METEORS AND AEROLITES. 291 



minates over the other elementary substances entering into 

 their composition; and this is associated occasionally with 

 crystallised minerals resembling closely some of those found 

 in our own rocks. While the materials, however, are thus 

 alike, they differ much in their arrangement and propor- 

 tions from any compound bodies hitherto known to us; 

 and are of deep interest therefore as representing an aggre- 

 gation, distinct from that of the earth, of the same elements 

 existing beyond its sphere. Almost might we venture 

 to call them specimens of planetary matter, since that 

 which exists in the space intermediate between the earth 

 and other planets may have the same relation to both. 

 And if indulging in such speculation, we may go yet 

 farther, and find argument in these facts for that great 

 theory of modern astronomy, which regards all the planets 

 as formed by the successive condensation of rings of nebulous 

 matter concentric with the Sun; the matter being the 

 same but differently aggregated, from physical causes varying 

 during the condensation of each planet. 



Though no new element has yet been discovered in me- 

 teoric stones, we must not carry this negative beyond present 

 proof. Analyses of other specimens may afford other results ; 

 and we are not yet warranted in omitting any opportunity 

 of further research. Besides the chance of new ingredients, 

 such examination enables us to classify with more certainty 

 these products of other regions of space, and thereby better 

 to interpret the mystery of their origin and movements. 



Another speculation still occurs in connection with aerolites. 

 The researches of the last fifty years have disclosed to us 

 some twenty new substances, hitherto undecomposed, and 

 most of them metallic in kind. Certain of these substances 

 exist only in single specimens ; others are rare in occurrence 

 and small in quantity. It has puzzled naturalists to conceive 

 the purpose which matters thus scanty and insulated can fulfill 



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