290 METEORS AND AEROLITES. 



In theory this cannot happen without some certain amount 

 of positive effect. In reality, we must consider the augmenta- 

 tion so small that it may be disregarded as a cause of any 

 change in the motions or condition of our planet. M. 

 Haidinger and Baron Reichenbach of Vienna have made 

 some curious calculations on the subject; but they are want- 

 ing in those numerical facts which alone can give value to an 

 estimate of this kind.* 



We may notice here a curious remark of Olbers, that no 

 meteoric stones have ever been found embedded in strata of 

 the secondary or tertiary formations ; and we have no direct 

 proof, therefore, that any fell previously to the last great 

 change of the earth's surface. This negative fact, however, 

 cannot yet be admitted into argument. The careful exami- 

 nation of such rocks is still of recent date, and fossils of other 

 kind have alone been sought for. Moreover, many meteoric 

 stones are ^ so easily disintegrated, by the iron they contain 

 passing into the state of hydrated oxide, that they may have 

 become wholly incorporated with the earthy masses sur- 

 rounding them. The chances, therefore, are exceedingly 

 great against their detection in these rocks : but time may 

 yet show, what must meanwhile be deemed most probable, 

 that the phenomenon of their fall existed long before man 

 had his place allotted him on this our globe. 



We have in some part already adverted to the remarkable 

 inferences and suggestions derived from the composition of 

 meteoric stones. These bodies afford us glimpses into the 

 history of matter foreign to the earth on which we ourselves 

 live. They represent another domain of nature; yet con- 

 nected with our own by the signal fact, also derived from 

 them, that the matter is the same in kind as that which 

 surrounds us here. Iron, as we have seen, largely predo- 



* M. Haidinger calculates, on various grounds, that the weight of the 

 aerolites which every year fall upon the earth may be about 450,000 Ibs, 



