I9I3-] STEVENSON— FORMATION OF COAL BEDS. 89 



condition in the "bottoms" of large and small streams alike. The 

 fragments in the nnderclay, mentioned b}^ Barrois, Ashley and 

 Gresley, were not deposited with the clay but before it ; their dis- 

 tribution is wholly similar to what is seen now. The mode of 

 transference to the coal, as described by Barrois, is in accord with 

 what one may see in actual bogs ; once transferred by plants rooted 

 in the underclay, they would be removed successively into higher 

 portions by plants rooted in the bog — for there is every reason to 

 believe that the Coal Pleasures plants had as much liking for peat 

 soil as is shown by many towering plants of the present day. 



At the same time, the writer recognizes that the suggested ex- 

 planation is not altogether satisfactory at some localities, where the 

 required conditions cannot be proved. 



Microscopic Features of Coal. 



The unaided eye can discern many features of coal in the bed ; it 

 can group types into glance, matt, cannel, fusain; at times, it can 

 find relations between a certain type of coal and the plants which 

 produced it, so gaining insight into possibly contrasted origin of 

 glance and matt coals ; it can recognize great difference of physical 

 features in the several benches of a coal bed, which lead to convic- 

 tion that each bench may have had its own peculiar history, may 

 have been formed under its own peculiar conditions, very different 

 from those of the other benches. But one quickly discovers that 

 intimate structure of coal can be ascertained only by aid of the 

 microscope, since to the unaided eye, the great mass of coal is wholly 

 structureless. 



Nicol and Witham appear to be the first to apply this method of 

 investigation, which Witham utilized especially in studying the 

 structure of fossil plants. Hutton was the first who made a study 

 of the coal itself. In a slice of coal, prepared by Witham, Hutton^^ 

 observed some remarkable cells within the portions which showed no 

 vegetable structure. He made sections of the coals mined at New- 



^" W. Hutton, " Observations on Coal," Proc. Geo!. Soc. London, Vol. I., 

 1834, pp. 415-417; also in Land, and Edinb. Phil. Mag., Vol. II., 1833, pp. 

 302-304. 



