COAL FIELDS. 205 



past years or centuries or ages. Some of these forms of stored power, 

 men have long known and valued, but with the really great accumula- 

 tions, they have but comparatively recently become acquainted. 



These accumulations are found in soils, which, originally composed 

 of the disintegrated portions of the earth's rocky crust, have been 

 gradually enriched by the remains of vegetable and animal life. Centu- 

 ries have been spent in storing a fertile soil with this transformed sun 

 power. 



A second example of stored sun power is to be found in forest 

 growths. They always stand for centuries of accumulation. A forest 

 consists of air, moulded and subdued temporarily by the sun's rays, but 

 ready to pass back into the atmosphere again, and bound to restore, as it 

 either burns or decays, all the heat by which it grew. 



Peat bogs, in the third place, furnish a similar example of stored 

 sun power. Built up of humbler forms than forests, they still represent 

 in all respects the same great laws of accumulation. They stand for the 

 separation of large amounts of carbon from the air through the agency 

 of the solar ray. 



But the accumulations of power that have been already noted shrink 

 into insignificance when compared with the coal seams of the geological 

 scale, which represent the forests and the peat bogs of earlier ages in the 

 earth's history. These are the great accumulations of power. Taking 

 their place as they do, in orderly fashion, among the stratified deposits of 

 the earth's crust, and going back in many instances to a high antiquity, 

 we rightly name Diem fossil power. 



Sir William Dawson estimates that a foot of coal requires for its 

 origin the patient growth and slow decay of a hundred of the forests 

 out of which it was formed, for of this vegetable growth only a remnant 

 was saved. For many thousands of years for every foot of coal, we can 

 be sure, the sun must have poured down its floods of light and heat up- 

 on these Carboniferous swamps. The light and heat were absorbed 

 there in the processes of plant growth, were locked up in leaf and stem 

 and spore, were buried beneath the sediments of an advancing sea, were 

 converted at last into stone, became a part of the earth's crust, but still 

 retaining their original nature, still containing, literally and truly, the 

 light and heat, the power of the ages of the early world in which they 

 had their birth. 



The fossil power stored in coal began to be turned to some small account 

 in England several years hundred years ago, but there were only a few 

 districts in the kingdom that could readily avail themselves of th new 

 found supplies. The impossiblity of transporting coal on the large 

 scale forbade any general development of it. All the great applications 

 of the stored power of the world belong to the nineteenth century and 

 the most important of them belong to the last fifty years. What has been 

 ione within this century constitutes by far the most important chapter in 



