NOT OF TERRESTRIAL ORIGIN. 



substances capable of discharging or sublimating the matter of 

 meteoric stones. 



To these objections we may add others. Although it may be 

 admitted, as Arago argues, that the constituent principles of 

 aerolites should really exist in the atmosphere, and that they 

 only escape analysis because of their extreme minuteness, it 

 would still be necessary to explain with such feeble and 

 such dispersed elements a sudden precipitation, yielding stones 

 of several hundred weight, such as those preserved at Ensen- 

 heim, in Alsace, or 3000 or 4000 stones of various dimensions, 

 like those which were separated and shot off by the 1'Aigle 

 meteor, which we shall presently notice. It would be necessary 

 to assign the cause that combines the scattered molecules, 

 and forms them into a single mass. It is not affinity, for 

 the elements composing aerolites are not generally in a state 

 of combination, but simply agglomerated and held together 

 in juxta-position. And yet, if they are not subjected to any 

 mutually attractive force, these little globules ought to fall 

 separately as they are formed. It is in vain to object that they 

 might be suspended, for a greater or less time, by a cause analogous 

 to that which, according to the ingenious hypothesis of Volta, 

 balances the particles of hail between two clouds, so as to give 

 them time to enlarge by the addition of new layers of ice. The 

 fact still remains, that these latter have never been seen to 

 amount to several hundred weight, though the elements that 

 form hail are much more abundant in the air than those of 

 which aerolites are supposed to be formed. Besides, in Yolta's 

 theory, the suspension of hail in the atmosphere is attributed to 

 the reciprocal action of electric clouds, a cause which cannot be 

 in like manner adapted to the formation of aerolites, since 

 the meteors that carry them sometimes burst in the clearest 

 weather. 



But even granting all this, and admitting the formation of 

 aerolites in the atmosphere by some unknown agency, how shall 

 we account for the circumstances attending their collision with 

 the surface of the earth ? According to this theory, they would 

 move to the surface of the earth by the operation of terrestrial 

 gravity alone, and would meet the earth with a velocity due to 

 the height from which they fell. Now the actual velocities with 

 which they are known to strike the earth could never be 

 acquired under the mere agency of terrestrial gravity, through 

 any height within the ordinary limits of the air. 



But if the velocity of the meteorites be incompatible with this 

 theory, their direction is still more so. Their obliquity could 

 never be produced by any conceivable atmospheric current. 



139 



