SCIENCE OF COMMON THINGS. 95 



Aerolites. Appearance. Composition. 



matter which are sometimes seen to fall from the 

 atmosphere. 



It is derived from the Greek words, acp (atmosphere), and Xi0<>? (a stone). 

 A meteor is distinguished from an aerolite by the fact that it bursts in 

 the atmosphere, but leaves no residuum except a vapor-like smoke ; 

 while the aerolite, which is supposed to be a fragment of a meteor, comes 

 to the ground. 



613 What is the weight of those aerolites which have been known to fall 

 from the atmosphere ? 



Their weights vary from a few ounces to several hun- 

 dred pounds, or even tons. 



614 At what height in the atmosphere are meteors supposed to 



appear f 



Their height above the earth has been estimated to 

 vary from eighteen to eighty miles. 



615 With what velocity do they move ? 



The velocity of these bodies is somewhat more than 

 three hundred miles per minute, though one meteor of 

 immense size, w r hich is supposed to have passed within 

 twenty-five miles of the earth, moved at the rate of 

 twelve hundred miles per minute. 



616 What is the value of such estimates ? 



Owing to the short time the meteor is visible and its 

 great velocity, accurate observations cannot be made 

 upon it ; and all estimates respecting their distance, 

 size, etc., must be considered as only approximations 

 to the truth. 



617 What is the general appearance of aerolites f 



Most of them are covered with a Hack shining crust, 

 as if the body had been coated with pitch. When 

 broken their color is ash-grey, inclining to black. 



Very many of the meteorites which have fallen at different times and 

 m different parts of the globe, resemble eacli other so closely, that they 

 would seem to have been broken from the same piece or mass of matter. 



618 What is their composition ? 



Great numbers of aerolites have been analysed, and 

 found to contain nineteen or twenty different elementary 

 substances. But for the most part they consist of malle- 

 able iron and niokel. 



