Page:Geology and Mineralogy considered with reference to Natural Theology, 1837, volume 1.djvu/402

 398 that reduction, is an instance of arrangement so happily suited to the purposes of human industry, that it can hardly be considered as recurring unnecessarily to final causes, if we conceive that this distribution of the rude materials of the earth was determined with a view to the convenience of its inhabitants."

Let us briefly consider what is the effect of mineral fuel, on the actual condition of mankind. The mechanical power of coals is illustrated in a striking manner, in the following statement in Sir J. F. W. Herschel's admirable Discourse on the study of Natural Philosophy, 1831, p. 59.

"It is well known to modern engineers that there is virtue in a bushel of coals, properly consumed, to raise seventy millions of pounds weight a foot high. This is actually the average effect of an engine at this moment working in Cornwall.

The ascent of Mont Blanc from Chamouni is considered, and with justice, as the most toilsome feat that a strong man can execute in two days. The combustion of two pounds of coal would place him on the summit."

The power which man derives from the use of mineral coal, may be estimated by the duty done by a pound, or