ORIGIN OF METEORITES — BERWERTH. 313 



ness follows and the solid masses forming the kernel of the fireballs 

 fall to earth in separate fragments, or as a shower of stones. 



These solid masses, consisting of stone or iron, which reach our 

 planet from space, and are transformed into balls of fire only in our 

 atmosphere, we call meteorites. Such Weltspahne (world frag- 

 ments) , as Chladni once called them, have been given different names 

 at different times according to the conception which people had of 

 their origin or their character, as baetylus or beseelte stones, sky 

 stones, thunderstones (ceraunites, brontoliths) , thunderbolts, air 

 stones, moonstones (uranoliths), and at present they are often called 

 aeroliths, a name first used by Blumenbach in 1804. 



Concerning the origin of these stone and iron masses opinions have 

 greatly varied from time to time. 



When Chladni's epoch-making work (The Pallas Iron, 1794) over- 

 came the doubt as to the falling of stone and iron masses from the 

 air, people began to seek explanations for the mysterious and still 

 incomprehensible phenomena of the Feuerkugeln and to advance 

 opinions as to their origin. 



Passing over the beautiful, mythical conceptions of the oriental 

 peoples, which have been already referred to, and the assumption in 

 the middle ages that they might be due to lightning, one can generally 

 divide into two gi'oups those holding opinions as to the origin of 

 meteorites — that is, into supporters of the hypothesis that they came 

 from space and did not belong originally to the earth and its atmos- 

 phere, and the supporters of the hypothesis that they did originally 

 belong to our planet. Each of these two main groups falls again 

 into subgroups, first the supported of the hypothesis that the meteo- 

 rites come from unlimited space and the supporters of the hypothesis 

 that they are ejected from lunar volcanoes. The second large group 

 upholding the terrestrial origin of meteorites is divided into two 

 sections, those who think that they originated from the constituents 

 of the atmosphere and those who consider them ejected from terres- 

 trial volcanoes. 



A suggestion of Proust that meteorites may come from the poles 

 of our eai'th because there the iron can not have oxidized, on account 

 of the eternal cold, may here be mentioned only as a curiosity. 



Chladni named the supporters of the four special hypotheses cos- 

 mists, lunarists, atmospherists, and tellurists. To the cosmists 

 Chladni himself belonged first of all. He considered it possible that 

 the meteorites might be original or chaotic material (" Urmaterie") — 

 that is, aggregates of matter which existed in space and which had 

 never belonged to a larger world body, but which might furnish the 

 material from which such world bodies might be formed. Many of 

 the nebula may be nothing else than such shining material spread 

 through enormous spaces. Originating from these world clouds 



