Chandler (1965) demonstrates that the large-scale problems of management became obvious in the middle of the 19th century with the rise of the great railroad systems, such as the Pennsylvania and the Baltimore and Ohio. New methods had to be invented for mobilizing, controlling, and apportioning capital, for operating a widely dispersed system, and for supervising thousands of specialized workmen spread over hundreds of miles. The railroads solved all these problems and became the model for all large businesses. The main innovators were three engineers, Benjamin H. Latrobe of the Baltimore and Ohio, Daniel C. McCallum of the Erie, and Thomson of the Pennsylvania. They devised the functional departments and first defined the lines of authority, responsibility, and communication, together with the concomitant separation of line and staff duties which have remained the principles of the modern American corporation.