David Forbes — On Meteorites. 



231 



per-centage composition of aerolites will be best obtained by a 

 glance at the figures here given, which show the average of the 

 numerical results of all the most trustworthy chemical analyses 

 made up to date, as calculated by Eeichenbach : — 



Silica ... 



Iron ... 



Magnesia 



Alumina 



Sulphur 



Nickel... 



Lime ... 



40-00 

 25-00 

 20-00 

 2-00 

 2-00 

 1-50 

 1-50 



Chromium 



Manganese 



Sodium 



Other elements ... ... ... 



Oxygen, Hydrogen, and loss 



0-50 

 0-33 

 0-33 

 1-34 

 5-50 



100-00 



One of the most extraordinary points in the chemistry of 

 meteorites is the discovery made by the late Professor Graham, 

 that meteoric iron contains, occluded in its substance, a large amount 

 of hydrogen gas, which may be regarded as a sample of the atmo- 

 sphere in which it was formed, and consequently as indicating cos- 

 mical conditions totally different from those which obtain on our 

 sphere. It is also strange that the metal nickel, which is compara- 

 tively rare on earth, and never occurs in the metallic or alloyed 

 state, should be so constant in meteorites of all classes. 



We now come to the most abstruse part of our inquiry, The 

 Origin of Meteorites — a problem which from its nature must, to a 

 great extent at least, depend for its solution on theoretical deductions. 

 Speculations on the origin of falling stars seem to have early engaged 

 the mind of man, and hypotheses, often as strange as they are 

 numerous, were brought forward to account for these phenomena. 

 Thus the old Lithuanian mythology explains falling stars by sup- 

 posing that at the birth of each infant which comes into the world, 

 the Spinstress Werpeja, who spins the thread of its destiny, attaches 

 a star to its extremity, which then hangs up in the heavens and 

 shows its light as long as the being it represents lives, but with the 

 termination of its mortal career, the thread breaks, and the star, 

 falling to the earth, becomes extinguished. 



The ancient Greek philosophers, who, although they paid but little 

 attention to natural, and especially observational science, did not, 

 however, neglect to occupy themselves with speculations on the 

 origin of meteoric phenomena, and advanced several hypotheses to 

 account for falling stars and meteorites, which it must be admitted 

 actually contain the germs of most if not all the more modem 

 theories. One of these hypotheses explained meteorites to be masses 

 of matter previously raised from' the earth's surface by tempests, 

 which had again fallen down ; and Plutarch mentions that Anaxa- 

 goras taught that the ether surrounding the earth is fiery in nature, 

 and by the force of its circumvolution tears away masses of rock 

 from the earth, sets them on fire, and turns them into stars. It is 

 not necessary to make more than mere mention of this hypothesis ; 

 but it may be noticed as a curiosity, that in August, 1858, a 

 supposed meteoric shower fell at Birmingham, throwing down 

 numerous pieces of black stone, rounded on the edges, and about 

 the size of walnuts. The chemical analysis of these, however, showed 

 them to be fragments of the Eowley Hills basalt, which had evidently 



