Natural Movement of Water in Semi-arid Regions. (McGee.) Irrigation in the United States. Dept. Commerce and Labor Census Bureau. Irrigation Projects of the U. S. Reclamation Service. Reports of Irrigation in various states. Apply to Governor. CHAPTER V. COAL When we begin to study the mineral resources of the country we pass to conditions altogether different from those which we have been considering. Heretofore we have been dealing with resources that can be renewed, the soil by proper management, the forests by replanting, the waters by nature's own processes; but the fuels, the iron and many other mineral resources once used are gone for ever. As to their importance Andrew Carnegie says: "Of all the world's metals iron is in our day the most useful. The opening of the iron age marked the beginning of real industrial development. To-day the position of nations may almost be measured by its production and use. Iron and coal form the foundation of our prosperity. The value of each depends upon the amount and nearness of the other. In modern times the manufacturing and transportation industries rest upon them, and with sufficient land and a fertile soil, these determine the progress of any people." We are sometimes told that we need have no anxiety about the future, that new discoveries and inventions will take the place of the present fuels, and even substitutes for minerals will be devised long before the supply is exhausted. This may be true, and in a way the future must take care of itself, but until new inventions have actually been made it is criminal to waste present resources and blindly trust that time will make our folly appear good judgment and foresight. We have vast mineral resources unused; the present generation, even its children and its children's children need have no fear of a shortage. But in the use of those resources that are steadily and for ever diminishing we must look a long way into the future. We are under the most solemn obligation to take only our part of the store, and leave the rest untouched and unspoiled for those who are to come after us. When we consider what these mineral resources have done for our country in the last fifty years, when we realize that it is only by having cheap and abundant coal, iron, and copper that our railroads, our various electric systems, and our great manufactories have been developed, we can realize our duty to give the coming generations an equal opportunity to develop their ideas. The yearly products of the mines of the United States are now valued at more than $2,000,000,000. Sixty-five car-loads of freight out of every hundred carried by our railroads are made up of mineral products. More than a million men are employed at the mines, and more than twice that number in handling and transporting mine products.