SHALES AND METALLIFEROUS ORES. 185 



centage of silver which many of them yield the lead-ores 

 being generally less or more argentiferous. 



Such are the products we derive from the Coal-formation, 

 and such the benefits they have conferred and are still con- 

 ferring on our country. Statisticians may set down their 

 amounts in weights and measures and their values in money, 

 but no method of computation can fully convey an idea of 

 the advantages, physical, intellectual, and moral, we enjoy in 

 possessing such productive and accessible coal-fields. Had 

 the coals been in one field, the ironstones in a second, and 

 the limestones and fire-clays in a third, they would have 

 still been prized and sought after ; but when the whole are 

 found in the same field, and often in the same mine, their 

 value is a hundredfold enhanced, and their importance 

 becomes more distinctly appreciable. Nor can it be over- 

 looked that, situated as most of these coal-fields are, in the 

 lower districts of our island, they are peculiarly accessible 

 by water and readily reticulated by railways the Bristol 

 Channel, the Mersey, the Tees, Wear, Tyne, Forth, and 

 Clyde all opening their ports for convenient transport to 

 other and less favoured localities. Nor is it to Britain 

 alone that the advantages of her coal-fields extend the 

 whole world, through her machinery and manufactures, par- 

 ticipates in the boon, and the impetus thereby given to 

 human progress will descend to future ages. Her steam- 

 engines, manufacturing machinery, railroads, water and gas 

 distribution, telegraphs, and steamships are the giant off- 

 spring of her coal-fields ; and wherever the sound of these 

 is heard or their influences felt new activities and industries 

 are awakened, and on industry and commerce are ever founded 

 the surest hopes of civilisation and refinement. Strange, 

 as we have before remarked, that the mere physical opera- 

 tions of the earth's remotest ages should be so intimately 



