UNCLE IN ENGLAND. 119 



tinguished, and its stem passing into a stratum 

 of sandstone rock. The lower end was com- 

 pletely bituminated, and it burned with a clear 

 flame ; yet the upper part, though scarcely al- 

 tered in the grain or apparent texture of the 

 wood, was converted into sandstone similar to 

 that by which it was enclosed. Round the stem 

 there was a space of about an inch in thickness 

 filled with coal, which renders it probable that 

 the same process that converted the roots into 

 coal acted upwards on the bark. The rock con- 

 tains innumerable remains of plants ; some of 

 which are so perfect that their species have been 

 made out, and no pencil could trace their deli- 

 cate ramifications with greater nicety. 



"In short," continued my uncle, " it appears 

 more than probable that every species of coal 

 has proceeded from vegetable matter of different 

 kinds, but under different circumstances ; and 

 that its chemical change was effected under the 

 pressure of deep water. In one stage of that 

 process it must have been in a soft pulpy state, 

 like the lowest part of a deep peat-bog ; for this 

 is the only way that I can account for the im- 

 pression of leaves, canes, seed-vessels, and shells, 

 which are so commonly found on the external 

 surface of coal." 



My uncle shewed us a beautiful specimen of 

 a fern leaf, where the impression was as perfect 

 as if it had been made with wax. >" ' 



