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sound, has no physical basis, for, so far as one can discover, 

 active volcanoes do not exist : and Prof. R. S. Ball has virtually 

 excluded the ancient volcanoes by pointing out that if a lunar 

 projectile once misses the earth its chance of ever reaching it 

 is too small to be worthy of mention. Nor is it probable 

 that they are portions of a lost satellite of the earth or are 

 due to a collision of two planets, for in each of these cases 

 we should expect to have received some of the larger frag- 

 ments which must at the same time have been produced. It 

 has further been shown that, although the explosive force 

 necessary to carry a projectile so far from one of the smaller 

 planets that it would not return, is not very large, yet the 

 initial velocity requisite to carry the body as far as the 

 earth's orbit is so considerable and the chance of hitting the 

 earth so slight that a more probable hypothesis is, to say the 

 least, desirable. If these bodies have been shot from vol- 

 canoes, Mr. Ball is himself inclined, upon mechanical grounds 

 alone, to believe that the projection took place in bygone 

 ages from the volcanoes of our own planet ; for as such a pro- 

 jectile, having once got away from the earth, would take up 

 a path round the sun which would intersect that of the 

 earth, every one of them would have a chance of some time 

 or other meeting it again at this point of intersection and 

 of appearing as a meteorite. 



The high velocities and the peculiar motions of these bodies 

 are, however, not consistent with any of the theories which 

 would confine them to the solar system. Their origin must, 

 therefore, be assigned to that convenient part of space called 

 interstellar, of which nothing is known : if at any time a real 

 connection can be traced between meteorites and shooting 

 stars, we may begin to hope for a solution of this difficult 

 problem. 



To those who may wish to inquire more closely into the 

 questions suggested by the preceding pages the following 

 are a few of the publications which may be recommended 

 for perusal: — 



Chladni (E. F. F.) — Ueber den Ursprung der von Pallas 

 entdeckten Eisenmasse, und einige damit in Verbindung 

 stehende Naturerscheinungen. Riga und Leipzig, 1794. 



