306 MEMOIR ON METEORITES. 



portions detached by the mechanical and chemical action to 

 which they are subjected? To this I will assent as soon as the 

 existence of that body or those bodies is proved. Are we to 

 suppose that each meteorite falling to the earth is thrown off 

 from a different sphere which becomes entangled in the atmos- 

 phere? If so, how great the wonder that the earth has never 

 intercepted one of those spheres, and that all should have struck 

 the stratum of air surrounding our globe (some fifty miles in 

 height), and escaped the body of the globe, 8,000 miles in 

 diameter. It is said that the earth has never intercepted one 

 of these spheres; for if we collect together all the known 

 meteorites, in and out of cabinets, they would hardly cover 

 the surface of a good-sized room, and no one of them could 

 be looked upon as the maternal mass upon which we might 

 suppose the others to have been grafted. And this would 

 appear equally true if we consider the known meteorites as 

 representing not more than a hundredth part of those which 

 have fallen. 



If it be conceived that the same body has given rise to them, 

 and is still wending its path through space, only seeming by 

 its repeated shocks with our atmosphere to acquire new vigor 

 for a new encounter with that medium, the wonder will be 

 greater that it has not long since encountered the solid part 

 of the globe; but still more strange that its velocity has not 

 been Long since destroyed by the resistance of the atmosphere, 

 through which it must have made repeated crossings of over 

 one thousand miles in extent. 



But it may be said that facts are stronger than arguments, 

 and that bodies of great dimensions (even over one mile in 

 diameter) have been seen traversing the atmosphere, and have 

 also been seen to project fragments and pass on. Now of the 

 few instances of the supposed large bodies I will only analyze 

 the value of the data upon which the Wilton and Weston me- 

 teorites were calculated ; and they are selected because the 

 details connected with them are more accessible. ■ The calcu- 

 lations concerning the latter were made by Dr. Bowditch ; but 

 his able calculations were based on deceptive data; and this is 

 stated without hesitation, knowing the difficulty, admitted by 

 all, of making correct observation as to size of luminous bodies 

 passing rapidly through the atmosphere. Experiments that 



