2. _The extraction of coal and other mineral deposits reduces for future generations a supply already limited._ The coal deposits in the earth have only recently been drawn upon. A small city like Ithaca probably uses to-day a greater quantity of coal than was used in all Europe two centuries ago. The large deposits of coal and their early development in England long gave a great advantage to English industry over that of other countries. In England, however, has first been felt the fear of the exhaustion of the coal-supply. Professor Jevons, in 1861, sounded the note of alarm; he prophesied that because the coal deposits of America were many times as great as those of England, industrial supremacy must inevitably pass to America. Already the supremacy in coal and iron production has passed to America, and that in textiles soon will come. In England the accessible supply of coal is limited, deeper shafts must be sunk, and the coal gotten with greater difficulty and at greater expense. Coal has risen in price in England within the last few years, and will continue to rise in the future. The coal deposits of America are thirty-seven times as great as those of England, but even these will soon be exhausted. And yet on the part of all except the coal trust, there appears in America a thoughtless disregard for the future. Supplies of copper, iron, and lead in favored positions are likewise limited, and are being rapidly centered in the hands of great companies. The increasing demand for these products insures a steadily rising income from their annual use. The value of the mines, being based on the series of incomes they will yield, may increase while their unused treasures dwindle in quantity. [Sidenote: Many natural resources are being rapidly exhausted] 3. _The exhaustion of natural stores of material is due to civilization, but it threatens to put an end to industrial progress._ The savage does not go deep enough to use up permanently the world in which he lives. He uses the fruits that he finds, and those fruits are, almost without exception, renewed the next year. The only mines that were worked out in ancient times were gold and silver mines, while the mines of useful metals were touched but lightly. Within the last century the earth's crust has been exploited with startling rapidity. Scientific knowledge and mechanical improvement have combined to unlock the storehouses of the geologic ages. At the ever-increasing rate of their use, many important materials must be exhausted in the not far distant future. While it is probable that substitutes will be discovered for many of them, the outlook in some directions has little promise. To treat terminable incomes, exhaustible sources of supply, as permanent sources of income, leads alike to unsound theory and to reckless practice. CHAPTER 12 INCREASE OF RENT-BEARERS AND OF RENTS § I. EFFORTS OF MEN TO INCREASE PRODUCTS AND RENT-BEARERS