=What Conservation Means.=—Conservation means three things: [Sidenote: 1. Retention.] First, that public lands still in the hands of the nation and the states shall not be thoughtlessly turned over to private corporations and individuals for their own profit, but shall be administered so far as practicable by the public authorities for the benefit of the whole country; second, [Sidenote: 1. Retention.]that such portions of our timber, coal, oil, and mineral resources as have already passed into private hands shall be so regulated by law as to prevent their wasteful exploitation; and [Sidenote: 3. Replacement.]third, that the government shall do its best to encourage the replacement of such natural resources as can be replaced (for example, by the reforesting of land and the restocking of lakes with fish). [Sidenote: Coal and iron.] =The Mines.=—No country can ever become great in industry unless it has ready access to minerals, especially iron and coal. It was the possession of iron and coal in great quantities that served to make England during the nineteenth century the industrial leader of Europe. Various regions of the United States possess these great stores of mineral wealth and have made good use of them. There is one great difference between mineral resources and other natural resources, namely, that when minerals are once taken from the earth there is no way of renewing them. Soil can be replenished, and forests regrown; but minerals form an endowment which, when once drawn from the bowels of the earth, can never be replaced. Hence the urgent need for a policy of conserving these important sources of national wealth. Coal and iron, while they are the natural resources upon which the growth of industry mainly depends, are not the only forms of wealth drawn from below the surface of the ground in this country. [Sidenote: Other minerals.] In the mining of silver and gold the United States is one of the foremost among the various producing countries. Copper, lead, oil, zinc, aluminum, quicksilver, and other natural materials are also taken from the earth in large quantities each year. [Sidenote: The earlier practice.]