1885-6.] on the Story of a Meteorite. 333 



The velocity of a sufficient number of these falling stars, for 

 instance, has been ascertained within due limits by Brandes and 

 others ; and M. Joule has shown conclusively, that in regard of the 

 greater number of these bodies — the heat, equivalent to the mechanical 

 effect due to their original vis viva, and destroyed by the resistance 

 of the atmosphere — is such as would melt the body and dissipate it 

 into fragments. 



In case of smaller velocities, nothing beyond inflammation or 

 white heat might ensue ; but far oftener than we imagine, these 

 falling stars are utterly dissijjated by the agency now spoken of, and 

 reach the earth in the form of mere meteoric dust. 



This special difficulty removed from Chladni's cosmical theory, 

 other problems remained. First, Have these stones, or meteoric 

 planets, a special or assignable origin ? 



The lunar hypothesis of Laplace has frequently found favour. 

 But it ought not to be judged by the form in which it was proj)osed 

 by its founder. 



The idea that these meteors are directly shot towards us by 

 lunar volcanoes in present action, is consistent neither with existing 

 observation of the condition of the moon, nor with the dynamical 

 essentialia of the problem. 



But it does not follow that those vast lunar craters — such as 

 Tycho — the result evidently of enormous cataclysms, have not con- 

 tributed their part in driving among the interplanetary spaces, masses 

 of broken rock, that may on occasion come within the range of the 

 sjDecial attraction of our globe. But secondly, is it necessary to 

 search for any confined or special origin ? Is it not manifest, on 

 the contrary, that masses of such bodies are most widely diffused, and 

 may form an essential part — not of our solar system merely — but of 

 the material universe, in so far as man can discern it ? " 



Joule's Explanation of the Heating of Meteorites. 



" Behold, then, the wonderful arrangements of Creation. The 

 earth, in its rapid motion round the sun, possesses a degree of living 

 force so vast that, if turned into the equivalent of heat, its temperature 

 would be rendered at least 1000 times greater than that of red-hot 

 iron, and the globe on which we tread would in all probability be 

 rendered equal in brightness to the sun itself. 



And it cannot be doubted that if the course of the earth were 

 changed, so that it might fall into the sun, that body, so far from 

 being cooled down by the contact of a comparatively cold body, 

 would actually blaze more brightly than before, in consequence of 

 the living force with which the earth struck the sun being converted 

 into its equivalent of heat. Here we see that our existence depends 

 upon the maintenance of the living force of the earth. 



On the other hand, our safety equally depends in some instances 

 upon the conversion of living force into heat. 



