they are burned and broken by the resisting medium. Long before 

 they have gone through the tenth part of the atmosphere, the meteor- 

 ites usually are arrested and fall to the ground. If these bodies are 

 sent out from the earth's volcanoes, they left the upper air with the 

 same velocity with which they now return to it. This the law of gravi- 

 tation demands. What energy must have been given to the meteor- 

 ite before it left the volcano to make it traverse the whole of our at- 

 mosphere and go away from the earth with a planetary velocity ! Is 

 it reasonable to believe that volcanoes were ever so potent, or that the 

 meteorites would have survived such a journey ? 



No one claims that the meteors of the star-showers, nor that their 

 accompanying comets, came from the earth's volcanoes. To ascribe a 

 terrestrial origin to meteorites is, then, to deny the relationship of the 

 shooting-star and the stone-meteor. Every reason for their likeness is 

 an argument against the terrestrial origin of the stones. 



To suppose that meteors came from any planets that have atmos- 

 pheres involves difficulties not unlike to and equally serious with those 

 of a terrestrial origin. The solar origin of meteorites has been serious- 

 ly urged and deserves a serious answer. The first difficulty which this 

 hypothesis meets is that solid bodies should come from the hot sun. 

 Besides this, they must have passed without destruction through an 

 atmosphere of immense thickness, and must have left the sun with an 

 immense velocity. Then there is a geometric difficulty. The meteor- 

 ite shot out from the sun would travel under the law of gravitation 



