The materials are abundant for the history of American industry in the last fifty years. They exist largely in the form of official documents. Any one ambitious of studying this subject in great detail should consult, first of all, the catalogs issued by that very valuable institution, the Government Printing Office. The Bureau of Corporations has published elaborate reports on such industries as petroleum (Standard Oil Company), beef, tobacco, steel, and harvesting machinery, which are indispensable in studying these great basic enterprises. The American habit of legislative investigation and trust-fighting in the courts, whatever its public value may have been, has at least had the result of piling up mountains of material for the historian of American industry. For one single corporation, the Standard Oil Company, a great library of such literature exists. The nearly twenty volumes of testimony, exhibits, and briefs assembled in the course of the Federal suit which led to its dissolution is the ultimate source of material on America's greatest trust. As most of our other great corporations--the Steel Trust, the Harvester Company, the Tobacco Company, and the like--have passed through similar ordeals, all the information the student could ask concerning them exists in the same form. The archives of such bodies as the Interstate Commerce Commission and Public Utility Commissions of the States are also bulging with documentary evidence. Thus all the material contained in this volume--and much more--concerning the New York traction situation will be found in the investigation conducted in 1907 by the Public Service Commission of New York, Second District. American business has also developed a great talent for publicity. Nearly all our big corporations have assembled much material about their own history, all of which is public property. Thus the American Telephone and Telegraph Company can furnish detailed information on every phase of its business and history. Indeed, one's respect for the achievements of American industry is increased by the praiseworthy curiosity which it displays about its own past and the readiness with which it makes such material accessible to the public. Despite the abundance of data, there is not a great amount of popular writing on these subjects that has much fascination as literature or much value as history. The only book that is really important is Miss Ida M. Tarbell's "History of the Standard Oil Company," 2 vols. (new edition 1911). Of other popular volumes the present writer has found most useful Herbert N. Casson's "Romance of Steel" (1907), "History of the Telephone" (1910), and "Cyrus Hall McCormick: His Life and Work" (1909); J.H. Bridge's "Inside History of the Carnegie Steel Company" (1903); "Henry Ford's Own Story" as told to Rose Wildes Lane (1917).