iv.] THE COAL IN THE FIRE. 93 



common or bituminous coal; and then gradations 

 between common coal and culm, or anthracite, such as 

 is found in South Wales. Have you not a right to say, 

 " These are all but varieties of the same kind of thing 

 namely, vegetable matter ? They have a common 

 origin namely, woody fibre. And coal, or rather 

 culm, is the last link in a series of transformations from 

 growing vegetation ? " 



This is our first theory. Let us try to verify it, as 

 scientific men are in the habit of doing, by saying, If 

 that be true, then something else is likely to be 

 true too. 



If coal has all been vegetable soil, then it is likely 

 that some of it has not been quite converted into 

 shapeless coal. It is likely that there will be vegetable 

 fibre still to be seen here and there ; perhaps leaves, 

 perhaps even stems of trees, as in a peat bog. Let us 

 look for them. 



You will not need to look far. The coal, and the 

 sands and shales which accompany the coal, are so full 

 of plant-remains, that three hundred species were 

 known to Adolphe Brongniart as early as 1849, and 

 that number has largely increased since. 



Now one point is specially noticeable about these 

 plants of the coal ; namely, that they may at least have 

 grown in swamps. 



First, you will be interested if you study the coal 

 flora, with the abundance, beauty, and variety of the 

 ferns. Now ferns in these islands grow principally in 

 rocky woods, because there, beside the moisture, they 

 get from decaying vegetable or decaying rock, especi- 

 ally limestone, the carbonic acid which is their special 

 food, and which they do not get on our dry pastures, 



