104 POPULAR SCIENCE MONTHLY. 



The plain, precious in peaceful times, affords a poor shelter when war 

 is raging. 



So, also, the value of the different qualities of ground varies in 

 different epochs. In the times when agricultural resources consti- 

 tuted the only or principal element of wealth, all the advantages 

 appertained to lands in which the best qualities for tillage were 

 combined. In the present age, the natural geological constitution of 

 the soil is not of such paramount importance. As the earth has be- 

 come better known, as scientific conditions of fertility have been 

 ascertained through chemical analysis, man has learned to improve 

 ^Nature by adding to soils the indispensable elements they did not 

 already possess. Mechanical progress, creating increased facilities 

 for transportation, and giving more perfect agricultural tools, has 

 acted in the same direction. There is no soil so refractory that it 

 may not be brought to reason by suitable application of fertilizing 

 or corrective elements. By means of agricultural geology, which 

 has been raised to a science, man can completely transform the 

 natural value of any soil. 



Different sorts of land have likewise values for mining not less 

 unequal than their adaptations to agriculture. The minerals and 

 coal with which industry is fed, and which have become the principal 

 factors of wealth and power, have not been distributed at hazard 

 over the globe. The beds exist in direct relation with the geological 

 constitution. When we compare the fitness of different lands for 

 mining and for agriculture, we most often find an incompatibility 

 of qualities. The primary mineral and coal lands, when decom- 

 posed, yield chiefly hard gravels, cold and sterile. Secondary and 

 Tertiary soils, on the other hand, almost destitute of minerals, most 

 often have the looseness and the variety of composition that render 

 them most friendly to remunerative cultivation. In view of these 

 contrasts we are able to comprehend the importance of the revo- 

 lution which modern scientific advance has provoked in causing 

 preponderance of economical advantages to pass from agricultural 

 fitness to adaptation to mineral and industrial exploitation. The 

 equilibrium of the regions of the earth has been disturbed. Coun- 

 tries long neglected on account of their barrenness have been peopled 

 all of a sudden because they contained coal; while other countries, 

 which by virtue of their excellent agricultural soil had become chief 

 centers of life, find themselves relegated to the second rank because 

 that same rich agricultural soil affords nothing in the way of manu- 

 facturing facilities. 



All climates, likemse, are not equally agreeable to man. Some 

 are unhealthy, like those of marshy regions and equatorial countries, 

 and hinder man's establishment within them, or condemn him to a 



