. THE SMITHSONIAN INSTITUTION. 171 



ofi'from a different sphere which becomes entangled in the atmo- 

 sphere? If so, how great the wonder that the earth has never inter- 

 cepted 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 

 eaid 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 ap- 

 pear equally true, if we consider the known meteorites as represent- 

 ing 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 tliat 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, throup;h which it must have made repeated cross- 

 ings of over 1,000 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 pro- 

 ject fragments and pass on. Now, of the few instances of the sup- 

 posed large bodies, I will only analyze the value of the data upon 

 which the Wilton and Weston meteorites were calculated ; and they 

 are selected, because the details connected with them are more acces- 

 sible. The calculations 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 observations as to size of luminous bodies 

 passing rapidly through the atmosphere. Experiments, that would 

 be considered superfluous, have been instituted to prove the perfect 

 fallacy of making any but a most erroneous estimate of the size of 

 luminous bodies, by their apparent size, even when their distance from 

 the observer and the true size of the object are known ; how much more 

 fallacious^ then, any estimate of size made, where the observer does 

 not know the true size of the body, and not even his distance very 

 accurately. 



In my experiments, three solid bodies in a state of vigorous^ in- 

 candescence were used : 1st, charcoal points transmitting electricity ; 

 2d, lime heated by the oxy-hydrogen blowpipe ; 3d, steel in a state 

 of incandescence in a stream of oxygen gas. They were observed on 

 a clear night at different distances, and the body of light (without 

 the bordering rays) compared with the disk of the moon, then nearly 

 full, and 45° above the horizon. Without going into details of the 

 experiment the results will be tabulated. 



