IV. 



THE COAL IN THE FIRE. 



MY dear town-dwelling readers, let me tell you now 

 something of a geological product well known, happily, 

 to all dwellers in towns, and of late years, thanks to 

 railroad extension, to most dwellers in country 

 districts : I mean coal. 



Coal, as of course you know, is commonly said to 

 be composed of vegetable matter, of the leaves and 

 stems of ancient plants and trees a startling state- 

 ment, and one which I do not wish you to take 

 entirely on trust. I shall therefore spend a few pages 

 in showing you how this fact for fact it is was dis- 

 covered. It is a very good example of reasoning from 

 the known to the unknown. You will have a right to 

 say at first starting, " Coal is utterly different in look 

 from leaves and stems. The only property which they 

 seem to have in common is that they can both burn/' 

 True. But difference of mere look may be only owing 

 to a transformation, or series of transformations. 

 There are plenty in nature quite as great, and greater. 

 What can be more different in look, for instance, than 



