THE MEXICAN METEORITES. 
51 
It is comparatively easy to detect a mass of meteoric iron 
on the surface of the earth on account of its weight and 
appearance, but it is extremely difficult for any one to recog¬ 
nize a stony meteorite except after careful examination. 
For these reasons nearly all the discovered meteorites are 
composed principally of nickeliferous iron. 
It is of some interest, therefore, to ascertain from the availa¬ 
ble data the probable quantitative relations of the two classes 
of meteorites. 
Masses of meteoric iron have fallen on this continent on 
four different occasions. The aggregate weight of these irons 
is 96.7 kilograms. Other falls have been reported, but those 
phenomena are not well attested. The total weight of stony 
meteorites whose fall has been observed on this continent is 
1,192.3 kilograms. From this data it appears that the ratio 
of the weight of iron to stony meteorites is as 1 to 12.33. 
The aggregate weight of meteoric iron observed and dis¬ 
covered to date on this continent is 138,590 kilograms or about 
153 tons. 
If the above ratio of iron to stony meteorites obtains in all 
these cases there should have been, to correspond to this 
mass of iron, a fall of about 1,880 tons of stony meteorites, or 
in all, of both classes, over 2,000 tons of meteoric matter 
precipitated upon the earth. 
