Von Hoff on the Origin of Meteoric Stones. 



be caused by friction in the air, or by the compression of the 

 air, the greatest degree of heat must be attained in the lowest 

 part of the atmosphere ; and from the high degree of tempera- 

 ture which we may assume is proper to the falling bodies at the 

 greatest height where the fiery phenomenon is visible, this degree 

 of heat ought to be so increased at the time the stone reaches 

 the earth, that the mass should no longer retain its solid form. 

 It is true that traces are said to have been found of partial melt- 

 ing or softening in fallen meteoric masses, such as impressions 

 of stones, attached or imbedded stones, &c.* but such cases seem 

 to be of extremely rare occurrence, and the traces themselves 

 very indistinct. On the other hand, most of the meteor- 

 olites, even the masses of iron, as, for example, that of Agram, 

 and that of Ellbogen, known by the appellation of the " Ver- 

 wunschter Burggraf" have arrived at the earth's surface as 

 massive and thick lumps, or have penetrated the earth like solid 

 balls from cannons.* They must therefore have acquired their 

 solid form, and become hard, at considerable heights above the 

 earth. If they had reached the earth in a melted condition, 

 they would have formed a broad, thin mass, like tin or flattened 

 lead. 



Thirdly, Meteoric masses (with the exception of masses of 

 native iron) have the characters of crystalline primitive rocks. 

 If we assume that these are fragments of such rocks belonging 

 to the moon, we must suppose that, during their passage, they 

 have undergone no change in their interior, at least no change 

 caused by fusion. The product of such an operation would 

 not be a granular mixture of several mineralogically simple and 

 crystalline substances. But the extremely thin shaggy crust 

 which generally surrounds meteoric stones, shews that probably 

 two distinct operations have taken place, of which one has not 

 affected the interior, but only the exterior. The masses of na- 

 tive iron, in particular, have that remarkable crystalline internal 

 structure (the Wittmannstadt figures)^ which is not produced 

 by fusion, but points to the original formation of the mass. 



From all these circumstances, it seems to me to follow, that 

 the operation of the medium through which meteoric stones 



" Chladni's " Feuermeteore," p. 41. 

 f Schreiber's " Beitrage," p. ^. 



