He was not to remain long in the telegraph business, however, for Thomas A. Scott, superintendent of the Pittsburgh division of the Pennsylvania Railroad, offered him a position at a salary of $35 a month. Carnegie promptly accepted, and on February 1, 1853, at the age of seventeen, entered the employ of the road. His promotion was rapid, and he rose to be superintendent of the Pittsburgh division before the success of his other ventures caused him to resign from the service. These ventures were, in the first place, investment in the newly-developed oil-fields of Pennsylvania, which yielded a great profit, and afterwards the establishment of a steel rolling-mill, in the development of which he found his true vocation, building up the most complete system of iron and steel industries ever controlled by an individual. Some idea of the value of the business may be gained from the fact that, when the United States Steel Corporation was organized in 1901 to take over Mr. Carnegie's interests he received for them, first mortgage bonds to the amount of three hundred million dollars. It is this sum which he has been disposing of for years. Unlike most other philanthropists, he has not used his wealth to endow a great university, but has devoted it mainly to another branch of education, the establishment of free public libraries. He conceived the unique plan of offering a library building, completely equipped, to any community which would agree to maintain it suitably, and, by the beginning of 1909, had, under this plan, given nearly fifty-two millions of dollars for the erection of 1858 buildings, of which 1167 are in this country. Among his other great gifts was one of $12,000,000, for the founding at Washington of an institution "which shall, in the broadest and most liberal manner, encourage investigation, research, and discovery, show the application of knowledge to the improvement of mankind, and provide such buildings, laboratories, books, and apparatus as may be needed." The sum of ten millions was given to the great Carnegie Institute, of Pittsburgh; still another ten millions were given to Scottish universities, and still another for the purpose of providing pensions for college professors in the United States and Canada; and finally five millions for the establishment of a fund to be used for the benefit of the dependants of those losing their lives in heroic effort to save their fellow-men, or for the heroes themselves, if injured only. What great benefaction will next be announced cannot, of course, be foretold, but that some other announcement will some day be forthcoming can scarcely be doubted, since Mr. Carnegie has announced his ambition to die poor.