which fell in the County of Limerick. 357 



their surface, the fractured parts excepted, although internallv 

 they exhibit no such appearance. 



In whatever part of the world those stones are found, they 

 exhibit very nearly the same appearance as to colour, texture, 

 fracture, &c. and on analysis give the same ingredients, some- 

 times varyin'4; verv iittle in their proportions. 



Tlie stone wliich fell a few years ago in the county of Tip- 

 perary, and whifh weighed seven pounds and a half, was found 

 by my analysis to consist of the same substances with many 

 which had fallen on different parts of the globe, according to 

 the analyses of Mr. Howard. 



The following are the constituents of those stones, viz. 

 Silex in large quantities. 

 Magnesia. 



Iron in its metallic state. 

 Nickel in small proportions. 

 Sulphur and oxide of iron. 



As no other mineral substance hitherto discovered on our 

 globe consists of the above ingredients, we must consider them as 

 foreigners. Some philosophers suppose that thev are projected 

 from the volcanoes of the moon — that they are projected from 

 the earth by means of volcanoes — that they are produced in the 

 atmosphere by the gradual accumulation of minute and invisible 

 atoms, &c. But as these speculations are inconsistent with sound 

 I)hilosophy, or even with plausible hypotheses, I shall drop the 

 subject here. 



It is supposed by Cladini that they never belonged to anv 

 planet, and that they were opaque wandering masses, before they 

 reached the confines of our atmosphere. This, certainly, is the 

 most rational mode of accounting for their presence in the situa- 

 tion in which we first behold them in the atmosphere. 



However, to account for their becoming luminous or red hot, 

 when they descend into the upper regions of our atmosphere, 

 regions of eternal frost, has been a desideratum with me, and en- 

 gaged much of my attention some time past. 



These masses, like all other ponderable materials, contain 

 specific heat round their atoms and particles ; in moving through 

 the atmosphere they collect electricity ; and tiiis continues in- 

 creasing, as there is no other solid matter in those upper regions 

 to prevent its accumulation*. When they acquire a sufficient 

 quantity of electric matter, the entire or a portion of their specific 

 heat is liberated, and much of it is thrown on their surface; this 



• TIiP upper part of the atnios))lierc which extends beyond the reach of 

 clouds, contains a considerable quantity of free electricity, as the phaino- 

 ncnon of the aurora boreuU* suOicit'ntly rvlnees. 



Z 3 jjlves 



