574 THE POPULAR SCIENCE MONTHLY 



these fine results, that makes wanton destruction of soils criminal and 

 points the rebuke to public authorities and legislative bodies, when they 

 halt at reasonable measures of conservation. We can not grind rocks 

 in a mill and make soil. The operation is at once too large and too 

 delicate, demanding the silent intervention of mechanical and chemical 

 forces, of atmosphere, water, heat and life, through long periods of time. 



When the land has suffered a glacial invasion, much of its ancient 

 soil has been lost in the sea, and such as remains is moved from its 

 place and mixed with a large body of drift, mechanically broken from 

 fresh bed rock. This latter material is not soil until it has been sub- 

 jected to the atmospheric and vital processes which fit it for its function 

 of mediation between the rocky planet and the plant life of the world. 



In a non-glacial region, all the soils, save along rivers, or on steep 

 slopes, have been formed by the decay of the bed rocks in place, and 

 this decay does indeed, and fortunately, in favored regions, proceed 

 swiftly. It may be some compensation for people subject to disaster 

 on the slopes of Vesuvius or Etna, that the friable lavas and ash, in that 

 genial climate, speedily become soil. On a lava stream still warm, at 

 the foot of Vesuvius, baskets of earth, suitably spaced for vines, have 

 been deposited, and the lava itself in a year or two will be hospitable 

 to the roots. 



Stone from the quarry is popularly thought to be a durable building 

 material, but only the most compact and resistant varieties, and these 

 in a favorable climate, can make any approach to permanence. Granites 

 are regarded as indestructible, but the title of granite to serve as the 

 standard and symbol of strength is clouded when we remember that 

 many beds of soft clay owe their accumulation to the decay of one 

 of the chief mineral constituents of this rock, a decay in which the 

 atmosphere has been a powerful agent. Granite that can be excavated 

 with pick and shovel betokens the ceaseless activity of the gases and 

 waters of the earth's surface. 



Some of you will recall the promptness of atmospheric attack upon 

 the obelisk of Central Park after it was transplanted from its arid 

 habitat of millenniums. Many of the beautiful structures of the Oxford 

 colleges, boasting not three centuries of antiquity, are under restoration 

 piece by piece, showing an apparent hoary age through the solvent work 

 of the atmosphere upon their unstable calcareous material. No marble 

 monument has stood in the open air for half a century and retained its 

 polish, and it must have been an exceptional piece of monumental stone 

 if it does not now crack and scale and take on the look of age. Every 

 humid climate with large temperature range introduces a ceaseless 

 struggle with the destructive forces of the atmosphere, whose sum of 

 hostility to the structures of man is far greater than that of flood, fire 

 or earthquake. 



The energies of the atmosphere mechanically applied, bring before 



