6io THE POPULAR SCIENCE MONTHLY. 



It is undeniable that there is yet much to be done in this domain. 

 But the results obtained by Ferrier are so encouraging that we hope 

 this new way of studying cerebral physiology will be followed and 

 explored with more care than ever. 



-- 



A PIECE OF COAL. 



By E. S. CALVIN. 



A LUMP of coal black and grimy, and repulsive to sight and 

 touch as it is is, perhaps, not the most promising subject that 

 could be selected for Sabbath-evening reflections. But, if there are 

 sermons in stones, why not in coal ? The black thing, that we would 

 rather not handle when we have any proper regard for cleanliness, 

 becomes an object of interest when we find it exerting energy in the 

 engine-furnace or shedding warmth and radiance around our household 

 hearth. It becomes an object of yet greater interest when we come 

 to learn its wonderful history ; for every common bit of coal that 

 we are accustomed to see has a history with which is wrapped up the 

 story of one of the most interesting and critical periods in all geo- 

 logical time. It is the lessons and promises of this far-off history of 

 the coal that constitute the theme for to-night. 



Fifty years ago an attempt to tell the history of the coal would, no 

 doubt, have seemed, to all but a very few, not only hopeless, but 

 absurd. Since then the methods of questioning Nature and making 

 her tell her own history have been so much improved, and have been, 

 withal, so energetically applied, that very much, which our grand- 

 fathers would have set down as past finding out, has become the men- 

 tal property of every well-instructed schoolboy. 



There are many different kinds of coal, and coal belongs to many 

 different epochs in the world's history, but that which we find in the 

 coal-fields of Iowa and Illinois may be taken as the type of what is 

 usually understood, the world over, when coal is mentioned. Let us 

 fix our attention on a piece of such coal. To extort from that expres- 

 sionless thing any facts bearing on its history would seem discouraging 

 enough. We may look at it just as long as we please ; we may break 

 it to pieces with the hammer and examine it bit by bit, and it is altogeth- 

 er likely that we will be left just as wise and just as hopeless as when 

 we began. Pass it over to the chemist, and he will tell us that it is 

 made up of combustible matter of which so much is fixed and so much 

 volatile, with a certain percentage of earthy substances and traces, 

 perhaps, of ever so many elements that we never heard of before. The 

 information is interesting in many respects it is of the highest im- 

 portance but for the purposes of the present discussion it amounts. 



