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CONSERVATION AND CIVILIZATION. 
ARTHUR L. FoLry, Head of the Department of Physics, Indiana University. 
Not until recently has man begun to think of nature’s resources in 
the light of the old saying that “one can not eat his cake and have it.” 
Today the subject of the conservation of these resources is being discussed 
by men of science in every Civilized country on the globe. Nevertheless 
it must be admitted that the full import of the question is not yet appre- 
ciated by many science men, while the public generally scarcely knows 
what the discussion is about. A few years ago the writer heard an 
address in which the speaker pointed out the importance of conserving 
the soil. A fellow citizen in speaking of the address said he did not under- 
stand what the speaker meant, that the earth is made of piud and that no 
one need be fearful of a shortage. The observation led to the reflection 
that people too are made of mud, some of it not very fertile. Perhaps our 
citizen did not know that the average productivity of the unfertilized soil 
of Indiana is but half of what it was when he was a boy. Perhaps he 
does not know that all animal life is dependent on plant life, and that 
plant life is dependent on a few soluble constituents of the soil which 
form but a small and diminishing per cent. of what he calls mud. Per- 
haps he does not know that the removal of timber and the cultivation 
of hillsides permit the rains to dissolve and carry away the soluble 
constituents and so impoverish the soil, and that every year thousands 
of acres of land, here in his own State, Indiana, are ruined in this man- 
ner. He does not know that every year the Mississippi River robs the 
Mississippi Valley of hundreds of millions of tons of that upon which its 
fertility depends, and that all other streams are doing relatively the same 
thing. 
But I am not to discuss the conservation of our soil, nor the con- 
servation of our timber or our food supply. I shall not discuss the con- 
servation of air or water, although the time has passed when we can say 
“as free as the air we breathe or the water we drink.” Good pure air 
is not free to everybody, by any means. If it were there would be no 
