METEORIC STONES AND SHOOTING STARS. 



The second circumstance worthy of attention is, that these 

 bodies rarely strike the surface of the earth in a direction 

 either vertical or nearly so. They generally come in a direction 

 very oblique to the plane of the horizon. It may be asked, how 

 the direction in which they strike the earth can be ascertained 

 unless they are seen, which rarely happens, at the moment of 

 their fall. Their direction is rendered manifest by the manner 

 in which they penetrate the surface of the ground which they 

 always do, and to a depth more or less considerable. 



The velocity of their motion when they encounter the earth 

 is another circumstance of much importance. This velocity is 

 discoverable by observation on their movement while visible, as 

 well as by inferring the force with which they struck the ground 

 from the depth to which they penetrate it. 



It is accordingly found by means of such observations that 

 their velocities belong to the kind of motions which characterise 

 the bodies of the solar system, and such as are never witnessed 

 in the motions of terrestrial bodies. They are velocities which 

 could not be imagined to be imparted by the earth's gravitation 

 to any masses attracted from points within the limits of the 

 atmosphere. 



4. On examining the physical condition, and analysing the 

 constituents of the masses thus precipitated, several circum- 

 stances worthy of notice are presented. In whatever way 

 they fall, whether from fire-balls visible at night, from a cloud 

 in the day, or from a clear and serene sky, they exhibit a 

 general and striking resemblance in their form, their external 

 crust, and their constituents. When recently fallen, they have 

 always a temperature more or less elevated. They exhibit a 

 shining black and apparently burnt surface, and their con- 

 stituents are generally iron, nickel, cobalt, manganese, chromium, 

 copper, arsenic, tin, potash, soda, sulphur, phosphorus, and 

 carbon, being in all about a third of the elementary substances 

 to which terrestrial bodies have been reduced by chemical 

 analysis. These constituents are found with some exceptions to 

 be the same at whatever epochs and at whatever parts of the 

 earth these bodies may have fallen. 



It is important to observe here, that the iron and nickel are 

 almost always in the metallic form a state in which they are 

 never known to exist naturally on the surface of the earth. These 

 metals, when found in the earth, are invariably combined with 

 oxygen, and it is their oxydes only which have a place among 

 natural terrestrial substances. The iron and nickel used in the 

 arts are obtained by the decomposition of the ores in the 

 processes of metallurgy. 

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