E. Wether ed — Structure of Coal. 515 



In conclusion, Dr. Croll's theory seems inadequate ; alteration of 

 currents and winds are the most powerful causes suggested hitherto : 

 further investigations ought to be made as to the nature and extent 

 of the last series of changes in the outlines of the continents of the 

 globe. 



15. — On the Structure of English and American Carboniferous 



Coals. 

 By Edward Wethered, F.G.S., F.C.S. 



THE author had examined several seams of coal from England and. 

 America. He pointed out that they were not always made up 

 of one continuous bed of coal, but often comprised several distinct 

 beds. In the case of the well-known Welsh ' four feet ' seam there 

 were four distinct strata of coals, separated by clay beds of a few 

 inches thick. In the case of the ' Splint Coal ' from Whitehill 

 Colliery, near Edinburgh, the seam presented three clearly defined 

 beds of coal, but these were not separated by partings of any kind. 



"With a view of testing the ' Spoi-e Theory ' of the origin of coal, 

 as propounded by Professor Huxley, the author had obtained a por- 

 tion of the ' better bed ' seam intact for a thickness of 10 inches from 

 the top. He had examined this inch by inch, by preparing thirty- 

 three microscopic sections. At the top was 3| inches of dull lustrous 

 coal, termed ' laminated coal.' This the author found to be practically 

 a mass of macrospores and microspores. Below this there was a 

 change in the character of the seam. Spores became less numerous ; 

 in places they were scarce, the mass being made up of vegetable 

 tissue and a substance to which the author gives the term ' hydro- 

 carbon.' He could not, therefore, support Professor Huxley in 

 saying that the 'better-bed' coal was 'simply the sporangia and 

 spore cases of plants.' The assertion would, however, apply to the 

 first ?>\ inches of the seam. The ' splint coal ' from Whitehill 

 Colliery was a better example of a spore coal than the ' better-bed.' 

 The bottom stratum was 4 inches thick, and presented a dull lustre 

 with thin bright layers traversing at intervals. The dull portion 

 was a mass of spores and spore cases, but these did not enter the 

 bright layers. A vertical section cutting a bright layer, bounded on. 

 either side by dull lustrous coal, showed plenty of spores in the dull 

 coal, but in the bright not one was detected. The second bed in this 

 seam was 1 foot thick ; it was of a brighter lustre than the 4 inches 

 below, but two layers could be distinctly made out, one more lustrous 

 than the other. In the dullest of the two spores were found, which, 

 however, were less numerous than in the bed below, and were, also, 

 of a different variety. In the bright layers the spores were absent. 

 The top bed of the seam was also 1 foot thick, and might be defined 

 as a mass of spores, chiefly microspores, except in the bright layers. 



The American coals examined were collected by the author from the 

 Warrior Coalfields of Alabama, and from near Pittsburgh, Penn- 

 sylvania. The same structural affinities were noticed as in the 

 English coals, and the author therefore came to the conclusion that 

 the English and American Carboniferous coals had a common origin. 



