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find no principles ; they can, therefore, be of n'o use to any 

 man." What the law of gravitation is in astronomy, what 

 steam is in mechanics, what the Constitution of the United 

 States is in government, the beginnings of epochs, such is the 

 newly developed science of chemistry, in agriculture. That 

 light and heat from the sun, that water, air and earth were 

 necessary to vegetation, was understood. Experience had 

 shown that certain crops were better adapted to some soils 

 than to others ; that a succession of different crops Avas better 

 than a succession of the same crops ; that fallows increased 

 the vegetative power of the land. These and such as these 

 empirical rules were known and obeyed ; and yet, in spite of 

 husbandry of this sort, crops would in time deteriorate, and the 

 soil lose its virtues beyond the skill of the fiirmer to devise the 

 means of restoration. The writings of Columella and Varro, 

 while they disclose a system of Roman husbandry, most care- 

 ful, methodical and painstaking, at the same time reveal the 

 appalling, irremediable fact, that the production per acre had 

 largely diminished. Tilled with the ancient fjaith that the 

 golden age of the race was in its prime, and that then the arts 

 were divinely established in their perfection, the Roman 

 farmers dreamed that a declining agriculture was due to some 

 lost charm, some missing precept, which tradition had failed 

 to transmit down the course of the centuries from hero ances- 

 tors taught by the gods. Modern agriculture has exhibited 

 the same stages of decadence. But modern science has re- 

 vealed the causes of such decline and placed within the con- 

 trol of man the powers that will enable him to resist this 

 downward tendency, if he will but use them. Earth, air, and 

 water have been resolved into their priomordial elements. A 

 searching analysis has shown what essentials of its life and 

 substance, the plant draws from the soil, and what from the 

 atmosphere. The microscope has revealed the complex physi- 

 ology through which by a subtle alchemy the sun in the 

 heavens converts the mineral earth, and air and water, into 

 an organic growth that is food for the nations. Among the 



