Apiul, 1841.] 9 



donations to library. 

 Journal of the Asiatic Society, (Nos. 16, 17, 18,) for 1840. 



From Dr. Morton. 

 First Memoir on Porcelain Earths, by Alexander Brongniart. 



From Dr. Morton. 

 View of the soil and climate of the United States, by C. F. 



Volney. Svo. Philadelphia, 1S04. From Dr. Morton. 

 Bulletin of the National Institution. Washington, 1840. 



From the Institution. 

 Annual Report of the Geology of Maryland, for 1840, by J. 



F. Ducatel. from the Author. 

 Geological Survey of Michigan, for 1S39 and 1840, by Dr. 



D. Houghton. From the Author. 

 First and Second Annual Reports of the Geological Survey 

 of Ohio, for 183S, by W. W. Mather. From the Author. 



Professor Johnson offered some observations on the me- 

 chanical structure of Coal, with evidences of the contempo- 

 raneous origin of its various kinds. 



The question of the identity and contemporaneousness of the 

 two great divisions of the coal measures of Pennsylvania, has 

 sometimes occupied the attention of geologists. A similar question 

 is occasionally agitated in Europe, in reference to the Anthracite 

 and Bituminous coal fields of that quarter of the world. 



Among the arguments in favour of the contemporaneous deposi- 

 tion of the coal in the two regions, those which are derived from 

 the similarity of the accompanying measures or members of the 

 coal series in the two regions, and the resemblance or identity of 

 the fossil organic remains accompanying the coal in both cases, are 

 not the least weighty. The presence of large bodies of carbonate 

 of iron interposed among the coal beds in both coal districts, is an 

 analogous circumstance strongly corroborative of the opinion that 

 both varieties of coal were produced under circumstances at least 

 strongly resembling each other. 



Another circumstance favourable to the supposed similarity of 

 circumstances which accompanied the deposition of anthracite and 

 bituminous coal, is the resemblance in mechanical structure of the 

 two kinds. This may, at the first enunciation, seem somewhat 



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