18 METEORITES ON THE EARTH. 



comprehend, though it may not altogether explain, some views con- 

 cerning the nature of the earth's internal heat, its form, and its 

 relations to the solar system. Even if the hypothesis is true, there 

 is great probability that the final condensation of each globe was 

 gradual ; and that after the main fiery mass of our planet was formed, 

 smaller cooled masses fell into it and bombarded the earth, and fur- 

 nished new fuel for combustion and added to the earth's size, just 

 as the falling-in of such masses appears to furnish the fuel which 

 keeps the sun burning. This probability is great because meteorites 

 from time to time still fall to the earth, and in past time may well 

 have fallen in far greater numbers. Sir William Thomson speaks of 

 Temple's Comet of 1 866 as consisting of minute planets, " of which 

 a few thousands or millions fall towards the earth annually about the 

 1 4th of November, when we cross their track." These minute planets 

 called meteorites vary in weight from a few ounces to a few tons. 

 They have been repeatedly seen to fall, and sometimes explode when 

 near the earth. They have been found on the surface or buried a 

 few feet in the earth, in all parts of the World from one pole to the 

 other. 



Inferences from Meteorites. A large number of the specimens 

 in the British Museum are from America ; a few have been found 

 in our own islands, many in various parts of Europe, and no small 

 number in India. Some of the largest are from Australia and 

 Greenland. These masses are either crystalline compounds of 

 native iron with a moderate percentage of nickel, or else consist of 

 such minerals as form volcanic rocks, often with a little metal 

 scattered in them. A few meteorites contain bituminous sub- 

 stances such as upon the earth are only produced under the 

 influence of plant or animal life ; but it is impossible to say how 

 those chemical compounds originated in meteorites. In the Arctic 

 regions minute spherical particles of iron are sometimes brought down 

 from the air in snow, as though the earth occasionally entered clouds 

 of meteoric dust. A like cause must account for the red rain which 

 fell at Blank enburg in 1819, and owed its colour to cobalt chloride; 

 and in some soils, as at Lahisberg in Austria, nickel and cobalt occur 

 at the surface, though there are no neighbouring mineral veins or 

 rocks from which such elements could be derived. Among the 

 substances which compose meteorites are the minerals which are 

 named Labradorite, anorthite, orthoclase, augite, hypersthene, bronzite, 

 enstatite, olivine, Hauyne, graphite, chromite, magnetic pyrites, all of 

 which may be found in volcanic rocks of a more or less basaltic 

 character ; while in addition there are iron, nickel, cobalt, tin, 

 copper, lead, manganese, sulphur, phosphorus, chlorine, nitrogen, 

 oxygen, and hydrogen. 1 We know of no masses of metal on the 

 earth which correspond in composition or mode of occurrence with 

 these meteoric masses, unless some meteoric iron found in Green- 

 land Basalt is to be regarded as originally terrestrial in origin. The 

 meteorites, however, which now fall belong to an altogether different 

 1 Flight, History of Meteorites, "Geological Magazine," 1875. 



