The Supply and Waste of Goal. 317 



THE SUPPLY AND WASTE OF COAL. 



BY PEOFESSOR D. T. ANSTED, M.A., P.E.S. 



Op all subjects connected with geology, there is not one that 

 possesses more varied interest than coal or mineral fuel. Of 

 its origin and history as a mineral we know little, but that 

 little is extraordinary and unfamiliar, constantly exciting 

 inquiry and attention, and left undecided, notwithstanding the 

 most repeated and the closest investigation. The structure of 

 coal is still a puzzle to the microscopist, to the botanist, and to 

 the geologist. Certainly of organic origin, there is still doubt 

 as to whether some varieties were derived from vegetable or 

 animal life. Certainly vegetable, as much at any rate is, no 

 one has been able to say positively what part was tree vegeta- 

 tion, what was leaf, and what woody tissue, while a good deal may 

 have been once peat-bog, or mere accumulation of sea-weed. 

 And if the origin of coal is so open to discussion, its geo- 

 logical history is no less so. Who can examine a good natural 

 section in a shaft, or even the rock laid bare by a railway cutting* 

 in a coal country, without being struck by the marvellously 

 frequent alternation of seams of coal, shales, and sandstones? 

 A hundred distinct coal seams, of thickness varying from a 

 tenth of an inch to a dozen feet, in a thickness of a thousand 

 feet of strata, is the smallest complication presented to us. In 

 a large majority of the seams it will perhaps be found that 

 rootlets of plants extend down from the coal into a bed of clay 

 below. In others, there will be absolutely no connection of 

 any kind between the coal and the underlying or overlying rock, 

 whether sandstone or shale. Not unfrequently, a band, called 

 a parting, of black clay, will be found in the middle of a bed or 

 seam of coal. Now and then the roof or overlying bed of a 

 coal seam is made up entirely of clayey material, in the form of 

 leaves, twigs, and branches of trees, while sometimes a similar 

 appearance will be visible in sands where there is no coal 

 whatever. So much for the association and the mode of 

 accumulation; but what shall we say to the mechanical position 

 in which it is found ? In England we are so accustomed in all 

 our coal-fields to find the coal-seams broken and crushed — 

 lifted here out of place; dropped there fifty or a hundred 

 fathoms and lost sight of; re-appearing, where least expected, by 

 another fault; dipping at a high angle in one place, and 

 horizontal in another; the dip considerable, but in the opposite 

 direction, in a third — that we are apt to fancy this to be the 

 normal, or, at least, a necessary condition. An English 

 coal-miner hardly believes that a coal-field can be in proper 

 order without it, and some of our well-meaning but somewhat 



